- Sleep Science

Transcription

- Sleep Science

SUPPLEMENT
VOLUME
6 1
ISSN Print 1984-0659
ISSN On-line 1984-0063
A publication of Associação Brasileira do Sono
(ABS) and Federação Latinoamericana de
Sociedades do Sono (FLASS)
2013
Full text
available for
download at
the web site
www.sleepscience.com.br
ISSN Print 1984-0659
ISSN On-line 1984-0063
Official publication of Associação Brasileira de Sono e Federação
LatinoAmericana de Sociedades de Sono
Sleep Science 2013 v. 6, supplement 1, p. s1-s80, 2013
Editor in Chief
Monica Levy Andersen
Associated Editors
Managing Editor
Claudia Moreno
Geraldo Lorenzi-Filho
Lia Rita Azeredo Bittencourt
Gabriel Natan Pires
Editorial Board
Arne Lowden (Stockholm, Sweden)
Dalva Poyares (São Paulo, Brazil)
Darwin Vizcarra (Lima, Peru)
David Gozal (Louisville, USA)
Denis Martinez (Porto Alegre, Brazil)
Diego Golombek (Buenos Aires, Argentina)
Ennio Vivaldi (Santiago, Chile)
Fernanda Louise Martinho (São Paulo, Brazil)
Fernanda Ribeiro Almeida (Vancouver, Canada)
Fernando Louzada (Curitiba, Brazil)
Francisco Hora (Salvador, Brazil)
James Krueger (Washington, USA)
John Araújo (Natal, Brazil)
Katsumasa Hoshino (Botucatu, Brazil)
Ligia Lucchesi (São Paulo, Brazil)
Lucia Rotenberg (Rio de Janeiro, Brazil)
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Translation: American Journal Experts (AJE)
©2013 - Sleep Science
Contents
Sleep Science 2013 v. 6, Supplement 1, p. s1-s80 2013
3
ORGANIZATION
EDITORIAL
4
The 24/7 Society: from chronobiology to practical life
Claudia Roberta de Castro Moreno, Frida Marina Fischer, Lúcia Rotenberg
SCIENTIFIC PROGRAM
5
Program
ABSTRACTS
9
Keynote Speaker
10
Thematic Session
21
Workshop
23
Oral Session 1
26
Oral Session 2
29
Oral Session 3
31
Oral Session 4
34
Special Session
37
Poster Sessions
75
AUTHOR INDEX
Scientific Committee of the
21th International Symposium on Shiftwork and Working Time
Organization
The Symposium is a biannual event organized by members of the Working Time Society, and of the Scientific Committee on Shiftwork and Working Time of the International Commission on Occupational Health (ICOH).
Local Organizing Committee
Claudia Roberta de Castro Moreno (Chair)
Frida Marina Fischer
Lucia Rotenberg
With the collaboration
Aline Silva-Costa
Andréa Luz
Andressa Martins
Daniela Wey
Elaine Marqueze
Heloisa Moreno
Leana Araújo
Lúcia Lemos
Luna Gonçalves
Samantha Turte
Suleima Vasconcelos
Scientific Committee
Adam Fletcher - Australia
Arne Lowden - Sweden
Claudia Moreno - Brazil
Debra Skene - United Kingdom
Diane Boivin - Canada
Drew Dawson - Australia
Fernando Louzada - Brazil
Frida Fischer - Brazil
Friedhelm Nachreiner - Germany
Goran Kecklund - Sweden
Hans van Dongen - United States
Johannes Gartner - Austria
John Axelsson - Sweden
Lee Di Milia - Australia
Liliane Teixeira - Brazil
Lucia Rotenberg - Brazil
Marco Túlio Mello - Brazil
Masaya Takahashi - Japan
Mikael Sallinen - Finland
Philip Bohle - Australia
Philip Tucker - Sweden
Sampsa Puttonen - Finland
4
EDITORIAL
The 24/7 Society: from chronobiology to
practical life
A large number of people ensure every night the continued provision of healthcare,
public safety, water and sewage treatment, refuse collection, energy production, telecommunications, oil extraction, transportation, food production, continuous process of a large number
of industries, convenience stores, among other activities.
This supplement of Sleep Science is an important contribution for the dissemination of
the current knowledge about shiftwork and working time. This number includes all abstracts
presented at the 21st International Symposium on Shiftwork and Working Time. The symposium addresses the cost of this situation, which is not merely financial, but also concerns the
health, social and family life of individuals who work while most of the community sleeps.
This cost and the approaches to minimize it according to the scientific state of the art are the
main focus of the Symposium.
This symposium is organized every two years since 1969. It is sponsored by the Working Time Society affiliated with the International Commission on Occupational Health. This is
the only international meeting whose central theme is the organization of shift and night work
and working time as important variables associated with workers´ health. The importance of
this subject in global terms is manifested by the wide diversity of countries that have already
hosted this Symposium: Germany, Norway, Italy, Finland, Sweden, Poland, Netherlands, Bulgaria, France, Scotland, Austria, England, Japan, Australia and Unite States of America. This
is the second time that this Symposium is being held in South America; it was also hosted by
Brazil in 2003, when it was coordinated by the same team that organizes the present 2013 edition, including researchers from the University of São Paulo and Oswaldo Cruz Foundation.
The scope of the Symposium ranges from fundamental biology- clocks, sleep and metabolism to the repercussion of the 24/7 society on everyday life, such as the impact of sleep
disorders on occupational health, safety and performance, circadian stress, shiftwork and the
influence of light, cancer and shiftwork, socially sustainable working hours and other topics.
The 2013 edition of the Symposium includes four presentation modalities: thematic sessions,
oral sessions, posters, and workshops for practical discussions on work schedules and the
health and safety of workers.
We hope you all enjoy this Sleep Science edition!
Claudia Roberta de Castro Moreno
Chair - School of Public Health/University of São Paulo
Frida Marina Fischer
Co-chair - School of Public Health/University of São Paulo
Lúcia Rotenberg
Co-chair - Oswaldo Cruz Institute/Oswaldo Cruz Foundation
Sleep Sci. 2013;6(Supl 1):s4
11
SCIENTIFIC PROGRAM
Program
Monday, Nov 4th
17:00-18:00h Opening Session
17:00-17:15h Claudia Roberta de Castro Moreno-Chair
Symposium Shiftwork 2013
17:15-17:30h Kazutaka Kogi-ICOH President
17:30-17:45h Frida Marina Fischer-Working Time Society
President
17:45-19:00h Keynote Speaker
Keynote Speaker: Debra Skene, UK.
Linking Clocks, Sleep and Metabolism
Chair: Lucia Rotenberg, Brazil.
19:00h Cocktail
20:00h Dinner
Tuesday, Nov 5th
8:30-10:30h 1st Thematic Session
Impact of Sleep Disorders on Occupational Health, Safety and Performance
Chair: Shantha Rajaratnam, Australia.
Co-chair: Steven Lockley, USA.
• Rajaratnam S. “Operation Healthy
Sleep: Impact of sleep disorders on
occupational health, safety and performance in police officers”.
• Howard H. “Sleep disorders screening
programs in commercial vehicle drivers”.
• Lockley S. “Operation stay alert: The
effects of a sleep and sleep disorders
management program on workplace
health and safety in firefighters”.
• Barger L. “Development and validation of a questionnaire to assess shift
work disorder”.
• Härma M, Vanttola P, Merikanto I,
Puttonen S, Sallinen M, Hublin C,
Virkkala J, Müller K. “Shift work disorder in professional traffic: prevalence
and association with objective and
subjective sleep and sleepiness”.
10:30-11:00h Coffee Break
11:00-12:30h Oral Session 1
12:30-14:00h
14:00-16:00h
16:00-16:30h
16:30-18:30h
New Trends in Working Hours
Chair: Steve Popkin, USA.
Co-chair: Masaya Takahashi, Japan.
• Mellner C, Toivanen S, Keller Celeste
R. “On the interrelationships between
work hours, time-spatial flexibility,
switching off, sleep, restitution and
health among “New” employees in
knowledge intense work in Sweden”.
• Arlinghaus A and Nachreiner F. “Health effects of supplemental work from
home in the European Union”.
• Oinas T, Anttila T, Nätti J, Hartikainen A. “The coming of 24/7 society?
Trends in timing of work in 1987-2010
in Finland”.
• Wong I, Smith P, Mustard C, Gignac
M. “Does changing shift schedules
influence the risk of work injury?”
• Snow JZ, Popkin S, Howarth H, Coplen M. “Application of knowledge
transfer in making shiftwork research
relevant and accessible to an unpredictably scheduled rail workforce”.
• Kogi K, Yoshikawa T, Hosaka T ,
Michinaga M , Imamura S. “Practical
guidelines for improving working time
arrangements and job content of health care workers”.
Lunch
Poster Session 1
Coffee Break
Workshop
Experiences With Resistance of Workers
Towards Change and How to Address it
Chair: Johannes Gärtner, Austria.
Co-chair: Lee Di Milia, Australia.
• Fletcher A. “Case-report”
• Korompeli A. “Resistance of workers
towards change: how common to nursing personnel?”
• Mello MT. “Shift and night work:
Perspectives on difficulties with intervention”.
• Di Milia L. “Case-report”
Sleep Sci. 2013;6(2 Supl 1):s5-s8
12
•
18:30-20:00h
20:00-21:00h
van de Ven HA, van der Klink JJL,
Koolhaas W, Brouwer S, Bültmann
U, Goudswaard A, de Looze MP,
Shaw WS. “Shift Your Work: Towards
sustainable work participation by new
shift systems, experiences from the
Netherlands”.
• Gärtner J. “Experiences with resistance of workers towards change and
how to address it-Case Ambulance
Service”.
Dinner
Wts Business Meeting
•
Wednesday, Nov 6th
8:00-10:00h
10:00-10:30h
10:30-12:30h
2nd Thematic Session
Circadian Stress, Shiftwork and the Influence of Light
Chair: Arne Lowden, Sweden.
Co-chair: Marie Dumont, Canada.
• Rea MS. “Ecological measurements of
circadian entrainment and disruption”.
• Dumont M. “How much light is
needed to regulate the rhythm in
shiftwork?”
• Figueiro M. “Light and alertness: is
there an alternative to blue?”
• Eastman C. “How to use light and dark
to adapt to shiftwork”.
Coffee Break
Oral Session 2
Working Hours and Sleep
Chair: Goran Kecklund, Sweden.
Co-chair: Mikko Härma, Finland.
• Flo E, Pallesen S, Moen EM, Waage S,
Bjorvatn B. “Shift-rotations with less
than 11 hours rest periods predict shift
work disorder, excessive sleepiness and
pathological fatigue in nurses at one
year follow-up”.
• Lombardi DA, Jin K, Vetter C, Courtney TK, Folkard S, Arlinghaus A,
Liang Y, Perry MJ. “The impact of
work shift starting time on sleep patterns and alertness prior to injury in
the People’s Republic of China”.
• Waage S, Pallesen S, Moen BE, Flo E,
Di Milia L, Bjorvatn B. “Shift work
disorder among Norwegian nurses”.
10:30-12:30h
12:30-14:00h
14:00-16:00h
Sargent C, Lastella M, Halson SL,
Roach GD. “Got sleep? The impact
of early morning training on the sleep
of Australian elite athletes”.
• Vanttola P, Härmä M, Viitasalo K, Hublin C, Niemelä P, Sallinen M, Virkkala
J, Puttonen S. “Sleep in shift work
disorder: findings from a field study”.
• Roach G, Zhou X, Ferguson S, Dawson D, Sargent C. “Are two sleeps
better than one? The impact of split
work-rest schedules on the amount
and quality of sleep obtained”.
• Benedito-Silva AA, Silva-Costa A,
Griep RH, Rotenberg L . “Work stress,
work hours and sleep complaints
among nursing workers”.
• Kecklund G, Ingre M, Åkerstedt T.
“What characterizes good and bad
shift schedules?”
3rd Thematic Session
Socially Sustainable Working Hours
Chair: Philip Tucker, Sweden.
Co-chair: Philip Bohle, Australia.
• Garde AH, Albertsen K, Hansen ÅM,
Hvid H, Lund H. “Self-rostering- a way
to socially sustainable working hours”.
• Tieves D. “A Biographical Approach to
the Social Effects and Consequences
of Shift Work".
• Tucker P, Bejerot E, Kecklund G,
Aronsson G, Åkerstedt T. “Doctors’
work schedules and work time
control”.
• Bohle P. Pitts C “Working Hours,
Work Organisation and Sustainable
Work”.
• Muurlink O, Peetz D, Murray G,
Loudon R. “Social consequences
of workaholism among long-hours
wage-earners”.
Lunch
4th Thematic Session
Cancer and Shiftwork
Chair: Kristan Aronson, Canada.
Co-chair: James Burch, USA.
• Burch J. “Use of biological markers
to study disease mechanisms in
shiftworkers”.
13
•
16:00-16:30h
16:30-18:30h
18:30-20:00h
20:00-21:00h
Aronson K. “Cancer, biomarkers and
shiftwork”.
• Yong M, Hammer PG, Emrich K,
Nasterlack M, Blettner M. “A retrospective cohort study of shift work and
incident cancer risk in German male
chemical workers”
• Rabstein S, Harth V, Pesch B, Justenhoven C, Baisch C, Schiffermann M,
Heinze E, Brauch H, Hamann U, Ko
Y, Brüning T. “Associations of polymorphisms in circadian genes, shift
work and breast cancer in the German
GENICA study”.
Coffee Break
Poster Session 2
Dinner
Trainnee Social (for Early Career Researchers, only)
Chairs: John Axelsson, Sweden.
Imelda Wong, Canada.
Anna Arlinghaus, Germany.
Adam Fletcher, Australia.
Thursday, Nov 7th
08:00-10:00h 5th Thematic Session
Shiftwork and the Individual-The Future
of Shiftwork Research
Chair : T homas K anter mann, T he
Netherlands
Co-chair: Till Roenneberg, Germany.
• Gamble LK, Johnson LR, Thomson
BS, Griffie JT, Young EM. “Circadian
misalignment of the central circadian
clock with sleep/wake rhythms and
eating patterns in hospital shift work
nurses”.
• Boivin DB and Boudreau P. “Physiological and behavioural impacts of circadian adaptation to night shift work”.
• Papantoniou K, Pozo OJ, Marcos J,
Middleton B, Skene DJ. “Night shift-work, melatonin and sex hormones
biomarkers”.
• Vetter C, Fischer D, Mehlmann
J, Roenneberg T. “Effects of a
chronotype-based shift schedule on
sleep, wellbeing, and social life”.
•
Kantermann T, Duboutay F, Haubruge D, Skene DJ, Hampton S, Boudjeltia
KM, Kerkhofs M, Schmidt-Trucksäss
A. “Social jetlag and cardiovascular risk
in rotating shift-workers”.
10:00-10:30h Coffee Break
10:30-13:00h Special Session
Overview : Hans van Dongen, USA.
Mathematical models and fatigue at work
Chair: Ana Amélia Benedito-Silva, Brazil.
11:00-13:00h Fatigue: Methods and Models
Chair: Hans van Dongen, USA.
Co-chair: Christopher Steele, USA.
• van Drongelen A, Boot CRL, Hlobil
H, Smid T, van der Beek AJ. “The
effectiveness of a mobile health intervention (MORE Energy) on fatigue in
airline pilots. A randomized controlled
trial”.
• Lehrer A and Popkin S. “Measure matters: advancing next generation fatigue
model efficacy using an integrative
8-state framework”.
• Lederle K, Jackson P, Sheffield D.
“Identifying fatigue hazards and checking compliance against company and
industry standards in a global mining
operation”.
• Ingre M, Van Leeuwen W, Kecklund
G, Åkerstedt T. “Second generation
Three Process Model (TPM) of
alertness for better assessment of
individual risks”.
• Dahlgren A, van Leeuwen WMA,
Kircher A, Lützhöft M, Barnett M, Kecklund G, Åkerstedt T. “Fatigue at sea:
a simulator study of sleepiness, sleep
and neurobehavioural performance
during different watch schedules”.
• Hursh SR. “Harmonizing Sleep Estimation with Sleep Measurements
in Support of Shift Work Fatigue
Modeling”.
• van Dongen H, Whitney P, Hinson JM,
Jackson ML. “Feedback Blunting: A
Novel Mechanism Underlying Deficits
in Real-World Decision Making Due
to Sleep Loss”.
13:00-14:00h
Lunch
14:00-15:30
Oral Session 3
14
14:00-15:30h
Physical and Mental Health
Chair: Frida Fischer, Brazil.
Co-chair: Giovanni Costa, Italy.
• Marchand A and Durand P. “Work
and mental health: The contribution
of work hours and schedules”.
• Shochat T, Saharov G, Nadir Y, Keren
A, Brenner B. “Hemostatic markers
and sleep quality among shift work
and day work female nurses”.
• Davies-Schrils K, Burch K, BarnesFarrell J, Cherniack M. “The prospective influence of sleep discrepancy in
occupational burnout”.
• Nätti J, Anttila T, Oinas T, Hartikainen A. “Permanent and rotating
night work and mortality: Prospective
study among Finnish employees in
1977–2008”.
• Costa G, Anelli MM, Castellini G,
Fustinoni S. “Stress and sleep in nurses
employed in “3 x 8” and “2 x 12” fast
rotating shift schedules”.
• Lennernäs M, Nyberg M, Johansson
M, Wetterstrand M. “Meals and shift
work: food choice, time of day and
meal environments-three important
dimensions for rest and health”.
Oral Session 4
Genes, Rhythms and Light
Chair: Benita Middleton, UK.
Co-chair: Greg Roach, Australia.
• Hansen J. “Is night shiftwork, including light-at-night a promoter for
breast cancer development?”
• Lowden A and Garefelt J. “Winter depression among day and shift workers
above the Arctic Circle”.
• Bochkarev M, Ragozin O, Simonov
V. “Sleep and melatonin level in
shift-workers living in the Far North
region”.
• Kosmadopoulos A, Sargent C, Zhou
X, Darwent D, Dawson D, Roach
GD. “The effect of circadian phase
and prior wake on neurobehavioural
performance during a split 28-h forced
desynchrony schedule”.
•
15:30-16:00h
16:00-17:30h
16:00h-20:00
20:00h
Mehlmann JL, Fischer D, Vetter C,
Roenneberg T. “The Effect of Chronotype on Strategic Sleep Behaviour
in Shift Workers”.
Coffee Break
Trainee Session (for Early Career Researchers, only)
Chairs:
John Axelsson, Sweden.
Imelda Wong, Canada.
Anna Arlinghaus, Germany.
Adam Fletcher, Australia.
Free Time
Gala Dinner
Friday, Nov 8th
9:00-10:00h
10:00-10:30h
10:30-12:30h
12:30-13:00h
13:00-14:30h
Keynote Speaker
Till Roenneberg, Germany.
Changes of Sleep Across Time
Chair: Lúcia Rotenberg, Brazil.
Coffee Break
Nutrition, Metabolism and Physical Activity.
Chair: Simon Folkard, UK.
Co-chair: Elaine Marqueze, Brazil.
• Couter Van E. “ Sleep loss, circadian
misalignment and cardio-metabolic
risk.”
• Marqueze EC, Moreno CRC. “Physical activity and irregular-shift work:
cardiometabolic aspects”.
• Imai T, Kuwahara K, Nishihara A, Kochi T, Miyamoto T, Nakagawa T, Kabe
I, Mizoue T, Dohi S. “Overtime work
and prevalence of diabetes among
Japanese workers: J-ECOH Study”.
• Portela LF, Griep R, Silva-Costa A,
Fonseca MJM, Bastos LS, Toivanen
S, Rotenberg L. “Exposure to night
work and body mass index among
Brazilian nurses”
• Tucker P and Folkard S. “Shiftwork,
metabolic dysfunction and safety: a
review”.
Closing-Wts General Assembly
Farewell Lunch
15
ABSTRACTS
Keynote Speaker
K1
LINKING CLOCKS, SLEEP AND METABOLISM
Skene, DJ
Chronobiology, Faculty of Health and Medical Sciences, University of Surrey,
Guildford, UK
[email protected]
The circadian timing system drives the cyclic processes observed
in most physiological functions including sleep/wake, feeding and
metabolism. The circadian system comprises a master clock located
in the hypothalamic suprachiasmatic nuclei (SCN) and peripheral
clocks found in most body tissues. For optimal functioning correct
temporal coordination between the central SCN clock and peripheral clocks is maintained via feedback/feed forward neuroendocrine
and autonomic mechanisms. The environmental light/dark cycle is
the primary time cue synchronising the SCN clock and its output
circadian rhythms to 24h.
Relevant to the physiology of shift work, evidence linking circadian clocks and metabolism, and between sleep deprivation/sleep
restriction, circadian desynchrony and metabolic disorders is accumulating. Measuring human circadian timing has traditionally relied
on assessment of SCN-driven circadian rhythms, such as melatonin, cortisol and core body temperature, melatonin timing being
considered the most reliable marker of circadian phase. Studying
circadian regulation of metabolism and assessing the relative importance of photic and non-photic time cues (e.g. food, exercise,
sleep/wake behaviour) for entrainment, however, also requires reliable markers of peripheral clocks in humans. Early studies reported circadian variation in clock gene expression in peripheral blood
cells and buccal tissue which can be phase shifted by appropriately
timed light. Our recent data show that the core clock mechanism
in peripheral leucocytes is compromised during acute sleep deprivation (suppressed expression of the clock gene BMAL1; induced
expression of the heat shock gene HSPA1B; increased melatonin
production). For human metabolism-clock studies, serial sampling
of subcutaneous white adipose tissue offers promise. We recently
demonstrated robust 24 h rhythms in gene expression in adipose
tissue in three experimental groups: lean, obese-non-diabetic and
obese-Type 2 diabetic groups. Nocturnal plasma melatonin concentrations were significantly higher in obese-non-diabetic subjects
compared to weight-matched Type 2 diabetic subjects and lean controls, whereas there was no difference in the amplitude or timing of
leptin rhythms between the groups. Elucidation of the underlying
mechanisms linking metabolic disease, circadian clock misalignment and sleep restriction requires a global “systems” approach.
Metabolomics is the untargeted investigation of small molecule
metabolite profiles that provides a novel and powerful tool, which may provide a better representation of functional phenotype
than changes in DNA, RNA and proteins. We have recently established an untargeted liquid chromatography-mass spectrometric
(LC-MS) method to measure metabolite rhythms in human plasma.
In healthy volunteers, 1069 metabolite features were detected with
19% showing significant time of day variation. These metabolites
include corticosteroids, bilirubin, amino acids, acylcarnitines, and
lysophospholipids. Defining time of day and circadian variation
in the human metabolome as well as the effect of light/dark and
sleep deprivation/restriction on metabolite rhythms will provide an
important baseline for future metabolomic studies in shift workers.
DJS is a Royal Society Wolfson Research Merit Award holder.
K2
CHANGES OF SLEEP ACROSS TIME
Roenneberg T1, Winnebeck E1, Hidalgo PM2, Levandovski R2
Institute of Medical Psychology, Ludwig-Maximilian-University, Germany
Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Brazil
[email protected]
1
2
We cannot simply fall asleep whenever we are tired but sleep best
within a temporal window provided by our biological (circadian)
clock. Light and darkness synchronise this clock but do so differently across individuals, producing chronotypes (from ‘larks’
to ‘owls’) depending on genetic background, age and sex and
light-exposure. Our body clocks have increasingly delayed in recent
history because we illuminate our nights and hardly spend time outside. As a result, chronotypes can now differ by as much as twelve
hours and sleep times have become much too late for traditional
work schedules. According to different sources, sleep duration has
shortened up to 2 hours over the past century - compared to our
ancestors, we seem to skip a whole night’s sleep every week. According to our database on human sleep behaviour (> 150,000 entries), workday sleep duration has shortened by 38 minute over the
past ten years but remained stable on free days. This discrepancy
is due to a constant battle between the social and biological clocks
(social jetlag). Only 13% of people do not experience social jetlag,
while 80% need alarm clocks to wake up on workdays. Free access
to (electrical) light probably has the strongest impact on sleep. For
millions of years, our clocks synchronised to the natural alternation
of day and night, of light and darkness. Now that we can self-select light and darkness, sleep is the only time when our body clocks experience darkness (by closing our eyelids and by retreating
into a dark room). This self-synchronisation via sleep has added a
completely new dimension to our daily temporal programme. As
a result, we have become a sleep-deprived society with documented consequences such as metabolic problems, increased risks to be
overweight or obese and/or a smoker, higher alcohol and caffeine consumption and signs of depression. In view of these drastic
changes in sleep behaviour and their consequences for health, we
need a fresh approach by measuring sleep in the field and compare
the results with what we can observe in the sleep lab. We have to
collect data from people living in different states of modernisation
(from those who live without electricity to those who live in large cities). Modern life offers a host of “experimental” conditions,
from shift-work and DST changes, to people living near and far
from the equator, or east versus west in time zones. We have to take
advantage of modern technologies to learn more about sleep in real
life, by recording thousands of people. Only then, we will be able
to find measures that counterbalance the effects of modern society
on sleep (including the consequential detrimental effects on health).
Sleep Sci. 2013;6(Supl 1):s9-s74
16
Thematic Session
1st Thematic Session
Impact of Sleep Disorders on Occupational
Health, Safety and Performance
TS 1.1
OPERATION HEALTHY SLEEP: IMPACT OF SLEEP
DISORDERS ON OCCUPATIONAL HEALTH, SAFETY
AND PERFORMANCE IN POLICE OFFICERS
Rajaratnam SM1,2,3, Barger LK1,2, Lockley SW1,2, Shea SA1,2,4,
Wang W1,2,5, Landrigan CP1,2,6, O’Brien CS1, Qadri S1, Sullivan JP1,
Cade BE1, Epstein LJ1,2,4 White DP1,24, Czeisler CA1,2, for the
Harvard Work Hours, Health and Safety Group
Division of Sleep Medicine, Department of Medicine, Brigham and Women’s
Hospital, USA
2
Division of Sleep Medicine, Harvard Medical School, USA
3
School of Psychology and Psychiatry, Monash University, Australia.
4
Sleep Health Centers, USA
5
Channing Laboratory, Department of Medicine, Brigham and Women’s
Hospital and Harvard Medical School, USA
6
Division of General Pediatrics, Department of Medicine, Children’s Hospital
Boston, Harvard Medical School, USA
[email protected]
1
Sleep disorders are common, costly and treatable, but often remain
undiagnosed and untreated. Police officers with untreated sleep disorders may suffer long term health consequences, and may pose an
immediate risk to themselves and the public whom they serve. This
study aimed to quantify the associations between sleep disorder
risk and adverse health, safety and performance outcomes in police officers. We conducted a cross-sectional and prospective cohort
study with surveys over time, examining risk of sleep disorders,
health status, burnout, and performance(1). 4,957 police officers in
North America volunteered to complete surveys following recruitment through letters to police agencies, advertisements in police
magazines, and visits to two police departments. The main outcome
measures were comorbid health conditions, performance and safety outcomes. At baseline, 40.4% of participants screened positive
on survey for at least one sleep disorder. Obstructive sleep apnea
(OSA) was most common (33.6%), followed by moderate to severe insomnia (6.5%), shift work disorder (5.4% overall, and 14.5%
of night workers), restless legs syndrome (1.6%), and narcolepsy
(0.4%). Most (64-100%, depending on disorder) were undiagnosed.
28.5% showed excessive sleepiness and 26.1% reported falling asleep while driving at least monthly. Positive screening for OSA was
associated with increased prevalence of physical and mental health
conditions. During a two year follow-up interval, those prospectively identified as screening positive for a sleep disorder had greater
risk of on-the-job injuries; all-cause absenteeism; fatigue-related
and non-fatigue related errors/safety violations; uncontrolled anger
towards suspects/citizens; citizen complaints; administrative errors;
and falling asleep while driving, while stopped in traffic, while at police meetings, and while on the telephone. Sleep disorders are common among police officers, and are associated with adverse health,
safety and performance outcomes. Screening programs should be
implemented to identify and treat sleep disorders in this population.
REFERENCES
1. Rajaratnam SM, Barger LK, Lockley SW, Shea SA, Wang W, Landrigan
CP, O’Brien CS, Qadri S, Sullivan JP, Cade BE, Epstein LJ, White DP,
Czeisler CA (2011). Sleep disorders, health and safety in police officers.
JAMA. Dec 21;306(23):2567-78.
TS 1.2
SLEEP DISORDERS SCREENING PROGRAMS IN
COMMERCIAL VEHICLE DRIVERS
Howard M1, Wilkinson V1, Swann P2, Hare D1
Institute for Breathing and Sleep, Austin Health & University of Melbourne,
Australia
2
Department of Road Safety Vicroads, Australia
[email protected]
1
Introduction: Sleep disorders are common amongst commercial
vehicle drivers and contribute to increased risk of accidents and
injuries. We implemented a sleep disorders and cardiovascular risk
screening and education program in the road transport industry in
Victoria, Australia and evaluated the change in workplace injuries
before and after implementation of the program.
Methods: A three year health screening and education program was
run within truck yards. Companies were approached in conjunction with the Transport Workers Union. Education about fatigue,
sleep disorders and cardiovascular risk factors was provided in the
workplace. Nurses visited workplaces to provide confidential health screening. The screening included the Epworth Sleepiness Scale
(ESS), the Multivariable Apnoea Prediction Index (MAPI), sleep and
work habits, cardiovascular risk factors (smoking, blood pressure,
blood glucose, family history and cholesterol) and alcohol intake.
Written feedback was provided with recommendations for follow-up
of specific problems. This included advice about the likely causes of
sleepiness and specific advice about minimizing sleepiness based on
this information. Compliance with follow-up was estimated using a
reply paid card returned by doctors and a random telephone survey
of drivers referred for follow-up. Workplace injury data was collected
for 12 months pre and post the program from companies involved in
the first six months of the program (800 drivers).
Results: Eighty-seven percent of 134 companies approached participated in the program. 11992 drivers participated in education
sessions. 3975 drivers undertook individual health screening.1868
drivers were referred for follow-up of medical conditions, with
215 drivers referred for urgent review. Nineteen percent of drivers
had excessive sleepiness (ESS > 11), 24% were at high risk of
sleep apnoea (MAPI > 0.5) and four percent regularly fell asleep
whilst driving. Undiagnosed diabetes and severe hypertension were
identified in three and five percent of drivers respectively. 59% of
drivers attended for the recommended follow-up. New lost time
injuries fell from 17.1 to 14.2 per hundred drivers per year following
introduction of the program (p < 0.05).
Conclusion: A large scale sleep disorders screening program was
feasible with the assistance of union and industry support. Undiagnosed excessive sleepiness, hypertension, diabetes, and high risk
for obstructive sleep apnoea were common. There was moderate
compliance with recommended follow-up. There was a reduction
in workplace injuries following the program, however it is possible
that other factors contributed to the fall in injury rate.
Support: Project funding from Worksafe Victoria and the Transport Accident Commission. We gratefully acknowledge input from
The Transport Workers Union, Victorian Transport Association
and Vicroads
17
TS 1.3
TS 1.4
THE DEVELOPMENT AND VALIDATION OF A
QUESTIONNAIRE TO ASSESS SHIFT WORK DISORDER
Barger LK1,2, Ogeil RP3, Drake CL4, O’Brien CS1, Ng KT3,
Rajaratnam SM1,2,3
SHIFT WORK DISORDER IN PROFESSIONAL
TRAFFIC: PREVALENCE AND ASSOCIATION
WITH OBJECTIVE AND SUBJECTIVE SLEEP AND
SLEEPINESS
Härma M, Vanttola P, Merikanto I, Puttonen S. Sallinen M,
Hublin C, Virkkala J, Müller K
Division of Sleep Medicine, Department of Medicine, Brigham and Women’s
Hospital, USA
2
Division of Sleep Medicine, Harvard Medical School, USA
3
School of Psychology and Psychiatry, Monash University, Australia
4
Henry Ford Hospital, Sleep Disorders and Research Center, USA
[email protected]
1
Introduction: Shiftwork, including working during the overnight
hours extended duration shifts, early morning start times and other
variable work hours, comprises approximately 15% of the full-time
workforce in the United States, almost 23% of the workforce in
Japan, 16% in Australia, 18% in the United Kingdom, and 13% in
France. These non-standard work hours present a challenge to the
circadian system, and these shifts are associated with adverse health
and safety consequences. Shift work disorder (SWD) is a primary
circadian rhythm sleep disorder indicated by excessive daytime
sleepiness and/or insomnia associated with a shiftwork schedule.
SWD is under-recognized by primary care physicians, in part due to
the lack of standardized screening tools. Therefore, we sought to
develop and validate a questionnaire to screen for high risk of SWD
in a shift working population.
Methods: Interviews with shift workers and focus groups of sleep
physicians helped guide the development of the 26-item questionnaire. Shift workers recruited from both previously scheduled sleep
clinic appointments (n = 155) and the general population (n = 156)
completed the questionnaire and were evaluated by a physician in
one of 18 sleep clinics across the United States. Guided by a flow
chart that operationalized the ICSD-2 criteria for SWD, the physician
diagnosed each shift worker as either positive or negative for SWD.
Results: Responses to the items in the questionnaire were compared to the physicians’ diagnoses. In the primary analysis (n = 232),
the responses were entered into a series of discrimination function analyses to determine the diagnostic value of the items and
the fewest number of questions with the best predictive value. The
function was then cross-validated (n = 79). A final 4-item questionnaire was produced (89% positive predictive value, 62% negative
predictive value, sensitivity = 0.74; specificity = 0.82).
Conclusions: This SWD Screening Questionnaire may be appropriate for use in sleep clinics and primary care settings to aid in
the diagnosis of SWD. The questionniare may also be usfeul in
research studies to assess the risk of adverse health, safety, and performance outcomes associated with SWD and in the development
of appropriate interventions.
Support: This work was supported by research funding from
Cephalon, Inc. following submission of a research proposal by the
investigators. Cephalon (now Teva Pharmaceutical Industries Ltd.)
markets medications that are approved by the U.S., Food and Drug
Administration for the treatment of Shift Work Disorder.
REFERENCES
Barger LK, Ogeil RP, Drake CL, O’Brien CS, Ng KT, Rajaratnam SM. Validation of a questionnaire to screen for shift work disorder. Sleep. 2012 Dec
1;35(12):1693-703. doi: 10.5665/sleep.2246. PubMed PMID: 23204612;
PubMed Central PMCID: PMC3490362.
Development of Work and Organizations, Finnish Institute of Occupational
Health, Finland.
[email protected]
Introduction: The diagnostic criteria of shift work disorder (SWD,
according to ICSD-2) include (i) complaints of insomnia or excessive sleepiness temporally associated with work schedule, (ii)
the duration of symptoms of 4 weeks or longer, (iii) sleep log or
actigraph monitoring of 7 days or longer showing the work shift
association and (iv) exclusion of other reasons for sleep disorders.
We are not aware of earlier studies on the SWD prevalence using
the required sleep log data. The aim of the current study was to
study the prevalence of SWD among a random sample of train
drivers and traffic controllers and to compare prevalences obtained
with different SWD criteria. Secondly, we studied the association of
SWD to objective and subjective sleep.
Methods: 280 randomly selected train drivers and railway traffic
controllers (256 males, 26 females; age 26-61 years) were investigated using questionnaires, 3 weeks sleep/wake diaries and laboratory tests of sleep/wakefulness (polysomnography and MWT).
Diary based SWD (DIARY-SWD) was estimated with the following
criteria: insomnia during morning (M) or night (N) shifts but not
during the free days or high prevalence of excessive sleepiness (KSS
ratings 7 or higher) during M or N shifts but not during evening (E)
shifts. DIARY-SWD was compared to questionnaire based SWD
(SURVEY-SWD) with questions on the perceived abnormalities in
sleep or wakefulness and their relationship with working hours and
another questionnaire for SWD (SHIFT-SWD), focusing on the
existence of any frequent shift-dependent insomnia or sleepiness
complaints (6 questions) related to M or N shifts but not to the days
after 2 weeks on holidays.
Results: The prevalence of DIARY-SWD, SURVEY-SWD and
SHIFT-SWD was 30.1%, 17.4% and 18.0%, respectively. Only 8%
(n = 18) of the shift workers fulfilled both the SHIFT-SWD and
the DIARY-SWD criteria. 7 out of these 18 subjects had still either AHI > 15, or frequent PLMS, suggesting that only 5% of the
participants had a clear SWD fulfilling all the 4 required criteria
of ISCD-2. Shift workers with the DIARY-SWD reported more
difficulties to wake up before M-shifts and higher sleepiness during N-shifts based on the questionnaire. Based on the comparison
with sleep diary data, SHIFT-SWD questionnaire was more sensitive than SURVEY-SWD to detect severe sleepiness and dozing-off
during the night shifts. DIARY-SWD was related with lower (24%)
but SURVEY-SWD with higher (41%) co-morbidity of clinical
sleep disorders based on either AHI > 15 or frequent PLMS.
Conclusion: The prevalence of SWD is strongly related to the used
specific criteria. SHIFT-SWD questionnaire was sensitive to detect
severe sleepiness and dozing-off during the night shifts. SWD
among train drivers and railway traffic controllers showed high
co-morbidity with other clinical sleep disorders.
Support: This study was supported by a grant from the Finnish
Work Environment Fund (111102).
18
2nd Thematic Session
Circadian Stress, Shiftwork and the Influence of
Light
TS 2.1
ECOLOGICAL MEASUREMENTS OF CIRCADIAN
ENTRAINMENT AND DISRUPTION
Rea, M
Lighting Research Center, Rensselaer Polytechnic Institute, USA
[email protected]
Although circadian entrainment is an accepted term, little has been
done to quantify the degree of entrainment or disruption individual
organisms exhibit. Conceptually, entrainment can be characterized
as the synchrony of a periodic response with a periodic stimulus.
A variety of behavioral, physiological and hormonal responses
vary in amplitude over a 24 h period. The degree to which these circadian rhythms are synchronized to the daily 24-h light-dark
cycle can be measured with a technique known as phasor analysis.
To begin, proximate light-dark exposures patterns must be continuously measured over several cycles (i.e., days and nights) together with one or more periodic responses by the organism. The
synchrony between the measured 24h light-dark pattern and, for
example, the measured activity-rest pattern is assessed in terms of
their resonance (phasor magnitude) and phase (phasor angle). The
greater, the phasor magnitude; the greater, the degree of circadian
entrainment. The phasor angle indicates the organism’s photic niche, an organism is diurnal when its activity-rest pattern is in phase
with the proximate light-dark pattern (e.g., humans) and nocturnal
when activity-rest is counter phased with the light-dark exposure
pattern (e.g., mice). More subtly, phasor angle indicates whether
an individual response pattern is advanced or delayed with respect
to the light-dark pattern. Several studies have been carried out
using phasor analysis to quantify circadian entrainment exhibited
by laboratory rodents (mice and rats) and by several populations
of humans. School-age children were typically well entrained (large phasor magnitudes and consistent (diurnal) phasor angles). In
sharp contrast, individuals with Alzheimer’s disease (AD) living in
conventional nursing home environments often show no circadian
entrainment (phasor magnitudes near zero and indeterminate phasor angles). Importantly, the impact of interventions can be quantified using phasor analysis. Greater daylight exposure in the summer
serves to help improve circadian entrainment in persons with AD
as reflected by an increasing phasor magnitude in these individuals.
It is also possible to compare circadian entrainment across species.
Nocturnal rodents and diurnal humans on regular, 24h light-dark
cycles exhibit very similar phasor magnitudes but, obviously, mirrored phasor angles. Significant for future parametric studies of
circadian disruption on human health, rodents and humans also
show similar phasor magnitudes when exposed to different shift
schedules. Indeed, both rodents and humans show monotonically
decreasing and quantitatively similar phasor magnitudes with increasing shift-nights per week. Thus, phasor analysis provides a
method for quantifying circadian disruption in the field and in the
laboratory as well as a bridge between ecological measurements of
circadian entrainment in humans and parametric studies of circadian disruption in animal models.
Sponsors: Center for Disease Control, National Institute on Drug
Abuse, National Institute on Aging, Office of Naval Research.
TS 2.2
HOW MUCH LIGHT IS NEEDED TO REGULATE
THE RHYTHM IN SHIFTWORK?
Dumont M
University of Montreal and Chronobiology Laboratory, Center for Advanced
Research in Sleep Medicine, Sacre-Coeur Hospital of Montreal, Canada.
[email protected]
Introduction: Two contrasting effects of light exposure have
been examined in relation to shiftwork. On the one hand, artificial
bright light exposure during night work can be used as a powerful tool to adjust the circadian rhythms of night workers. On the
other hand, light exposure during night work has been proposed
as a potential cause of increased cancer risks in night workers,
because of the acute suppressing effects of light on melatonin
secretion. Therefore, both increased and decreased light levels at
night have been recommended to improve night workers’ circadian adaptation and health.
Results: Here we review the results of our field and laboratory
studies concerning the relationships between light exposure in
night workers and both circadian adaptation and melatonin secretion. A first series of studies compared the 24h profiles of
light exposure in night nurses with and without circadian adaptation. Results showed that circadian adaptation was not related
to light intensity but instead to the relative timing of light and
dark exposure over the 24 hours. Similar light-dark profiles were
then tested in the laboratory and were found to produce partial but significant adjustments of the circadian clock in a night
work simulation, without bright light exposure during the night.
A second series of studies measured the 24 hour melatonin production in rotating night workers during both night and day/
evening shifts. Melatonin secretion was not suppressed during
night work in this population. However, a correlation between
light intensity during night work and 24h melatonin production
suggested that higher light intensity at night may cause circadian disruption, thereby reducing total melatonin production.
Back to the laboratory, the evolution of melatonin production
over 4 consecutive days of simulated night work also supported
the hypothesis that melatonin production can be reduced in night workers not by a direct suppressing effect of light, but as a
consequence of the internal circadian disruption caused by the
re-entrainment process.
Conclusions: It is possible to adjust the rhythms of night
workers with bright light exposure at night. However, an adjustment to night work is followed by another misalignment
when returning to day work or days off. In shiftworkers, the
circadian system has to go through a period of internal disruption each time it re-entrains to a new rest-activity cycle. Reduced
melatonin production could be one of the consequences of the
disruption caused by re-entrainment. Biological rhythms need
stability. A partial but stable adjustment of circadian rhythms,
maintained by judicious timing of light and dark exposure, may
help night workers to achieve internal stability and hopefully be
more alert, rested and healthy.
Support: The Natural Sciences and Engineering Research
Council of Canada, and the Canadian Institutes of Health
Research.
19
TS 2.3
LIGHT AND ALERTNESS: IS THERE AN ALTERNATIVE TO BLUE?
Figueiro, MG
Lighting Research Center, Rensselaer Polytechnic Institute, USA
[email protected]
Introduction: Rotating-shift nurses are typically entrained to a
day-shift schedule; therefore, coping with night-shift becomes harder as a result of the natural tendency to be asleep at night. Studies
have shown that exposure to high levels of bright light at night
(levels typically > 2500 lux at the cornea) increases alertness, measured subjectively and objectively and positively affects certain types
of performance tests(1). The suppression of melatonin by light at
night may mediate the positive effects of light on nocturnal performance and alertness. However, acute melatonin suppression or
disruption of the melatonin cycle by light at night has been linked
to increased risk of cancer in animal models. Therefore, while there
is a benefit of exposing shift workers to light at night, the long-term
side effects of this light exposure are still not fully quantified. The
goal of this series of studies was to test whether narrowband long-wavelength (630-nm) light, which does not suppress melatonin,
can positively impact measures of alertness and performance.
Methods: A series of nighttime studies were performed where
measures of objective (electroencephalography) and subjective
(Karolinska Sleepiness Scale) alertness as well as performance were
collected while subjects either remained in darkness or were exposed to short-wavelength (470-nm), long-wavelength (630-nm) or
“white” (2700 K) lights. Data were collected in the early evening, at
the middle of the night, and at end of the night.
Results: Exposures to 470-nm and 630-nm lights in the middle
of the night increased beta and reduced alpha power relative to
preceding dark conditions, although only 470-nm light significantly
suppressed melatonin relative to darkness(2). Both 470-nm and
630-nm lights significantly increased nighttime cortisol levels, heart
rate, and reduced reaction times in the psychomotor vigilance test.
In a follow-up experiment, we showed that both 630-nm and 2700
K lights decreased reaction times on a GONOGO task, while there
was no significant difference in auditory reaction times after exposure to 630-nm light and 2700 K light compared to darkness. Compared to darkness, alpha and alpha theta power was significantly
reduced after 630-nm light exposure, but not after 2700 K light.
Conclusions: Our findings suggest that the melatonin pathway does
not seem to be the only light-sensitive pathway that can affect alertness and performance at night(3,4). Long-wavelength light can positively affect measures of performance and alertness without suppressing melatonin. These lighting solutions need to be tested in the field.
Sponsor: Office of Naval Research
REFERENCES
1.
2.
3.
4.
Eastman, C.I., et al., J Biol Rhythms, 1995.10(2):p.157-64.
Figueiro, M.G., et al., BMC Neurosci, 2009.10:p.105.
Phipps-Nelson, J., et al., Sleep, 2003. 26(6):p 695-700.
Vandewalle, G., et al., Curr Biol, 2006. 16(16):p.1616-21.
TS 2.4
HOW TO USE LIGHT AND DARK TO ADAPT TO
SHIFTWORK
Eastman CI
Biological Rhythms Research Laboratory, Behavioral Sciences Department,
Rush University Medical Center, USA.
[email protected]
The sleep, performance, health, and safety problems associated
with shift work are caused by circadian misalignment between the
internal circadian clock and activities such as work, sleep and eating.
The typical countermeasures, such as caffeine and other stimulants,
sedatives to facilitate daytime sleep, naps, and education about sleep
hygiene and circadian rhythms, are the components of most fatigue risk management plans. These approaches have limited benefits
because they do not address the underlying cause of the problems
which is circadian misalignment. I will review studies in which we
reset (phase shifted) the circadian clock to partially align with a night work, day sleep schedule by controlling exposure to light and
dark. This method includes sleep in the dark soon after night shifts,
sleep scheduled late on days off, a little bright light during night
work to help delay the circadian clock, sunglasses on the way home
from the night shift to attenuate phase advancing light, and outdoor light exposure (the light brake) after waking in the afternoons
to keep the clock from delaying too far. We structure the time for
sleep after night shifts and sleep on days off, so that their times
partially overlap. The light dark schedule delays the circadian clock
so that the sleepiest time of day, which occurs around the body
temperature minimum, falls within this overlap. Thus, sleep can be
improved when it occurs during the daytime after the night shifts
as well as on days off. Delaying the sleepiest time of day out of the
time for night work and into the daytime sleep time also improves
night shift performance. I will give some practical advice on how to
implement this type of schedule.
This research was supported by grant R01OH003954 from the
United States National Institute for Occupational Safety and Health
(NIOSH) of the Centers for Disease Control and Prevention (CDC).
The contents are solely the responsibility of the author and do not
necessarily represent the official views of NIOSH or the CDC.
3rd Thematic Session
Socially Sustainable Working Hours
TS 3.1
SELF-ROSTERING - A WAY TO SOCIALLY SUSTAINABLE WORKING HOURS
Garde AH1, Albertsen K1,2, Hansen ÅM1,2, Hvid H3, Lund H3
National Research Centre for the working Environment, Denmark
University of Copenhagen, Denmark
3
Roskilde University, Denmark
[email protected]
1
2
Objective: The aim was to explore the effects of self-rostering on
health, recovery, work-family balance and psychosocial work environment. We also elucidate the mechanisms through which recovery and health are affected and interpret the results in light of the
different implementation processes.
Methods: A prospective, quasi-experimental intervention study
with a 12 months follow-up was conducted. Twenty eight workplaces were allocated to either an intervention implementing self-rostering or reference group. Intervention A encompassed possibilities
to specify preferences for starting time and length of shift down
to 15 minutes intervals. In interventions B and C employees could
choose between a number of predefined duties.
In interventions A and C, but not B, employees were invited to solve discrepancies between preferences and need for resources by voluntarily altering their preferences after the first schedules had been
made. A total of 1065 participants (response rate = 79%) were included at baseline and 1074 at follow-up (response rate = 73%).
Information on sleep, need for recovery, work-family balance and
psychosocial work environment was obtained from questionnaires.
Process evaluation encompassed interviews at baseline and
20
follow-up. Objective workplace reports of working hours were
obtained. Statistical models tested the interaction between group
(intervention A-C and reference) and time (baseline and follow-up).
Results: The interventions were initiated with different purposes, and managers and employees had different expectations to
the outcome. Perceived influence on working hours increased in
interventions A and B, but not in C. In intervention A, need for
recovery, work-family balance and some psychosocial work environment factors improved. In intervention B, somatic symptoms,
mental distress, sleep, need for recovery, work-family balance and
the psychosocial work environment improved. In intervention
C, work-family balance and psychosocial work environment factors deteriorated. The odds ratio of having short and long shifts
increased in intervention A.
Conclusion: Overall implementation of self-rostering was followed
by positive effects on recovery, health, work-family balance and social support from colleagues. However, the results differed between
the intervention groups and may be related to differences in implementation and the perceived degree of influence on working hours.
The study was supported: by a grant from The Danish Working
Environment Research Fund.
REFERENCES
K Albertsen, AH Garde, K Nabe-Nielsen, ÅM Hansen, H Lund, H Hvid.
Work life balance among shift workers - results from an intervention
study about self-rostering. Int. Arch. Occup. Environ. Health. DOI
10.1007/s00420-013-0857-x (E-pub)
AH Garde, K Albertsen, K Nabe-Nielsen, IG Carneiro, J Skotte, SM Hansen,
H Lund, H Hvid, ÅM Hansen. Implementation of self-rostering (the
PRIO-project): Effects on working hours, recovery, and health. Scand. J.
Work Environ. Health. 2012 38(4):314-326, doi:105271/sjweh.3306.
ÅM Hansen, K Albertsen, A Hogh, H Lund, H Hvid, AH Garde. Self-rostering and psychosocial factors at work - A mixed methods intervention
study. Submitted
TS 3.2
A BIOGRAPHICAL APPROACH TO THE SOCIAL EFFECTS AND CONSEQUENCES OF SHIFT WORK
Tieves, D
Institute for Work, Skills and Training (IAQ), University Duisburg-Essen, Germany.
[email protected]
Introduction: Shift work and other flexible working time arrangements have been a part of workers’ lives since the beginning of
industry and service work (Messenger 2011).
In today’s 24 hour society, with a rising number of women in the
workforce and dual earner couples working outside the traditional
time frame, the demands on the social life of workers become more
complex (Mills & Täht 2010, Presser 2003), which implies the need
for researchers to also take the social demands and possible resources into consideration (Presser 2003). In this study, I therefore ask
how workers integrate shift work and the rising social demands into
their biographies, which demands they face in their social lives, and
which resources they can use to cope with the demands.
Methods: Consequently, the methodology takes the biography into
consideration and simultaneously allows for an integration of social demands and resources into one model. With the whole life
situation as a basis for research, I chose narrative-biographic interviews (Schütze 1983) to collect data. The transcripts are analyzed
according to the biographic case-reconstruction (Rosenthal 2011),
which reconstructs narrated and experienced life before contrasting
them. The result is a case structure for each individual case, to which the research questions are then applied. This allows me to design
a model of social demands and resources.
Results: The case structures show, that - due to the lack of an institutional framework for support - shift workers and their families find
individual solutions for the social problems they are facing. Most of
them are premised on the desynchronized life caused by their different time frame compared to the societal timeframe. This becomes visible in areas like child care, activities with friends, etc. Their
individual solutions are based on biographical structures. Although
some of the interview partners report advice from the employer side
towards e.g. healthy eating, social aspects are not included in prevention. The case structures also indicate that those workers, who use
individual solutions, cope much better with the specific demands of
shiftwork than those who do not have them available. The individual
solutions are therefore considered as resources.
Conclusion: The resources and demands found in the case structures are brought together to build a multi-dimensional model
regarding social effects of shiftwork and taking into account the
biographical perspective. Some of the aspects (e.g. socialization)
can be connected with earlier findings from Altheit et al. (1986),
Neuloh (1975) and Presser (2003).
The model not only shows resources (e.g. solidarity in shift groups),
but places them in connection to demands (e.g. attending family
events) and the biographical background (e.g. earlier experiences of
solidarity). Therefore it can be used to improve social life of shift
workers taking into account their whole life situation.
TS 3.3
DOCTORS’ WORK SCHEDULES AND WORK TIME
CONTROL
Tucker P1, Bejerot E1, Kecklund G1, Aronsson G2, Åkerstedt T1
Stress Research Institute, Stockholm University, Sweden
Psychology Department, Stockholm University, Sweden
[email protected]
1
2
Doctors in many countries have traditionally worked long hours, particularly in the early stages of their career, with overnight duties and
on-call work being common. Their work schedules are an important
determinant of their own wellbeing and that of their patients. The current study sought to identify which aspects of doctor’s working time
arrangements are the most important predictors of sleep, health, workfamily balance, patient care and attitudes towards work. A cross-sectional survey was conducted in which a representative sample of doctors
in Sweden (N = 1534) completed a questionnaire about working conditions, wellbeing and patient care (response rate 53.1%).
Regression analyses examined the associations between working
time parameters (i.e. having influence over ones’ work hours; access to flexitime; shifts longer than 12 hours; short inter-shift
intervals - “quick returns”; frequency of on-call duties, night shifts
and weekend working; having rest days before and after night shifts;
weekly work hours) and a range of outcomes.
The analyses adjusted for age, sex, job grade and medical specialty.
Working a lot of unpaid overtime was associated with impaired sleep, poorer wellbeing, greater work-family conflict, more negative
attitudes, and greater concerns regarding the risk of malpractice.
Doctors who worked frequent long shifts (longer than 12 hours)
were more likely to report impaired sleep, to have considered changing their current job situation (e.g. changing employer), and to be
concerned about the risk of malpractice due to high workload.
Long weekly work hours and short inter-shift intervals were both
positively associated with greater likelihood of being reported for
malpractice. Frequent weekend working was associated with poorer
sleep, poorer wellbeing, more negative attitudes towards work,
poorer patient care and greater work-family conflict. There were
few negative associations with frequent night work, although there
were indications that the combination of high work demands and
night work leads to insufficient recovery.
21
Work time control (WTC) was one of the most consistent predictors
of the various outcomes. Doctors who were able to exert influence
over how and when their work hours were scheduled tended to report
better sleep, health and work-family balance, more positive thoughts
about their work, and more positive perceptions of patient care.
A separate analysis considered whether WTC buffered the negative
effects of demanding work schedules, by examining the interactions
between WTC and some of the other working time parameters.
WTC attenuated the positive associations between frequency of
extended shifts and stress; frequency of short inter-shift intervals
and fatigue; frequency of night duties on short sleeps; and
frequency of unpaid overtime and fatigue.
The findings highlight the importance of matching doctors’ work
hours to individual needs and preferences. Optimizing the balance between schedule flexibility and patient needs could enhance
doctors’ health, patient care and staff turnover.
TS 3.4
WORKING HOURS, WORK ORGANISATION AND
SUSTAINABLE WORK
Bohle P, Pitts C
Ageing, Work and Health Research Unit, Faculty of Health Sciences, The
University of Sydney, Australia.
[email protected]
Introduction: Sustainable work can be defined as forms of employment in which workers are productively engaged in jobs that
enhance their psychological and economic well-being while balancing the interests of employers, workers and their families (Kossek & Berg 2013). A key objective is to promote work-life balance
and health. Precarious (insecure) work, long and irregular working
hours, and high work intensity generally undermine sustainability
(Clarke et al. 2007; Hirsch 2005) but have expanded markedly in
many countries. This paper tests models of the structural relationships between key variables influencing sustainability, including
precariousness, working hours, and psychosocial factors at work.
Methods: Computer-aided telephone interviewing was used to collect survey data from 714 workers aged 45-65 who were randomly
sampled from a representative database of 4.8 million Australian
households. The participants’ mean age was 54.6 years (SD = 5.0)
and mean weekly working hours were 34.7 (SD = 13.9). Four hundred and two (56.3%) were female.
Results: Structural equation modelling (using partial least squares) revealed complex relationships between precariousness, work
intensity and reward pressure, duration and regularity of working
hours, hours control, work-life conflict and health that were largely
consistent with previous evidence.
Conclusions: These findings suggest that sustainable work, when
measured in terms of better work-life balance and subjective health, can be enhanced by expanding positive elements of work organisation, such as individual control over working hours, or by
diminishing deleterious ones, such as reward pressure.
REFERENCES
Clarke, M., Lewchuk, W., de Wolff, A. & King, A. (2007). ‘This just isn’t
sustainable’: Precarious employment, stress and workers’ health. International Journal of Law and Psychiatry, 30, 311-326.
Hirsch, D. (2005). Sustaining working lives: A framework for policy and practice. Joseph Rowntree Foundation: York, UK. Kossek & Berg (2013).
Sustainable workforce: Initiative on workplace flexibility and the employment relationship.
http://www.thesustainableworkforce.org/index.php/sustainable-workforce
(accessed 13 June 2013)
TS 3.5
SOCIAL CONSEQUENCES OF WORKAHOLISM
AMONG LONG-HOURS WAGE-EARNERS
Muurlink O, Peetz D, Murray G, Loudon R
Centre for Work, Organisation and Wellbeing, Griffith University, Australia.
[email protected]
Introduction: A number of influential writers on ‘workaholism’ apply Oates’ (1968) standard addiction template, seeing
workaholism as uncontrollable ‘overconsumption’ of work with
serious social and health consequences (Porter, 1996). Countering the addiction view, the drive theory of work argues that
regular work is ‘healthy, desirable, and in fact protective from
many illnesses’ (McMillan et al., 2003: 168). We examine the predictors and social consequences of overwork in the context of
a highly paid occupation in which extra hours typically translate
directly into extra earnings through overtime premiums. And
uniquely we focus on core objective manifestations of workaholism amongst long-hour, high wage workers, defining workaholics as shiftworkers who work at least 48 hours a week, and either want to work more hours in their job or were taking on
additional work outside their main employment.
Methods: The analysis is based on a cohort of 2752 members
of the Australian Construction, Forestry, Mining and Energy
Union’s Mining and Energy Division (CFMEU-MD). Wave 1
included a number of standardised scales including the GHQ12 and Revised Dyadic Adjustment Scale, as well as social impact measures. Respondents were asked about their actual and
desired working hours and any other employment they engaged
in outside their main job.
Results and Conclusion: A cohort of 170 workaholics were
identified in the sample, and compared with their peers, initially through chi square analysis. This group did not feel any
less connected with their community than their peers did, nor
did they socialise any less with co-workers. With the exception
of sporting bodies, workaholics were as actively involved with
most community organizations. They were marginally less satisfied with their degree of involvement in household activities
and much less likely to get together frequently with family and
friends. No differences were found for psychosocial stress or
marital discord. Differences between workaholics and others
were not explained by gender, marital status, how long the respondents had been in the industry, how long they had been with
their current employer, their sense of security in their job or
their intention to leave the industry. However, workaholics were
significantly less educated than their counterpart s and had been
significantly longer on their current roster pattern. The results
suggest the need for a more nuanced view of workaholism than
suggested by either the addiction or drive theories.
Support: Australian Research Council and CFMEU-MD.
REFERENCES
1. McMillan, LHW, et al. (2003). Workaholism: A review of theory, research,
and future directions. Int. Rev. Ind. Org. Psy, 18, 167-190.
2. Oates, WE (1968) On being a “workaholic”. Pastoral Psy, 19(8),16-20.
Porter, G. (1996).
3. Organizational impact of workaholism. J. Occup. Health Psy, 1(1),70.
22
Cancer and Shiftwork
TS 4.1
USE OF BIOLOGICAL MARKERS TO STUDY DISEASE MECHANISMS AMONG SHIFTWORKERS
Burch JB
South Carolina Statewide Cancer Prevention & Control Program, University
of South Carolina, USA
Department of Epidemiology and Biostatistics, Arnold School of Public
Health, University of South Carolina, USA
Dorn Department of Veteran’s Affairs Medical Center, USA
[email protected]
Introduction: Shiftwork induces stress, sleep loss, and fatigue, disrupts circadian rhythms, and alters endocrine, immune, and cognitive
function. It has been associated with increased accident and injury
rates and several major adverse health outcomes, including cardiovascular disease, stroke, diabetes, and cancer. These impacts are observed in critical work sectors, such as health care, transportation, public
utility and safety, manufacturing, and military occupations.
Methods: This presentation will describe biomarkers that can be
used to examine disease processes among shiftworkers as well as
approaches for minimizing their inherent limitations or uncertainties. A biomarker can be defined as a characteristic of a living
organism (physiological, biochemical, cellular, or molecular) that
can be accurately and reproducibly measured to reflect: the interaction between a living system and a potential health hazard; the
likelihood, presence, or severity of disease; responses to therapy, or
disease prognosis. Shiftwork can elicit changes in immune, neurological, psychological, endocrine, sleep-wake, and metabolic systems.
Thus, there are ample opportunities for characterizing shiftwork
perturbations using biomarkers. Genetic or epigenetic alterations
in clock genes and the corresponding potential for altered cell cycle
dynamics represents another promising area of investigation. Virtually every human physiological process has a circadian rhythm.
Concepts such as ‘circadian disruption’ or ‘chronodisruption’ that
are used to describe potential health-related impacts of shiftwork
can manifest in different ways, including the misalignment of endogenous rhythms with external cues (phase shifts); reductions in
rhythm amplitude; or via endogenous rhythm desynchronization
(e.g., uncoupling between central and peripheral clocks). One of
the challenges in studying shiftwork-related biomarkers derives
from a lack of understanding of which of these alterations exert
pathological effects that increase disease risk or diminish survival.
Other issues also merit consideration, such as the specific schedule
characteristics that have adverse impacts, the relative detrimental
or beneficial effects of coping strategies that shiftworkers utilize,
participant compliance with biospecimen collection, and the timing
of biomarker quantification in relation to disease latency.
Results: Biomarkers commonly used to assess shiftwork-related impacts (e.g., melatonin or cortisol biomonitoring, or sleep-wake patterns
assessed via wrist actigraphy) have an established biological rationale.
Other less common but potentially useful measures include autonomic function (heart rate variability, body temperature, blood pressure,
which can be readily assessed via portable data-logging devices); clock gene expression or methylation; or circulating concentrations of
inflammatory cytokines, growth factors, or neurotransmitters.
Conclusion: If used in a systematic and focused manner, biomarkers offer the opportunity to characterize critical physiological
or biochemical lesions among shiftworkers that can effectively be
targeted for disease prevention or intervention efforts.
TS 4.2
SHIFT WORK, BIOMARKERS AND CANCER
Aronson JK
Public Health Sciences, Faculty of Health Sciences; School of Environmental
Studies, Faculty of Arts and Science; Cancer Care and Epidemiology, Queen’s
Cancer Research Institute, Queen’s University, Canada
[email protected]
Introduction: While shift work is associated with several health effects, the focus here is on pathways to cancer. Studies
with breast cancer as the outcome have conflicting results, and
some have shown increased risk associated with only longterm shiftwork including nights. Comprehensive methods of
exposure assessment to capture the diversity of shift patterns
are needed. Various pathways from shift work to cancer are
hypothesized to involve melatonin, sex hormones, unsynchronized core and peripheral functions, sleep disruption, and vitamin D. Further, circadian gene variants such as in NPAS2,
CLOCK, PER1, PER3, CRY2 and TIMELESS have been associated with cancer risk.
Methods: We have conducted two types of studies addressing
shift work: 1) a population-based breast cancer case-control
study; and 2) biomarker studies of female nurses working a
pattern of two 12hr days, two 12-hr nights (DDNN), and five
days off. In Vancouver BC and Kingston ON, our case-control
study (1042 breast cancer cases, 1051 controls) assessed lifetime occupations and investigated 100 SNPs in 14 clock-related
genes. Odds ratios in an additive genetic model for the subgroup of European-ancestry (645 cases, 806 controls) were
calculated using a two-step correction for multiple testing. In
our biomarker studies, we used objective measures of light,
collected multiple daily urine and saliva samples for melatonin,
controlled for natural circadian rhythm, and recently have included actigraphy, cortisol, and sleep quality data.
Results: With one-third of cases and controls ever employed
in shift work, associations with duration demonstrated increased risk for ≥ 30 years (OR = 2.21, 95% CI: 1.14-4.31),
and results are similar for workers in health and non-health
occupations. SNPs rs3816360 in ARNTL and rs11113179 in
CRY1 displayed significant associations with breast cancer,
and rs3027188 in PER1 was marginally significant; however,
none was significant following adjustment for the false discovery rate. One SNP (rs3027188 in PER1) displayed a significant interaction with ethnicity (European vs. Asian) with
respect to breast cancer risk. In our biomarker study, melatonin patterns are virtually unaffected by this DDNN shift
schedule, and nurses working at night are in dim lighting
conditions that only slight decreases melatonin levels.
Conclusion: Long-term shift work in a diverse mix of occupations, not only among nurses, is associated with increased
breast cancer risk in our study. If shift work causes circadian
disruption, this has not yet been convincingly reflected in associations with circadian gene variants. The DDNN shift work
pattern and dim light while working at night may not affect
melatonin levels. Future work includes assessment of breast
cancer risk in relation to other SNP pathways such as DNA
repair, genetic interactions with shift work history, and assessment of risk among non-Caucasians and among professions
other than health care.
23
TS 4.3
A RETROSPECTIVE COHORT STUDY OF SHIFT
WORK AND INCIDENT CANCER RISK IN GERMAN
MALE CHEMICAL WORKERS
Yong M1, Hammer PG2, Emrich K3, Nasterlack M1, Blettner M2
Occupational Medicine and Health Protection, BASF SE
Institute for Medical Biostatistics, Epidemiology, and Informatics, Johannes
Gutenberg University Mainz, Germany
3
Cancer Registry of Rhineland-Palatine
[email protected]
1
2
Introduction: Human evidence of carcinogenicity concerning
shift and night work is inconsistent. Most published studies focused on breast cancer risk in women. Few studies examined prostate
cancer risk, mostly in pilots and male flight attendants, and in few
industry-based cohorts with limited numbers of exposed cases.
Even less evidence exists regarding other cancers. In our previous
study in a cohort of male production workers, we found no increase in total mortality and cancer specific mortality related to shift
work. The present study extends these analyses to cancer incidence.
Methods: The initial cohort consisted of male production workers
(14,037 shift and 17,095 day), employed in the company for at least
one year between 1995 and 2005. The present analyses were based
on workers from this cohort residing in the German federal state of Rhineland-Palatinate (12,609 shift and 15,219 day). Incident
cancer cases from the 10-year period 2000-2009 were identified
through record linkage with the cancer registry of Rhineland-Palatinate. Information on exposure to shift work and potential confounders, including age, smoking status, job level, and employment
duration was extracted from the personnel and health records. Cox
proportional hazard models were used to estimates hazard ratios
(HR) with 95% corresponding confidence interval (CI) adjusted for
potential confounders.
Results: Between 2000 and 2009, 518 and 555 incident cancer
cases (excluding non-melanoma skin cancer) occurred among rotating shift and day work employees, respectively, and 146 and 191
thereof were prostate cancer cases. Compared to never shift work,
shift workers did not experience a significantly increased risk of all
cancers (HR = 1.04; 95% CI: 0.89-1.21), nor for prostate cancer
(HR = 0.93; 95% CI: 0.71-1.21).
Conclusion: With 337 cases of prostate cancer in a cohort of 27828
workers, our study is (one of) the largest studies on shift work and
prostate cancer to date. The present analyses did not provide supporting evidence for a carcinogenic effect of the shift system employed in our industry. The potential impact of latency time will be
discussed.
Support: This study was supported by the Deutsche Gesetzliche
Unfallversicherung (DGUV) (grant no. 617.0 - FP-0332)
TS 4.4
ASSOCIATIONS OF POLYMORPHISMS IN CIRCADIAN GENES, SHIFT WORK AND BREAST CANCER IN
THE GERMAN GENICA STUDY
Rabstein S, Harth V, Pesch B, Justenhoven C, Baisch C, Schiffermann M, Heinze E, Brauch H, Hamann U, Ko Y, Brüning T
Institute of Prevention and Occupational Medicine, German Social Accident
Insurance (IPA), Institute of the Ruhr-University Bochum, Germany
[email protected]
Introduction: Recently, the role of night-shift work in breast
cancer development has been intensively discussed. Common variants in genes that regulate the circadian system may modify the
observed risks of shift work. So far, the influence of polymorphisms in circadian genes on breast cancer development is widely unknown. Here, we hypothesized that circadian genes influence breast
cancer risk and may modify the risk of night shift work to develop
breast cancer.
Methods: The population based case-control study Gene-ENvironment Interaction and Breast CAncer (GENICA) was conducted
in the Greater Region of Bonn, Germany. Shift work and detailed
shift work characteristics were assessed in subsequent telephone
interviews. Seven polymorphisms in circadian genes AANAT, ARNTL, CLOCK, CRY2, MTNR1B, NPAS2, and PER2 were genotyped. Associations between polymorphisms, shift work and breast
cancer could be investigated for 1022 controls and 1014 cases. Risk
estimates were calculated as odds ratios (ORs) with 95% confidence intervals (CIs) conditional on age and adjusted for hormone
replacement therapy, number of mammograms and familial breast cancer. Test for interactions as well as methods for Multifactor
Dimensionality Reduction will be presented.
Results: First results indicate elevated risk estimates for polymorphism rs8150 of gene AANAT (GC+CC vs. GG: OR 1.17; 95% CI
1.01-1.36). In women that ever worked in shift for at least one year
we found an elevated risk estimate for polymorphism rs10462028
in CLOCK gene (OR 3.53; 95% CI 1.09-11.42).
Conclusion: Our study suggests that polymorphisms in circadian
genes may be associated with breast cancer and may also modify the
risks of shift work for breast cancer. However, the results are limited
by low prevalence of night work and variant genotypes. Therefore
a pooling of studies would improve the statistical power to analyze
the influence of circadian genes in breast cancer development.
Shiftwork and the Individual - The Future of
Shiftwork Research
TS 5.1
CIRCADIAN MISALIGNMENT OF THE CENTRAL
CIRCADIAN CLOCK WITH SLEEP/WAKE RHYTHMS
AND EATING PATTERNS IN HOSPITAL SHIFT
WORK NURSES
Gamble LK1, Johnson LR1, Thomson BS1; Griffie JT2, Young
EM3
Dept. of Psychiatry, University of Alabama at Birmingham, USA.
School of Nursing, University of Alabama at Birmingham, USA.
3
Dept. of Medicine, Cardiovascular Disease Div., University of Alabama at
Birmingham, USA.
[email protected]
1
2
Introduction: Shift work is associated with an increased risk of
developing cancer, mood disorders and cardiovascular, metabolic,
gastrointestinal diseases. A potential mechanism for shift-work
induced pathology is circadian misalignment, which occurs when
sleep/wake/feeding patterns are out of sync with endogenous clock-controlled rhythms and/or the environment. Hospital nurses are
an ideal subject sample for shift work because (i) their alertness and
performance is crucial for health and safety of patients, and (ii) they
often undergo highly irregular schedules due to attempts to follow
a normal day schedule on their days-off for family/social reasons.
We recently defined off-shift sleep strategies used by hospital nurse
shift-workers and found that certain strategies (such as sleep deprivation) were maladaptive, suggesting that future studies should also
focus on selection of off-shift behavioral sleep strategies and the
resulting circadian misalignment.
Methods and Results: In this presentation, we will first present
data from a self report survey (Biological Clocks questionnaire and
24
the Standard Shiftwork Index) that was administered to a diverse
cohort of shift work nurses. First, we will identify several contributing factors (e.g., race, age, work experience, family responsibilities,
chronotype, etc.) to behavioral sleep strategy selection. Second, we
will present preliminary data from a second follow-up, 10-day study
in a subset of 18 nurses in which we measured misalignment of
rhythms in sleep/wake behavior, core body temperature, nutrient
intake, melatonin, cortisol, and circadian clock gene expression in
peripheral blood mononuclear cells.
Conclusion: The results of these studies will shed light on the
potential mechanisms by which off-shift sleep strategies differentially impair adaptation to shift work. Overall, this project will
have implications for improving nurses’ health through informed
recommendations regarding sleep strategies and may lead to work
schedule interventions.
Support: Supported by the UAB Department of Vision Sciences,
UAB Comprehensive Diabetes Center, and the UAB Center for
Clinical and Translational Science (UL1 TR-000165) from the National Center for Advancing Translational Sciences (NCATS) and
National Center for Research Resources (NCRR) component of
the National Institutes of Health (NIH).
more UaMT6s than those in the control group during sleep episodes preceding night shifts (p = 0.007).
Conclusions: Our findings suggest a better circadian alignment to
the work and sleep schedules in police officers who followed our
experimental 25h day schedule compared to those who worked their
conventional rotating schedule. Although excretion rate of UaMT6s
during all sleep periods was comparable between groups regardless
of the type of shifts, significant differences were observed between
groups during night shifts. These results suggest that considering
circadian physiology in shift scheduling can be beneficial.
Support: Operating grants: IRSST. Salary support: FRSQ (DBB)
and IRSST (PB).
TS 5.3
NIGHT SHIFT-WORK, MELATONIN AND SEX HORMONES BIOMARKERS
Papantoniou K1,2,3, Pozo OJ2,4, Marcos J2,4, Middleton B5, Skene
DJ5,Espinosa A1,3,4, Castaño-Vinyals G1,3,4, Kogevinas M1,3,4
Centre for Research in Environmental Epidemiology (CREAL), Spain
Universitat Pompeu Fabra (UPF), Spain
3
CIBERESP, Spain;
4
IMIM, Spain;
5
Chronobiology, University of Surrey, UK;
[email protected]
1
2
TS 5.2
PHYSIOLOGICAL AND BEHAVIOURAL IMPACTS
OF CIRCADIAN ADAPTATION TO NIGHT SHIFT
WORK
Boivin DB; Boudreau P
Centre for Study and Treatment of Circadian Rhythms, Douglas Mental Health
University Institute, Department of Psychiatry, McGill University, Canada
[email protected]
Introduction: Most shift work schedules disregard the physiology of the endogenous circadian system. This situation leads to a
state of chronic misalignment between the endogenous circadian
system and the sleep-wake cycle. The aim of this presentation is
to review the impacts of circadian misalignment on physiological
and behavioural parameters. Results of an innovative 25h day work
schedule in police officers on patrol will be presented.
Methods: Eighteen healthy police officers (age ± SD: 28.1 ± 3.9 y;
15 women, 3 men) were studied in the field on their 35-day roster.
Police officers in the control group (n = 12) followed their conventional rotating work schedule comprised of day, evening, and night
shifts. Police officers in the intervention group (n = 12) followed an
experimental work schedule based on 25h days. On this schedule,
work and rest days included scheduled sleep and periods of 8h20
and 16h40, respectively, with 9h45 shifts during work days. On the
experimental schedule, shifts starting between 04:00 and 11:59 were
considered “day shifts”, those starting between 12:00 and 19:59
were considered “evening shifts”, and those starting between 20:00
and 3:59 were considered “night shifts”. Six officers participated in
both conditions, and 3 officers of the experimental schedule were
excluded because of non-compliance to the experimental protocol (n = 2) and a preexisting medical condition (n = 1). Urine
samples were collected before, after, and during (if needed) each
main sleep period. These samples were assayed for their content
of 6-sulfatoxy-melatonin (UaMT6s), and the rate of excretion was
calculated during the main sleep period. A two-way mixed design
ANOVA (factors: group x type of shift) was used. A t-test was used
for between-group comparisons, based on the a priori prediction
of a difference in UaMT6s excretion rate during night shifts.
Results: The two-way ANOVA revealed no significant interaction
(p = 0.33), nor main effect of group (p = 0.82), or type of shift
(p = 0.068). The t-test comparing the hourly rate of UaMT6s revealed that officers in the intervention group excreted significantly
Objectives: Night shift work has been associated with higher breast cancer risk. It has been proposed that night shift workers experience light-induced suppression of melatonin production. Melatonin has direct oncostatic properties and a potential interplay with
reproductive hormones. However, reproductive hormones have
been understudied in relation to night shift work. In this cross-sectional study the hypothesis was that night shift workers produce less
melatonin and more estrogens, progestagens and androgens compared to day workers. Changes in the daily rhythm of the hormones
were also evaluated.
Methods: 75 permanent night workers and 42 day workers of both
sexes, aged 22-64 years, were recruited from 4 companies in Barcelona, Spain. Participants collected urine samples from all voids
over 24 hours on a working day. Simultaneously they wore a data
logger that continuously recorded their light exposure. Sociodemographic, occupation and lifestyle information was collected for each
participant by interview. Levels of 6-sulfatoxymelatonin (melatonin
metabolite) and 25 steroid metabolites were measured in all urine
samples collected. Individual cosinor analysis was performed for
6-sulfatoxymelatonin and steroid metabolites to evaluate their rhythmicity. From the cosinor analysis we estimated the peak time of
production (acrophase) and the total 24h output calculated from
the area under the curve (AUC) for each metabolite. Geometric
means (95% CI) were calculated for each parameter and the Wilcoxon-Mann-Whitney test was used to compare levels between night
and day worker s. In comparisons subjects with a significant 6-sulfatoxymelatonin rhythm were included (9 subjects were excluded).
Results: Sociodemographic and lifestyle characteristics of day and
night shift groups were not significantly different. Total 6-sulfatoxymelatonin production over a 24h period was significantly lower
(p = 0.003) in night compared to day workers (geometric mean (95%
CI) 272 (236-314) vs 386 (308-483) ng 6-sulfatoxymelatonin/mg
creatinine, respectively). Peak time of 6-sulfatoxymelatonin production occurred almost 3 hours later (p < 0.001) in night shift workers
compared to day shift workers (9.0 h (8.1-9.9) vs 5.5 h (5.02-5.9) ,
respectively). Both differences persisted after adjustment for a wide
range of potential confounders such as age, BMI, sex, menopausal
status, menstrual cycle phase, sleep duration, alcohol consumption,
caffeinated beverages and drug use. Total estrogen, progestagen and
25
androgen levels tended to be higher among night workers in premenopausal women, but differences were not statistically significant.
Conclusions: This study indicates that night shift work is associated
with both a reduction and a phase delay of the 6-sulfatoxymelatonin
production on a working day. Potential differences in sex steroid
profiles between night and day workers are also suggested among
premenopausal women. In the conference results for the full set of
hormones will be presented as well as results taking into account
personal light exposure.
TS 5.4
EFFECTS OF A CHRONOTYPE-BASED SHIFT
SCHEDULE ON SLEEP, WELLBEING, AND SOCIAL
LIFE
Vetter C, Fischer D, Mehlmann J, Roenneberg T.
Institute of Medical Psychology, Ludwig-Maximilian-University Munich,
Germany
[email protected]
Objectives: Shift schedules usually consider social, production-related, and medical factors. Circadian disruption - proposed as one
of the main mechanisms underlying the detrimental health effects
of shift work - is advised to be kept at a minimum. Yet, the high
inter-individual variability of phase of entrainment (chronotype)
indicates that exposure to certain shifts may affect physiology and
behavior differentially, depending on chronotype. Our aim was to
implement and evaluate a chronotype-based shift schedule.
Methods: At baseline (2-2-2 fast-forward rotating schedule), employees worked 6 morning shifts (MS), 6 evening shifts (ES), and
6 night shifts (NS) within 4 weeks. In the subsequently introduced
chrono schedule, one group with very early chronotypes (early 1)
worked 14 MS, 4 ES and no NS, one of very late chronotypes (late 2)
worked 14 NS, 4 ES and no MS, while two intermediate groups
worked relatively less NS (early 2: 6 MS, 8 ES, 4 NS), or MS (late 1:
4 MS, 8 ES, 6 NS). 48 employees filled out sleep logs, assessing daily
sleep/wake behavior, wellbeing and sleep quality, 20 wore actimeters.
We further asked the participants to give a global satisfaction rating,
and one specifically regarding their social life. We used rANOVA to
compare the effects of groups and schedules on outcome variables
across baseline and two time points within the chrono schedule.
Results: Sleep duration increased during the chrono schedule, especially within the early 1 and late 2 on work days. The slightly shortened
sleep duration on free days suggests that the chrono schedule reduced
sleep deprivation during the workweek, thereby minimizing catch-up
sleep on free days. Social jetlag was reduced in early 1 and 2, while in
late 2, social jetlag on night shifts correlated with chronotype, suggesting an heterogeneous impact of the schedule, depending upon how
late an employee was. Sleep quality and wellbeing slightly increased in
the chrono schedule, whereas only the early 1 showed a paralleling increase in satisfaction with social life. Overall, the earlier groups were
(highly) satisfied with the chrono schedule (80-95% of the employees),
while this was true for approximately 50% in the late 2.
Conclusions: This first chronotype-based shift schedule significantly improved subjective and objective measures of sleep behavior
and wellbeing by reducing exposure to problematic shifts (i.e. morning shift for later chronotypes, night shifts for earlier ones).
Yet, this improvement was heterogeneous across groups, indicating
further need of adjustment of such schedules. Considering individual
chronotype in designing shift schedules appears a promising mean to
potentially minimize adverse long-term health effects of shift work.
Support: This work was supported by industry grants to TR
(Thyssen Krupp Steel Europe, Siemens AG) and a fellowship of
the Hanns Seidel Foundation to DF.
TS 5.5
SOCIAL JETLAG AND CARDIOVASCULAR RISK IN
ROTATING SHIFT-WORKERS
Kantermann T1, Duboutay F2, Haubruge D3, Skene DJ4,
Hampton S4, Boudjeltia KM5, Kerkhofs M5, Schmidt-Trucksäss A6
Chronobiology, RuG, NL
CBMT Charleroi, BE
3
ArcelorMittal Industeel Belgium, BE
4
Chronobiology, University Surrey, UK
5
Médecine Expérimentale, ULB, BE
6
Sports Medicine, University Basel, CH
[email protected]
1
2
Objectives: Whether the direction of shift-work rotation plays
a role in the increased cardiovascular risk in shift-workers is not
known and literature shows conflicting results. In a shift-work field
study we assessed chronic cardiovascular risk using pulse wave velocity (PWV), associated metabolic biomarkers and social jetlag
(circadian disruption) in fast clockwise (CW) and slow counterclockwise (CC) rotating shift-workers. Day workers (DW, minimum 5
years of no shift-work) served as controls.
Method: Male steel workers (n = 77, 32 fast clockwise (CW),
30 slow counterclockwise (CC), 15 day workers (DW); mean age
42 ± 7.6 yrs) provided information about demographics, health,
stimulant consumption, sleep timing, social jetlag and chronotype
(phase of entrainment). PWV, blood pressure (BP) and heart rate
(HR) was collected (08:00-12:30) in controlled posture conditions
(no caffeine/smoking/exercise) in 63 workers. Forty of these
workers (15 CW, 16 CC, 9 DW) provided fasting blood samples
(06:00-08:00) for plasma glucose, insulin, vitamin D, apolipoproteins A and B (ApoA, ApoB), high and low density lipoproteins
(HDL, LDL), total cholesterol (tCH), non-esterified fatty acids
(NEFA), homeostatic model assessment (HOMA, to quantify insulin resistance and beta cell function), triglycerides (TG), minimally oxidized LDL (mox-LDL), C-reactive protein (CRP) and
interleukin-8 (IL-8).
Results: Shift-workers (CW+CC) and DW did not differ in age,
body mass index, waist-hip-ratio, BP, HR, stimulant consumption
and chronotype. Social jetlag was highest in shift-workers and varied with both morning, late and night shifts and with chronotype.
In all workers HR and social jetlag were significantly positively
correlated (covariate: age). Social jetlag and HR were significantly
positively correlated with ApoB and HR was significantly positively correlated with TG and tCH (covariate: age). The individual’s
shift-work load (ISL, based on work schedule, shift-working years
and social jetlag) was significantly associated with PWV (covariates: age and BP). PWV was not different between CW and CC.
Glucose and HOMA were significantly lower in CW compared to
DW and CC (ANOVA). There were no differences in insulin, vitamin D, ApoB, HDL, LDL, tCH (ANOVA), NEFA, ApoA, TG,
mox-LDL, CRP, IL-8 (Kruskal-Wallis) levels between the three
groups.
Conclusions: This study shows that social jetlag is associated
with increased HR and PWV in shift-workers. There was no difference in PWV between clockwise and counterclockwise rotators.
Why fasting glucose and HOMA was lowest in CW workers remains to be clarified. Future studies of shift-workers in different
shift rotations are warranted to understand better the differential
effects of shift-work on individual shift-workers and their health
indices.
Funded by the DFG (German Research Foundation) and the 6th
Framework Project EUCLOCK (018471)
26
Nutrition, Metabolism and Physical Activity
TS 6.1
PHYSICAL ACTIVITY AND IRREGULAR-SHIFT
WORK: CARDIOMETABOLIC ASPECTS
Marqueze EC, Moreno CRC
School of Public Health, University of São Paulo, Brazil.
[email protected]
Introduction: Shift work is associated with a high prevalence of a
number of diseases, including cardiometabolic diseases, such as obesity.
Methods and Results: In this study we review researchs concerning the relationships between physical activity and shift work. Earlier studies found little difference in the level of physical activity
between shift workers and day workers. Although shift workers had
a good knowledge about the importance of physical activity, they
also had greater difficulties implementing and maintaining an active
lifestyle. Possible increased perceived exertion and fatigue during
physical activity when this is performed at night or in the early
morning represents one of a multitude of barriers to maintain a
physical activity program. Other important factor for implementing
and maintaining an active lifestyle is lack of time. Indeed, there
is compelling evidence that shift work exerts a negative influence
on physical activity in some working populations. The relationship
between shift work and cardiometabolic diseases can in part be
explained by changes in lifestyle, such as lack of physical activity,
eating habits, especially the decline in meals and increase in energydense snacks, as well as changes in circadian patterns of metabolic
and appetite-related parameters. Obesity is more prevalent in shift
workers than day workers. Possible reasons why shift workers are
more overweight and obese than day workers when both groups
are moderately active, could be the benefits of physical activity in
lowering weight have not yet been confirmed in intervention studies in shift workers. For instance, it could be the case that physical
activity may actually exacerbate some of the problems associated
with desynchronization in shift workers, for example, post exercise
fatigue levels during a work period.
Conclusion: In our study with irregular-shift workers, the practice
of physical activity was not associated with reduced presence of
the cardiometabolic risk factors. In this case, moderate leisure-time
physical activity was insufficient to attenuate either the higher BMI
associated with this type of irregular-shift work or the level of
appetite-related hormone, as leptin.
Support: CNPq - 474199/2008-8 and CNPq - 200388/2010-0
TS 6.2
OVERTIME WORK AND PREVALENCE OF DIABETES AMONG JAPANESE WORKERS: J-ECOH STUDY
Imai T1, Kuwahara K2, Nishihara A1, Kochi T3, MiyamotoT4,
Nakagawa T5, Kabe I3, Mizoue T2, Dohi S6
Azbil Corp
National Center for Global Health and Medicine
3
Furukawa Electric Corporation
4
Nippon Steel & Sumitomo Metal Corporation
5
Hitachi, Ltd.
6
Mitsui Chemicals, Inc.
[email protected]
1
2
Introductions: Working long hours has been considered as a
potential health hazard, but its relation to the risk of diabetes is
unclear. The objective of this study is to investigate the association
between overtime work and prevalence of diabetes among Japanese
workers.
Methods: Study participants were 41,081 workers of four companies that participated in Japan Epidemiology Collaboration on Occupational Health (J-ECOH) Study and provided health checkup
data including self-reported information on overtime. Diabetes
was defined as 1) fasting glucose ≥ 126 mg/dL (7.0 mmol/l), 2)
HbA1c ≥ 6.5% (48 mmol/mol), 3) current use of antidiabetic drug,
or 4) self-reported physician-diagnosed diabetes. The prevalence of
diabetes was calculated according to overtime work (< 45, 45-79,
80-99, or ≥ 100 h/month). Logistic regression analysis was performed to obtain odds ratio of diabetes for each category of overtime
work with adjustment for age, sex, company, smoking status, and
body mass index.
Results: Comparing with the shortest overtime category
(< 45 h/month), the other categories showed a lower prevalence of
diabetes: 8.8%, 6.7%, 5.8%, and 7.0% for the shortest (<45 h/month)
through longest overtime category (≥ 100 h/month), respectively.
The corresponding multivariable-adjusted odds ratios (95% confidence interval) were 1, 0.87 (0.79-0.95), 0.80 (0.63-1.02), 0.93
(0.66-1.32), respectively. Stratified analyses showed that the association did not materially differ according to age, sex, body mass
index, shift work, smoking, sleep duration, alcohol drinking.
Conclusion: Contrary to prior expectation, long overtime work
was not associated with increased prevalence of type 2 diabetes
in a large Japanese working population. Rather, a slightly lower
prevalence of diabetes was observed among workers who worked
long overtime.
Support: This study was supported by grants from the Occupational Health Promotion Foundation and the Industrial Health
Foundation.
TS 6.3
EXPOSURE TO NIGHT WORK AND BODY MASS INDEX AMONG BRAZILIAN NURSES
Griep RH1, Bastos LS3, Fonseca MJM2, Silva-Costa A1,2, Portela
L F1, Toivanen S4, Rotenberg L1
Laboratory of Education on Environment and Health, Fiocruz, Brazil;
National School of Public Health, Fiocruz, Brazil;
3
Scientific Computation Program, PROCC-Fiocruz, Brazil;
4
NCC Property Development AB, Sweden.
[email protected]
1
2
Objective: The aim of this study is to investigate the relationship
between exposure to night work and body mass index (BMI) among
registered nurses.
Methods: A cross-sectional analyses was performed comprising
2,411 nurses (2,134 women and 277 men) at public hospitals in
Rio de Janeiro, Brazil. They completed a comprehensive questionnaire with data related to socio-demographics, professional work,
as well as health habits and lifestyles. The night shift variable was
defined as the number of years of exposure to night work. Both
exposure to night shift (past and current night work) and BMI
were measured as continuous variables. To establish the association, a gamma regression model was used with identify link function. Residual analysis was performed to check the adequacy of the
model. Data were analyzed using the free software R, version 2.15
(R Development Core Team, Vienna, Austria).
Results: The association between BMI and time of exposure to
night work was statistically significant for both women and men
after adjustment for co-variables: β = 0.034 [0.006, 0.061] and
β = 0.080 [0.021, 0.138], respectively. In the final model, considering all co-variables in the reference values, the estimated BMI
for female workers was 24.7 [24.2, 25.2] for those who have never
27
worked at night. After 10 years of night work, the BMI increased
to 25.1 [24.6, 25.5]. Among men the estimated BMI was 25.4 [24.1,
26.7] for those who have never worked at night; after ten years of
exposure to night work the BMI increased to 26.6 [25.5, 27.7].
Conclusion: Findings suggest that night shift plays a role in the
increase of BMI. Prevention strategies should be based on educational programs aimed at dealing with lifestyle challenges associated
with night work. Further studies are needed to understand
biological mechanisms and the complex behavioral and social
changes experienced by night-shift workers.
TS 6.4
SHIFTWORK, METABOLIC DYSFUNCTION AND
SAFETY: A REVIEW
Tucker P1, Folkard S2
Department of Psychology, Swansea University, United Kingdom & Stress
Research Institute, Stockholm University, Sweden;
2
Université Paris Descartes, France & Department of Psychology, Swansea
University, United Kingdom.
[email protected]
1
In the past researchers appear to have assumed that the adverse effects
of shiftwork on safety were solely mediated by the acute effects of sleep deprivation and/or circadian disruption. Indeed we have previously
reviewed many of the acute trends in safety associated with various
features of shift systems (Folkard & Tucker 2003) and have used these
to develop a “Risk Index” to predict the likely impact of any given shift
system (Folkard & Lombardi 2004). However, while it would appear
that such an index may be useful to compare the relative safety of different shift systems, it would now appear that it may considerably underestimate the overall risk associated with shiftwork compared to that of
day work. Thus a growing number of studies have compared the risk
of day and shift or night workers and have found odds or hazard ratios
that are substantially higher than those that would be predicted from
the Risk Index. Further, there is increasing evidence that the odds or
hazard ratio for shift versus day work may be even higher if only more
serious injuries are considered (Violanti et al. 2012).
This pattern of findings suggests that shift and night work may also
be associated with a chronic increase in risk, although the mechanism(s) underlying such an increase are obscure. There is some evidence
that shiftwork may chronically impair cognitive abilities (Cho et al.
2000; Rouch et al. 2005) but again it is unclear how such impairment
may be mediated. The present paper will explore the possibility that at
least some of the chronic impairment of safety may be mediated by
the increase in metabolic dysfunction that has been fairly consistently
observed in epidemiological studies. It will briefly review the evidence linking (i) shiftwork and safety, (ii) shiftwork and constituents of
metabolic dysfunction, (iii) metabolic dysfunction and safety. It will
attempt to assess the extent to which the chronic impairment of safety in shiftworkers, and especially nightworkers, may be mediated by
metabolic dysfunction, and whether this in turn might be mediated
by the shortened sleep durations of shiftworkers.
REFERENCES
Cho, K., Ennaceur, A., Cole, J. C. & Suh, C. K. (2000). Chronic ‘‘jet lag’’ produces cognitive deficits. Journal of Neurosciences, 20, 1-5.
Folkard, S. & Lombardi, D.A. (2004). Towards a “Risk Index” to assess work
schedules. Chronobiology International. 21, 1063-1072.
Folkard, S. & Tucker, P. (2003). Shiftwork, safety and productivity. Occupational Medicine. 53, 95-101.
Rouch, I., Wild, P., Ansiau, D. & Marquié, J-C. (2005). Shift work experience,
age and cognitive performance. Ergonomics, 48, 1282-1293.
Violanti, J.M., Fekedulgen, D, Andrew, M.E., Charles, L.E., Hartley, T.A., et al.
(2013). Shift work and long-term injury among police officers. Scandinavian Journal of Work, Environment & Health, online first. doi:10.5271/
sjweh.3342
Workshop
Experiences With Resistance of Workers
Towards Change and How to Address it
W1
RESISTANCE OF WORKERS TOWARDS CHANGE:
HOW COMMON TO NURSING PERSONNEL?
Korompeli A
Faculty of Nursing, University of Athens, Greece
[email protected]
Working around the clock is common for many occupations, as
nurses. Working shifts for nurses is something inevitable. Shift is a
complex scheduling problem that affects nurses’ life on a daily, weekly and annually basis. A high quality roster should be the balance
between workload among nursing personnel and their preferences,
in order to succeed effective workforce.
In this presentation, there is an attempt to quote the experience
having the role of planning shift rotas for nursing personnel. In
the most greek hospital settings, personnel scheduling problems are
solved manually, which a very time consuming task and challenging
because of different staffing needs on different days and shifts.
This presentation is about Cardiological Care Unit of 12 beds, with
the following members of staff: 1 head nurse, 13 regular nurses, 1
caretakers.
Greek nurses work 8h shift rotas, 40h per week in three shift
types, morning (7.00-15.00), afternoon (15.00-23.00) and evening
(23.00-7.00). Every Tuesday, the head nurse has the obligation to
create a roster programme for the next week.
The main criteria followed for the scheduling part of the shifts
rotas, based on artificial intelligence methods and organizational
structure and characteristics are:
• the coverage of the shift, meaning the scheduled number of
nurses needed for a shift
• how fair is the schedule for all operating personnel
• stability, meaning how the nurses perceive the schedules (in
terms of consistency, predictable on/off days and weekend
work).
• flexibility and compliance: how well the rotating shifts can
adapt to changes like absenteeism, maternal live.
• individual differences towards to shiftwork
However, as it is human nature to resist, there were some complaints.
Most of nurses expressed their worries in casual conversations with
their colleagues or the head nurse. The main reasons for complaints
are when working hours did not fit well with family and social
commitments and cultural activities outside work and personnel
suffer from social jetlag.
The experience gained from scheduling shift rotas for nursing
personnel can be summarized to the following statements:
• straight forward discussions with the operating personnel in
terms of what they think of the working shifts, to learn what
is expected of the head nurse
• the head nurse should create the right expectations for the personnel in the real hospital situations
• the development of a decision support technology that can
deal with the uncertainty and unforeseen circumstances such
as staff sickness and emergencies.
• Finally, it is impossible in practice to satisfy all the constraints.
Consequently, requirements are treated in order of importance.
28
W2
SHIFT AND NIGHT WORK: PERSPECTIVES ON
DIFFICULTIES WITH INTERVENTION
Mello MT
Universidade Federal de São Paulo - UNIFESP, Brazil
Centro de Estudos em Psicobiologia e Exercício - CEPE, Brazil
[email protected]
The aim of this presentation is to demonstrate the primary difficulties
with intervention among companies that rely on shift or night work.
The data for this presentation are based on companies that contact
the Multidisciplinary Center for the Study of Drowsiness and Accidents (Centro Multidisciplinar em Sonolência e Acidentes - CEMSA) to develop partnerships or arrange for services. Agreements or
work contracts are drafted to specify CEMSA’s actions, which can
include assessments and interventions in the areas of psychology,
social work, nutrition, work shifts, fatigue, and education. Information on workers and their families is also collected.
The most critical point of an intervention is a company’s identification of what is needed from CEMSA. Another critical point is that
companies often fail to measure the costs of accidents that can be attributed to reductions in the physical or cognitive/mental abilities of
workers. Companies tend to display low levels of understanding of
the potential benefits that CEMSA can provide for company profits
(cost-benefit ratio), which may be related to workers having little education and little experience outside of their company. The CEMSA
process begins with a diagnosis and assessment of a company’s situation. The next step is a proposal for an intervention and suggestions
for smaller company policy changes, such as shift changes or changes
to social conduct. The company must be prepared to receive the suggestions and, when necessary, to alter company policy.
Companies do not always effectively communicate the role of
CEMSA to their employees, and therefore, employees generally fail
to report their difficulties because they are afraid of losing their
jobs or being negatively impacted by the data that CEMSA collects.
The data may show that employee lifestyles are incompatible with
the work and rest times that are required for the professional activities to be safely conducted.
Thus, there is the need for continuous educational development of
workers and their families. In relation to shift and night work, all
parties must understand safe behavior and appreciate workers’ need
to obtain proper rest at home.
Acknowledgements: The authors acknowledge the Research Incentive Fund Association (Associação Fundo de Incentivo à Pesquisa - AFIP), Multidisciplinary Center for the Study of Drowsiness
and Accidents (Centro Multidisciplinar em Sonolência e Acidentes
- CEMSA), and Center of Studies in Psychobiology and Exercise
(Centro de Estudos em Psicobiologia e Exercício - CEPE).
W3
SHIFT YOUR WORK: TOWARDS SUSTAINABLE
WORK PARTICIPATION BY NEW SHIFT SYSTEMS,
EXPERIENCES FROM THE NETHERLANDS
van de Ven HA1, van der Klink JJL1, Koolhaas W1, Brouwer S1,
Bültmann U1, Goudswaard A2, de Looze MP2, Shaw WS3
University of Groningen, the Netherlands
TNO, Hoofddorp, the Netherlands
3
Liberty Mutual Research Institute for Safety, USA.
[email protected]
1
2
Aim and background of the project: In view of ageing worker populations and signs of decreasing shift work tolerance with increasing
age, four industrial companies with 24/7 production locations in the
Netherlands agreed to participate in the on-going ‘Shift Your Work’
study. The aim of the project is to increase sustainable work participation by designing and implementing new shift systems.
Main steps of the project & your role in that project: The project
was set-up to 1) sent out a baseline questionnaire to assess current
health status, work functioning, work-family conflict and the need
for a roster change among N = 650 (response N = 432 (66.5%)) shift
workers of four different companies with a special focus on older
workers, 2) discuss the possibilities of a roster change based on the
results of the baseline questionnaire, and 3) design and implement a
new roster (if applicable). The presenter was the contact person for
all four companies and was/is involved in all steps of the project.
How & when became the resistance visible - what were explicit reasons for resistance, what are the reasons you assume?
Resistance of workers became visible when asked about possible
consequences of a roster change. Although 30% (N = 127) of the
shift workers indicated they would like individual adjustments of
their roster, only 23%-33% (N = 28-42) of them would still consider an adjustment if it would affect their salary, job content or
workplace. Resistance might be further affected by new regulation
allowing less opportunities for older workers to retire early or (partially) withdraw from burdening shifts. Besides, roster preferences
are highly individual, complicating a possible roster change process.
What were the consequences of the resistance, how did the
project develop? The results of the baseline questionnaire were
reported back to the management. The management of three
companies postponed a roster change for the moment, due to 1)
comparable scores of older and younger workers on health status,
work functioning and work-family conflict, 2) a lack of workers
aged 60 years and older (due to previous regulation allowing early
retirement) and 3) harsh economic times. One company wanted to
further explore possibilities of implementing flexible shift systems.
At the time of writing this abstract, a proposal of a flexible shift
system pilot is being prepared.
What can we learn from these experiences for future
projects: Roster changes can affect workers in many ways, besides
new working times. To overcome resistance of workers, proposals
should therefore be presented in a clear manner including all consequences and without hidden agendas. However, change processes
are time consuming due to involvement of several organizational
levels (e.g. production management, human resources, workers) and
a little bit of luck is needed in terms of beneficial economic times.
W4
EXPERIENCES WITH RESISTANCE OF WORKERS
TOWARDS CHANGE AND HOW TO ADDRESS IT CASE AMBULANCE SERVICE
Gaertner J
XIMES GmbH & Vienna University of Technology, Austria
[email protected]
1. Company/organisation & setting: A small ambulance service
was forced to rethink its schedules for several units due to legal
issues. Management was under pressure to react.
2. Project aim and personal role: The management wanted a new
schedule that was fine in legal terms. In addition the schedule should be healthier and more employee friendly. We were
asked for an offer as external consultants.
3. Project plan, proposed steps (and a rational for these steps):
We suggested a three-step plan that concentrated work on a
few days in the company in order to be fast and to focus our
energy
• In a first step, a four-hour workshop, we introduced ourselves
and discussed the project plan as well as what information regarding the status quo was needed
29
•
•
4.
5.
6.
7.
In a second step, the data was collected and analysed.
The third step consisted of six short meetings with approx. 15
participants each in two days (“Power-Sessions”). Time between meetings was used to write the minutes, rethink things, prepare the following meeting, etc. As learned in earlier projects,
two consultants are needed to run such meetings efficiently.
How where employees involved, what was the resistance? The employees were represented by employee representatives
in these meetings. Middle managers from units concerned participated directly in the meetings.
Discussed reasons for resistance and discussed options to address it? - The main fears of employees were loss of jobs or
loss of income (less overtime). Both issues were addressed in
the first meeting. The CEO guaranteed jobs and some overtime
How did the project develop? - The project developed as
planned regarding the development of schedules. It needed
an additional meeting, step four, (including preparation by the
consultants) to develop a joint understanding of future planning processes (i.e., how should draft schedules be refined to
consider leave, additional tasks, etc.).
Two important lessons learned - Key factors for success/failure: It seems that clarifying financial and job issues early on in
the process reduced resistance tremendously. Concentrating
the design process on a short period of time helped to keep
persons involved.
Oral Session 1
New Trends in Working Hours
OS 1.1
ON THE INTERRELATIONSHIPS BETWEEN WORK
HOURS, TIME-SPATIAL FLEXIBILITY, SWITCHING
OFF, SLEEP, RESTITUTION AND HEALTH AMONG
“NEW” EMPLOYEES IN KNOWLEDGE INTENSE
WORK IN SWEDEN
Mellner C1, Toivanen S2, Keller Celeste R3
Department of Psychology, Stockholm University
CHESS (Centre for Health Equity Studies), Stockholm University/Karolinska
Institute,
3
Instituto Medicina Social (IMS), Universidade Estadual do Rio de Janeiro,
Brazil
[email protected]
1
2
Intoduction: During the past decades profound changes have
taken place within working life where established domains and
boundaries between work and private life have been challenged by
increasing global competition and ever faster changing markets.
This has led to more flexible forms of work organization and to
a rapid development of boundary transcending information- and
communication technologies (ICT). ICT make mobile and boundaryless work possible for an increasing number of individuals,
described as the emergence of the 24/7 society. As such, more and
more work is performed outside regular work hours and at other
places than the traditional work place. This is the case especially for
the “New Employees” working within knowledge intense sectors
under so-called ‘New Working Conditions’ which are characterized by professional job autonomy, project based team work, management by objectives, and strict deadlines. This modernization of
work organization has not only led to more freedom for employees
in terms increased time-spatial flexibility regarding work, but also
to an ongoing intensification of work. Under these working conditions time-spatial flexibility may have negative consequences in terms of work-related stress spilling over in employees’ private lives.
Blurred boundaries make it less easy for employees to free themselves from work. Hence, time-spatial flexibility might make it easier
to work overtime or to ponder over work during family or leisure
time. This, as a consequence, may contribute to insufficient time for
rest and restitution and subsequent poor health.
Purpose: We set out to explore the interrelationships between
work hours, time-spatial flexibility, switching off from work, sleep,
restitution and health among employees in knowledge intense work
in Sweden. Path analysis using regression was conducted for examining the interrelationships between amount of hours worked per
week, time-spatial flexibility in terms of when and where work is
performed, switching off from work on leisure, sleeping problems,
restitution and health complaints.
Design: In 2010 a web-questionnaire was sent to all employees at a
work unit (n = 1238, response rate 65 %) at an international telecom
company in Sweden. 27.4 % were females and the mean age 41.2 years.
Results: In the path analysis, poor restitution and health complaints
were directly related to inability to switch off mentally from work
during leisure and to sleeping problems. They were indirectly related,
through the inability to switch off, to long work hours and high time
-spatial flexibility, i.e., working boundaryless in time and space.
Conclusion: Results are of value for health promotion in flexible work organizations to support employees to achieve successful
boundary management and subsequent restitution and health.
OS 1.2
HEALTH EFFECTS OF SUPPLEMENTAL WORK
FROM HOME IN THE EUROPEAN UNION
Arlinghaus A, Nachreiner F
Gesellschaft für Arbeits-, Wirtschafts- und Organisationspsychologische
Forschung (GAWO) e.V., Germany
[email protected]
Work organization in developed industrial societies has changed
towards higher temporal and spatial flexibility of work. At least for
certain occupations, new communication technologies (e.g., email,
cell phones) contribute to the blurring of boundaries between work
and personal life by offering the possibility to be available always
and everywhere. Being contacted for work-related matters outside of regular/normal working hours and working in the free time
(as indicators for “supplemental work”, in addition to the regular
working time) may lead to long working hours, interrupt and reduce
time for recovery from work-related strain, and could potentially
lead to an interference of work with biological and social rhythms
needed for recovery, sleep, and social participation. However, little is known about how supplemental work affects worker health
and well-being. Therefore, this research question was addressed in
a secondary analysis of the European Working Condition Surveys
2005 and 2010, which are cross-sectional, publicly available surveys
representative of the workforce in all European member states.
A total of n = 23,760 employees (2005) and n = 34,460 (2010) were
included. Both surveys contained variables on self-reported demographic characteristics, working conditions, working hours, and several
health outcomes (different work-related health problems, sickness absence, and occupational accidents in the last year). In 2005, information
was available about the self-reported frequency of work-related contacts outside of regular working hours. In 2010, a different question
was asked about the self-reported frequency of working in the free
time in order to meet work demands. Multifactorial logistic and linear
regression models were estimated to predict the health outcomes by
(1) being contacted outside of regular working hours (in 2005) and (2)
working in the free time (in 2010), controlling for demographic characteristics, working conditions, and several working hour characteristics
(e.g., control over working times, working hrs/week, variable working
hours, unusual working t imes, and shift work).
30
The findings indicated an increase in the risk of health impairments
for employees reporting to be sometimes or often contacted by their
employer outside of their regular working times (in 2005), and for
workers who frequently worked in their free time to meet work demands (in 2010) in comparison to workers with no contacts and no
work in their free time. Both predictors showed a structurally similar
relation to reported health outcomes, and therefore seem to measure
two different dimensions of the construct “supplemental work”.
Thus, regulating the amount of supplemental work could be a strategy to decrease the risk of health impairments in employees and to
sustain work ability over the course of the working life. However,
additional research quantifying the actual time use and extent of
supplemental work is necessary to estimate the potential underlying
effect pathways.
OS 1.3
THE COMING OF 24/7 SOCIETY? TRENDS IN TIMING OF WORK IN 1987-2010 IN FINLAND
Oinas T1, Anttila T1, Nätti J2, Hartikainen A1
Department of Social Sciences and Philosophy, University of Jyväskylä,
Finland
2
School of Social Sciences and Humanities, University of Tampere, Finland
[email protected]
1
Objectives: There is much discussion about the changing boundaries of work and private life accompanied with the thesis of
emerging 24/7 society. This is often conceptualized as change
from industrial to post-industrial working time regime. The normal
working time i.e. approximately 8 hour working day with daytime
work and free weekends is characteristic to the industrial working
time regime. The hypothesized post-industrial working time regime is by contrast usually characterized by deregulation of collective
norms and consequently diversification of the length and pattern
of working time. There are however surprisingly few studies addressing the tenability of this hypothesis. Our study will address
this issue by using large scale representative national surveys with
detailed time use diaries covering over two decades in Finland.
Methods: The data consists of three Finnish time use surveys
(FTUS) covering over two decades (1987-1988, 1999-2000, 20092010). The FTUS is a representative national sample-survey, in which
participants keep accurate records of their time use (in 10 minutes
periods) for two 24 hours periods. Using diary information we will
examine changes in the prevalence of working at unsocial hours in
both 24 hours (after 6 pm) and seven days (weekends) cycle. The
analysis was restricted to employees and working days (n = 8192).
We use multivariate logistic models to analyze the effects of survey
year on the prevalence of working outside normal working time controlling for different background factors (sex, age, marital status, children, and education). In addition, analyses are conducted separately
for sub-sample of employees working regular day hours.
Results: According to results the share of employees working after
6 pm increased from 33% in 1987 to 46% in 1999, but decreased
slightly by 2009 to 42%. We found no significant change in the share
of employees working at night (between 11 pm and 6 am). However,
working at evenings (from 6 pm to 11 pm) increased clearly between
1987 and 1999, but decreased by 2009. Similarly, the share of employees working at weekends increased from 29% in 1987 to 52% in
1999. Again, there was slight decrease in weekend work from 1999 to
2009. These changes were mainly due to the increase in working at
Saturdays. Differences between survey years stayed significant after
adjusting for covariates and working time arrangement.
Conclusion: According to our results there is evidence of increase
in working at unsocial hours both at 24 hour cycle and seven days
cycle between 1987 and 2009 in Finland. However, during last decade there has been significant decline in the prevalence of unsocial
working hours. Results support to some degree the hypotheses of
change from industrial towards post-industrial working time regime
and a 24/7 society. However, results also indicate that Finland has
reached a turning point in this development.
OS 1.4
DOES CHANGING SHIFT SCHEDULES INFLUENCE THE RISK OF WORK INJURY?
Wong I1, Smith P1,2, Mustard C1, Gignac M1
Institute for Work & Health, Canada
Monash University, Australia
[email protected]
1
2
Evidence has shown that night-shift workers have an increased risk
of work injury in comparison to daytime workers. It has been speculated that awake during normal sleeping hours may contribute to
fatigue and thus increase propensity for work injury. Therefore, it
could be postulated that a shift schedule change may affect fatigue
and influence risk of work injury.
The objective of this longitudinal study was to examine the risk
of work injury with shift schedule change. Secondary analysis of
Statistics Canada’s Survey of Labour and Income Dynamics, a national survey of labour market activity, was completed. The main
outcome measure, occurrence of work injury, was defined using the
receipt of workers compensation. Respondents were followed over
3 years to assess changes in shift schedule between 2008 to 2009
and receipt of injury compensation in 2010.
Four categories of shift change were developed: day-shift only, day- to
night-shift, night- to day-shift, and night-shift only. We hypothesized
those who switched from day- to night-shift work would be at the
greatest injury risk in comparison to those who remained in only day
or night-shift work. Those remaining in night-shifts for long periods
may represent a survivor bias. We also hypothesized that switching
from night- to day- shifts may improve fatigue and lessen work-injury
risk in comparison to those who switch from day to night.
Multivariable logistic regression was used to examine the risk of
work injury by shift change. Potential confounders included age,
sex, education, household income, job permanency, weekly hours
worked, job tenure and physical requirements of the job.
Among our study population, 60.9% remained in day-shifts, 7.6% switched from day to night, 8.0% switched from night to day and 23.3%
remained in night-shifts. Regression results showed that in comparison
to those who remained in day-shifts in 2008 and 2009, the highest risk
of work injury was among those who switched from night- to day-shift
(OR 1.64, 1.02-2.94) followed by those who remained in night shift
(OR 1.41, 1.05-2.02). Differences in the risk of injury between those
who switched from day - to night-shift (OR 1.20, 0.67-2.13) and those
who remained in day-shifts were not statistically significant.
Our results were contrary to our hypotheses. Workers who switched from night - to day-shifts may have included those who were
unable to adapt to night-shifts and could have been the least healthy of all workers, increasing their risk for work injury. Those who
switched from day- to night-shifts may have benefitted from protective effects of day-shift work. Our short follow-up period may
not have been sufficient to examine long-term patterns in work-injury risk following a schedule change. Future studies should consider a longer follow-up period to gain a better understanding of
fluctuations of injury risks over time.
31
OS 1.5
OS 1.6
APPLICATION OF KNOWLEDGE TRANSFER IN
MAKING SHIFTWORK RESEARCH RELEVANT AND
ACCESSIBLE TO AN UNPREDICTABLY SCHEDULED RAIL WORKFORCE
Snow JZ1, Popkin S1, Howarth H1, John A2, Coplen M3
PRACTICAL GUIDELINES FOR IMPROVING WORKING TIME ARRANGEMENTS AND JOB CONTENT
OF HEALTH CARE WORKERS
Kogi K1, Yoshikawa T2, Hosaka T2, Michinaga M2, Imamura S2
Human Factors Research and System Applications Center of Innovation at
the U.S. Department of Transportation (DOT) , USA
2
Volpe National Transportation Systems Center (Volpe)
3
Federal Railroad Administration, DOT, USA
[email protected]
1
Introduction: Many terms describe the process of putting knowledge into action. In the United Kingdom and Europe, the terms
“implementation science” or “research utilization” commonly are
used. In the United States, such terms include “diffusion,” “research
use,” and “knowledge transfer.” Canadians use the terms “knowledge transfer,” “knowledge exchange,” and “knowledge translation.”
The focal elements across the different terms are knowledge and
its movement beyond simple dissemination to the use of specialized knowledge. To address the Symposium theme, this session will
discuss the inextricable connection between knowledge production
(research/development), knowledge transfer (education/use), and
knowledge impact (behavior/action) in relation to the critically important subject of fatigue in safety-sensitive transportation jobs.
Specifically, the Railroaders’ Guide to Healthy Sleep website, a suite
of multimedia tools and resources for on-call railroad shiftworkers,
will be presented as an applied example of the “knowledge triad.”
Methods: Despite nearly a century of research on how the human
body, mind, and subsequently, health and performance are affected
by hours of work and the related wake-rest schedule, a fundamental gap exists between our understanding of basic research and the
successful application of that basic research to industrial and field
settings. To bridge that persisting gap between research and action, a
key question remains: What are the best practices when applying the
current science to inform workers and decision makers? Methods
and approaches employed in the case example include target-audience needs assessment; “think-aloud” user testing, stakeholder-panel
review, and website analytics. The multiple-method approach is
systematic and purposeful and contributes to the evaluation of the
website development, implementation, and use to inform decision
-making about the improvement and success of such investments in
knowledge-transfer products. Currently, the communications strategies, such as outreach and dissemination, aim to increase awareness
of the website as a sleep-health resource based on medical research.
The long-term project goals and evaluation intend to understand in
what ways and to what extent the website increases knowledge and
behaviors about sleep science, health and hygiene.
Results: Since project inception, a vertical-integration strategy has
fostered “buy-in” across stakeholders. The involvement of sponsors, content experts, researchers, administrators, evaluators, and
workers has been integral to project fruition. Moreover, a collaborative network has emerged and is contributing to knowledge-transfer
penetration across the railroad industry.
Conclusion: Knowledge translation strategies may vary according to
the targeted user audience, e.g., shiftworkers, managers, policy makers, and public, and the type of knowledge being translated, e.g., clinical, biomedical, and policy. Understanding of the different decision
makers, their needs, and the context for decision making is essential
before embarking on any knowledge translation strategy. Although
the specific example is primarily transportation-related, the themes
of knowledge transfer, “knowledge triad,” and measuring impact of
science and implementations are useful for all domains.
Institute for Science of Labour, Kawasaki, Japan
Japan Medical Association, Tokyo, Japan
[email protected]
1
2
Objective: Multifaceted workplace actions are usually needed
to improve complex working time arrangements of health care
workers. A range of practical actions are essential to address staffing problems, heavy workload, teamwork quality and patient safety.
Recent experiences in developing action-oriented guidelines for
multifaceted improvements of health care conditions are presented
to discuss practical types of improvements useful for improving
work schedules and job content together.
Methods: Recent experiences in developing health care work
redesign procedures for improving working time and job design were reviewed. Based on survey results on views of health
care workers about required improvements, we assisted a project team on health support measures for health care staff in
developing practical guidelines for implementing locally effective measures. The results of applying an action-oriented checklist for improving workplace conditions of physicians and
nurses were examined to work up a set of practical guidelines
addressing both working time and job content.
Results: The project team summarized support measures required for improving health care work conditions with a focus
on accessible working time arrangements. The team identified
a range of workplace needs concerning workload, job stress,
shift schedules and social support. This led to the formulation
of an action-oriented checklist for proposing adequate support
measures in each local situation. The checklist covered multifaceted support measures including work schedules, ergonomic
and psychosocial factors, social support and work-life balance
aspects. A special attention was paid to the compliance with
working time regulations often found difficult in health care
settings. The results of applying the checklist in a number of
hospitals and clinics revealed that the multifaceted support
measures should be taken for (i) securing sufficient resting periods between and within shifts in addition to avoiding excessive overtime, (ii) improving both physical and psychosocial
strains at work, (iii) protection from violence and harassment,
and (iv) support for improving work-life balance. As a result,
practical guidance materials have been distributed nationwide
to health care facilities summarizing available options for improving both working time and job content, including psychosocial factors. It is suggested to promote the use of “action
checklists” and the participatory approaches to stepwise improvements while addressing both working time and job contents in the local context.
Conclusion: In developing practical guidelines for working time
arrangements of health care workers, it was confirmed essential
to emphasize a range of support measures effective for improving both work schedules and job content including psychosocial
factors. In particular, the guidelines that focus on support for stepwise progress towards decent work time and better job content
by active participation of health care workers.
32
Oral Session 2
Working Hours and Sleep
OS 2.1
SHIFT-ROTATIONS WITH LESS THAN 11 HOURS
REST PERIODS PREDICT SHIFT WORK DISORDER,
EXCESSIVE SLEEPINESS AND PATHOLOGICAL FATIGUE IN NURSES AT ONE YEAR FOLLOW-UP
Flo E1, Pallesen S1,2, Moen EM2, Waage S1,2, Bjorvatn B1,2
Norwegian Competence Center for Sleep Disorders, Haukeland University
Hospital
2
University of Bergen, Norway
[email protected]
1
Introduction: We investigated whether annual number of shifts
separated by less than 11 hours (quick returns) could predict sleep and
health problems one year later.
Methods: 1224 nurses responded to a questionnaire-based survey in
2009 (T1) and 2010 (T2). Crude and adjusted logistic regression analyses were completed to assess the association between annual number
of quick returns at T1 and each of these dichotomized outcome variables at T2: Shift Work Disorder (SWD), excessive sleepiness (ES;
Epworth Sleepiness Scale, > 10), pathological fatigue (Chalder Fatigue
Scale, summed binary scores > 4), and anxiety and depression (Hospital Anxiety and Depression Scale, each > 8) controlling for age, gender,
the outcome variable in question at T1, number of nights at T1, and
change in quick returns and night shifts from T1 to T2 (no change
± 5 days, increased or decreased). Significance was set to p < 0.05.
Results: The following results are based on the adjusted analyses:
The number of quick returns at T1 was related to an increased
risk of SWD at T2 (OR = 1.01, 95% CI = 1.00-1.01). A decreased
number of quick returns (OR = 0.62, 95% CI = 0.43-0.91) from
T1 to T2 was related to reduced risk of SWD at T2. The number
of quick returns at T1 was not associated with ES, however, a decrease in quick returns from T1 to T2 entailed a reduced risk of
ES at T2 (OR = 0.68, 95% CI = 0.47-0.99). The number of quick
returns at T1 entailed an increased risk of pathological fatigue at T2
(OR = 1.01, 95% CI = 1.00-1.01). Decrease in number of quick returns from T1 to T2 showed a reduced risk of pathological fatigue
at T2 (OR = 0.60, 95% CI = 0.43-0.83). There was no association
between quick returns at T1 and anxiety or depression at T2.
Conclusion: The number of quick returns at T1 predicted SWD
and pathological fatigue at T2, while a decrease in quick returns
from T1 to T2 was associated with reduced risk of SWD, ES and
pathological fatigue at T2.
OS 2.2
THE IMPACT OF WORK SHIFT STARTING TIME ON
SLEEP PATTERNS AND ALERTNESS PRIOR TO INJURY IN THE PEOPLE ’S REPUBLIC OF CHINA
Lombardi DA, Jin K, Vetter C, Courtney TK, Folkard S, Arlinghaus A, Liang Y, Perry MJ
Liberty Mutual Research Institute for Safety, Harvard School of Public Health,
USA
[email protected]
Introduction: Early work shift start time and night shifts are associated with reduced sleep duration and poorer sleep quality, leading
to increased fatigue levels, performance decrements and adverse safety and health outcomes (Härmä, 1993; Tepas & Carvalhais, 1998;
Folkard & Lombardi., 2005; Willamson et al., 2011; Vetter et al.,
2012). This study investigates the impact of work shift starting time
on sleep patterns, including duration and quality, and time awake
until injury in a large epidemiological field study (Jin et al., 2012)
of hospitalized workers with severe work-related hand injury in the
People’s Republic of China (PRC).
Methods: Participants were workers admitted for treatment of a
sudden-onset, traumatic injury to the upper-extremity at two handsurgery hospitals and nine general hospitals in three industrially-developed cities in the PRC. Face-to-face interviews were conducted
at the hospitals using a structured questionnaire administered in
Chinese (cross-translated) by trained interviewers, collecting data
on work environment, equipment, practices, and worker-related exposures. Participants also reported timing of work schedules, time
and duration of rest breaks, injury date and time and for the two
previous sleep episodes prior to injury, their sleep start and wake times, sleep quality, and alertness/sleepiness. Parametric and non-parametric regression models compared sleep duration, sleep quality,
time awake until injury, in varying shift start times by 3h increments
across the 24h while adjusting for age, gender, daily hours worked,
shift duration, and day of injury.
Results: 703 hospitalized workers (96.4%) completed face-to-face
interview within 4 days of injury; 527 (75.0%) were male, with a
mean (± SEM) age of 31.8 ± 0.4 years. Overall, workers worked
relatively long weekly (55.7 ± 0.6h) and daily work hours (8.6 ±
0.07h). Average sleep duration before injury was 8.5h (± 0.07), and
showed significant variations (p-value < 0.05) across work shift increments, with shortest sleep among workers starting their shifts
from “21:00-23:59” (5.6 ± 0.8h) and “00:00-02:59” (6.1 ± 0.6h),
compared to the majority of workers who started their shifts from
“06:00-08:59” (8.7 ± 0.07h). Time from wake until time of injury
was 6.6 ± 0.2h, amongst this day-working group, while workers
who started their shifts later, i.e., “15:00-17:59” and “18:00-20:59”,
were awake for a significantly longer time (9.7 ± 0.6h and 9.7 ±
0.6h, respectively). Sleep quality (generally quite well) and alertness/
sleepiness (generally alert) did not significantly vary across increments of work shift time.
Conclusion: Results for PRC workers suggest sleep duration is
lowest among workers starting shifts late night and early morning
(21:00-02:59), in agreement with previous findings. However, with
more than 8.5h of sleep on average on work days, Chinese workers
slept much longer than typical US day workers (Sleep in America
Poll, 2012, 6:44 on workdays, 7:35 on free days), despite early work
starting times. Further analyses will examine potential reasons for
variation in sleep durations (i.e., impact of individual chronotype
and/or geographical location).
OS 2.3
SHIFT WORK DISORDER AMONG NORWEGIAN
NURSES
Waage S1,2, Pallesen S1,2, Moen BE1,2, Flo E2, Di Milia L3,
Bjorvatn B1,2
University of Bergen, Norway.
Haukeland University Hospital, Norway.
3
Central Queensland University, Australia.
[email protected]
1
2
Introduction: Shift work is associated with sleep problems and
negative health. Few longitudinal studies on shift work related
problems exist. The aim of the study was to assess shift work
disorder (SWD) after a two years follow-up, and to find predictors
associated with this diagnosis among Norwegian nurses.
Methods: 1533 nurses participating in a survey on shift work,
sleep and health responded to questionnaires including variables in
terms of insomnia (Bergen Insomnia Scale), sleepiness (Epworth
33
Sleepiness Scale), anxiety/depression (Hospital Anxiety and
Depression Scale) and circadian preference (Diurnal Scale) at
baseline and two years later at follow-up.
Results: The prevalence of SWD was 35.7% at baseline compared
to 28.6% at follow-up (p < .001). Adjusted logistic regression
analyses showed a significant association of having SWD at
follow-up and the following variables measured at baseline; number
of nights worked the last 12 months (OR = 1.01, 95% CI = 1.011.02), having SWD (OR = 5.19, 95% CI = 3.74-7.20), sleepiness
(OR = 1.08, 95% CI = 1.04-1.13), use of melatonin (OR = 4.20,
95% CI = 1.33-13.33), use of bright light therapy (OR = 3.10,
95% CI 1.14-8.39), and symptoms of depression (OR = 1.07, 95%
CI = 1.00-1.14). In addition, changing work hours from night work
at baseline to not having night work at follow-up also showed a
significant association (OR = 0.12, 95% CI = 0.07-0.22).
Conclusion: The prevalence of SWD in this population was
high, but still comparable to other studies. Possible predictors of
developing SWD over time were identified.
OS 2.4
GOT SLEEP? THE IMPACT OF EARLY MORNING
TRAINING ON THE SLEEP OF AUSTRALIAN ELITE
ATHLETES
Sargent C1, Lastella M1, Halson SL2, Roach GD1
Appleton Institute, CQUniversity, Australia.
Department of Physiology, Australian Institute of Sport, Australia.
[email protected]
1
2
Introduction: In many ways, elite athletes can be considered a special type of shiftworker. Not only are they required to train almost
every day, they train long hours and often start very early in the
morning. Data from hundreds of shiftworkers indicates that consecutive work days, long hours, and early morning starts significantly
reduce the time available for sleep, yet little is known about the
impact of training schedules on the sleep of elite athletes. This
appears to be a considerable oversight given that good sleep is essential in the preparation for, and the recovery from, high-intensity
training.
Methods: Data were collected from 70 elite athletes from seven
sports. Participants wore wrist activity monitors and completed
self-report sleep/training diaries for two weeks during normal training. Data from the activity monitors and sleep diaries were used
to calculate bedtime, get-up time and sleep duration. Data from
the training diaries were used to categorise sleep periods as one
of two types: a sleep period that preceded a training day or a sleep
period that preceded a rest day. The effect of day type on the sleep variables was assessed using mixed model analyses. A separate
analysis was conducted to examine the impact of training start time
on sleep duration.
Results: On nights that preceded training days, participants went
to bed at 22:30 ± 01:00h (mean ± SD), arose at 06:36 ± 01:12h and
obtained 6.5 ± 1.3h of sleep. On nights that preceded rest days,
participants went to bed at 23:30 ± 01:24h, arose at 08:12 ± 01:36h
and obtained 6.8 ± 1.7h of sleep. Statistical analyses revealed that
on nights prior to training days, bedtimes and get-up times were
significantly earlier, time spent in bed was significantly shorter and
the amount of sleep obtained was significantly less, than on nights
prior to rest days. There was also a marked effect of training start
time on sleep duration. For every hour that the start of training
was advanced from 09:00h to 05:00h, sleep duration was reduced
by ~30 min.
Conclusion: The major finding of this study is that the amount
of sleep obtained by athletes is greatly influenced by their training
schedule. On nights prior to training days, the athletes spent less
time in bed and obtained less sleep compared with nights prior
to rest days. Furthermore, sleep duration decreased as a function
of training start time. The greatest impact on sleep was observed
when training began at or before 06:00h. Prior to these sessions, the
athletes obtained only 4.8h of sleep. In the short term, this level of
sleep truncation could impair an athlete’s ability to train effectively,
and in the long term, may lead to illness or injury.
Support: This study was supported by the Australian Research
Council and the Australian Institute of Sport.
OS 2.5
SLEEP IN SHIFT WORK DISORDER: FINDINGS
FROM A FIELD STUDY
Vanttola P1, Härmä M1, Viitasalo K2, Hublin C1, Niemelä P2,
Sallinen M1, Virkkala J1, Puttonen S1
Development of Work and Organizations, Finnish Institute of Occupational
Health, Finland.
2
Finnair Health Services, Finland.
[email protected]
1
Introduction: Shift work disorder (SWD) is defined as complaints
of insomnia or excessive sleepiness associated temporarily with
work schedule overlapping the habitual sleep phase. Here we present the first results of an ongoing field study examining how sleep
of employees with SWD differ from their non-SWD controls in
connection with different shifts and days off.
Methods: The study involved 20 male shift workers from a technical maintenance unit of a Finnish airline company. We assessed
SWD with a 6-item questionnaire on symptoms of insomnia and
tiredness while working different shifts and after two weeks on holiday. Participants experiencing at least one symptom very often/
continuously in connection to shifts, but rather or very rarely/never
after two weeks on holiday were classified into the SWD group
(n = 14, average age 42.2 years, range 34-59). Participants experiencing at least five symptoms rather or very rarely/never on shifts
and during holidays served as controls (n = 6, average age 49.2
years, range 41-58). Subjective sleep was measured using questionnaires and a 3-week sleep diary. Objective sleep variables were collected using an actigraph during a three week period and a wireless
1-channel system recording sleep EEG from the forehead in connection with two morning shifts, two night shifts and two days off.
Results: The subjective and objective total sleep time did not differ
between the groups in general or on working days or days off. However
the SWD group evaluated their daily sleep need higher than the controls (average 8.0 and 6.5 hours, respectively, p < 0.05). They also experienced somewhat more stress (p < 0.05) and showed a trend toward
less flexible sleeping habits (p = 0.057). Reported awakenings before
the morning shifts, after the night and evening shifts and between the
days off were at a similar level between the groups. However, the SWD
group reported poorer sleep quality (p < 0.05) across all days. They also
reported longer sleep latencies (p < 0.05) and had lower sleep efficiency
(p < 0.05) before the morning shifts, after the night shifts and between
the days off. Nonetheless, the levels indicated rather good sleep quality
for both groups. By means of actigraphy, sleep latency differed significantly only on the days off (SWD: average 7.9 minutes, controls:
2.3 minutes, p < 0.05). Further, the SWD group showed longer EEG
based slow wave sleep latencies on the days off (28.7 minutes) than
the controls (9.5 minutes, p < 0.05). The other EEG measures did not
differ significantly between the groups.
Conclusion: Our results imply that although the amount of sleep of employees with suggested SWD does not significantly differ from their shift work tolerant colleagues, their recovery from a
work shift seem to be compromised by poorer sleep quality.
Support: The study was funded by The Finnish Work Environment Fund (111102).
34
OS 2.6
ARE TWO SLEEPS BETTER THAN ONE? THE IMPACT OF SPLIT WORK-REST SCHEDULES ON THE
AMOUNT AND QUALITY OF SLEEP OBTAINED
Roach G, Zhou X, Ferguson S, Dawson D, Sargent C
Appleton Institute for Behavioural Science, Central Queensland University,
Australia.
[email protected]
Introduction: In most shiftwork industries, consolidated schedules,
with a single work and rest period each day, are typically favoured
over split schedules, with two work and rest periods each day. Consolidated schedules are most common because it is widely accepted that
(i) a single consolidated sleep is more restorative than two split sleeps,
and (ii) it is less disruptive to employees’ family and social lives to
have one, rather than two, work periods each day. However, there are
several lines of converging evidence - e.g. from field studies, recovery
studies, napping studies, etc - to indicate that splitting work into two
periods and having two shorter sleeps each day may have some benefits. Therefore, the aim of this study is to compare the sleep obtained
by people operating consolidated and split work-rest schedules.
Methods: The participants in this study are healthy adult males
aged 18-30y. The study has a between-groups design consisting of
two conditions: (i) consolidated work-rest schedule, and (ii) split
work-rest schedule. Both conditions employ a forced desynchrony
protocol (i.e. 28-h ‘day’ length, dim light, no time cues) such that
sleeps occur across all circadian phases. In both conditions, the sleep:wake ratio is set at 1:2, equivalent to 8h in bed and 16h of wake
per 24-h day. The only difference between the two conditions is that
the consolidated condition has one sleep period (1 x 9.3h) and one
wake period (1 x 18.7h) every 28h, and the split condition has two
sleep periods (2 x 4.7h) and two wake periods (2 x 9.3h) every 28h.
Results: Data collection and analysis has been completed for the
consolidated condition (n = 14). For the split condition, data collection has occurred with 8 participants and 8 more will be recruited,
but no data analysis has occurred. In the consolidated condition,
participants obtained the equivalent of 7.2 (± 1.0)h sleep per 24h
day [mean(± SD)]; they had a sleep efficiency of 83.3(± 13.1)%;
and their sleep was structured such that 4.0(± 2.2)% was stage 1, 53.4(± 7.6)% was stage 2, 18.8(±5.3)% was slow-wave, and
23.8(± 5.7)% was REM. When data collection is completed for the
split condition, analyses will be conducted to determine whether
there are differences in the quantity and/or structure of sleep between the two conditions.
Conclusion: If split work-rest schedules are found to be effective at limiting the fatigue risk associated with shiftwork, by providing more sleep and/or sleep of better quality than that provided
by consolidated sleep-wake schedules, then they could be ideal in
work settings where shiftworkers are separated from their normal
family/social lives (e.g. fly-in fly-out mines) and/or where the need
for family/social time is secondary to the task (e.g. emergency responses to floods, bushfires, tsunamis, earthquakes, etc).
Support: This study was financially supported by the Australian Research Council.
OS 2.7
WORK STRESS, WORK HOURS AND SLEEP COMPLAINTS AMONG NURSING WORKERS
Benedito-Silva AA1, Silva-Costa A2, Griep RH2, Rotenberg L2
Programa de Mestrado em Modelagem de Sistemas Complexos, School of
Arts, Science and Humanities, University of São Paulo, Brazil.
2
Laboratory of Education on Environment and Health, Oswaldo Cruz Foundation,
Brazil.
[email protected]
1
Introduction: Sleep is known to be influenced by work life, including aspects related to work hours and job adverse psychosocial characteristics. The aim of this study was to examine the relationship between sleep complaints and factors related to work and
background/lifestyles among nursing teams.
Methods: A cross-sectional study was conducted at three public
hospitals in Rio de Janeiro, Brazil. All nursing teams engaged in assistance to patients (nurses, nursing assistants and nurse aides) were
invited to participate (n = 1509). A multidimensional questionnaire
was administered with questions about sleep complaints, such as
(i) insomnia (difficulty falling sleep, difficulty maintaining sleep
or early morning awakening), unsatisfactory sleep and insufficient
sleep. Information on work included work hours per week, work
schedule, the demand-control scale as well as a question on inability to free oneself of thoughts of work during leisure time, which
was supposed to be a link in the relation between stress and sleep.
Data on background/lifestyles, such as gender, age, marital status,
body mass index (BMI), smoking and physical exercise habits were
also included in the instrument. Multiple logistic regression models
were used to estimate adjusted odds ratios and their respective 95%
confidence intervals.
Results: The item representing inability to stop thinking about
work during free time yielded the highest odds ratio for all sleep
complaints (or = 2.50, or = 2.95 and or = 2.30 for insomnia, unsatisfactory sleep, and insufficient sleep, respectively). Long work
hours, night work and high work demands proved to be risk indicators for unsatisfactory sleep (or = 1.65, or = 1.71 and or = 1.48,
respectively) while physical exercises were associated with reduced
risk (or = 0.56). Insufficient sleep was also predicted by long work
hours, night work and high work demands (or = 1.88, or = 1.63,
or = 1.55, respectively). Physical exercises were associated with a
reduced risk for insomnia (or = 0.74). Work hours, work schedule
and job demands, which were associated with both unsatisfactory
and insufficient sleep, were not related to insomnia complaints.
Conclusions: Results confirm the inability to stop worrying about
work during free time as a relevant risk factor for sleep quality. Insomnia complains, usually used for population studies on sleep, is
not suitable to detect differences related to work hours and work
schedules, confirming previous results on night and shift workers.
OS 2.8
WHAT CHARACTERIZES GOOD AND BAD SHIFT
SCHEDULES?
Kecklund G , Ingre M , Åkerstedt T
[email protected]
Introduction: The design of shift schedules is assumed to be important for sleep, health and social problems. The purpose of this
study was to estimate the prevalence of different shift schedule characteristics in a randomized sample, to what extent these characteristics was considered to cause severe problems and are associated
with poor sleep, impaired health and social complaints.
Methods: 2,031 individuals (response rate: 58%), who had work
hours outside the time interval of 19:00h and 07:00h was interviewed by Statistics Sweden and filled in a brief survey. The mean
age of the participants was 42 years, 62% were women, and 61%
worked full time. The most common occupational sector was health care (42%) followed by industry workers (10%). The survey
included questions of whether the participants schedule included
a specific characteristic, and if they responded “yes”, they had to
consider whether it was a severe problem for them. The survey also
included questions on sleep, health, and social problems.
Results: The most common shift schedule characteristics were day
shifts (88%), evening shifts (82%), long (≥ 10 hours) work shifts
35
(54%), temporary planned rosters (50%), mixed day and night shifts
(46%), and short rest (< 11 hours) between shifts (38%).
The shift characteristics that were rated as causing the most severe
problems were short rest between shifts (28%), split shifts (27%),
and many (≥ 5) shifts in a row (25%). In addition, many shift
workers considered low possibility to influence work hours (36%)
and insufficient possibility to plan ahead (30%) as severe problems.
The prevalence of shift workers that considered night work to be a
severe problem was relatively low (12%). There were clear gender
differences and women reported a higher prevalence of severe problems for most of the shift schedule characteristics. Multiple logistic regression analyses with health and sleep problems as the outcomes showed that night work was the strongest predictor, followed
by short rest between shifts, and early (start time ≤ 6:00h) morning
work. Irregular start times of the work shift and short rest between
shifts were the strongest predictor of social problems.
Conclusions: A good work schedule from shift workers point of
view should include high work time control (good possibility to
influence working times), predictable working time that permits
planning ahead, and avoid short rest time between shift, split shifts,
and many consecutive work days. The results also support the
hypothesis that shift workers mainly pay attention to social factors
when they judge work schedules. However, there are large individual differences and what constitutes a severe problem with a shift
schedule is also associated with age, gender, family situation and
biological factors.
Support: The study was supported by AFA Insurance and carried
out within Stockholm Stress Center.
Oral Session 3
Physical and Mental Health
OS 3.1
WORK AND MENTAL HEALTH: THE CONTRIBUTION OF WORK HOURS AND SCHEDULES
Marchand A1, Durand P2
School of Industrial relations, and Institute of Public Health, University of
Montreal.
2
Équipe de recherche sur le travail et la santé mentale (ERTSM), Institute of
Public Health, University of Montreal.
[email protected]
1
Objectives: The specific contribution of working time and work
schedules on workers mental health is a controversial issue. This
study aimed at a better understanding of the role these factors
using a model encompassing the stress promoted by constraints-resources embedded in structures of daily life (workplace, family,
social networks outside the workplace) and worker individual characteristics (demography, physical health, psychological traits, life
habits, stressful childhood events)
Methods: Data were collected in 2009-2012 over a random sample
of 63 workplaces clients of the insurance company Standard Life
(Québec, Canada). Overall, a random sample of 2162 employees
participated in the survey, for a response rate of 73.1%. Mental
health was measured with three instruments: The General Health
Questionnaire short-form 12 items (GHQ-12), the Beck Depression inventory (BDI-21) 21 items, and burnout with the emotional
exhaustion component of the Maslash Burnout Inventory General
Survey (MBI). Working hours were measured per week and work
schedules were evaluated by the frequency of exposure to day, evening, and night shift, and exposure to irregular work schedule.
Other work factors included skill utilization, decision authority,
physical psychological demands and social support from colleagues
and supervisor. The family situation took into account the marital,
parental and economic statuses, and the stress experienced in the
martial and parental relationships. The social network outside was
evaluated over the social support provide outside the workplace.
Individual characteristics encompassed gender, age, physical health
problems, alcohol and smoking, personality traits, and as stressful
life events before the age of 18 years. Multilevel regression models
where used to analyze the data.
Results: Variables in the models explain 29.9% of psychological distress, 44.8% of depression and39.2% of burnout. Working
hours per week are positively related to psychological distress and
burnout, while irregular work is associated with higher level of burnout. Work hours as well as day, evening and nigh shifts are not
associated with depression. Other work factors, family situation,
non-work social support and individual characteristics are strongly
related to the three mental health outcomes. Further analysis reveals gender interacting with irregular work schedule and night shift
on the burnout level.
Conclusion: These results suggest the work hours per week and
irregular work schedule promote a modest contribution to the experience of mental health problems in workers. However, irregular
schedule and night shift seem to operate differently on men and
women experience of burnout. Overall, other work factors, family
situation, non-work social support and individual characteristics
were contributing more to the outcomes. The results of this study suggest expanding approaches in occupational mental health in
order to avoid coming to erroneous conclusions about the role of
working hours and work schedule to the development of mental
health problems in the workforce.
OS 3.2
HEMOSTATIC MARKERS AND SLEEP QUALITY
AMONG SHIFT WORK AND DAY WORK FEMALE
NURSES
Shochat T1, Saharov G2, Nadir Y2, Keren A2, Brenner B2
Department of Nursing, Faculty of Social Welfare and Health Sciences,
University of Haifa, Israel.
2
Coagulation Institute, Rambam Health Care Campus, Israel.
[email protected]
1
Introduction: The haemostatic system has a significant impact on
cardiovascular morbidity. Epidemiologic studies indicate an increased risk of cardiovascular diseases amongst shift workers. Such
increased risk may be attributed to circadian misalignment of haemostatic markers and to restricted sleep time. To reveal some of
the underlying mechanisms of cardiovascular morbidity in the shift-work population, we performed a comparison of the profiles of
haemostatic markers and sleep quality among healthy shift working
vs. daytime working female nurses. It was hypothesized that alterations in the haemostatic system and poor sleep may be found
in shift workers. Accordingly it was predicted, that haemostatic
markers would be elevated and that sleep quality would be decreased in rotating shift workers compared to regular day workers.
Methods: Thirty day working and thirty rotating shift working
female nurses ages 30-45 were recruited at Rambam Health-Care
Campus (total n = 60). Nurses were included if they were healthy,
did not smoke, had a BMI ≤ 30, had no family history of CVD at
a young age, were not using medication on a regular basis (except
oral contraceptive pills), did not have a fever in the past month
and were not pregnant. Rotating shift workers had to have at least two (non day) shifts and at least one night shift per week. For
each participant, blood was drawn at 07:00 in the morning (not
following a night shift) for the measurement of 6 markers of coagulation, including PAI-1, Heparanase procoagulant activity, tissue
36
factor + heparanase complex, protein C, D-dimer and fibrinogen.
Sleep quality was assessed by self report (Pittsburgh Sleep Quality
Index, PSQI).
Results: PAI-1 levels were significantly higher among shift work
nurses compared to day work group (36.6 ng/ml vs. 24.3 ng/ml, p <
0.05). In shift workers, Heparanase procoagulant activity was 2-fold
and tissue factor + heparanase complex was 1.5-fold compared
to day work nurses (both p < 0.05). Sleep quality was significantly
lower for shift compared to day workers (p < 0.001). No group
differences were found for Protein C, D-dimer and fibrinogen.
Conclusions: PAI-1 and heparanase markers were significantly elevated and sleep quality reduced in rotating shift work compared to
day work nurses. Such alterations in healthy rotating shift workers
suggest preclinical disturbances in the haemostatic system, which
together with reduced sleep quality may contribute over time to
future cardiovascular morbidity.
OS 3.3
THE PROSPECTIVE INFLUENCE OF SLEEP DISCREPANCY IN OCCUPATIONAL BURNOUT
Davies-Schrils K1, Burch K1, Barnes-Farrell J1, Cherniack M2
Department of Psychology, University of Connecticut, USA.
University of Connecticut Health Center, USA.
[email protected]
1
2
Introduction: Occupational burnout has been increasingly studied
as an outcome of chronic stress. In addition to a significant body of
research that demonstrates the influence of stressful work conditions on experiences of burnout, insufficient sleep has been shown
to be a significant factor contributing to burnout. In such studies,
self-reported average daily sleep durations of less than 6 hours are
typically classified as insufficient sleep. However, distinct from between-person differences in sleep duration, adults also report differences in the duration of sleep they feel they need for good functioning. Recurring discrepancies between the sleep adults perceive
they need and what they obtain may be a more powerful predictor
of burnout than classifications of insufficient sleep duration that
ignore individual differences in perceived sleep duration needs. In
the present study, we examined the prospective influence of sleep
duration discrepancy (defined as non-congruence between average
sleep duration and duration needed for good functioning) on burnout. We hypothesized that sleep discrepancies would account for
unique variance in burnout, beyond that accounted for by stressful
work conditions and other sleep characteristics.
Methods: Data were derived from an ongoing longitudinal study
investigating the effects of age and working conditions on work
capacity and worker well-being. Our analyses included data from
a total of 330 workers from 5 manufacturing organizations in
New England who completed surveys at two different time points
approximately one year apart. The surveys include measures of
work schedule, stressful work conditions (schedule control, decision authority, psychological and physical work demands), and
self-reports of sleep quality, noncontinuous sleep, sleep duration,
sleep duration needed for good functioning, and burnout at both
points in time.
Results: Hierarchical multiple regression was used to examine prospective relationships between stressful work conditions,
various sleep indicators and burnout. Organization, job type, work
schedule, gender, age and second job status were used as controls
in each analysis. Polynomial regression was used to test the incremental relationship between sleep discrepancy and burnout, and
response surface analysis was used to examine the nature of the relationship. Consistent with prior research, stressful work conditions
were significantly related to burnout. In addition, low sleep quality
accounted for significant variance in burnout after work conditions
were included in the model. Furthermore, as predicted, high sleep
discrepancy was related to burnout, accounting for significant unique variance in burnout beyond that accounted for by work conditions and other sleep variables.
Conclusion: In addition to traditional measures of stressful work
conditions, subjective indicators of sleep quality and sleep discrepancy may help predict burnout among manufacturing workers.
Further, organizations should seek ways to support and encourage
their workers to achieve greater congruence between the amount
of sleep they typically get and the amount they believe they need.
Support: Grant Number 5R01OH008929-05 from the National
Institute for Occupational Safety and Health.
OS 3.4
PERMANENT AND ROTATING NIGHT WORK AND
MORTALITY: PROSPECTIVE STUDY AMONG FINNISH EMPLOYEES IN 1977-2008
Nätti J, Anttila T, Oinas T, Hartikainen A
School of Social Sciences and Humanities, University of Tampere, Finland;
Department of Social Sciences and Philosophy, University of Jyväskylä,
Finland.
[email protected]
Introduction: There is a considerable amount of evidence showing
that night work is associated with increased morbidity. However,
only few studies have focused its relation to mortality. This study investigates the relationship between the type of working time
arrangement (permanent night work, rotating night work and day
work) and mortality among wage and salary earners.
Methods: The data consisted of pooled representative working
conditions surveys (1977, 1984, 1990, 1997, 2003) on Finnish
employees (n = 22593), which was merged with register-based
follow-up data in Statistics Finland covering years 1977-2008. In
the working conditions surveys employees were asked what their
working time arrangement was: regular day work (06:00-18:00 h),
regular evening work, regular night work, 2-shiftwork, 3-shiftwork,
or other working time arrangement. The analysis was restricted to
employees who worked 20 hours or more per week. In this study
we compare employees with permanent night work (regular night
work, n = 134), rotating night work (3-shiftwork, n = 1289) and
regular day work (n = 14763). The relative risk of death was examined by conducting Cox proportional hazards analyses for the permanent, rotating night workers and day-time workers (as reference
group). The results were adjusted to background (age, gender, level
of education, family situation), health (longstanding illness, pain
symptoms, and psychosomatic symptoms) and work related factors (physical and psychological demands, perceived hurriedness,
and flexitime).
Results: Permanent night workers had a 1.82-fold higher risk of
mortality (95% CI 1.13-2.95) than day-time workers after adjusted
for background, health- and work-related factors. Among rotating
night workers no significant association was observed.
Conclusions: The present study indicated that permanent night
workers had higher risk of mortality than day-time workers. Additional research on other potential factors and mechanisms behind
the factors linking permanent night work to mortality is needed.
37
OS 3.5
STRESS AND SLEEP IN NURSES EMPLOYED
IN “3 X 8” AND “2 X 12” FAST ROTATING SHIFT
SCHEDULES
Costa G, Anelli MM, Castellini G, Fustinoni S
Department of Clinical Sciences and Community Health, University of
Milano, and IRCCS “Ca’ Granda - Ospedale Maggiore Policlinico” Foundation,
Italy.
[email protected]
The study was aimed at assessing the impact of 3 types of fast rotating shift systems on stress, fatigue, sleep and hormonal secretion.
Subjects: Among 294 hospital nurses, examined in a survey on work
related stress, three groups of 10 nurses were randomly selected for
a comparison of three shift work schedules:
a) 10 working in the resuscitation unit on a “3 x 8” shift system in
a 5-day cycle with a “quick return”: Afternoon (14-21); Morning
(07-14) and Night (21-07); End of Night shift; 2 Rest days; b) 10
working in the surgical ward on a “3 x 8” shift system in a 6-day
cycle with a “quick return”: Afternoon; Morning; Morning and Night; End of Night shift; 2 Rest days; c) 10 working in the delivery
room on a “2 x 12” shift system in a 5-day cycle: Daywork (07-19);
Nightwork (19-07); End of Night shift; 2 Rest days. Seventeen nurses were women and 13 men, aged between 23 and 46 years (mean
34.3) and with work seniority between 1.4 and 28 years (mean 11.4).
All were in good health and not taking any medication.
Methods: They have been submitted to a semi-structured interview
including the Standard Shiftwork Index, the Job Demand-Control and
the Effort Reward Imbalance questionnaires, the Epworth sleep scale.
During the whole shift cycle, the nurses recorded their activity and rest
periods by actigraphy and personal diaries, assessing sleepiness by the
Karolinska Sleepiness Scale and quality of sleep by a 10-point visual
scale. They also took saliva samples at 0700 and 2300 of each working
and rest day for dosage of cortisol, cortisone and melatonin.
Results: The nurses reported more sleep troubles in both “3 x 8”
than in “2 x 12” shift schedule. According to actigraphy, in both
“3 x 8” shift schedules the duration of night sleep between afternoon and morning shifts is reduced by 35% as compared to rest
days, and sleep between morning and night shifts in the same day
lasts less than 3 hours on average, showing a significantly higher
fragmentation in both occasions.
Also subjective sleepiness is significantly higher before night shift
in both “3 x 8” shift schedules than in the “2 x 12” one. In the surgery ward, where they can nap/sleep up to 3 hours during the night
shift, the nurses have a 40% shorter sleep in the morning after. In
the “2 x 12” shift schedule the night sleep duration between Day
and Night shift is the same as in the rest days.
As far as hormonal secretion, cortisol and cortisone did not change
significantly their normal circadian phase in all the three shift schedules, whereas melatonin showed a more irregular pattern.
OS 3.6
MEALS AND SHIFT WORK: FOOD CHOICE, TIME
OF DAY AND MEAL ENVIRONMENT - THREE IMPORTANT DIMENSIONS FOR REST AND HEALTH
Lennernäs M1, Nyberg M2, Johansson M3, Wetterstrand M4
Occupational and Public Health Sciences, University of Gävle Sweden.
Food and Meal Sciences, University of Kristianstad, Sweden.
3
Digital Design, School of Health and Society, University of
Kristianstad, Sweden.
[email protected]
1
2
The meaning of the work meal is for example to contribute to daily
intake of energy and nutrients, bring pleasure, enable cognitive
restitution, improve work performance and to be a social event.
Shiftwork is associated with metabolic disorders like obesity and
cardiovascular disease, stress and sleep disorder. This might be
due to a tension between the body´s needs and the organization
of work hours. Work tasks are transitioning from muscle-work to
cognitively demanding tasks. As a consequence, the need for dietary energy decrease and the need for cognitive restitution during
work sessions probably increase. The body´s need for nutritional
foods, eaten in accordance with biological and social rhythms and
relations, are disturbed by compressive and irregular work hours.
The prevalence of health disorders in shiftworkers indicate that
there might be limits for how to far the body´s flexibility to regulate
food intake can be pushed by work hours before negative consequences for metabolism, cognitive and physical work performance
appear. Eating is a behavior and social rhythms, work hours included, might mislead or supportive, the biological regulation of food
intake. Also work meal ambience probably influences consumption,
eating rate, experience, wellbeing and restitution.
Despite the strong evidence for a relationship between diet and health, research on the effects on working life on eating behavior and
work meals in shift workers is more or less absent.
This might be due to the interdisciplinary nature and complexity
to understand determinants and consequences of eating behavior.
Sociologists identify changes in work life towards eating in social
isolation, unplanned and irregular meals, replacing meals by grazing
of single foods and also “eating on the go”.
Nutritionists identify that an increased risk for obesity, diabetes and
cardiovascular disease might be a result of chronically eating and
sleeping at abnormal circadian times, and also due to lack of a social life that supports a structure of eating. Psychologists identify
that cognitive failure and work accidents might be prohibited by
eating foods and meals at work in a restorative context.
Eating behavior in shift workers is a compromise between antagonistic
biological, environmental and social factors. Nutrition and meal research, and also interventions, in work places need to be interdisciplinary involving the food producer perspective (food service at work),
the nutritional perspective (food intake at meals with special emphasis
on meal timing and the pattern of how much is consumed over the
day), the psychological and social perspective (the interaction of people
and meals, the significance and meaning of meals to individuals and
groups). Also the environmental psychology perspective (psychosomatic effects of the physical environment) should be applied.
Oral Session 4
Genes, Rhythms and Light
OS 4.1
IS NIGHT SHIFTWORK, INCLUDING LIGHT-ATNIGHT A PROMOTER FOR BREAST CANCER DEVELOPMENT?
Hansen J.
Danish Cancer Society Research Center, Denmark
[email protected]
Introduction: There is mounting evidence that night shiftwork, including light-at-night may increase the risk of female breast cancer.
There is further experimental evidence suggesting that exposure
to light-at-night may have a promoting effect on already initiated
breast cancers. The promoting evidence is, however, less clear from
epidemiological studies. The aim of the present study is to elucidaSleep Sci. 2013;6(Supl 1):s9-s74
38
te an eventual promoting effect by studying the duration of years
from night-work exposure to the diagnosis of manifest breast cancer. If night-shift work primarily promotes cancer development,
an eventual increased breast cancer risk should be observed at a
relatively short time period after the onset of night-shift work, and
the relative risk in premenopausal women should be higher than in
postmenopausal risk because night shiftwork is more prevalent in
younger ages and rarely starts in post-menopausal period.
Methods: In total 1157 women (23% nurses and 77% other employees), diagnosed with breast cancer (2000-2004) at an age less
than 70 years, participated in two independent nationwide casecontrol studies on night shiftwork (at least one year working about
8 hours in the interval from 7 pm and ending before 9 am) and risk
of breast cancer.
In total 2658 breast cancer free controls subjects were frequency
matched on age to the controls in each of the case series. Information on the entire work life, including night shift-work and known
and potential risk factors for breast cancer (i.e. reproduction, BMI,
alcohol, HRT, heredity and diurnal preference) was obtained from
both cases and controls by telephone interviews. Relative risks (RR)
and their 95% confidence intervals, adjusted for potential confounders, were estimated by use of logistic regression models, conditional on 5-years age groups. Lag periods were calculated as years
between the first reported night shiftwork exposure and yea r of
diagnoses.
Results: The overall adjusted RR of breast cancer after nightwork
was 1.8 (1.3-2.8), with an increasing RR by increasing years of night
work (p = 0.001). The RR for women with a lag time of less than
10 years was 1.2. The median distance between first night shiftwork
and breast cancer diagnosis was 14 years. The RR for pre- and
post-menopausal women were 1.4 (p = 0.09) and 2.4 (p < 0.001),
respectively.
Conclusion: This study shows that the highest relative risk of breast cancer after night shiftwork appears among post-menopausal
women and no increased risk is observed the first 10 years after
first shiftwork exposure. Overall, this study provides little evidence
that nightwork may primarily act as a promoter for breast cancer.
OS 4.2
WINTER DEPRESSION AMONG DAY AND SHIFT
WORKERS ABOVE THE ARCTIC CIRCLE
Lowden A, Garefelt J
Stress Research institute, Stockholm University, Sweden.
[email protected]
Introduction: Light is the most important synchronizer of our
biological clock and important factor for adaptation to irregular
work hours. High latitudes in winter and windowless work places
could reduce natural daylight exposure. An artic mining company,
with winter polar nights, offered a unique opportunity to examine
the scarcity of light. Groups working under and above ground, with
and without night shifts were studied. The purpose of study was to
analyse whether light exposure was associated with health and wellbeing and what levels of light intake are needed to avoid problems.
Methods: The study questionnaire sample consisted of workers
in a mining company in the north of Sweden (n = 1273, response
rate 68%). The workers were classified into six categories: daytime,
shifts with nights, shifts without nights - above or below ground.
Winter depression was measured by a single-item question (having
more problems with depression, fatigue or lack of energy during the
autumn/winter compared to other seasons) and if yes; how severe
these problems were evaluated. Daylight exposure was asked for in
connection to both workdays and free days. All questions concerned the preceding three months, encompassing the darkest period
of the year. An ordinal logistic regression was carried out to analyse
the proportional odds ratio, OR, for mild as well as pronounced
winter depression. Independent variables were work category and
light exposure, controlled for gender, age and education.
Results: 63.6% (n = 809) reported having more problems with depression, fatigue, or lack of energy during winter. 25.3% (n = 322)
considered their problems as being “pronounced”, “serious” or a
“paralyzing”. Over 30% were exposed to < 1h of daylight on both
workdays and free days, 43% were exposed to > 1h of daylight
on either workdays or free days and 22% were exposed to > 1h
of daylight on both workdays and free days. Exposure to < 1h on
either workdays or free days was associated with an increase OR
by 1.37 (1.04-1.81) for winter depression compared to the reference (> 1h on both workdays and free days). Exposure to < 1h of
daylight on both workdays and free days was associated with an OR
of 1.89 (95% CI 1.26-3.15). With daytime workers above ground
as the reference, only one other group showed a significant different OR; respondents working 3-shift above ground, with OR 0.70
(0.50-0.97). Age was associated with an OR of 0.98 (0.97-0.99) and
being a female with OR 1.65 (1.26-2.17). Educational level was associated with increased ORs for all educational levels, compared to
the reference (≥ 3 years at university).
Conclusions: Mild forms of winter depression are affecting a
major part of the population in northern Sweden being associated
with the lack of natural daylight exposure.
Support: Swedish Council for Working Life and Social Research.
OS 4.3
SLEEP AND MELATONIN LEVEL IN SHIFT-WORKERS LIVING IN THE FAR NORTH REGION
Bochkarev M1, Ragozin O2, Simonov V2
Sibservis Co LLC, Khanty-Mansiysk, Russia.
Khanty-Mansiysk State Medical Academy, Department of Hospital Therapy,
Khanty-Mansiysk, Russia.
[email protected]
1
2
Introduction: Shift work is an essential part of healthcare working
pattern to delivery of comprehensive medical care 24 hours a day.
Shift work’s desynchronisation of physiologically determined circadian rhythms has a major effect on the sleep and performance.
Seasonal daylight changes in the Far North region in Russia on 61st
North latitude is an additional influence factor to body clocks. Day
length is of importance when predicting individual response to night work. The aim of the current study was to determine sleep and
melatonin level of healthcare shift workers in natural conditions of
the Far North region.
Methods: 136 healthcare workers in 61°N completed questionnaires in 2 weeks periods around winter (minimal daylight length 5h 33
min) and summer solstice (maximum daylight length 19h 19 min).
There were 53 men (32.4, SD 6.2) and 83 women (36.8, SD 7.7).
There are 3 shifts: 24h shift (79 participants) with 48 h rest; 12h
shifts with 36h rest period (36 participants) and 8h day shift (21 participants). Intensity of patients’ sleep disturbances was estimated
by the questionnaire Subjective estimation of sleep characteristics
(Vejn A., Levin J., 1998), poor sleep quality was defined of ≤ 19.
Sleepiness was measured by Epworth Sleepiness Scale, pathological
sleepiness is ≥ 10. Participants collected morning urine samples in
dim light conditions before and after shift for assessment of the
urinary metabolite of melatonin, 6-sulphatoxymelatonin (aMT6s).
Data were analyzed using repeated measures ANOVA.
Results: There were no significant differences in seasons in sleep
quality and sleepiness for 12h and 24h shifts. The worst sleep quality was for day- shift in winter (17.4+2.0) compared to summer (21.4
+ 3.6, p = 0.05). Sleep latency for 8h shift was higher in winter and
number of awakenings higher in summer compare to 24h shift.
Results of Epworth scale didn’t show pathological sleepiness in all
39
groups. 8h day-shift reported more daily sleepiness in winter than
in summer (8.11 + 2.4 vs. 4.25 + 1.8, p = 0.04). A6MTs was higher
in 24h shift in winter, 12h shift in summer and associated with worse sleep quality and higher sleepiness.
Conclusion: The finding that daily workers have higher sleepiness
and better sleep characteristics than shift workers is unexpected.
Our results showed seasonal changes in sleep quality and sleepiness
for daily workers with worse scores in short day length period. We
think that daily workers are more susceptible to seasonal changes
of daylight. Future studies should examine factors that contribute
more stability of sleep among shift workers (chronotype, objective
sleep measure).
OS 4.4
THE EFFECT CIRCADIAN PHASE AND PRIOR
WAKE ON NEUROBEHAVIOURAL PERFORMANCE
DURING A SPLIT 28-H FORCED DESYNCHRONY
SCHEDULE
Kosmadopoulos A, Sargent C, Zhou X, Darwent D, Dawson
D, Roach GD
Appleton Institute, Central Queensland University, Australia.
[email protected]
Introduction: Extended wakefulness and misalignment of the
circadian and sleep/wake systems contribute to poor neurobehavioural performance, particularly during night shifts. Emergency
services personnel work for long shifts at all times of the day, so
are at a higher risk of having accidents. Scheduling multiple short
work-rest cycles per day could help to maintain functional capacity. This is because it would allow for at least one shift during the
daytime, some sleep at night, and shorter durations of wakefulness.
Recent studies suggest that daytime naps can help maintain daytime
performance. However, the extent to which a split work-rest schedule could maintain performance at night is unknown. Therefore,
our aim was to identify the effect of circadian phase and prior wake
on neurobehavioral performance during a split-sleep forced desynchrony (FD) protocol.
Methods: Eight (out of an eventual 16) male participants lived
in a sound-attenuated time-isolation laboratory for 12 days at the
Appleton Institute. The schedule began with 2 adaptation and 1
baseline days, and was followed by 7x28-h FD periods (FD1-FD7).
FD periods were subdivided into two 14-h cycles with a rest-to-wake ratio of 1:2 (i.e., 2 x 4.7h time in bed and 2 x 9.3h wake per 28-h).
Neurobehavioural performance was assessed using mean response
times (RT; in milliseconds) on a 10-min psychomotor vigilance task
(PVT). The PVT was performed 2h after waking and at 2.5h intervals during wake periods. Circadian phase was estimated using
continuously recorded core body temperature (CBT).
Results: Participants had a mean (± SD) age of 22.6 (± 3.4) years
and body mass index of 22.1 (± 2.0) kg/m2. The mean RT obtained
at baseline was 222.3 (± 16.2) ms and was maintained across the
study, with the mean RT at FD7 being 221.8 (± 21.0) ms. Repeatedmeasures mixed models ANOVA indicated statistically significant
fixed effects of prior wakefulness [F(2,119) = 4.43, p = .014] and
circadian phase [F(5,119) = 12.30, p < .001], but not for their interaction [F(10,119) = 1.62, p = .11]. Mean RT was fastest at the
circadian acrophase (216.9 ± 17.5 ms) and slowest at the circadian
nadir (227.3 ± 17.2 ms). From 2h to 7h of prior wake, mean RT
increased from 220.5 ms (± 16.7) to 224.2 ms (± 18.6).
Conclusion: The effects of circadian phase and prior wake were
present, but their influence on performance was very small. This suggests that splitting the work-rest schedule may assist in minimising
neurobehavioural impairment during the night and towards the end
of the shift. While it may not be practical for long-term operations due to social and family costs, implementing a schedule of
fast rotating short shifts may be useful for reducing the fatigue risk
of personnel during highly demanding emergency situations for
several days.
Support: This study has received funding from the Australian
Research Council.
OS 4.5
THE EFFECT OF CHRONOTYPE ON STRATEGIC
SLEEP BEHAVIOUR IN SHIFT WORKERS
Mehlmann JL , Fischer D , Vetter C , Roenneberg T
Institute of Medical Psychology, Ludwig-Maximilians-University Munich,
Germany.
[email protected]
Introduction: Shift work is one of the biggest challenges for human circadian clocks in modern societies. Recent research shows
that the timing and duration of the main sleep phase is modulated by chronotype and the type of shift worked on (morning shift,
evening shift, night shift). However, the impact of chronotype on
strategic sleep behaviour (such as not sleeping after the last night
shift, not sleeping before a morning shift) or on napping behaviour
in shift workers has not been examined yet.
Methods: The impact of chronotype on napping behaviour as a
function of shift schedule and of the type of shift worked on is
examined using a database of 1300 employees working in different
shift systems (e.g. fast-forwards, fast-backwards or permanent night
shifts), who have completed the Munich ChronoType Questionnaire for shift workers (MCTQShift) as well as a subsample of about
140 shift workers, who filled out sleep logs on a daily basis. Additionally, the link between sleep duration, sleep quality of the main
sleep episode and nap frequency, timing and duration is analysed. A
multitude of statistical methods, such as chi-square tests, repeated
measures ANOVAs, as well as logistic and multiple regression is
used to analyse strategic sleep behaviours in shift workers.
Results: Preliminary analyses of the sleep log data showed a significant higher frequency of later chronotypes napping after morning
shifts when compared to night shifts (p < 0.05). Conversely, earlier
types tend to nap before night shifts more often than after morning
shifts (p < 0.001). Intermediate types have to compensate their sleep deficit accumulated during morning shifts and night shifts in an
equal amount. Shorter sleep duration and worse sleep quality of the
main sleep phase was associated with napping length. Last, chronotype was positively associated with nap timing and duration on
morning shift days and free days after night shifts, with later types
napping later in the day and taking longer naps.
Conclusion: Considering chronotype does not only account for
variability in timing and duration of main sleep episodes, but also
reveals chronotype-specific patterns in strategic sleep behaviour.
Napping-behaviour is on the one hand highly related to different
sleep parameters of the main sleep phase (e.g. sleep duration and
sleep quality). Conversely, chronotype modulates nap timing, nap
frequency and nap duration, depending on the shift worked on.
These findings add to the growing body of literature emphasizing
the importance of chronotype when studying the effects of shift
work on sleep, health and cognition.
Support: This work was supported by industry grants to TR
(ThyssenKrupp Steel Europe AG and Siemens AG).
40
Special Session
Mathematical models and fatigue at work
S1
THE EFFECTIVENESS OF A MOBILE HEALTH INTERVENTION (MORE ENERGY) ON FATIGUE IN
AIRLINE PILOTS. A RANDOMIZED CONTROLLED
TRIAL
van Drongelen A , Boot CRL , Hlobil H , Smid T , van der
Beek AJ
Department of Public and Occupational Health, EMGO Institute for Health
and Care Research, VU University Medical Center, the Netherlands.
[email protected]
Objective: A considerable percentage of flight crew reports to be
fatigued regularly, partly caused by irregular, long working hours, and
the crossing of time zones. Fatigue can lead to impaired performance
during work, and prolonged fatigue can lead to several health problems. The objectives of this study were 1) to obtain insight in crosssectional relations between pilots’ characteristics and fatigue related
measures and 2) to investigate the effectiveness of an intervention
consisting of tailored advices regarding exposure to daylight, optimising sleep, physical activity, and nutrition on fatigue in airline pilots.
Methods: In total 502 pilots of a large airline company were included and randomly allocated to either an intervention or a control
group. Inclusion criteria were: (i) having access to an Apple or Android Smartphone or tablet, and (ii) not being on sick leave for more
than four weeks at the moment of recruitment. The intervention
group received tailored advices about optimal exposure to daylight,
sleep, physical activity and nutrition. The flight- and participant-specific advices were available on a special developed Smartphone
application, supported by a website with background information.
The control group was referred to the standard available information of the airline company. The primary outcome of the study was
perceived fatigue measured by the Checklist Individual Strength
(CIS). Secondary outcomes were need for recovery, quality of sleep, sleep, dietary and physical activity behaviour, knowledge about
these factors, general health, and sickness absence. Outcomes were
measured at baseline and at three and six months after baseline.
Results: In the cross sectional analyses at baseline, all adjusted for
age, it was found that:
• 60% of the participants proved to be morning types. These
pilots were significantly older than the evening types (42.2 vs.
38.8 years).
• Evening type pilots were significantly more fatigued than morning type pilots (p = 0.001).
• First and Second Officers proved to perceive more fatigue
compared to Captains (p = 0.001).
• First Officers had a lower quality of sleep than Captains (p =
0.02).
• First and Second Officers had more need for recovery than
Captains (p = 0.001).
• Long-haul pilots were significantly more fatigued than
short-haul pilots (p = 0.04). No significant differences between
These groups were found on need for recovery.
After the baseline questionnaire, the participants were equally allocated among the intervention and control group concerning aircraft type, job title, age and gender.
Conclusion: It was found that older and more experienced pilots
experienced less fatigue and need for recovery than their less experienced and younger colleagues. The outcomes of the mobile
health intervention (MORE Energy) using tailored advices will be
presented at the symposium. If proven effective, this intervention
can be applied as practical education tool in fatigue management
for pilots.
S2
MEASURE MATTERS: ADVANCING NEXT GENERATION FATIGUE MODEL EFFICACY USING AN INTEGRATIVE 8-STATE FRAMEWORK
Lehrer A1, Popkin S2
MacroSys LLC, USA.
US Department of Transportation Volpe Center, USA.
[email protected]
1
2
Introduction: Is there a human fatigue thermometer capable of
reliable, accurate, and valid personalized risk measurement? Can it
map real-world safety and performance risk prospectively and retrospectively? Though current models offer limited global insight
and may even target constrained aspects of transportation cohorts,
next generation models stand to retool predictive relevance by integrating multi-dimensional interactions among internal and external
predictors. Indeed, US Department of Transportation efforts suggest an overarching framework to guide fatigue model development
as one of several strategies to better identify actionable thresholds,
foster compliance, and support scheduling, accident investigation,
and hours-of-service rulemaking. Current models emerged from
inventor ingenuity and the zeitgeist of three decades, where advances spawned algorithms via initial discoveries of the underlying
neurobiology; computer proliferation; growth in processing power,
graphics, and statistical software; evolving corporate willingness
to manage risk, and budding research consulting practices aimed
at unraveling fatigue’s nefarious impact. The past five years were
even more formative, seeing advances in science, technology, and
communications position model development in unprecedented
ways. This moment leverages a ubiquitous, mobile internet, accelerated developments in data analytics, personalized medicine, social
media, nanosensor technology, psychometrics, and an increasing
understanding that individual differences and stress resilience predict 24/7 performance, safety, and wellness. The thermometer can
be built.
Methods: Gap analyses were conducted across twelve fatigue models, including seven tested at Seattle’s 2002 Fatigue and Performance Modeling Workshop, four contemporaneous models, and
a hypothetical model integrating the proposed framework. The
authors reviewed journal articles and related literature, including
critiques of the “Seattle Seven” and syntheses of fatigue, alertness,
stress resilience, and coping processes. Model features included
inputs, mechanisms, outputs, validation techniques, and functional
goals. Surveys sought sample perspectives among model developers, academics, transportation management, labor, regulators, and
accident investigators.
Results: Broadly, model inputs rely heavily on time of day and
sleep history in two-process variations of alertness, merging competing homeostatic sleep pressure and circadian alertness. Though elements of actionable output emerged, no current model
optimally captured real-world risk, lacking a robust and balanced
framework of internal and external inputs. Models paled beyond
average behavior prediction and typically neglected individual difference effects. Sleep/wake cycles were often deduced using work
hours-not surprisingly, models showed significant levels of variability and unexplained variance. Algorithms were not optimally tuned to map chronic or task-specific fatigue risk, yet these remain
pervasive individual prediction challenges.
41
Conclusion: Fatigue Modeling 2.0 anticipates next generation utility through an integrative 8-State framework balancing internal and
external inputs. Beyond largely physiological considerations, an inclusive biopsychosocial platform advances performance science to
facilitate increasingly applicable, multi-dimensional model development. It is the authors’ hope that modelers consolidate data and
collaborate towards an 8-State specification framework to optimally
predict and manage fatigue, further supporting alert, safe operations.
S3
IDENTIFYING FATIGUE HAZARDS AND CHECKING COMPLIANCE AGAINST COMPANY AND INDUSTRY STANDARDS IN A GLOBAL MINING OPERATION
Lederle K1, Jackson P1, Sheffield D2
Clockwork Research Ltd.
2
Newmont Mining, USA.
[email protected]
1
Introduction: In 2011, Newmont Mining - one of the world’s
leading producers of gold, operating mine sites on five different
continents - launched a global standard for Fatigue Risk Management (FRM Standard). This established a policy, set out roles and
responsibilities of management, supervisors and employees for
managing fatigue, and encouraged each mine site to introduce a
Fatigue Risk Management Plan (FRMP). To assess site compliance with the FRM Standard an assessment tool was developed, and
fatigue risk management consultants Clockwork Research were
commissioned to undertake site evaluations across Newmont’s
global operations. In addition to assessing compliance, Clockwork
sought to identify fatigue hazards, existing controls and evaluate
fatigue risk at each site. This paper reports on the first seven site
evaluations, describes the process and offers recommendations
for other operators seeking to introduce FRMPs. It also provides
a unique opportunity to compare how different cultural groups
experience and cope with fatigue.
Methods: Data collection at each site involved two phases: Phase 1) Pre-visit analysis of all rosters worked on-site, using fatigue
analysis software, to identify groups to be interviewed while onsite. Selection criteria were roster pattern (those associated with
highest predicted levels of fatigue took precedence), number of
employees working that roster, and nature of work (those involved
in safety critical work being priority). Phase 2) Site visit lasting 12
days, during which in-depth, semi-structured interviews were conducted with managers, supervisors and groups of up to six employees. Discussions with employees focused on their roster, sleep
patterns when working days and nights, home situation, lifestyle
and out-of-work activities that may impact on fatigue, as well as
understanding and experience of fatigue. Data collected on actual
sleep patterns was used to refine the fatigue analysis of rosters.
Interviews with management focused on their understanding of
fatigue and their role with respect to fatigue management, and the
controls they have put in place to manage the fatigue of their workforce. The site assessment audit tool was completed using interview
data and by reviewing site-specific fatigue-related documentation.
All data analysis and feedback were carried out while on-site.
Results: Three main categories of fatigue contributors were identified: i) roster, ii) lifestyle and iii) work-related. Formal and informal
controls were identified. Audit tool outcomes were used to generate
a site-specific FRMP, detailing the steps required to better manage
fatigue, and to achieve greater compliance with the Standard.
Conclusion: Newmont’s approach is an example of industry
best practice in fatigue risk management which has enabled senior
management to make valid, informed comparisons between the
sites. The development of a standard against which different
parts of an operation can be audited is a powerful mechanism for
encouraging compliance across a geographically distributed and
culturally diverse population.
S4
SECOND GENERATION THREE PROCESS MODEL
(TPM) OF ALERTNESS FOR BETTER ASSESSMENT
OF INDIVIDUAL RISKS
Ingre M, van Leeuwen W, Kecklund G, Åkerstedt T
[email protected]
Fatigue modelling is an important tool for evaluating work-hours
and the risk for sleepiness/fatigue on the job. Most fatigue models
(including the three process model of alertness, TPM) typically give
predictions of group mean values of sleepiness/fatigue for various
situations. Such predictions are not ecologically valid as estimates
of risks and cannot be used to assess the number of subjects that
are likely to experience severe sleepiness in a given situation. The
present study had three main objectives aiming to overcome such
limitations of the first generation TPM:
1. Statistically validate all the individual components of TPM
(S + C + U + W).
2. Estimate an equation for probabilities of severe sleepiness.
3. Estimate the magnitude of systematic individual differences
to provide reference limits accounting for 90%, 75% and 50%
of the population.
We analyzed data from 157 subjects that had signed up in a crowd
sourcing effort of airline crews using a mobile phone application.
The “app” collected data about sleep patterns and subjective sleepiness (Karolinska Sleepiness Scale, KSS, 1-9) and submitted it to
a central database over wireless internet. A total of 13751 ratings of
sleepiness were collected from 147 male and 10 female “aircrew”
with a mean age of 43 years. We used the TPM to predict alertness
levels for all observed ratings. A multilevel generalized linear mixed effect regression model with a logit link function was used to
predict the probability of observed severe sleepiness (KSS ≥ 7) in
addition to estimating the systematic variation between individuals
in sleepiness propensity as a random effect over the intercept in
the model.
The result confirmed that all individual model components added
to the prediction (p < .05) of mean sleepiness. We then used the
total TPM (alertness) score to predict sleepiness and the probability of severe sleepiness (KSS ≥ 7) in addition to estimating a
random intercept accounting for systematic individual variation
in sleepiness propensity. The results showed large individual differences in sleepiness propensity suggesting that the 75% and
90% reference limits are .62 and 1.00 KSS units above the predicted mean. Predicted probability of severe sleepiness remained
at low levels (pr < .10) during a normal day even when accounting for 90% of the population but peaked during the subsequent
night wake at pr = .54 for an average subject and at pr = .70 and
pr = .80 for reference limits accounting for 75% and 90% of the
population.
The TPM is implemented in easy to use R-code that produces
predicted probabilities of severe sleepiness for any sleep/wake
schedule with reference limits and heat coloured plots indicating
risks and can be obtained upon request from the author. R is an
open source statistical package and can be freely downloaded for all
major operating systems at: http://cran.r-project.org/
42
S5
FATIGUE AT SEA: A SIMULATOR STUDY OF SLEEPINESS, SLEEP AND NEUROBEHAVIOURAL PERFORMANCE DURING DIFFERENT WATCH SCHEDULES
Dahlgren A1, van Leeuwen WMA2, Kircher A4, Lützhöft M5,
Barnett M3, Kecklund G2, Åkerstedt T2
Royal Institute of Technology, Sweden.
Stockholm University, Sweden.
3
Linköping University Hospital, Sweden.
4
Chalmers University of Technology, Sweden.
5
Warsash Maritime Academy, UK.
[email protected]
1
2
Fatigue at sea is a great safety risk and has been shown to contribute
to maritime accidents. The aim of the present study was to examine
sleepiness, sleep and performance under controlled conditions in
two of the most common watch systems at sea.
Ninety active seafarers were studied during one week of simulated
bridge- or engine room-work during a voyage in the English Channel and North Sea. Participants were randomly assigned to work in
either a 6/6 watch schedule (6 hours of work followed by 6 hours
off) or a 4/8 watch schedule (4 hours of work followed by 8 hours
off) in simulators in Gotheburg, Sweden or a 6/6 watch schedule
working on either bridge or in the engine room inin Warsash, UK.
Both subjective (diary ratings) and objective (polysomnographic recordings and psychomotor vigilance tasks) measures were used to
measure sleep, sleepiness and neurobehavioural performance.
Results showed that a relatively high proportion of seafarers (up to
50%) fell asleep at some point during the week. Both objective and
subjective measures showed an increase in sleepiness during the
night and early morning for both the 6/6 and 4/8 watch systems.
Furthermore, sleepiness increased and neurobehavioural performance decreased during the course of the watch.
A simulated disruption to normal operation (i.e. overtime work)
resulted in an increase in sleepiness and decrease in performance in
both watch schedules. When comparing the two watch schedules,
our results demonstrated that participants in the 6/6 system had
greater levels of sleepiness and more episodes of sleep while on
watch. We also observed accumulative effects in the 6/6 system,
with greater levels of sleepiness towards the end of the week.
The findings indicate that fatigue is an critical issue, especially during nights and early mornings and towards the end of the watch.
Fatigue also seems to be a greater issue when working in a 6/6
schedule and these problems accumulate already during a working
period as short as a single week.
S6
HARMONIZING SLEEP ESTIMATION WITH SLEEP
MEASUREMENTS IN SUPPORT OF SHIFT WORK
FATIGUE MODELING
Hursh SR
Institutes for Behavior Resources, Inc., USA 21218
[email protected]
Introduction: Prescriptive hours of service regulations do not
fully address the dynamic sleep and circadian factors that can create fatigue under shift work schedules. Fatigue risk management
systems apply a variety of scientific tools to provide a more complete solution to shift work fatigue. One of those scientific tools
is fatigue modeling that estimates the sleep patterns and performance consequences associated with any pattern of shift work. For
modeling to be a useful tool for fatigue assessment, the accuracy
of sleep estimation is pivotal and we describe here a method to
harmonize sleep estimates with actual sleep measurements using an
iterative computer simulation process.
Methods: In order to demonstrate the ability to harmonize sleep
estimation with actual sleep patterns, we cooperated with an aviation
maintenance organization that often works extended and additional
shifts to address critical technical demands. Volunteers wore actigraphs during the performance of normal work duties. The recorded
sleep were combined with work records and processed through the
SAFTE-FAST fatigue model. The same work schedules were then
processed through the model to estimate sleep. The difference between actual and estimated sleep was then minimized using an iterative computer process. The result was a harmonized sleep estimation
algorithm that improved the estimation of performance.
Results: The process was fully automated and required about 24
hrs of computer time to explore a matrix of 6000 possible sleep
estimation parameters. The computer harmonization process was
successful in estimating average sleep per day to within 1% of actual sleep amounts and matching the daily pattern of sleep with an
accuracy over 87% comparing minute by minute of each individual
subject. The result was an overall improvement of estimated performance compared to estimates prior to harmonization.
Conclusion: Fatigue modeling is a useful aid to shift work fatigue
risk management and its value can be maximized by harmonizing
sleep estimates to actual sleep measurements. A computerized system was successfully demonstrated that makes harmonization of
sleep estimates a practical tool for improving fatigue modeling as a
fatigue management tool.
Support (if any): This work was supported by a contract with the
US Federal Aviation Administration and a private aviation carrier.
S7
FEEDBACK BLUNTING: A NOVEL MECHANISM
UNDERLYING DEFICITS IN REAL-WORLD DECISION MAKING DUE TO SLEEP LOSS
van Dongen H1, Whitney P2, Hinson JM2, Jackson ML3
Sleep and Performance Research Center, Washington State University, USA.
Department of Psychology, Washington State University, USA.
3
Melbourne School of Psychological Sciences, University of Melbourne,
Australia.
[email protected]
1
2
Introduction: We investigated the effects of total sleep deprivation
(TSD) on decision making, specifically the updating of decision-relevant information based on feedback.
Methods: N = 27 healthy subjects (22-40y; 37% female) completed
an in-laboratory study involving two baseline days, randomization
to 62h TSD (n = 13) or control (n = 14), and two recovery days.
A decision task embedded in a go/no-go paradigm was administered at 48h intervals: during baseline, after 51h TSD (or well-rested
control), and after recovery. The task required speeded responses
to two numeric stimuli while withholding responses to two other
numeric stimuli. Subjects did not know in advance which stimuli
were in the go (response) and no-go (withhold) sets. Furthermore,
after a random number of trials about halfway through the task, the
mapping of go and no-go stimuli was reversed without warning.
On each trial, subjects had 750ms to respond or withhold. Both
before and after reversal, subjects were to acquire the mapping of
go and no-go stimuli based on accuracy feedback after each choice.
Skin conductance response (SCR) was recorded throughout
the task, and SCR amplitude provided an index of affective
reactions to information processing. In a follow-up experiment examining the effects of simulated attentional lapses on
task performance, N = 40 non-sleep deprived subjects (18-
43
25y; 60% female) were randomized to perform the task either
with feedback on all trials or with feedback omitted on 20%
randomly selected trials.
Results: At baseline, pre-reversal hits increased and false alarms
(FAs) decreased (p ≤ 0.001), demonstrating that subjects acquired
the mapping of go and no-go stimuli. Reversal of the mapping
briefly disrupted performance, after which hits increased and FAs
decreased again (p < 0.05) as expected. After 51h TSD, pre-reversal
performance improved less than in well-rested controls (p ≤ 0.01).
Moreover, after reversal, the TSD group no longer differentiated
the go and no-go stimuli (p > 0.05). Following recovery sleep, task
performance in the TSD group improved, but not to the level of
controls (p < 0.05). SCR amplitudes revealed that sleep loss-induced deficits in task performance were associated with blunting of
affective reactions to choice accuracy feedback (p < 0.05). In the
follow-up experiment, omitting feedback on 20% of trials did not
produce significant declines in performance (p > 0.25), indicating
that simulated attentional lapses could not adequately explain the
task performance deficits induced by TSD.
Conclusion: Sleep loss was associated with blunted affective reactions to choice accuracy feedback and degraded ability to utilize
feedback to improve decision making. This finding reveals a novel
mechanism for how sleep deprivation may cause deficits in decision
making. For real-world decision making, which often requires acquisition and updating of information over time based on outcome
feedback, the mechanism of feedback blunting provides new insight into how sleep loss may lead to catastrophic decision outcomes.
shift, at 03:00, and at bed and wake times, approximately at 09:00
and 15:45, respectively. Melatonin secretion was expressed in percentages of each individual participant’s average value for the assessment of underlying rhythm. Night workers were then classified to
the “partially adjusted” (N = 7) or “non-adjusted” (N = 10) groups
based on the percentage of melatonin secretion in the middle of
the night shift: “partially adjusted” workers produced less than 60%
of their daily melatonin at this time point while the "non-adjusted"
night workers produced 60-245% of the daily melatonin at night.
Results: “Partially adjusted” night workers presented a shifted
cortisol rhythm, while “non-adjusted” workers showed approximately the same cortisol levels at the three evaluated daily moments.
Furthermore, “non-adjusted” night workers spent on average 91
minutes less time in bed and had their sleep duration was 126 minutes shorter during workdays, as estimated by actigraphy, than the
“partially adjusted” night workers.
Conclusions: We conclude that a partial adjustment to night
work is associated with changes in cortisol rhythmicity and
improvements in the sleep of the permanent night workers.
Support: NIH grants HL105768 and CA167691.
IS IT DAY OR NIGHT? AN IN-DEPTH INTERVIEW
STUDY WITH PREVIOUS IMPRISONERS EXPOSED
TO SOLITARY CONFINEMENT AS A FORM OF TORTURE
Toivanen T1, Toivanen S2
Poster Sessions
Session I - November 5th
14:00-16:00 h
A - Chronobiology and shiftwork
PA 01
PARTIAL ADJUSTMENT TO PERMANENT NIGHT
WORK ESTIMATED BY MELATONIN RHYTHM INCREASES SLEEP DURATION
Reinhardt EL1, Fernandes PACM2, Markus RP2, Härmä M3,
Fischer FM4
Occupational Hygiene Division, Fundacentro, Brazil.
Biosciences Institute, USP, Brazil.
3
Human Factors at Work Centre, FIOH, Finland.
4
School of Public Health, USP, Brazil.
[email protected]
1
2
Introduction: In usual workplaces, permanent night shift systems
are unlikely to result in sufficient circadian adjustment in most individuals in order to improve sleep, but some adjustment may occur.
The aim of this study was to investigate the effects of a partial adjustment of circadian rhythms to permanent night work on cortisol
rhythm and sleep.
Methods: Seventeen permanent night workers (shift hours: 21:00
to 6:00) from a sanitary metals industry accepted our invitation
to participate in this study. Work schedule comprised 5 workdays
(Monday-Friday) followed by two days off (Saturday-Sunday). Night workers wore actigraphs (Motion Logger, Ambulatory Monitoring) and filled activity protocols for ten consecutive days. Workers
collected saliva samples for ELISA analysis of cortisol and melatonin three times during three workdays: in the middle of the night
Support: CAPES (grant number 8755/11-6), FUNDACENTRO,
FAPESP (grant number 2011-10503/4) and the Finnish Institute
of Occupational Health.
PA 02
Red Cross Centre for Tortured Refugees/RKC, Göta Ark 180,11872 Stockholm, Sweden.
2
Centre for Health Equity Studies |CHESS, Stockholm University /Karolinska Institute, 10609 Sweden.
[email protected]
1
Introduction: Torture is a severe global health problem resulting in
both hidden and overt handicaps, manifested as physical and psychological symptoms, psychosomatic complaints and stress related
disorders. Sleeping disorders including nightmares are among the
most prevalent and difficult problems among torture survivors. Isolation in a dark prison cell is an intensive pressure and a common
form of torture during longer or shorter time periods. Thus, a person is exposed to two extreme stressors: 1) solitary confinement
and 2) deprivation of the circadian rhythm. The Red Cross Centre
for tortured refugees (RCC) in Stockholm is one of the first centers in the world for rehabilitation of torture victims. Since 1985,
approximately seven thousand people have received treatment at
the centre until now (2013). During 1995-2008 a unique pilot project was conducted with torture survivors that had been exposed
to dark cell isolation. The aim of the project was to increase the
understanding of the consequences of this form of torture and to
respect the difficult experiences of the torture survivors. The project was initiated by RCC’s former director Rigmor Gillberg, a social
worker and psychotherapist, but the results were never published
because of her death.
Methods: Because the theme was very painful, only five patients,
all men, could be interviewed and participate in the project. They
answered 22 questions, for example: Describe how your cell looked
like; describe the lightness and darkness of your cell; could you
keep track of the rhythm of day and night; how were your sleeping
facilities organized; how did your life turn out after the torture? The
interviews took very long time, sometimes several years. The therapist took notes and wrote down the interviews which were analyzed
with qualitative analysis methods.
44
Results: During dark cell isolation perception via the sense organs
is weakened. The circadian rhythm is possibly maintained during
an initial period, probably a week or two, but after some time this
important function, the biological clock, is severely disturbed causing hormonal problems and sleeping disorders. Healthy dreaming
which processes daily experiences (i.e. what is to be forgotten fades
away, and what is to be remembered for the future is saved) does
not function any more. As a consequence, the human brain becomes extremely strained.
Conclusions: Solitary confinement seems to results in various
types of severe brain disturbances. The lack of light makes the torture really extreme. Rehabilitation of torture victims exposed to solitary confinement is very demanding and getting back to working
life is in most cases not a realistic option. More research is needed.
PA 03
LESS IS MORE? QUANTIFYING THE IMPACT OF
CONSECUTIVE SHIFTS ON THE CIRCADIAN
CLOCK IN ROTATIONAL WORK SCHEDULES
Fischer D , Mehlmann JL, Roenneberg T , Vetter C
Institute of Medical Psychology, Ludwig-Maximilian-University Munich,
Germany.
[email protected]
Introduction: Work schedules can have dramatic effects on sleep
timing and sleep duration, especially in rotating shift schedules where
employees have not only one, but several working times to cope with.
Within such schedules, the shift sequence is considered to entail a
differential impact on health, accident risks and wellbeing. Yet, detailed analyses are missing, particularly with regard to individual phase
of entrainment, i.e., chronotype. In this study, we aim at quantifying
the effects of different rotating shift schedules on the circadian clock (1) by analyzing sleep duration on work and free days and (2) by
proposing a new concept called ‘mid-sleep perturbations’ (MSP) that
calculates the individual mid-sleep delay or advance within a given
work schedule as a function of mid-sleep on previous days and chronotype. Taking into account both, preceding sleep-wake behavior
and individual phase of entrainment, (rotational) shift schedules can
be evaluated in high-resolution.
Methods: Employees working in four different rotating shift systems continuously filled out daily sleep logs and wore wrist actimetry
over the course of four to six weeks. Analyses of sleep duration and
MSP are conducted within a 3-level hierarchical linear model using
the statistics software HLM 7.0, accounting for the nested data structure. Time of sunrise and photoperiod are considered as covariates.
Results: Preliminary results show a three-way interaction between
type of shift, internal time (i.e., chronotype) and number of consecutive shifts: with more night shifts, i.e., 2 vs. 4, the difference between sleep duration on work and free days increases for earlier and
decreases for later chronotypes (r = - 0.84, p < .01), indicating an
improved circadian alignment in late types when exposed to more
than two night shifts in a row.
Conclusion: Our first results suggest that the number of consecutive shifts beneficial for an individual depends strongly on chronotype. The results of this study are intended to serve a science-based
evaluation and optimization of current shiftwork guidelines, particularly with regard to individual internal time.
Support: This work was supported by industry grants to TR (ThyssenKrupp Steel Europe AG and Siemens AG) as well as an individual PhD fellowship by the Hanns-Seidel-Foundation to DF.
PA 04
A SYSTEMATIC REVIEW OF HEALTH-RELATED
INTERVENTIONS IN SHIFT WORKERS EXPOSED
TO LIGHT AT NIGHT
Neil SE1, Pahwa M2, Demers PA2,3, Gotay CC1,4,5
School of Population and Public Health U of British Columbia.
Occupational Cancer Research Centre Cancer Care Ontario.
3
Dalla Lana School of Public Health U of Toronto.
4
Cancer Prevention Centre U of British Columbia.
5
BC Cancer Research Centre.
[email protected]
1
2
Introduction: Today, approximately 15-20% of the working
population in Europe and North America are employed in an
occupation requiring regular night or rotating shift schedules.
Associations between shiftwork and chronic disease have been
observed, but relatively little is known about how to mitigate
these adverse health effects. This systematic review aimed to
synthesize and evaluate the quality of interventions that have
been implemented in shift workers to reduce the effects on
chronic disease.
Methods: MESH terms and keywords related to shiftwork,
health, and interventions were developed and used to search
MedLine, CINAHL, and EMBASE for studies published on or
before August 13, 2012. Both randomized and non-randomized
interventions with the aims of improving workers health were
included. Studies conducted using volunteers in simulated night
shift environments, or studies only reporting on injuries or performance- or psychosocial-related outcomes were excluded. Data
on the magnitude and direction of health effects were extracted,
and individual study quality was assessed using a checklist adapted
from Downs and Black.
Results: Of the 5053 articles retrieved, 45 met inclusion and
exclusion criteria. Over 2439 male and female rotating and permanent shift workers were included, mostly from the manufacturing, health care, and public safety industries. Studies were
grouped into four intervention types: 1) shift scheduling; 2) controlled light exposure; 3) behavioural; and, 4) pharmacological.
Results generally supported the benefits of changing from backward, slowly rotating shifts to forward, quickly rotating shifts;
the use of both timed bright light and light-blocking glasses;
physical activity, healthy diet, and health promotion. Stimulants,
melatonin and other hypnotics showed limited and inconsistent
effects on workers’ health. Study quality ranged from scores of
8 to 27 on the 28-point scale. Lack of blinding of participants
and outcome assessors, as well as inadequate sample size, were
the most common study quality issues. No studies evaluated the
simultaneous use of multiple intervention types to improve health of shift workers.
Conclusion: A variety of approaches may be implemented by
employers and workers to improve the health of shift workers. Of the studies reviewed, there was substantial heterogeneity
with respect to study sample, interventions, outcomes, and quality. There is a need for further high-quality; workplace-based
prevention research conducted in shift workers in real workplace settings. Nevertheless, the review underscores the need for
rigorous, workplace-based research to further develop interventions that may help prevent occupational disease in this high-risk
population.
45
PA 05
PA 06
INVESTIGATION OF RELATIONSHIP BETWEEN
CIRCADIAN GENE POLYMORPHISMS, NIGHT WORK
AND BREAST CANCER RISK IN NORWEGIAN
NURSES
Lie Sigstad J-A1, Zienolddiny S1, Haugen A1, Kjuus H1, Anmarkrud K1,
Kjærheim K2
CHANGING AIRCRAFT INSPECTORS’ SHIFT RHYTHMS
Niemelä P1, Viitasalo K1, Hakola T2
National Institute of Occupational Health, Norway.
Cancer Registry of Norway.
[email protected]
1
2
Introduction: Breast cancer in women is the second leading
cause of mortality. Night work is an important occupational risk
factor that has been found to elevate the risk of breast cancer. Studies among female nurses, female airlines cabin crew,
and women working in the military, have shown significantly
increased risk of breast cancer in women with long duration of
working night shifts. Night work was classified as a “Group 2A”
carcinogen by the International Agency for Research on Cancer
(IARC) in 2007. The hypothesis is that night work and exposure to artificial light at night may disrupt the circadian rhythm.
The circadian rhythm is genetically regulated by circadian genes.
Polymorphisms in these genes, in combination with night work,
may contribute to individual differences in susceptibility to breast cancer. Up to date, only few polymorphisms in the circadian
genes Clock, Per and NPAS2 genes have been investigated in
relation to susceptibility to breast cancer in combination with
night work. In this study, we have investigated as many as 60 single nucleotide polymorphisms (SNPs) in 17 circadian genes in
1182 Norwegian nurses, and have analyzed the data in relation
to occupational exposure to night work.
Methods: A case-control study was nested within a cohort of
49402 Norwegian nurses, aged 35-74 years. The cases (n = 563)
were frequency matched with controls (n = 619). Exposure metrics applied included duration of night work, and number of
successive night shifts. The DNA was extracted from saliva and
genotyped for 60 SNPs in 17 circadian genes using the Sequenome iPLEX genotyping. The odds of breast cancer associated
with each SNP was calculated in the main effects analysis, and
also in relation to night shift work, using women with < 3 consecutive night shift work as the reference group.
Results: In the main effects analysis, CC carriers of rs4238989
and GG carriers of rs3760138 in the AANAT gene had increased risk of breast cancer whereas, TT carriers of BMAL1
rs2278749 and TT carriers of CLOCK rs3749474 had reduced risk. In regard to the effect of polymorphisms and night
work, in women with ≥ 4 night shifts, an increased risk of breast cancer was associated with variant alleles of SNPs in the
genes AANAT (rs3760138, rs4238989), BMAL1 (rs2290035,
rs2278749, rs969485) and ROR-b (rs3750420). In women with
3 consecutive night shifts, a reduced risk of breast cancer was
associated with carriage of variant alleles of SNPs in CLOCK
(rs3749474), BMAL1 (rs2278749), BMAL2 (rs2306074), CSNK1E (rs5757037), NPAS2 (rs17024926), ROR-b (rs3903529,
rs3750420), MTNR1A (rs131113549), and PER3 (rs1012477).
Conclusion: Significant and noteworthy associations with breast cancer were found among nurses who had worked 3 or more
consecutive night shifts indicating that circadian genes in combination with night work may affect risk of breast cancer.
Finnair Health Services, Finland.
Finnish Institute of Occupational Health, Finland.
[email protected]
1
2
Introduction: Different shift schedules and shift systems influence shift workers’ well-being. This study examines the effects of a
change in the order of days off in three rapidly forward rotating
shift systems on aircraft inspectors’ sleep, alertness, and well-being.
In addition, we examine the effects of the change on sharing the
flow of information, and the knowledge and expertise of inspectors work.
Methods: The study population consisted of 35 out of 42 aircraft inspectors who changed their shift schedules from MEN - (n = 8) or NME - - (n = 27) to ENM - - rhythm (M = morning,
E = evening, N = night, - = day off). The aircraft inspectors filled
in questionnaires on the following items: work satisfaction, sleep
and alertness, fatigue at work, recovery from shift work, sharing
knowledge, expertise at work and work-based learning. The baseline data was collected before the inspectors changed their rhythms
(December 2011) and follow-up data was collected three months
after the change (April 2012). The participation rates were 86% at
baseline and 62% at follow-up.
Results: The aircraft inspectors reported that they were satisfied
with their jobs. Fatigue at work was most prevalent in the morning
shifts. During the morning and night shifts, the inspectors’ sleep
time was inadequate for their sleep needs. However, the inspectors
rated their recovery from shift work as normal. One-fifth of the
respondents were dissatisfied with the NME - - and the ENM - schedules. However, compared to the NME - - rhythm, the ENM
- - rhythm had more positive effects on sleep, wakefulness, well
-being, general health, and social life. In addition, one-fifth of the
inspectors said that the change to the ENM - - rhythm improved
their opportunities to share their expertise, problem-solving skills
and mutual learning at work. The inspectors’ alertness was best
when working in the MEN - - rhythm compared to when working
in the two other rapidly forward-rotating shift rhythms, i.e. the
NME - - and the ENM - -.
Conclusion: The differences between the three shift schedules in this
study were minimal. However, the most recommendable is the forward-rotating shift system, which best promotes recovery after night shifts.
PA 07
CHRONOTYPE, SHIFT SPECIFIC SLEEP QUALITY
AND NEED FOR RECOVERY
van de Ven HA1, van der Klink JJL1, Vetter C2, Roenneberg T2,
Gordijn MCM2, de Looze MP3, Brouwer S1, Bültmann U1
University of Groningen, The Netherlands.
Ludwig Maximilian University Munich, Germany.
3
TNO, Hoofddorp, the Netherlands.
[email protected]
1
2
Introduction: The objective of this study was to examine the association between chronotype and sleep duration with shift specific
sleep quality and need for recovery.
46
Methods: This study was conducted within the sampling frame of
the ‘Shift Your Work’ study. The study sample comprised N = 265
shift workers of four different companies in the Netherlands. A
shift work adjusted version of the Munich Chronotype Questionnaire (MCTQShift) was used to assess chronotype, sleep duration
and napping behaviour. Based on the MCTQShift, we used the
midpoint of sleep after an evening shift (MSWE) as a proxy for
chronotype. Sleep quality was assessed with the Karolinska Sleep
Questionnaire (Disturbed Sleep Index (DSI), Awakenings Complaints Index (AwI), range 1-5). Need for recovery was assessed
with subscale of the Dutch Questionnaire on Perception and Judgement of Work (NFR, range 0-100). DSI, AwI and NFR were
assessed separately for the morning, evening, and night shift, and
dichotomized upon the upper quartile; MSWe and sleep duration
were divided into quartiles. Logistic regression was used to examine
the relation between chronotype, MSWE and sleep duration with
DSI, AwI and NFR, adjusted for naps, socio-demographic factors
and shift schedule.
Results: The average age of the study sample was 44.5 years (SD
8.3); average tenure in shift work 20.8 years (SD 8.9). The workers
reported the highest NFR (mean 42.06, SD 31.23) and shortest sleep duration (mean 5.61 hours, SD 1.72) during a night shift period,
and highest DSI (mean 2.37, SD 1.02) and AwI (mean 2.56, SD
1.88) during a morning shift period, indicating worst sleep quality.
During a morning shift period, the adjusted analyses showed that
later MSWE was associated with higher NFR (odds ratio 4.49, 95%
confidence interval 1.56-12.93) and higher AwI (4.43, 1.68-11.69),
while longer sleep duration was associated with lower DSI (0.29,
0.11-0.80). During an evening shift period, the adjusted analyses
showed that longer sleep duration was associated with higher DSI
(0.10, 0.03-0.31). During a night shift period, adjusted analyses
showed that later MSWE was associated with less disturbed sleep
(0.31, 0.12-0.80). Moreover, adjusted analyses showed that longer
sleep duration du ring a night shift period was associated with lower
NFR (0.30, 0.13-0.70), lower DSI (0.03, 0.00-0.20) and lower AwI
(0.19, 0.07-0.53).
Conclusion: Evidence was found for an association between chronotype and shift-specific sleep quality and need for recovery. In
particular later MSWE was associated with more awakenings complaints and higher need for recovery during the morning shift period. Sleep was most affected during a night shift period, reflected
by shorter sleep duration, more disturbed sleep, more awakenings
complaints, and a higher need for recovery. The results of this study indicate that future research should incorporate chronotype and
shift-specific measures.
PA 08
IMPROVING WELLBEING WITH BLUE-ENRICHED
LIGHT IN ROTATING SHIFT WORKERS
Middleton B1, Vandenbossche E1 , Morgan PL1, Rousseau1,2,
Kantermann T3, Haubruge D4, Schlangen LJM5, Kerkhofs M3,
Skene DJ1
Chronobiology, University of Surrey, UK.
University of Brussels, Belgium.
3
University of Groningen, Netherlands.
4
ArcelorMittal, Belgium.
5
Philips Research, Netherlands.
[email protected]
1
2
Introduction: Light has a variety of non-visual biological effects
(e.g. increased alertness, improved mood and phase shifting effects
on the circadian timing system). The established increased sensitivity of the circadian system to blue light has led to the development
of high color temperature blue-enriched fluorescent white light
sources and these are currently being tested in a variety of field
settings (e.g. care homes for older people, office workers, shift
workers).
Methods: Blue-enriched white light (17000 K, Philips) was installed in an operational control room in a steel factory after a 10
day baseline period. Data were collected in 14 male rotating shiftworkers, aged 36.9 ± 6.8 years (mean ± SD), over 6 weeks. Shifts
(8 h) were fast clockwise rotating 06:00-14:00 h; 14:00-22:00 h and
22:00-06:00h, 2 days each with 3 days over a weekend (followed by
2 days off). Participants were asked their opinion of the two light
conditions (baseline and 17000 K) on visual function and comfort and to compare the effect of both light conditions on their
mood and general wellbeing. Wrist-worn activity and light monitors
(AWL) were worn throughout the study with light sensors (HOBO
data loggers) attached to work uniforms. Participants were requested to complete daily sleep diaries, KSS and mood and alertness
VAS at the start, middle and end of night shift.
Results: Light levels in the control room were 56 ± 14 lux during
baseline and 168 ± 11 lux (mean ± SEM) during the 17000 K light
condition in the angle of gaze. Participants (n = 9) significantly
preferred the 17000 K lights in appearance, visual comfort, color
of objects and overall satisfaction (p < 0.01) and would recommend
it to others (p < 0.001).
There was no significant effect of the blue-enriched lights on irritability, headache, eye strain, eye discomfort, blurred vision, tired eyes or ability to concentrate. Comparison of the two lighting
conditions (n = 7) indicated improved visual comfort (5.9), mood
(4.6), performance (5.4) and vigilance (5.3) with increased energy
levels (4.7) and better sleep (5.4) during the 17000 K light condition (score > 4 is a positive effect) with less effect on anxiety (4.1),
appetite (4.3) and stress (4.3). On night shift, workers (n = 3) had
increased alertness, energy and feelings of relaxation mid-shift during the 17000 K intervention (p < 0.05).
Conclusions: Shift workers greatly appreciated the increased light
levels produced by installation of blue-enriched fluorescent 17000
K lights in their workplace. Visual comfort was significantly improved in addition to increased feelings of wellbeing, vigilance and
performance.
Support: Philips Lighting (Eindhoven, The Netherlands) for the lights and ArcelorMittal Industeel (Belgium) for access to the factory
and shift workers.
PA 09
INSOMNIA AMONG DAY AND SHIFT WORKERS
ABOVE THE ARCTIC CIRCLE - ASSOCIATIONS
WITH STRESS, LIGHT DEPRIVATION AND UNDERGROUND WORK
Garefelt J, Lowden A, Åkerstedt T
Stress Research Institute, Stockholm University, Sweden.
[email protected]
Introduction: The present study is part of a study on light, health
and sleep above the Arctic Circle in the north of Sweden, where
daylight hours vary from zero in December (polar nights), to 24
h in May-July (midnight sun). The purpose of this study was to
analyse if light deprivation could be an important factor for sleep
disturbances among shift- and daytime workers.
Methods: The study sample consisted of employees in a mining
company in the north of Sweden (N = 1273, response rate 68%).
Data was collected in January and February 2013 by an online questionnaire. The employees were classified into six work categories:
daytime, shifts with nights, shifts without nights - above or below
ground. Sleep disturbances were measured by the Karolinska Sleep
Questionnaire (problems falling asleep, repeated awakenings, too
47
early final awakening or restless sleep - with at least one item occurring ≥ 3 times/week). Fatigue was measured by a single-item
question. Stress was derived from a mean of three questions: having days feeling wound up/very pressured/stressed all the time.
All questions concerned the preceding three months, encompassing the darkest period of the year. An ordinal logistic regression
was carried out to analyse the proportional odds ratio, OR, for
“subclinical insomnia” (sleep disturbances) and “clinical insomnia”
(sleep disturbances and problems with fatigue). Independent variables were work category, light exposure and stress, controlled for
gender, age and education.
Results: In total, 16% suffered from sleep disturbances and 9%
met the clinical criteria for insomnia. Over 30% were exposed to
< 1h of daylight on both workdays and free days, 43% were exposed to > 1h of daylight on either workdays or free days and 22%
were exposed to > 1h of daylight on both workdays and free days.
Exposure to < 1h of daylight on both workdays and free days was
associated with an increased OR of 2.00 (95% CI 1.26-3.15) for
subclinical and clinical insomnia. However, exposure to < 1h on
either workdays or free days did not increase the OR compared to
the reference, > 1h both workdays and free days. Stress (scale 1-4,
mean 1.75, SD 0.59) was associated with an increased OR of 3.32
(2.55-4.31). Working shifts with or without nights over or below
ground were not related to insomnia, neither was age nor education. Being a woman was associated with an increased OR of 1.61
(1.10-2.34).
Conclusions: Stress and lack of exposure to daylight were both associated with increased odds ratios for insomnia, whereas working
shifts, with or without nights over or below ground, were not.
Support: Swedish Council for Working Life and Social Research.
PA 10
CASE-CONTROL STUDY OF PERIOD3 CLOCK
GENE LENGTH POLYMORPHISM AND COLORECTAL ADENOMA RISK
Burch JB, Alexander M, Steck SE, Zhang, H, Hurley TG,
Cavicchia P, Shivappa N, Guess J, Hébert JR
Cancer Prevention & Control Program, Dept. of Epidemiol. & Biostat. U. of
South Carolina (USC). Chen C-F: Greenwood Genetic Center, SC. Creek KE:
Dept. of Pharmaceut. & Biomed. Sci., USC.
[email protected]
Introduction: Circadian rhythm disruption has emerged as a novel
and potentially important cancer risk factor. Shift work is associated
with increased risks for colorectal and several other cancers. These
effects may be mediated by genetic variation or altered expression
of clock genes. However, their role in adenomatous polyp formation or subsequent colorectal cancer incidence has not been thoroughly investigated. A variable number tandem repeat (VNTR) length
polymorphism in the period 3 (PER3) clock gene (rs57875989) has
been associated with sleep homeostasis, chronotype, and premenopausal breast cancer. The 5-repeat allele may be more strongly
coupled to the circadian system than the 4/4 genotype, and such individuals may be more susceptible to factors that disrupt circadian
rhythms, such as shift work. This study tested the hypothesis that
the 5-repeat PER3 sequence is associated with increased risk of colorectal adenomatous polypformation among colonoscopy patients
undergoing colon cancer screening or surveillance.
Methods: Demographic, medical, occupational, and lifestyle factors were ascertained prior to colonoscopy. DNA was acquired
from a peripheral blood sample and genotype was established by
sizing PCR products via gel electrophoresis. Logistic regression
was used to calculate odds ratios (ORs) with 95% confidence intervals (CIs) by genotype among cases with histologically confirmed
adenomas (n = 49), and controls (n = 96) with a normal colon or a
hyperplastic polyp not requiring increased surveillance, after adjustment for age and recruitment site.
Results: Adenomas were detected in 34% of participants (average
age: 59 ± 9 years; 65% European American; 72% male). Genotype
frequencies for the PER3 VNTR (4/4: 47%, 4/5: 42%, and 5/5:
11%) were in Hardy-Weinberg equilibrium (p = 0.83) and there was
100% concordance with quality control repeat genotyping (10% of
samples). Adenoma risk was somewhat elevated among heterozygotes (4/5 genotype OR: 1.78, 95% CI: 0.80-3.88), and cases were >
3 times more likely to be homozygous for the 5/5 PER3 genotype
(OR: 3.63, 95% CI: 1.07-12.29) relative to those with the 4/4 genotype (combined 4/5+5/5 genotype OR: 2.03; 95% CI: 0.96-4.30).
Conclusion: Individuals with the 5-repeat PER3 length polymorphism had an increased risk of colorectal adenomatous
polypformation. This clock gene variant may serve as a novel biomarker of colorectal cancer risk among shift workers or in other
populations that experience circadian rhythm disruption.
PA 11
DIFFICULTY FALLING ASLEEP AND DAYLIGHT
EXPOSURE: DIFFERENCES BETWEEN BRAZILIAN
AND SWEDISH WORKERS.
Marqueze EC1,2, Vasconcelos S1, Garefelt J2, Fischer FM1,
Skene DJ3, Moreno CRC1, Lowden1,2
University of São Paulo, Brazil.
3
University of Surrey, UK.
[email protected]
1
2
Introduction: Exposure to light during the day has shown to affect
sleep positively as light is the main exogenous synchronizer for circadian misalignment. In general, workers who get little exposure to
light report sleep disturbances. In this context, the purpose of this
study was to evaluate predictors for difficulty falling asleep among
Swedish and Brazilian workers.
Methods: A cross-sectional design was performed including 1,273
workers (mean age 38.3 yr.) from a mining company located in northern Sweden (latitude 67°N; longitude 20°E) and 488 Brazilian
rubber tappers and industrial workers from a rubber factory (mean
age 37.5 yr.) located in north of Brazil (latitude 10°S; longitude
68°W). A logistic regression was conducted to predict difficulty
falling asleep (assessed by Karolinska Sleep Questionnaire), controlling for age, sex, education, occupation and electricity at home.
Results: Most of workers were males (78.3%), with a good education level (77.6% high school or more), worked as blue-collar
workers (54.5%) and had electricity at home (86.2%). Difficulty
falling asleep was reported by 25.4% of Brazilian and 17.5% of
Swedish workers, with a higher chance within the Brazilian sample (OR 2.10; CI 95% 1.35-3.25). Predictors for difficulty falling
asleep were: receiving < 1h of sunlight exposure during work and
free days (OR 2.13; CI 95% 1.42-3.20), smoking (OR 1.92; CI 95%
1.37-2.67), having neck/shoulder pain (OR 1.34; CI 95% 1.011.78), sleeping > 10h on free days (OR 1.51; CI 95% 1.03-2.20) and
perceiving not getting enough sleep (OR 3.70; CI 95% 2.83-4.85).
Conclusion: The strongest predictor for difficulty falling asleep
was not getting enough sleep, suggesting that both problems could
prevail in parallel. The higher incidence of difficulty falling asleep among Brazilian workers could possibly relate to differences in
work hours and sleep environment. Independent of latitude and
work hours, daylight exposure seems to be important for securing
an acceptable sleep latency.
Support: CAPES-Stint; CAPES; FAPESP-UniS; UGPN Research
Collaboration Fund, USP-UniS; CNPq; FUNTAC; FAPESP; Swedish Council for Working Life and Social Research.
48
14:00-16:00 h
B - Fatigue and performance
PB 12
SHARED PERCEPTIONS OF THE WORK ENVIRONMENT: THE IMPACT ON INDIVIDUAL FATIGUE IN
SHIFTWORKING NURSES
Pisarski A
School of Management, Queensland University of Technology, Australia
Barbour JP, School of Psychology, Griffith University, Australia
[email protected]
This quantitative paper investigates the effects of shared perceptions of the work environment on individual fatigue in shift
working nurses. We used multilevel regression analysis to examine
the responses of 1,635 nurses nested within 154 wards.
The results indicate that positive ward environments enabled job
control and team climate to reduce fatigue. The positive effects of
job control in reducing fatigue were only evident in wards characterized by a more positive team climate and lower work life conflict.
Conversely, in wards with negative team climate and high shared
work life conflict, individual job control had no impact on fatigue.
These results suggest that shared perceptions of the work environment play an important role in moderating between individual
perceptions and fatigue. Further research is needed to investigate
potential causal mechanisms in the development of shared workgroup perceptions and their influence.
PB 13
JOB STRAIN, WORKING HOURS, WORK LOAD AND
RECOVERY
Karhula K1,2, Härmä M1, Sallinen M1,3, Hublin C1, Virkkala J1,
Kivimäki M1,2,4, Vahtera J1,5, Puttonen S1,2
Finnish Institute of Occupational Health, Finland.
University of Helsinki, Finland.
3
University of Jyväskylä, Finland.
4
University College London, United Kingdom.
5
University of Turku, Finland.
[email protected]
1
2
Introduction: Previous studies have shown that shift work impairs
employees' alertness and undermines recovery, but there is limited
evidence how work stress, defined as the combination of high work
demands and low control, links to work load and recovery in shift
workers. We combined epidemiological and experimental field study
paradigms to explore the relationship of job strain with characteristics
of working hours, shift-dependent perceived work load and recovery.
Methods: Female health care professionals, mainly nurses and nursing
assistants (n = 95) were recruited from wards that belonged to the top
(high-strain group, HJS, n = 42) or bottom quartiles on job strain (low
-strain group, LJS, n = 53) based on a survey to employees in 5 health
care districts and 4 cities in Finland. Three-week measurements with
both naturalistic and pre-selected shift arrangements included data on
realized rosters, perceived work load and recovery. The three pre-selected work shifts, comparable for all participants with respect to circadian
rhythm and recovery, were the 3rd consecutive morning shift, the 1st
night shift and the 2nd day off.
Results: Average weekly working hours showed no difference between the job strain groups (HJS 37:15, LJS 37:55 h/wk, p = 0.30).
Participants’ own wishes in shift planning were more often taken
into account in the LJS-group (89 vs. 67%, p = 0.01). Compared to
LJS-group nurses, a larger proportion of HJS-group nurses had single days off (78.6 vs. 49.1%, p < 0.01) and quick returns < 9h (0.2
vs. 0%, p < 0.01) in naturalistic shift schedules. The rosters of HJSgroup included on average one morning shift more and, conversely
one extended shift less than the LJS-group (p = 0.01; p = 0.02). HJSgroup rated mental and physical work load more often too high than
LJS-group (33 vs. 9%; 24 vs. 6%, p < 0.01). HJS-group recovered on
average poorer from work after all shifts (p = 0.01) and after morning shifts (p = 0.02). During the three pre-selected days differences
between the groups were not statistically significant (p > 0.05).
Conclusion: High job strain among female shift workers is associated
with less work time control and unfavorable work schedule patterns
(e.g. quick returns). Ergonomics in shift planning and improved possibilities to influence working hours could reduce work strain of shift
workers.
Support: This study was supported by The Academy of Finland
(projects 124473, and 132944), The Work Environment Fund (project 107156), The SalWe Research Program for Mind and Body
(TEKES -the Finnish Funding Agency for Technology and Innovation, grant 1104/10).
PB 14
INCORPORATING COGNITIVE WORKLOAD
FACTORS INTO FATIGUE MODELLING TOOLS
Paterson L J, Darwent D, Clarkson L, Dawson D
[email protected]
Introduction: Fatigue is broadly understood as a consequence of
any combination of extended wake, reduced sleep, circadian disruption and time-on-task. Recent evidence implicates workload as
one time-on-task factor that may influence fatigue for Australian rail
workers. Given the safety-critical nature of rail operations, and the
known negative consequences of fatigue for health and safety, the
management of fatigue is of paramount importance. However, there
is currently no systematic method for managing fatigue related risk
associated with workload for Australian urban rail car drivers.
Methods: In Stage One of this research, aspects of workload contributing to fatigue in urban rail car drivers were identified using
a survey (n = 124), focus groups (n = 30), interviews (n = 28)
and participant observation (n = 14). The most salient aspects of
workload identified in Stage One were then assessed quantitatively
in Stage Two. Forty Australian urban rail car drivers completed
sleep and work diaries, including multiple measures of subjective
workload and fatigue, and wore wrist activity monitors for three weeks. The rail network was mapped and each section of track coded
according various parameters such as distance between stations,
number of level crossings, number of signals, and so on. These
were used to calculate a measure of cognitive workload.
Results: Regression analyses will be conducted to determine the relative contribution of cognitive workload to sleep, subjective workload
and fatigue. The focus of these analyses will be on predictors that are
a) measurable, b) consistent and c) knowable in advance.
Conclusion: It is anticipated that this project will result in one
of the first bio-mathematical fatigue modeling tools that includes
workload in the determination of fatigue related risk. This will potentially allow for a more holistic approach to fatigue management,
and ultimately a safer and more efficient urban railway.
49
PB 15
RECOVERY OF NEUROBEHAVIORAL FUNCTION
FOLLOWING A SIMULATED 8-HOUR ON/8-HOUR
OFF ROTATING SHIFT SCHEDULE
Hilditch CJ1, Short MA1,2, Centofanti SA1, van Dongen HPA3,
Kohler MJ1, Banks S1
Centre for Sleep Research, University of South Australia, Adelaide, SA,
Australia;
2
Bushfire CRC, Melbourne, VIC, Australia;
3
Sleep and Performance Research Center, Spokane, WA, USA.
[email protected]
1
Introduction: Shift work can lead to circadian misalignment and
sleep deprivation, resulting in increased fatigue and reduced cognitive performance. In an 8h on/8h off rotating shift schedule, circadian misalignment is likely to occur due to the rapidly rotating
shifts. It is not clear whether the schedule also induces sleep loss
and cumulative deficits in neurobehavioral performance - and if so,
how long these deficits will take to recover. The aim of the present
study was to explore neurobehavioral recuperation following four
24h periods on an 8h on/8h off rotating shift schedule.
Methods: As part of an ongoing study, eight healthy subjects (ages 2133; 4f) participated in a 9-day laboratory study. The study involved 2 baseline days (BL1, BL2; 10h time in bed (TIB) per day, 22:00h-08:00h);
4 days on a simulated 8h on/8h off rotating shift schedule (SS1-4) with
6h40 min TIB during each ‘off ’ period (i.e., a total of 10h TIB per
24h); and 2 recovery days (R1, R2; 10h TIB per day, 22:00h-08:00h).
Neurobehavioral tests were administered approximately every 2h during scheduled wakefulness. Tests included a 10 min psychomotor vigilance test (PVT) and the Samn-Perelli (SP) Fatigue Scale. Daily means
for the number of PVT lapses per test bout (reaction times > 500 ms)
and SP fatigue scores were compared between the BL, SS4, R1 and R2
days using repeated-measures ANOVA over days.
Results: A significant difference in PVT lapses was found between
BL (mean 0.83 ± 0.92 SD), SS4 (0.43 ± 0.37), R1 (0.35 ± 0.47), and
R2 (0.16 ± 0.22) (F = 4.6, p = 0.046). There was no significant difference in SP subjective fatigue scores (F = 0.95, p = 0.43).
Conclusion: A statistically significant difference in PVT lapses
was found between BL, SS4, R1 and R2. However, mean lapses
per test bout did not exceed 1 either before or after the rotating
shift schedule, and indicated no build-up of cognitive impairment
across the study. There was no significant difference in subjective fatigue across days. These results suggest that one consolidated 10h sleep opportunity sufficed to recuperate after four days
on the 8h on/8h off rotating shift schedule. To what extent one
consolidated 10h sleep opportunity would also suffice to recycle
back onto the rotating shift schedule without carry-over effects on
neurobehavioral functioning remains to be determined.
Support: Bushfire Cooperative Research Centre.
PB 16
MULTIDIMENSIONAL WORK STRESSORS OF OPERATORS IN IT ENABLED SERVICES IN DIFFERENT TIME ZONES
Nag A, Nag PK
National Institute of Occupational Health, Ahmedabad, India
[email protected]
Introduction: Information technology enabled services, including
call center or BPO services are growing in unprecedented rate across
nations. Apart from objective changes in the work environment and
cognitive demands of human-computer interaction, there are perceptible concerns of health and performance of the operators due
to their distinctive alienation and work being performed in different
time zones. The study examined the multi-dimensional work stressors of operators engaged in call center services and the association
of work stressors to health indicators.
Methods: One hundred and forty two operators of weekly rotating
shifts from a small size enterprise engaged in IT enabled services,
volunteered in the study. The assignments were based on work demand, and their duty roster did not repeat regular pattern. During the
study period, sampling was done from morning (N = 106), afternoon
(N = 29) and night shift (N = 7). The questionnaire administered
gathered data on ergonomics analysis of work and work method, including information on personal characteristics, self-reported health
complaints, stress symptoms, sleep disturbances, and MSD.
Results: The operators in call centers belonged to age range of 26.4
± 3.5 years, and the predominant health complaints include eye strain
(51.4%), headache (45%), chronic anxiety and depression (19%), and
indigestion (12%). The majority of the operators complained of bodily pain and discomfort, lower back (61%) being the most affected.
Nearly 2/3rd of the operators reported sleep and appetite disturbances, and disruption in social and domestic life due to work schedules. Sleep related disturbances were more in morning shift followed
by night shift. The preference of giving up the shift job and getting
a daytime job was high (73%) among the operators. Most workstations had inappropriate seat height, absence of foot rest, and
constraints of viewing distance. Mismatched poor workplace design (47%), postural discomfort (58%) were associated to pain in
lower back (OR 1.9), knee (OR 3.6) and upper back (OR 2.8). The
principal components analysis elucidated the component loading
of t he work stressors. The identified six components explained
65% of the total variance, covering work components, such as job
diagnostics, work station design, psychosocial variables, job specialization, work organization and mental load. While ~80% of the
operators were men, even in similar work and equipment interfaces,
the complex task behaviours manifested scatter in the component
loading between men and women operators.
Conclusion: The multi-pronged study provided an account of the
work-related as well as lifestyle related issues of the young workforce engaged in call center and allied services. The study substantiated
that the health and behavioural dimensions are the results of interaction of stressors associated with work and work environment.
PB 17
DAY AND EARLY-MORNING MAIL DELIVERY
Hakola T, Puttonen S , Konttinen J, Hopsu L
Finnish Institute of Occupational Health, Helsinki, Finland
[email protected]
Introduction: The purpose of this study was to investigate the effects of different work and working time arrangements on vigilance
and sleep in mail delivery.
Methods: Field data were collected for 14 days in a cross-sectional
descriptive study design. We selected participants from the larger
questionnaire, to form two groups: mail delivery (n = 25) and earlymorning delivery (n = 20). Mail delivery takes place in the daytime
on weekdays, and early-morning delivery at night-time, seven days
a week. The participants were assessed in both the summer and
the winter. We measured sleep-wake data using Actiwatch® AW7.
Participants marked their sleeping times, quality of sleep (5-point
scale), and alertness (KSS 9-point scale) at the start and at the end
of work shifts in a sleep-log.
Results: In mail delivery, the average daily working time was 7.6h
(SD 1.0) Average sleepiness was 3.6 (SD 1.4) in the beginning, and
4.1 (SD 1.5) at the end of the work shift. The average sleeping time
50
was 6.7h (SD 1.8) on work days, and 8.8h (SD 1.3) on days off.
Sleep efficiency was 87.5% on work days, and 88.6% on days off.
Self-rated sleep quality was “good” during all sleep periods (mean
2.3, SD 0.9), although some individuals had poorer sleep quality. In
early-morning delivery, the average daily working time was 4.1h (SD
1.1) Average sleepiness was 3.5 (SD 1.6) in the beginning and 4.4
(SD 1.7) at the end of the work shift. On work days, subjects slept
typically twice, both before (mean 3.1 h, SD 1.5) and after work 4.9
h (SD 2), with one overnight sleep on days off 8.0 h (SD 2.4). Sleep
efficiency was 85.3% before work, 87.6% after work, and 88% on
days off. Self-rated quality of sleep was “good” during all sleep
periods (mean 2.1, SD 1).
Conclusion: Mail delivery workers’ sleep was surprisingly short,
but they slept significantly more on days off. This may be due to
insufficient sleep during the work week. Early-morning delivery
workers usually slept before work and after work. Total sleeping
time was relatively long also on days off, suggesting some sleep
deficit from sleeping twice per night. Sleep efficiency did not seem
to be affected by split sleep. The quality of sleep was considered
good overall, but a few participants slept poorly in both groups.
The strain due to working times was at an acceptable level on average. Subjects had individual strategies for coping with the difficult
hours. In general vigilance level was moderate but some individuals experienced severe sleepiness at least once during the test period. People who have problems with sleep should be identified
and receive support to preserve their work ability, through lifestyle
guidance and fatigue management.
with an increase in working hours per week was estimated. Combining the results, we identified the reduction in weekly working time
theoretically needed for employees working on evenings, Saturdays,
and Sundays to achieve a similar proportion of health impairments
as reported by employees without these unusual times. For example, work on evenings increased the risk by 14%, and each additional
working hour/week increased the risk by another 2%.
Therefore, reducing the weekly working time by 7 hours for employees working on evenings should compensate the risk increase
by evening work (i.e., lead to a 14% risk decrease). Similar analyses
were conducted for work on Saturdays and Sundays. The results
showed a that reduction by 4 and 17 h/week would be necessary to
compensate the negative health effects of work on Saturdays and
Sundays, respectively, controlling for demographic characteristics,
work load, autonomy, and other working time characteristics.
The findings of this study show that unusual hours might be economically unprofitable if their negative effects were to be compensated
by additional free time. However, this form of compensation could
help minimizing the risk of impairments to occupational health and
safety caused by these unusual working times.
PB 18
1
TOWARDS A TEMPORAL COMPENSATION APPROACH FOR UNUSUAL WORKING HOURS - HOW
MUCH ADDITIONAL TIME OFF IS NEEDED TO
BALANCE OUT NEGATIVE HEALTH EFFECTS?
Nachreiner F , Arlinghaus A.
Gesellschaft für Arbeits-, Wirtschafts- und Organisationspsychologische
Forschung (GAWO) e.V., Germany.
[email protected]
The number of employees working in unusual working hours (i.e.,
evenings and weekends) is increasing in Europe and other developed economies. These working times interfere with biological and
social circadian and weekly rhythms which are needed for sleep,
recovery, and social participation. Thus, it is not surprising that these unusual working times can increase the risk of impairments to
occupational health and safety, and decrease the work-life balance,
as has been demonstrated in previous studies.
In Germany and other countries, it is common to receive a financial compensation (i.e., additional payments) for working at these
unusual times. These financial incentives, however, cannot compensate the lack of sleep, recovery, and social participation that occurs
when working on evenings and weekends. A different approach is
therefore, to compensate periods of elevated work strain with additional free time to allow for a sufficient recuperative rest and to
reset the occupational strain of the worker to a baseline level. The
question is, however, how much additional work-free time would
be necessary to compensate the negative health effects of work on
evenings and weekends. Therefore, we analyzed samples from the
3rd and 4th European Working Conditions Survey (2000, 2005), including employees from 15 and 27 EU member states, respectively
(n = 17,910, n = 23,934).
The risk of reporting at least 1 health impairment in association with
regular work on evenings, Saturdays, and Sundays was calculated in
multifactorial logistic regression models, controlling for demographic
characteristics, working conditions, control, and working hour variables (e.g., shift work). Additionally, the increase in health impairments
PB 19
SLEEPINESS IN LONG-HAUL TRUCK DRIVERS
WITH IRREGULAR WORKING HOURS
Pylkkönen M1, Sihvola M1, Hyvärinen HK1, Mutanen P1,
Sallinen M1,2
Finnish Institute of Occupational Health, Helsinki, Finland.
Agora Center, University of Jyväskylä, Finland.
[email protected]
2
Introduction: Sleepiness is known to be an issue among professional drivers as it may compromise safe driving. In previous studies,
driver sleepiness has been shown to result from conditions such as
irregular working hours and restricted time for sleep. The present
study sought to investigate the levels and contributing factors of
driver sleepiness among long-haul truck drivers.
Methods: Fifty-two drivers (mean age 38.1 years) from four medium-sized haulage companies underwent a two-week field-measurement phase as a part of an intervention study conducted in
2010-2012. The data comprised of a total of 474 shifts categorized
into morning (n = 143), day/evening (n = 109), and first (n = 93)
and successive (n = 129) night shifts. Driver sleepiness was measured hourly by the Karolinska Sleepiness Scale (KSS), sleep daily by
a diary and actigraph, and self-assessed daily sleep need by a sleep
questionnaire. Working hours were defined based on drivers’ diary
markings and the employers’ work-time accounting.
Results: The drivers rated themselves moderately to extremely sleepy (KSS ≥ 6) at least once in 20.7%, severely to extremely sleepy
(KSS ≥ 7) in 9.0%, and extremely sleepy (KSS ≥ 8) in 3.6% of
the first night shifts. The prevalence rates in the other shift types
were clearly lower (9.4-12.6%, 2.1-3.7% and 0.4-0.8%, respectively). A logistic regression analysis revealed a 3.85-8.33-fold greater
risk (odds ratio) of sleepiness (KSS ≥ 6) in the first night shifts
compared to the other shift types (p < 0.001). Other factors underlying driver sleepiness were prior sleep duration and efficiency,
self-assessed daily sleep need and shift duration. Sleep duration was
shortest before the morning (5:43h) and successive night (6:03h)
shifts and longest between the days off (7:36h). A one-hour decrease in prior sleep was associated with a 1.33-fold greater risk
of sleepiness (p < 0.0001). Sleep efficiency was highly comparable
among the shift types (87.3-87.8%) as well as between the duty and
non-duty days (87.8-88.3%). Mean daily sleep need was 7:45 hours,
an additional hour being associated with a 2.32-fold greater risk of
sleepiness (p < 0.001). A one-hour increase in shift duration was associated with a 1.13-fold greater risk of sleepiness (p < 0.0342). The
51
mean hourly KSS ratings peaked (4.3, SD 1.9) after 9 consecutive
hours of work during the first night shifts.
Conclusions: The results suggest that sleepiness at the wheel is
common among long-haul truck drivers, particularly during the first
night shifts, and that sleepiness momentarily reaches levels likely to
compromise safe driving. The present study stresses the importance
of effective measures to counteract driver sleepiness and claims for
skilful shift designs to enable sufficient recovery between duty hours.
Support: The Finnish Work Environment Fund (project no.
109378) and the Strategic Centre for Health and Well-being (Sal
We Ltd.) of the Finnish Funding Agency for Technology and Innovation.
PB 20
ASSOCIATION BETWEEN SHARPS-RELATED ACCIDENTS AND NIGHT/SHIFT WORK AT THE MULTIPROFESSIONAL TEAM FROM MATO GROSSO DO
SUL HEALTH ESTABLISHMENTS
Calonga SMS, Valente D, Teixeira LR.
Sergio Arouca National School of Public Health, Oswaldo Cruz Foundation,
Brazil.
[email protected]
Introduction: Occupational risks related to sharp material work
accidents are widely distributed in health establishments’ structure,
and the occupational exposure consequences can affect professional’s health in many ways, including emotional, social and even financial control.
Objectives: To analyze the factors associated to occupational accidents with biological material exposure among the multiprofessional health teams from the health establishments serving the Aquidauana municipality Unified Health System (hereby SUS), at Mato
Grosso do Sul state.
Methods: This descriptive, cross-sectional study, population-based
designed, was carried from January to May, 2012, using a semi-structured questionnaire concerning socio-demographic aspects,
living habits, occupational history, health patterns, accident description and the professional’s vaccinal schedule against Hepatitis B as
so as the anti-HB exams. Collected data were tested through stratified multiple logistic regression. Layers were analyzed as follow:
socio-demographic, lifestyle, job characteristics and related to sleep-wake cycle. “Gender”, “time of work” and “workplace” were
taken as control variables.
Results: From 340 workers, 46.2% related having had an accident
in the last year. When associated factors were analyzed together,
being female (OR = 1.31), being married (OR = 1.20) or divorced (OR = 1.76), having completed elementary (OR = 1.54), high
school (OR = 2.86) or graduated (OR = 1.71), 1-3 years work time
(OR = 1.71), 3-10 years (OR = 2.86) and above 10 years work time
(OR = 1.54), specialty working (OR = 1.80) or a high technologic
education (OR = 3.74), alternate shift (OR = 2.04), doubled-journey shift (12h diurnal - 7 days/week; OR = 7.14) and steady night
shift (OR = 3.17), related average use of physical exertion (OR =
1.77), low sleep quality (OR = 1.95) and having sleep medication
1-2 times (OR = 4.36) and 3 times and more a week (OR = 3.45).
Conclusion: Factors associated to work accidents are related to
women, married, divorced or separated and with children; education until graduation and longer work time; specialty working, at
a high technological level, alternate shift, night shift and doubledjourney of 12 diurnal hours; relating low sleep quality and psychotropic medication use. This study corroborates the need of a program based exclusively on the workers’ behavioral changes.
PB 21
NURSES’ WORKLOAD AND WORKING SHIFTS IN
INTENSIVE CARE UNIT (ICU) DEPARTMENT
Korompeli A, Chouliara A, Sourtzi P, Psallida V, Gavala Al,
Myriantheas P, Fildissis G, Baltopoulos G
National & Kapodistrian University of Athens, Faculty of Nursing, Greece
[email protected]
Introduction: During the last 20 years the age, the severity of illness, the complexity and the number of therapeutic interventions
needed for the patients admitted into the ICU is increasing. The
volume of the administrative tasks undertaken by nurses is increasing as well.
Objectives: The purpose of the study was to study ICU nurses’
subjective workload in the three 8 hour shifts.
Methods: The total number of participants was 100 nurses
working in different ICUs. The subjective workload was measured
with a short questionnaire, part of Standard of Shiftwork Index
questionnaire1 (highest score 20). In addition, nurses measured the
steps they made in each shift using a heart rate watch with chest
belt, which was set to pedometer mode (Crivit, Germany). Illness
severity was estimated by the APACHE II scoring system.
Results: The APACHE II score was 21.9 ± 0.7 (mean ± SEM).
The nurses to patients ratio was 1:2 and 1:3 for the morning shift
and for the afternoon & evening shifts respectively. The participants who completed the workload questionnaire and measured
steps were, 64 for the morning shift, 31 for the afternoon shift and
28 for the night shift. The subjective workload and the mean steps
(mean ± SEM) were 15.6 ± 0.3 and 7250 ± 329.8, 18.0 ± 0.3 and
8012 ± 493.0, and 14.0 ± 0.4 and 4600 ± 394.1 for the morning, afternoon and night shifts respectively. The subjective workload was
very well correlated (in the 39 nurses) with the steps in each 8 hour
shift: morning shift r = 0.382, p = 0.002, afternoon shift r = 0.416,
p = 0.005, and night shift r = 0.428, p = 0.023
Conclusion: It seems that nurses’ subjective workload in an ICU
department is very well correlated with the steps made in each shift.
The highest subjective workload and steps is observed in the afternoon shift, as nurses to patients ratio was higher and nurses are
involved to therapeutic interventions and not only to monitoring
as in night shift.
REFERENCES
1. Barton J, Spelten E, Totterdell P, Smith L, Folkard S, Costa G The Standard Shiftwork Index: a battery of questionnaires for assessing shiftworkrelated problems. Work & Stress, 1995;9(1):4-30.
PB 22
IF YOU CAN’T HANDLE THE HEAT, STAY AWAY
FROM THE FIRE: EVALUATING THE INFLUENCE OF
OCCUPATIONAL STRESSORS ON THE COGNITIVE
PERFORMANCE OF WILDLAND FIREFIGHTERS
Smith B, Cvirn M, Jay S, Ferguson S.
Appleton Institute, CQUniversity, Australia; School of Exercise and Nutrition
Sciences, Deakin University, Australia
[email protected]
Introduction: Australia is heavily reliant on a trained, volunteer
workforce for the emergency response to accidents and natural
52
disasters in remote areas. The likelihood of catastrophic wildland
fires in Australia is high given its climate, geography and land use
patterns. An estimated 220,000 volunteer firefighters represent the
first and last line of defence for prevention, management and suppression of wild land fires. Many hold full-time positions whilst
remaining ‘on call’ with their local brigade. They must be ready to
respond to emergencies with little notice, or attend wildland fires in
remote locations that span multiple days (‘fireground tour’). On the
fire ground, they experience long shifts in life threatening situations,
perform hard physical work in smoky, noisy, and hot conditions
often with little sleep in suboptimal sleeping conditions. Previous
studies have highlighted the isolated affects of stressors such as
sleep deprivation and heat on cognitive function, however these are
limited to laboratory-based studies that lack ‘real world’ relevance.
The degree to which these stressors affect cognitive performance
and fatigue over successive days of exposure while performing intermittent bouts of physical activity work has yet to be determined.
Methods: We developed an innovative simulation of a 3-day fireground tour that required participants to live on site. During
the daytime, measures of cognitive function (memory, vigilance,
complex attention, hand-eye coordination) and subjective ratings
(mood, fatigue, alertness, performance) were collected in between
bouts of physical work specifically designed to mimic real-world
firefighting. Participants were assigned to one of three conditions;
control (18-20deg day and night temperature, 8 hours sleep opportunity); heat (33-35deg day, 23-25deg night, 8 hours sleep), sleep
restriction (18-20deg day and night, 4 hours sleep). All participants
(anticipated N = 160) were active volunteer firefighters (aged 18-65)
representing various agencies across Australia.
Results: This paper will present the preliminary results from this study
(N = 60). Results indicate that cognitive performance varies little across
multiple days during the control condition, suggesting that regular intermittent physical activity over three days may not lead to a decrease in
cognitive performance. Performance across a range of cognitive functions declined in both the heat and sleep restriction conditions. Firefighters appear capable of recognising when they felt increased fatigue
and accurately detected changes in their performance.
Conclusion: This presentation will discuss the influence of heat
and sleep deprivation on volunteer firefighters’ cognitive performance. Findings provide an evidence base for fire and emergency
management agencies to better manage the impact of such stressors on their personnel. Frameworks, tools and guidelines for the
effective risk management of emergency service workers can then
be trialled and evaluated.
Support: This project was funded by the Bushfire CRC, and supported by the CFA, CFS, NSW and Tasmania RFS, ACT Parks
and Wildlife Service.
PB 23
DOES CONTROL OVER SHIFTS MODERATE THE
RELATIONSHIP BETWEEN AGE AND ADAPTION
TO SHIFTWORK?
Muurlink O, Loudoun R, Peetz D, Murray G
Centre for Work, Organisation and Wellbeing,
Griffith University, Australia.
[email protected]
Introduction: A growing body of research has identified a positive
relationship between individual choice in roster type and tolerance
to shiftwork. It is also generally accepted that ageing shiftworkers
need individual flexibility in working hours, owing to an increase in
individual differences in physical, social and personal needs, but it
is not known whether these workers have a higher need for control
over shifts. To address this gap this study compares younger and olSleep Sci. 2013;6(Supl 1):s9-s74
der shiftworkers on their perceived control over day-to-day aspects
of shiftwork and sleepiness and physical and psychological health.
Methods: Participants were 1270 male (95.4%) and female (4.6%)
shiftworkers drawn from wave 1 of a larger study of 2752 mine
workers from five states in Australia. Surveys were sent and returned via mail after obtaining home addresses for members of the
Construction, Forestry, Mining and Energy Union’s (CFMEU) Mining and Energy Division resulting in a response rate of 28.5%.
Data were collected on demographic and shift characteristics, control of day-today aspects of shiftwork (Allan et al., 2005) and health
outcomes including psychological well-being (GHQ-12), physical
health, work injuries, (modified version of the SMU-HQ, Watson
and Pennebaker, 1989) and sleepiness (SSI).
Results: Moderated regression analyses were used, with sleepiness, physical health and psychological health as dependent
variables indicating adaptation to shiftwork. Control at work, age
and interaction between age and control at work were the independent variables. To control for possible confounding factors we
included work hours per week and dummy variables for gender,
dependents living at home, sleep arrangements (at home/at work
location), shift type (rotating/fixed shift systems), length of shifts
(< 12 hours/12 hours +) and shiftwork exposure (< or > 10 years
on roster). Results indicated that control at work was negatively
correlated with sleepiness, psychological and physical ill-health. Results also showed statistically significant positive relationships between shiftwork exposure and sleepiness and physical ill-health and
relationships between age and sleep location and sleepiness with
workers aged 50 or more and workers sleeping on location reporting more sleepiness. Female shiftworkers reported fewer physical
ill-health symptoms.
Conclusion: The findings support previous research that emphasises the importance of control of shift related variables for older
workers but suggests that control is important to promote health
and work ability for all workers irrespective of age. Findings also
suggest that control over day-to-day aspects of shifts such as the
timing of breaks and intensity of work need to be considered alongside shift scheduling.
Support: Australian Research Council and CFMEU. Allen et al.
(2005). Influences on work/non work conflict. Journal of Sociology, 43, 219-239. Watson et al. (1989). Health complaints, stress, and
distress. Psychological review, 96(2), 234.
PB 24
WHO’S GOT THE WHEEL? BUILDING A COMMUNICATIONS-BASED SAFETY CULTURE TO REDUCE DROWSY DRIVING AND TRANSPORTATION
OPERATOR FATIGUE
Lehrer A1, Popkin S2
Macrosys LLC, USA.
US Department of Transportation Volpe Center, USA.
[email protected]
1
2
Introduction: Ever noticed another driver’s eyelids pointing south
or caught yourself slipping off a country road as drowsiness mounted? You are not alone. Drowsy driving and its commercial cousin-transportation operator fatigue-remain pervasive risks in a 24/7
culture content to assign alertness a back seat to near-term tasks
and wants. Alarmingly, The National Sleep Foundation’s 2008 Sleep
in America poll revealed that 36% of American adult drivers have
nodded off or fallen asleep while driving. Moreover, fatigue related
crashes, deaths, injuries, and costs remain unacceptable, driving the
National Transportation Safety Board to repeatedly place human
fatigue on its Most Wanted List of Safety Improvements, further
53
noting that fatigue risk affects drivers, mariners, train crews, pilots,
and pipeline controllers. How can we impart measurable behavioral
change amidst a backdrop of cultural tolerance for drowsy driving
and operator fatigue? The answers do not lie in science alone. Despite broad consensus on the basic underlying principles of sleep
and fatigue, a striking disconnect separates three decades of research from real-world practice. To foster action, successful outreach
must first trigger a cultural shift in thinking.
Methods: The U.S. Department of Transportation’s Safety Council
initiative on Fatigue and Hours of Service is overseeing the development of an Operator Fatigue Communications Campaign. Components include a toolkit of key messages, products, best practices,
and delivery mechanisms to stir public and commercial audiences
toward smarter decisions and behaviors concerning the effects and
prevention of fatigue. A cross-modal matrix targets internal and
external audiences, and a task team being further developed organizes efforts to create, vet, and ultimately disseminate content and
evaluate behavioral change and safety data. Interestingly, impactful
messaging to catalyze change does not imply authoritarian or regulatory approaches; rather, current methodology views messaging
as guiding safe behavior through assimilation of message intent.
Building on Kahneman and Tversky’s seminal work on heuristics,
Thaler and Sunstein’s Nudge Theory posits that indirect prompting
and positive reinforcement can produce desired behavioral outcomes. Creative expertise is being utilized in crafting such messaging
to better communicate and address drowsiness.
Results: Multiple and multisensory nudges, prompts, tags, slogans,
songs, videos, brochures, PSA’s and other materials are being developed. Frank indicators of fatigue’s harmful impact are also included. Content has not yet been disseminated, though initial development is far enough along where vital discussions and feedback can
both educate and inform strategic approaches.
Conclusion: Significant outreach opportunities have potential to
reduce drowsy driver and operator fatigue risk and incidents while
facilitating cultural transformation progressing from unacceptable
cross-modal risk to effective personalized risk management. Teaming data-driven methodology with creative insight and craft, the
DOT Safety Council’s Transportation Operator Fatigue Communications Campaign is well-positioned to save lives and material assets
while advancing transportation safety and safety culture.
PB 25
PERCEPTION OF FATIGUE AND PREVIOUS SLEEP
DURATION AND SLEEP QUALITY AMONG BRAZILIAN CIVIL AVIATION PILOTS
Wey D1, Licati P2, Fischer FM1, Menna-Barreto L3
Brazilian Civil Pilots Association.
3
School of Arts, Sciences and Humanities, University of São Paulo, Brazil.
[email protected]
1
2
Introduction: The 24 hour society demands a continuous production of goods and services. International travels pose a challenge to pilots since their working hours often misplace the normal
week-sleep cycle. As a vast number of reports show, chronic restriction of sleep duration reduce levels of wellbeing, alertness, situational awareness and work performance. Pilots’ fatigue is an important
issue in modern aviation operations. Fatigue can be due to a variety
of factors including work schedules, long journeys combined with
disruption of the biological rhythms. The purpose of this report is
to describe the time when fatigue was perceived, as well as previous
reported sleep duration and sleep quality.
Methods: A total of 301 captains and first officers from Brazilian airlines participated. Demographics: all men, mean age 36y,
SE = 0.5y. Participants filled out an online questionnaire, with 35
questions, regarding their work hours, sleep time, and perception
of fatigue. The participants filled out the questionnaire when feeling tired. The questionnaire was sent by e-mail to the pilots belonging to two Brazilian associations of civil aviation pilots. Data
collection took place between October 2012 and February 2013.
Results: The majority of participants (62%) were captains of regular air transportation, composing simple crews (two pilots). Fatigue
were reported mainly between 02:30-04:00 a.m. Regarding the last
three nights previous to the report of fatigue, the percentage of sleep
quality informed as “excellent” decreased and as “poor” increased.
However 44% of participants reported a “regular” sleep quality in
the previous night of fatigue reporting. The majority (64%) worked
in the evening/night hours; 43% reported work duration of 7.0 to
8.5 hours, and 38% worked longer- 9.0 to 10.5 hours the previous day
they perceived were fatigued. Sixty-four percent of the pilots who
reported fatigue slept less than 6.5 hours the previous night.
Conclusions: There are several factors involved in fatigue. Work
time, especially during the night must be carefully scheduled considering the previous condition of crew’s sleep. Work-related fatigue
should be systematically identified in order to avoid incidents, and
as a measure of crews’ health promotion.
PC 26
ENHANCING RESILIENCE TO FATIGUE IN PARAMEDICS
Paterson JL1, Sofianopoulos S2, Williams2,3
Ambulance Victoria, Australia.
3
Department of Emergency Health and Paramedic Practice, Monash University, Australia.
[email protected]
1
2
Introduction: The Australian paramedic workforce is in a state of
crisis, experiencing high rates of worker suicide, burnout, attrition,
sick leave and work disability. There is evidence that the fatigue associated with paramedics’ work schedules has negative consequences for worker’s health, safety and wellbeing. Traditional approaches
to understanding and managing fatigue risk have focused on the
influence of working time, however, we know that changing work
schedules can be difficult, if not impossible, for a number of reasons. It is necessary to consider other ways of understanding and
managing fatigue risk if we are to safeguard our paramedics against
multiple adverse outcomes. Using qualitative methods, the present
study will identify and promote factors that enhance resilience
towards fatigue in Australian paramedics.
Methods: Forty paramedics are currently being recruited from
ambulance services around Australia. Participating paramedics will
take part in a 45-60 minute interview with a member of the research team. Interviews have been designed to address four key research questions; 1) how do paramedics experience fatigue? 2) What
are common strategies used by paramedics to cope with fatigue risk
at work? 3) How effective are these strategies? 4) How do these
strategies influence individual wellbeing and resilience to fatigue?
Results: Preliminary investigations indicate that paramedics experience fatigue as a result of both direct (prior sleep/wake, circadian
disruption, task related factors) and indirect factors (study, family,
sleep hygiene, diet, exercise, mood). Interview notes and recordings
will be further analysed using nVivo software, following the principles common to qualitative data analysis; data immersion, coding,
categorisation and theme generation.
Conclusion: Preliminary findings indicate that working time alone cannot explain all instances of fatigue for working paramedics.
As such, strategies to manage fatigue need to address factors other
than the influence of working time. The findings of this research
will enable an understanding of strategies that paramedics employ
to manage fatigue at work, and how these strategies can help to
54
enhance the resilience of the individual, the team, and the organisation. These data will highlight areas for intervention and education
to minimise the experience of paramedic fatigue in the first case,
and the negative health and safety outcomes for paramedics and
patients as a result.
14:00-16:00 h
C - Working hours and sleep
PC 27
SLEEP QUALITY AND SLEEP-WAKE CYCLE OF
UNDER-GRADUATE UNIVERSITY NURSING STUDENTS AND CHANGES OVER THE YEARS OF
COURSE
De Martino M1, Vancini CR2, Cohrs CR2, Kiilian M3
School of Nursing, State University of Campinas, São Paulo, Brazil;
School of Nursing, Federal University of São Paulo, Brazil.
[email protected]
1
2
Introduction: Little is known about what factors contribute to or
exacerbate sleep difficulties in this population.
Objectives: The purpose of this study was to analyze the sleep
quality and sleep wake cycle in the undergraduate university nursing
students during along the course.
Methods: Volunteers were selected from a total of 92 students
(UNIFESP, Brazil) both genders, whose mean age was 21,62 years
old, answered the Pittsburgh Sleep Quality Index (PSQI) and Sleep
Diary completed for two weeks.
Results: The predominance of female subjects (96.24%) was
observed. As for the marital status, (96.9%) followed by married
(1.52%) and others (0.76%). It was observed that, for the first year
sleep quality was poor by the PSQI when compared to demonstrating that with classes for students of the third year the quality
was good, with a statistically significant difference for the Test QuiQuadrado (p = 0.024).
Conclusion: The quality of nocturnal sleep was better as compared to daytime sleep for both groups of students, statistically significant (p-value = 0.0112). It was found that students have a poor
quality of sleep, wake up once or twice per night, use the alarm
clock to wake up and have a habit of napping during the day.
Introduction: Working the night shift takes its toll in terms of
occupational safety, function and health of the employee. A scheduled nap has been demonstrated as a strategy with high potential for improvement in several indicators. However little is known
about the effects of a brief planned nap on health and functioning
of nursing staff on eight hour night shifts. This study examined the
effectiveness of a planned nap during the nadir of alertness on an
eight hour night shift, on subjective health measures (feelings of
sleepiness and vigor) and objective functional measures (cognitive
performance and evaluation of duty transfer) that reflect the performance of the nurse during the night shift.
Methods: In this prospective, within subjects experimental study
design with repeated measures, thirty (30) female and male nurses
working shifts were recruited by convenience sampling from several hospital wards at Bnei Zion Medical Center in Haifa. Inclusion
criteria: An appointment of 75% and above, at least one night shift
a week. Exclusion criteria: pregnancy, a diagnosed sleep disorder or
chronic medical conditions that may affect sleep and/or function.
Sleepiness, vigor, cognitive performance and evaluation of oral and
written transfer of the shift were compared with or without a 30
minute nap scheduled at 04:00 during the night shift. Nurses were
tested on two nights with and two nights without a nap, intermittently. Throughout the night shift, participants reported sleepiness
and vigor levels, number of cups of coffee they drank and adverse events, if any occurred. At 6:30 they performed two cognitive tests, the Letter Cancellation task (LCT) and the Digit Symbol
Substitution Task (DSST), and at 07:00 they transferred the shift to
the head nurse and were released to their homes. The head nurse
evaluated the nurses' oral and written shift transfer performance
by a nurse assessment questionnaire blinded to the experimental
condition. On nights with a planned nap, at 04:00, nurses went to
sleep in a dark quiet room for 30 minutes, and on nights without a
nap they continued their work as usual. To monitor sleep patterns
and duration, nurses wore an actigraph 24hrs before and during the
night shift.
Results: Lower levels of sleepiness at 05:00, 06:00 and 07:00 and
higher measures of vigor at 05:00, 07:00 were found on nap vs.
no-nap nights respectively (p < 0.01). Performance measures on
the LCT were significantly higher, and measures of the DSST were
higher, but did not reach significance (p < 0.08). Evaluation of written duty transfer was improved in nap vs. no-nap nights.
Conclusion: A planned nap is a cheap and simple strategy to
improve occupational safety and health of nursing staff and
to improve the safety and quality of patient care.
PC 29
Keywords: Sleep, Nursing, Students.
HOTEL MANAGERS: TO WORK AND SLEEP
PC 28
THE EFFECTS OF A SCHEDULED NAP ON NURSES' HEALTH AND PERFORMANCE DURING THE
NIGHTSHIFT
Shochat T1, Zion N 2,3
University of Haifa, Israel;
2
Bnei Zion Medical Center, Israel.
3
University of Haifa, Israel.
[email protected]
1
Leite CMG , Carvalho RJM
Members of Extension and Research Group in Ergonomics (GREPE),
Production Engineering Program (PEP), University of Rio Grande do Norte
(UFRN), Brazil.
[email protected]
Introduction: To assess the relationship between sleep and wakefulness in the work activity of managers of a luxury hotel, located
in Ponta Negra, in Natal - RN.
Methods: The study included the entire management team of the
hotel, i.e. six (6) managers from the following areas: general, governance, trade, reception, kitchen and maintenance. The largest age
group of managers is between 31 to 40 years old (62.5%), having
a married status and higher education (62.5%). Data collection was
carried out between 1 (one) month from 15/05 to 15/06/2012,
55
during a period of low and high hotel occupancy and tourist season, where managers often had to adopt regulations to carry out the
work activities related to each of them. Managers were interviewed
daily during the period analyzed, filling up Time Protocol of Daily
Activities, in which were recorded the information on the duration
of time at work, transportation, food, leisure, family, sleep, among
other activities.
Results: The results indicate a greater time devoted to work and
sleep, comprising respectively 37% and 30% of total daylight hours,
while the time spent in activities with family (15%), leisure (10%),
health (5%), other (3%), such as study, travel and personal hygiene.
Through the technique of conversational action, managers could
report situations of “over working” and lack of professional recognition, which makes them feel unmotivated in business and occupation, causing them to seek for another job, as well as complaints
about the relationship with family (50%), symptoms of musculoskeletal pain (84%) and difficulty sleeping (66.7%).
Conclusions: The activity of hotel managers varies regarding the
work demands according to the changes of high and low tourist season in the city, and also in relation to changes in high and low hotel
occupancy rates. This analysis shows that managers spend most of
their time at work or sleeping, leaving the other personal needs, as
investment in social activities and career aside. Thus, demotivation
and frustration at work arise as problems, as well as physical fatigue
and sleeplessness, as the managers relate themselves.
PC 30
TEENS BECOMING WORKERS FACE CHANGES IN
THEIR TIME BUDGET
Fischer FM1, Pinheiro F1, Wey D1, Luz AA1, Moreno CRC1,
Menna-Barreto L2, Teixeira LR3
School of Arts, Sciences and Humanities, University of São Paulo, Brazil.
3
National School of Public Health, Oswaldo Cruz Foundation, Brazil.
[email protected]
1
2
Introduction: A significant number of Brazilian adolescents
entered labor force as ap-prentices or trainees while attending high
school years. They work 6-8 hours during daytime and attend regular
evening school. Studying and work may affect time to per-form
daily activities. The aim of this study is to compare duration of
sleep, transport, study and free time before and after high school
students joined work.
Methods: The study was conducted during 2011/2012. Participants
were 33 adolescents (22 men), aged between 15-18 years (mean
15.9y, SD 0.9). The first phase of this study was carried out while
students attended regular high school in the evening (19-23h)
and were enrolled in a six-month training course, Mon-Fri, from
12:30-17:00. Once a week, the students also attended a computer
class during morning hours.
The whole training course was offered by a non-governmental
organization located in the outskirts of the city of São Paulo,
Brazil. It enhanced adolescents’ basic skills and provided them
the opportunity to be hired as apprentices or trainees. The second
phase of the study was conducted after the same students joined
the labor force (8:00-17:00), as apprentices or trainees, while still
attending regular high school in the evening hours. The students
(ST) filled out diaries during seven consecutive days registering
the duration of activities performed during waking hours, such as
transport, free time, study time and sleep, before and after they
joined work (WS). A multivariate ANOVA and Tukey’s post-hoc
were performed to compare the time spent by the students in each
of the activities, be-fore and after joining work.
Results: Significant differences were found in sleep duration
(F = 30.40; p < 0.01; MST > MWS), transport (F = 12.74; p < 0.01;
MST < MWS) and study (F = 269.23; p < 0.01; MST > MWS). Free
time was similar on both situations (ST = 450 min; WS = 410 min;
p > .05). On weekdays ST had longer sleep duration, except Fri-Sat
(F = 10.643; p < 0.01), and no difference was found on Sat-Sun;
transport duration was longer for WS in all days, but on Saturdays;
no differences were observed on Sundays (F = 12.43; p < 0.01);
study dura-tion was shorter for WS in all days, and no difference
was found on Sundays (F = 17.21; p < 0.01); and for free time, no
difference was found. On Sundays women have a lower duration of
free time comparing to men (F = 3.365; p < 0.01).
Conclusion: Performing concurrent activities such as work
and study significantly reduce the sleep duration and study time,
and thus, may affect teenagers’ development. Differences in free
time may not be found due to the double journey of activities of
teenagers. They tend to spend their time with so many activities, and
then, the free time available is similar for workers and non-workers.
Support: FAPESP: 2011/00029-3; 2011/14663-6;
301605/2009-2; 502139/2010-2 155524/2012-7.
CNPq:
PC 31
INDIVIDUAL DIFFERENCES AND JOB ADMISSION:
CHANGES OF THE SLEEP-WAKE CYCLE AMONG
WORKING HIGH SCHOOL STUDENTS
Wey D1, Moreno CRC1, Pinheiro F1, Teixeira LR2,
Menna-Barreto L3, Fischer FM1
School of Public Health, USP, Brazil.
National School of Public Health, Oswaldo Cruz Foundation, Brazil.
3
School of Arts, Sciences and Humanities, USP, Brazil.
[email protected]
1
2
Introduction: Working and study may reduce teenagers’ sleep
duration as they are required to wake up early and go to bed late.
However, facing the same work-study routine, students don’t react
the same way. Our purpose is described individual differences of
adolescents’ sleeping time before and after joining work.
Methods: Participants were 22 boys and 12 girls, aged 15-17 yrs
(mean = 16y, SD = 0.8y), living on the outskirts of São Paulo,
Brazil. From Mon-Fri they attended a 6-month training course
(12:30-17:00) at a non-governmental organization and high
school (19:00-23:00). A few months later they were employed as
apprentices or trainees (Mon-Fri, 8:00-17:00), and continue studying
in the evening. Before and after admitted to work, participants wore
actimeters and filled out diaries during five consecutive days. Sleep
onset, offset and duration were evaluated. Cluster analysis was used
to differentiate participants in groups according to their sleeping
time before and after joining work. Significant differences between
groups in each weekday were tested using ANOVA.
Results: Students (ST) were divided in two groups and when they
began to work (WS) they were re-clustered in two other groups
according to their sleep onset, offset, duration.
Sleep onset (groups 1 and 2): There were significant differences
from Mon-Fri between the groups before (p < 0.001) and after
joining work (p < 0.003): 25 from ST1 slept at 00:10 (SEM = 7
min); as workers, 20 from WS1 slept at 23:37 (SEM = 9 min) and
5 from WS2 at 00:54 (SEM = 15 min); 9 from ST2 slept at 01:40
(SEM = 16 min); as workers, 3 became WS1 and 6 became WS2.
Sleep offset (groups 3 and 4): There were significant differences
from Mon-Fri between the groups before (p < 0.04) and after
joining work (p < 0.009): 22 from ST3 woke up at 09:07 (SEM = 15
min); as workers, 15 from WS3 woke up at 06:04 (SEM = 10 min)
and 7 from WS4 woke up at 07:40 (SEM = 23 min); 12 from ST4
woke up at 07:34 (SEM = 23 min); as workers, 9 became WS3 and
3 became WS4. Sleep duration (groups 5 and 6): ST showed similar
sleep duration on weekdays. Significant differences were observed
56
from Mon-Tue (F = 9.44; p < 0.005) and Tue-Wed (F = 43.15;
p < 0.0001). After joining work, there were significant differences
from Mon-Fri between groups (p < 0.03): 23 from ST5 slept during
531 min (SEM = 11 min); as workers, 15 from WS5 slept during
362 min (SEM = 14 min) and 8 from WS6 slept during 450 min
(SEM = 16 min); 11 from ST6 slept during 416 min (SEM = 25
min), and as workers, 8 became WS5 and 3 became WS6.
Conclusion: After the admission as apprentices or trainees
significant effects were observed in all evaluated sleep parameters.
Individual differences were detected in the time series under analysis.
Temporal challenges tend to affect individuals in singular forms,
thus individual differences should be taken into consideration when
evaluating the effects of a new social routine, as observed in the
admission of young people at work.
Support: FAPESP (2011/00029-3;2011/14663-6);
(155524/2012-7;301605/2009-2).
CNPq
PC 32
SATISFACTION WITH WORK SCHEDULES IS A
CONTRIBUTING FACTOR TO REPORTED SLEEP
DISTURBANCES
Vasconcelos S1, Lowden A2, Skene DJ3, Fischer MF1, Marqueze
E1, Moreno CRC1
3
University of Surrey, United Kingdom.
[email protected]
1
2
Introduction: Nowadays, shift work is a reality for workers that
live in large urban centers as well as remote communities. Several
studies have shown factors associated with sleep quality and overall
sleepiness among urban shift workers, however there are no studies
of shift workers living in a rural equatorial community.
Methods: Cross-sectional study of 70 shift workers (slow rotation, anticlockwise) from an assembly line in a factory located in
Acre, Brazil (latitude 10° S; sunrise 06:00 h; sunset 18:00 h). The
average age was 25.6 years (± 0.7 SEM), mostly women (68.6%).
The working schedules were: morning shift (06:00-15:00 h);
evening shift (14:00-23:00 h); night shift (22:00-07:00 h). The
association between variables was performed using a multiple linear regression model (stepwise forward), which were tested on
three dependent variables: sleep quality, overall sleepiness and
waking disturbances (assessed by the Karolinska Sleep Questionnaire - KSQ), adjusted by sex and age. The independent
variables were marital status, children at home (under 15 yo),
diurnal preference (Diurnal Preference Scale); chronotype (Munich Chronotype Questionnaire for Shift Workers), number of
complaints of musculoskeletal pain (Nordic Questionnaire for
the Analysis of Musculoskeletal Symptoms), number of diseases
diagnosed by a physician in the last six months, satisfaction with
work schedules and interference of working hours with leisure
(measured by VAS).
Results: Mean (± SEM) sleep duration was significantly different between work shifts (morning = 6.29 ± 0.17 h; evening = 8.95 ± 0.18h;
night = 5.64 ± 0.29h; p < 0.01). Musculoskeletal pain was significantly
correlated with poor sleep quality (β = 0.19, p < 0.01), waking disturbances (β = 0.17, p = 0.02) and overall sleepiness (β = 0.23, p <
0.01). Workers more satisfied with their work schedules had significantly less waking disturbances (β = -0.97, p = 0.04) and sleepiness
(β = -0.96, p = 0.04).
Conclusion: Our results show that satisfaction with work
schedules is a contributing factor to reported sleep disturbances
irrespective of the location of the workplace. In agreement with
previous studies musculoskeletal pain was shown to associate with
poor sleep quality and other sleep problems.
Support: FAPESP-UniS; UGPN Research Collaboration Fund,
USP-UniS; CNPq; FUNTAC; CAPES; FAPESP.
PC 33
SLEEP ARCHITECTURE OF NOCTURNAL NAPS
MEASURED BY THE NON-CONTACT SHEET
SENSORS AND SLEEP REGULATIONS ON DUTY
PERIOD IN HOSPITAL NURSES WHO ENGAGED IN
14-HOUR NIGHT SHIFT
Sasaki T
The Chronic Fatigue Research Center, The Institute for Science of Labour.
[email protected]
Introduction: The 16 hour night shift typically done by Japanese
nurses has emerged as a major issue. Based on its concerns, the
Japanese Nursing Association presented its first Guidelines on
Night Shifts and Shift Work in Nurses in February 2013. However,
the 16 hour night shift already in place poses practical obstacles
to rapid replacement with an ergonomic 8 hour night shift, which
would require drastic changes in the current shift system. Recently,
one interim strategy instituted is a night shift of 12 to 14 hours that
allows for naps (90 min) during the shift. Therefore, in this study, we
investigated the relationship between the sleep architecture of naps
during the night shift working on a 14 hour night shift (19:00-09:00)
and sleep regulations of preceding the night shift. We used new
devices deployed under mattresses to evaluate sleep architecture.
Methods: The participants were all 30 nurses (28 women and 2
men) assigned to work the night shift in the internal ward. The
age of them was 26.7 ± 4.3 years (mean ± S.D.) and 73.3% were
unmarried. The three nurses assigned to each night shift took their
naps in succession, with the 1st nap (0:00-1:30; n = 43), the 2nd nap
(1:30-3:00; n = 48), and the 3rd nap (3:00 - 4:30; n = 48). They slept
either in the rest room next to the ward or in a nap room located
away from the ward. We measured naps totaling 139 person-days
over a period of 1.5 months.
Results: Sleep architecture of naps during the 3 nap periods showed
that SPT during the 1st, 2nd, and 3rd nap periods, respectively, was
70.8 ± 18.6 (mean ± SD), 63.4 ± 18.7, and 63.1 ± 16.3 min; WASO
was 7.3 ± 8.4, 4.9 ± 5.1, and 1.6 ± 4.6 min (p = 0001 between 1st
nap and the 3rd nap by Tukey HSD); SWS was 11.0 ± 10.0, 8.7 ±
9.0, and 11.9 ± 9.8 min; and REMS was 6.3 ± 3.6, 6.8 ± 3.4, and
5.5 ± 4.0 min.
It was a negative relationship between sleep during the preceding
off-night and daytime sleep just before the night shift (p < 0.001,
r = -0.3). The participants tended to postpone the bedtime on the
off-night before their assigned shift to ensure a long sleep during
the daytime before the night shift. On the off-night preceding the
day of the assigned night shift, sleep began between 01:00 and 01:59
or between 02:00 and 02:59 in the largest number of participants
(40.0% each), whereas it was started after 04:00 in as many as 17.0%
of the participants.
Conclusion: These findings indicate that nurses sacrifice personal
life and their sleep schedule to accommodate work duties, since
various events, including any sudden change in patient condition
or procedures related to a deceased patient, might preclude the nap
during night shift.
57
PC 34
PC 35
PARADIGM SHIFT IN COMMERCIAL DRIVER SLEEP
RESEARCH: FROM REDUCTIONIST APPROACHES
TO COMPLEX ADAPTIVE SYSTEMS
Apostolopoulos Y, Sönmez S, Wideman L, Ho Yu C, Hege A,
Oberlin D, Johnson A
SHIFTWORK PRACTICES IN THE UNITED STATES
NAVY: A STUDY OF SLEEP AND PERFORMANCE
IN WATCHSTANDERS ABOARD THE USS JASON
DUNHAM
Shattuck N, Waggoner L, Young R, Smith C, Brown S,
Matsagas P
University of North Carolina at Greensboro and Emory University, USA.
[email protected]
Introduction: Commercial driving involves irregular work
schedules, leading to erratic sleep patterns that produce circadian
misalignment and detrimental consequences for sleep quality,
cardiometabolic health, and safety. Prevalent epidemiology uses
linear statistics to reveal proportional relations among isolated
sleep-related risk factors and presumes unidirectional causality.
But understanding components of a complex problem-such as the
complex and dynamic context of commercial driver sleep health-is
not the same as understanding the entire issue at hand, because
“the whole is not always the sum of its parts.” Complex systems
approaches, reframe the problem by moving from using isolated
parts as the unit of analysis to the system as a whole. We merge
reductionist and complexity paradigms to: (1) Delineate the effects
of and interactions among non/work stresses, reactions to them,
and other individual non/work factors in truckers’ sleep-associated
comorbidities and hazards, and (2) Uncover underlying dynamic
mechanisms that influence risk factors that generate truckers’
persistent sleep problems in order to curtail their trajectories by
pinpointing high-leverage intervention points.
Methods: The Long-Haul Truck Drivers-Sleep Survey was used,
which measured drivers’ non/work environment (i.e., workhours),
occupational//individual health (i.e., diet/exercise patterns), sleep
patterns/disorders (i.e., sleep apnea), sleep-related comorbidities
(i.e., hypertension), and sleep-related occupational hazards
(i.e., accidents). Systematic sampling procedures were used to
collect survey and anthropometric data from 262 truckers at one
high-traffic truckstop on I-40 in North Carolina. Anthropometry
included body height/weight, sagittal measures, waist-to-hip/
waist-to-stature/height ratios, and blood pressure. Furthermore,
phlebotomy was conducted on 40% of the sample to test for
high-/low-density lipoprotein, total cholesterol, triglycerides,
fasting insulin, and glucose. Statistical analysis (SAS, LISREL) is in
progress; data are being analyzed using descriptive and multivariate
regression analyses and multilevel modeling. Findings will be used
to develop exploratory system dynamic models (Vinsem) involving
causal-loop - and stock-and-flow diagrams to deconstruct the
causative pathways to truckers’ sleep problems.
Results: While analysis is currently underway, preliminary results
indicate that the combination of long workhours, constantly
shifting schedules, mile-based pay, and chronically unhealthy diets
and sedentary behaviors place a heavy burden on truckers’ sleep
patterns with negative repercussions in the form of sleep apnea
and other sleep disorders, as well as general trucker health (i.e.
central obesity), and job performance (i.e., near misses). Following
the completion of data analysis, qualitative and quantitative
system dynamics modeling methodologies will be used to uncover
bidirectional (feedback and feedforward) loops among the most
salient risk factors such as non/work conditions, community and
stakeholder capacity, truckers’ lifestyles, and their sleep-related
problems.
Conclusion: This study is intended to place commercial driver
sleep health within the framework of complex adaptive systems
and calls for the integration of reductionist and complexity science
tools to develop and implement efficacious intervention configurations in occupational health.
Operations Research Department, Naval Postgraduate School, USA.
[email protected]
Introduction: It is well established that members of the military
get inadequate sleep. Shay (1998) traced sleep deprivation in the
military back to the ancient Greeks. In one of the first studies of
sleep in the U.S. military, Kleitman (1963) reported on the sleep patterns of Navy submariners in the 1950 s. Unfortunately,
all branches of the military seem steeped in this long tradition
of sacrificing sleep and the problem has only been exacerbated
by the 24/7 nature of continuous operations in the current defense climate. Despite efforts to address sleep deprivation in the
military, it still poses a serious threat to safety and operational
effectiveness. Sailors in the United States Navy are habitual shiftworkers, often working shifts that result in circadian misalignment equating to an 18 or 20 hour day without weekends or time
for recovery. Working other than a 24 hour day, especially shorter
days that impose a type of chronic jet-lag, is a well-known contributor to fatigue in the civilian shiftwork population. We proposed
the adoption of a 3-on/9-off circadian-aligned watch standing
schedule based on a 4-section watchbill where sailors stand 3 hour
watches that commence every 12 hours. We then documented
the work and rest patterns of the crewmembers working this alternative schedules as well as other traditional schedules aboard
the USS JASON Dunham (DDG 109), an Arleigh Burke class
destroyer (9300 tons).
Methods: As part of a larger data collection on 122 crewmembers, 33 U.S. Navy sailors participated in a two-week study exploring the impact of two watchstanding schedules on
sleep/wake patterns and performance in an operational environment. The alternative watchstanding schedule (the “3/9”)
involved standing 3 hours of watch followed by 9 hours off
watch. The standard schedule (the “6/6”) consisted of standing
6 hours of watch followed by 6 hours off watch. Each sailor
wore an actigraph, completed a daily sleep and activity log, and
performed a 3-minute psychomotor vigilance test before and
after standing watch.
Results: This preliminary analysis focused on sailors’ sleep
patterns. A mixed-effects ANOVA was used to examine the effects
of watchstanding schedule and day on total sleep time per 24 hour
period. Sailors working the alternative watchstanding schedule
received an average of 86 minutes more sleep compared to their
counterparts working the standard 6/6 schedule (F1, 302 = 22.06;
p < 0.001). The interaction between watchstanding schedule and
day of the study was also statistically significant (F11, 302 = 2.17;
p = 0.02).
Conclusion: Preliminary results indicate sailors working an
alternative watchstanding schedule get more sleep than those on
a standard schedule. Additional sleep gained using this alternative
schedule may have direct impact on sailors’ performance within the
surface navy community.
Support: This study was supported by the United States Navy
Bureau of Medicine, United States Navy N135H, and the Office
of Naval Research.
58
PC 36
TIMING AND DURATION OF SLEEP IN FINLAND
FROM 1987 TO 2010
Anttila T1, Oinas T1, Nätti J2
Dept. of Social Sciences and Philosophy, FIN-40014 University of Jyväskylä,
Finland.
2
School of Social Sciences and Humanities, FIN-33014 University of
Tampere, Finland.
[email protected]
1
Objectives: A shift from ‘9 to 5, Monday to Friday’ to the
‘24/7-society’, imply the weakening of socio-temporal structures
that may be a risk for our biological rhythms. One of 24/7-society’s
potentially adverse biological and social outcomes relates to sleep.
The aim of this paper is to analyze trends in timing and duration
of sleep in Finland.
Methods: The analysis is based on three Finnish Time Use
Surveys (FTUS), covering 12 months in 1987-1988 (n = 7588 days),
1999-2000 (n = 10551 days) and 2009-2010 (n = 7483 days). FTUS
is a sample-survey, in which participants keep accurate records of
their time use (in 10 minutes periods) for two 24 hours periods.
In addition, surveys include data from personal interviews. We
will apply multivariate linear models in pooled data to analyze the
effects of survey year on the timing and duration of sleep.
Results: The duration of sleep lengthened 8 minutes on weekdays
and 25 minutes on weekends during the period of 1987-2010.
The timing of sleep has changed, especially within the period
from 1987 to 2000. Among employed persons, estimated wake-up
time has been delayed 19 minutes on weekdays and 31 minutes on
weekends during the period of 1987-2010. The change over time is
statistically significant, after controlling for age, gender, number of
child, education and work hours. Estimated time of going to sleep
has delayed 7 minutes on weekdays and 4 minutes on weekends.
In addition to general trends of timing and duration of sleep, we
provide evidence on the socio-economic correlates of changing
sleep behavior.
Conclusion: Our results do not support the common assertion
that sleep duration has declined over the past few decades. In fact,
the time use diaries show that duration of sleep has increased.
The timing of sleep has also changed. It has delayed, especially on
weekends.
PC 37
ACCIDENT RISK FACTORS AMONG BRAZILIAN
SHIFT-WORKING TRUCK DRIVERS
Narciso FV1, Ruiz FS1, Souza JC2, Esteves AM3, Soares-Junior
RC2, Barreto A1, Raso V1, Tufik S1, de Mello MT1
Universidade Federal de São Paulo, Brazil.
Universidade Católica Dom Bosco, Brazil.
3
Universidade Estadual de Campinas, Brazil.
[email protected]
1
2
Introduction: Until recently, driving while drowsy has been a
major focus of highway safety initiatives aimed primarily at the
general public in Brazil. The present study aimed to investigate the
relationship between accident involvement, sleep patterns and the
health habits of shift-working Brazilian truck drivers.
Methods: We investigated 205 males’ shift-working Brazilian
truck drivers. The validated structured sleep questionnaire, the
“UNIFESP Sleep Questionnaire” was used to obtain relevant
demographic, clinical, and occupational data, including age,
current medical conditions, consumption of medications, habitual
snoring, smoking status, alcohol intake, use of hypnotic-sedative
and psychoactive drugs, sleep duration, pattern, disorders and
complaints, psychological disorders, physical activity, working
conditions, and accident history.
The “Accidents” variable was calculated by including those who
answered & ldquo;yes” to accident involvement according to the
participants’ occupation history. The data were analyzed using
correspondence analysis (ANACOR) and a logistic regression
model to identify the odds ratio of accident involvement, adjusted
by potential confounders.
Results: Our results generated two distinct truck drivers’ profiles.
For the first profile, we observed that drivers who reported
involvement in accidents appeared similar to those who reported
drug usage, driving more than 14 to 19 hours without rest, excessive
sleepiness, falling asleep while driving and sleep complaints.
Conversely, the second profile showed that subjects who were
not involved in accidents were similar to subjects who reported
no sleep complaints or excessive sleepiness, did not falling asleep
while driving and did not use drugs. We have also observed that the
variable contributing the most to these two profiles was overnight
travel, followed by falling asleep while driving and sleep complaints.
Our data also demonstrated that exposure to accidents was 4 times
higher for drivers who habitually drive during the night. We have
also observed a protective effect in terms of accident involvement
for drivers who usually work fewer than 12 hours per day.
Conclusion: In summary, our results confirmed our hypothesis and
highlighted how adequate sleep habits, as well as the consequences
related to sleep disturbances, are associated with drug consumption
and accident involvement by truck drivers in our study. These
data reinforce the need to be more attentive to the truck driver
population because they have a high propensity for accidents.
PC 38
SLEEP DURATION AND DAYTIME SLEEPINESS IN
EARLY MORNING SHIFT WORKERS
Birks RB, Wright Jr. PK
Sleep and Chronobiology Laboratory, Department of Integrative Physiology,
University of Colorado at Boulder, USA.
[email protected]
Introduction: Early morning shift work schedules are commonplace, yet limited data are available on the sleep and sleepiness
associated with such schedules. Therefore, we examined the sleep
duration, sleep quality and daytime sleepiness associated with
early morning shift work during days on and days off of work as
compared to a day work control group.
Methods: Twenty-three healthy adults (14 females) aged (32.6
± 9.2, Mean ± SD) participated. Subjects groups were n = 13
early morning shift work and n = 10 day work control. Early
morning shift work was defined as work shifts starting between 0300-0700h and day work was defined as work shifts starting
between 0800-1000h. Subjects were studied for one week that
included days on and day off work. Daily sleep logs and wrist
actigraphy recordings with concurrent light exposure assessment
(Actiwatch-L, Minimitter Respironics, Bend OR) were completed. The Karolinska Sleepiness Scale (KSS) was also completed
shortly after awakening from the major sleep episode and at the
beginning and end of the work shift.
On days off, subjects completed the KSS shortly after awakening,
1h after awakening and at a clock hour comparable to the end of
their work shift. Mixed-effects ANOVAs were used to analyze sleep
and sleepiness data.
Results: Findings show that subjective sleep duration was shortest
in early morning shift workers on work days and longest in early
morning shift workers on days off, with intermediate sleep durations
in day workers (Interaction p < 0.05). Subjective sleep disturbance
59
was greater, sleep quality was lower and KSS scores were higher in
early morning shift workers compared to day workers (main effects
p < 0.05).
Conclusion: Preliminary findings suggest that early morning
shift workers sleep less on work days and spend more time
obtaining recovery sleep on days off as compared to day workers.
Furthermore, that early morning shift workers report more sleep
disturbance, lower sleep quality and higher KSS scores than day
workers suggests that early morning shift work is associated with
sleep disturbance and daytime sleepiness.
Support: Undergraduate Research Opportunities Program at the
University of Colorado, Boulder, CO U.S.A.
PC 39
SLEEPINESS, ATTENTION AND VIGILANCE OF
SHIFT WORKERS BEFORE AND AFTER WORKING
TIME
Carvalho ANS1, Ruiz FS2, Narciso FV2, Koyama RG1, Saba A1,
Fernandes-Junior SA2, Tufik S2, Mello MT1,2
Centro Multidisciplinar em Sonolência e Acidentes, Brazil.
[email protected]
1
2
Night shift worker commonly report sleep complaints, sleepiness,
attention and vigilance impairments, which represents an important
risks and errors factor for accidents. The aim of the present study
was to investigate cognitive parameters regarding sleep parameters
at pre e post night shift work.
A total of 247 male shift workers were evaluating using a
correspondence analysis (ANACOR). The Epworth Sleepiness
Scale was used to evaluate sleepiness and the Psychomotor Vigilance
Test (PVT) assessed lapses and errors. All assessments occurred at
the beginning and the end of night shiftwork.
The shift workers were submitted to one night of polysomnography
(PSG) to evaluate sleep efficiency and presence of Obstructive
Sleep Apnea (OSA).
We have observed at the beginning of working time that all shift
workers showed similar lapses and errors responses regarding sleep
variables.
However, after a nightshift, our results generated two distinct shift
workers’ profiles. For the first profile, we have observed that shift
workers who demonstrated lapses and errors responses on PVT
presented excessive sleepiness, reduced sleep efficiency and OSA.
On the other hand, the second profile showed that shift workers
who not demonstrated lapses and errors responses on PVT had
better quality on sleep parameters (non-OSA, normal classification
according to Epworth Sleepiness Scale and adequate sleep
efficiency).
In summary, these data support that the shift workers that work at
night shiftwork have a highest propensity to present sleep disorders
and sleepiness, which may generally initiate fatigue chronic and
increase the number of errors and accidents.
PC 39
SLEEPINESS, ATTENTION AND VIGILANCE OF
SHIFT WORKERS BEFORE AND AFTER WORKING
TIME
Carvalho ANS1, Ruiz FS2, Narciso FV2, Koyama RG1, Saba A1,
Fernandes-Junior SA2, Tufik S2, Mello MT1,2
[email protected]
1
2
Night shift worker commonly report sleep complaints, sleepiness,
attention and vigilance impairments, which represents an important
risks and errors factor for accidents. The aim of the present study
was to investigate cognitive parameters regarding sleep parameters
at pre e post night shift work.
A total of 247 male shift workers were evaluating using a
correspondence analysis (ANACOR). The Epworth Sleepiness
Scale was used to evaluate sleepiness and the Psychomotor Vigilance
Test (PVT) assessed lapses and errors. All assessments occurred at
the beginning and the end of night shiftwork.
The shift workers were submitted to one night of polysomnography
(PSG) to evaluate sleep efficiency and presence of Obstructive
Sleep Apnea (OSA).
We have observed at the beginning of working time that all shift
workers showed similar lapses and errors responses regarding sleep
variables.
However, after a nightshift, our results generated two distinct shift
workers’ profiles. For the first profile, we have observed that shift
workers who demonstrated lapses and errors responses on PVT
presented excessive sleepiness, reduced sleep efficiency and OSA.
On the other hand, the second profile showed that shift workers
who not demonstrated lapses and errors responses on PVT had
better quality on sleep parameters (non-OSA, normal classification
according to Epworth Sleepiness Scale and adequate sleep
efficiency).
In summary, these data support that the shift workers that work at
night shiftwork have a highest propensity to present sleep disorders
and sleepiness, which may generally initiate fatigue chronic and
increase the number of errors and accidents.
PC 40
POLYSOMNOGRAPHY AND ACTIGRAPHY: RELATION BETWEEN THE CLASSIFICATION OF VARIABLES IN SHIFTWORKERS
Saba A1,2, Fernandes-Junior SA2, Stetner LA1, Koyama RG1,
Carvalho ANS1, Tufik S2, Mello MT1,2
[email protected]
1
2
Introduction: The polysomnography is the golden standard for
diagnoses of sleep disorders. Similarly, actigraphy is a validated
technique used to record the pattern of sleep/wake and
identification of certain disturbances(1). Despite the overestimation
or underestimation of some variables of actigraphy compared to
polysomnography(2), its use has been increasing in clinical practice
and in research.
Objectives: The aim of this study was to evaluate the relationship
in the classifications of the variables sleep efficiency and latency
between the gold standard and actigraphy.
Methods: The sample was made by forty-three men, workers in a regular fixed nocturnal scale who was underwent during slack day the
polysomnography and actigraphy simultaneously. The analysis of the
rest in actigraphy was based on sleep diary and was used Actwatch
64 (Respironics). The sleep parameters were categorized according to
Mitler and Miller(3) which defined as decreased sleep latency (< 5 minutes) and increased (> 30 minutes); Carskadom and Rechtschaffen(4)
established sleep efficiency as normal (≥ 85%) and decreased (< 85%).
Results: The ratings of sleep efficiency showed a significant
reasonable agreement assessed by Kappa (Kappa = 0.398,
p = 0.008). There was no statistical significance when assessed the
correlation between ratings of sleep latency in polysomnography
and actigraphy (p = 0.899). In the evaluation of continuous variables
was observed a significant moderate association only in total sleep
time (R = 0.586, p < 0.001).
60
Conclusion: The sleep efficiency showed an agreement reasonable
and sleep latency did not. It is recommended to increase the sample
to supplement the findings.
REFERENCES
1. Standards of Practice Committee. Practice parameters for the use of actigraphy in the clinical assessment of sleep disorders. Sleep 1995;18:285-7.
2. Rupp, T. L; Balkin, T. J. Comparison of Motionlogger Watch and Actiwatch actigraphs to polysomnography for sleep/wake estimation in
healthy young adults. Behav Res Methods. 2011 Dec;43(4):1152-60. doi:
10.3758/s13428-011-0098-4.
3. Mitler MM, Miller JC. Methods of testing for sleeplessness. Behav Med.
1996;21:171-83
4. Carskadon MA, Rechtschaffen A. Monitoring and staging human sleep.
In: Kryger MH, Roth TT, Dement WC, editors. Principles and Practice
of Sleep Medicine. 4th ed. Philadelphia: Elsevier Saunders; 2005. pp.
1359-1377.
PC 41
CPAP THERAPY AND QUALITY OF LIFE OF
BRAZILIAN RAILROAD WORKERS
Koyama RG1, Ruiz FS2, Stetner LA1, Saba A1, Tufik S2, de
Mello MT1,2
[email protected]
1
2
Introduction: The recent literature shows an increased incidence
of obstructive sleep apnea (OSA) in workers in the transportation
sector that lead to a significant reduction in the duration and
effectiveness of sleep. Excessive sleepiness is considered a problem
because it affects quality of life and has negative effects on
productivity and work safety.
On the other hand, there are no published studies related to
Continuous Positive Airway Pressure (CPAP) treatment in this group.
Objective: Our aim was to assess the effect of CPAP on quality of
life of railroad workers with Obstructive Sleep Apnea (OSA).
Methods: Fourty-four male railroad workers from a railway
company in Brazil underwent to a treatment with CPAP for six
months. The workers were guided to answer the Functional
Outcomes in Sleep Questionnaire (FOSQ) at CPAP baseline, 3, and
6 months of effective CPAP therapy. All workers were properly
informed about the confidentiality of data.
Results: 37 railroad workers (age = 42 ± 10 y, body mass index =
31 ± 5 kg/m2, AHI = 37 ± 23 events/h) were included in this
study. From the total, seven patients had difficulty complying with
CPAP for a variety of reasons (nocturnal cough, claustrophobia,
insomnia) and stopped with the CPAP treatment. Results are
presented as Median (Q1-Q3). It was not observed improvement,
in FOSQ score (baseline 18.3 [17-19] vs. 18.8 [17-19] vs. 18.3
[17-19], respectively, p = 0.77).
Conclusion: CPAP did not improve the quality of life of this
studied population probably because the workers probably have
omitted information, even when they were informed that all data
were highly confidential.
PC 42
PERCEPTIONS OF SLEEP, SLEEPINESS AND
SCHOOL PERFORMANCE AMONG APPRENTICES
AND TRAINEES
Luz AA, Fischer FM
[email protected]
Introduction: A significant number of high school and college
students in Brazil work more than 30 hours per week and study in
the evening hours. Several studies have shown the negative effects
on heath and sleep of young students due to extensive working
hours concomitant with evening classes. Excessive sleepiness
during classes are common complaints. The sleep/wake cycle of
adolescents are influenced by biological and social factors, which,
in conjunction with partial sleep deprivation could harm their
school performance. The purpose of this study was to identify and
analyze reports of young workers regarding their sleep and school
performance.
Methods: The current study was carried out in a nongovernmental
organization (NGO) located in the outskirts of São Paulo, Brazil.
Research participants were 20 apprentices and 20 trainees (14-20
years). All of them had been working (6-8 hours) during the
day, attending classes in the evening (4 hours) and attending the
NGO training program. Data collection was conducted between
September and November 2009. Sleep and school performance
were measured using semi-structured collective and individual
interviews. Empirical data analysis was performed using Content
of Analysis.
Results: The majority of participants (90%) mentioned that
simultaneous activities, such as work and study affected their sleep
time and school performance. The main factors related to excessive
sleepiness during evening classes that have been identified were:
partial sleep deprivation, the use of Internet after 11 pm to do
homework, waking up early (between 5 am and 6 am) to go to work.
A number of participants reported that their school performance
became worse due to the concomitant activities - work during the
day and attending classes in the evening hours. Moreover, physical
fatigue and excessive sleepiness were also mentioned as the main
factors responsible for the lack of attention and focus during
classes.
Conclusion: These results indicate that public policies related to
working adolescents should take into account the impact of long
working hours on their sleep, health and school performance.
Financial support: CNPq and FAPESP (grants # 563906/201203 and 2012/22005-1, respectively)
PC 43
EFFECTS OF SPLIT SLEEP/WAKE SCHEDULES ON
SUBJECTIVE FATIGUE AND SLEEPINESS
Zhou X, Sargent C, Darwent D, Kosmadopoulos A, Dawson
D, Roach GD
[email protected]
Introduction: Shiftwork is conventionally arranged in forms of
consolidated work/rest schedules that contain one rest period for
sleep per day. Alternatively, the rest period can be split into two or
more episodes per day, forming a split work/rest schedule.
Studies have shown that splitting otherwise consolidated night sleep
periods is neither beneficial nor detrimental to subjective states
than obtaining the sleep in a single episode. However, the effects
of splitting sleep periods that occur during daytime are unknown.
Such knowledge is essential for optimising shift schedules. The aim
of this study is to examine the effects of splitting sleep periods that
occur at different times of day on subjective states.
Methods: Twenty-two healthy young males were scheduled to 7 x
28-h days in a temporal-isolation laboratory. Each day, they spent
1/3 time in bed and 2/3 time awake. Given the day length is 4h
longer than the 24-h environmental light/dark cycle, each day began
4h later, and in effect, the timing of the daily sleep opportunity
systematically varied across days.
61
In a consolidated sleep/wake protocol (n = 14), the daily sleep
opportunity was given as a single period, whereas in a split sleep
protocol (n = 8; 8 more to be recruited) this opportunity was
divided into halves with 9.33-h scheduled wakefulness in between.
For both protocols, subjective fatigue and sleepiness were measured
every 2.5h during wake periods, using the Fatigue-Inertia subscale
of the Profile of Mood States and the Karolinska Sleepiness Scale,
respectively. For each individual, subjective ratings were averaged
within each 28-h period.
Results: The daily average fatigue and sleepiness ratings of the
two protocols were compared using two separate mixed-effects
ANOVAs with ‘Day’ (1 to 7) and ‘Condition’ (consolidated vs. split)
as fixed terms, and ‘Participant’ as a random term. Preliminary
analyses based on the current 22 participants revealed a significant
Day x Condition interaction for both measures. Subjective fatigue
in the split sleep condition was lower than that in the consolidated
sleep condition on day 4 and 5, when consolidated sleep periods
started during the subjective day and evening. In contrast, sleepiness
in the split sleep condition was greater than that in the consolidated
sleep condition on day 7, when the consolidated sleep period
started during the subjective night.
Conclusion: Our preliminary analyses indicate that the effects of
splitting an otherwise consolidated sleep schedule depend on when
the consolidated sleep period occurs. Splitting daytime or evening
sleep periods provides additional benefits from obtaining the sleep
in a single period, at least in terms of mitigating fatigue. Splitting
otherwise consolidated night sleep periods is detrimental, though,
for subjective sleepiness.
no experience on night shifts (reference group; n = 345) and (ii)
those working night shifts (n = 1,647). The second one focused
on nap habits during night shifts and self-reported hypertension.
Workers who reported on-shift naps were compared to those who
reported not to nap (reference group). Logistic regression analysis
was used to e valuate the association between napping during night
shifts and reporting hypertension.
Results: Mean age was 39.9 (SD = 10) years. Most participants
(87.2%) were engaged in 2 or 3 jobs, usually at different hospitals;
60.9% worked both at daytime and at night shifts considering all
jobs. Practically every worker (97.6%) worked in hospitals in which
napping for up to three hours during night shifts was informally
allowed. About half of the sample (n = 842; 49.6%) reported not
to sleep on the night shift whereas 856 workers (50.4%) reported
on-shift naps for up to three hours. Working at night increased
the odds of self-reported hypertension 1.8-fold (95% confidence
interval, 1.36-2.45) compared with day workers with no experience
on night shifts, after adjusting for age, physical activity, smoking
habits, and housework. Analysis of night workers revealed that
sleeping during the night shift reduced the odds of reporting
hypertension (OR = 0.79; 95% CI 0.63-1.00), compared to those
who reported not to sleep during the night shifts.
Conclusion: Results confirm literature data on higher prevalence
of hypertension among shift workers compared to day workers.
The potential positive effect of naps on blood pressure deserves
further investigation through automatic monitoring. Dipping
patterns and blood pressure control may be influenced by short
periods of sleep in night shifts.
Support: This study is funded by the Australian Research Council.
Session II - November 6th
16:30-18:30 h
D - Health and shiftwork
PC 44
NAPPING DURING NIGHT SHIFT AND SELFREPORTED HYPERTENSION AMONG NURSING
WORKERS
Rotenberg L1, Silva-Costa A1,2, Silva-Vasconcellos PR3,4, Griep RH1
Laboratory of Education on Environment and Health, Oswaldo Cruz
Foundation, Brazil.
2
National School of Public Health - ENSP/FIOCRUZ.
3
Universidade do Rio de Janeiro-Unirio, Brazil.
4
Oswaldo Cruz Institute-IOC/FIOCRUZ.
[email protected]
1
Introduction: Beneficial effects of napping during the night shift
include reduced fatigue and sleepiness, improved performance,
partial compensation for sleep loss, as well as influence on hormone
levels, thus affecting health. The potential influence of on-shift
napping on morbidity deserves attention. This study focuses
on self-reported hypertension, with the aim of (1) analyzing its
prevalence among day and night workers and (2) to verify whether
there is an association between taking a nap regularly during night
shifts and prevalence of hypertension among night workers.
Methods: This cross sectional study was carried out at 18 public
Brazilian hospitals in 2010-2011, comprising a total of 3,229
registered nurses. They completed a comprehensive questionnaire
with data related to sociodemography, physical health (self-rated
health, hypertension amongst other diseases), habits and lifestyles,
as well as information on current and former work hours. Only
women workers were included in the analysis. Statistical treatment
of data was carried out in two steps. The first one (assessing
self-reported hypertension considering work hours) was based on
classification of workers into (i) those working during the day with
PD 45
SHIFTWORK AND CARDIOMETABOLIC RISK
Rogers N.L, Di Milia L
Chronobiology & Sleep, Institute for Health and Social Science Research,
Higher Education Division, Central Queensland University, Australia.
[email protected]
Introduction: Circadian disruption and sleep loss have been
demonstrated to be associated with a number of physiological
changes, including perturbations to a number of cardiometabolic
indices. The circadian and sleep disturbances associated with
shiftwork have been implicated as risk factors for cardiometabolic
dysfunction in shiftworkers. Relative to day work, shiftwork has
been reported to be associated with an increased risk for: weight
gain, obesity and diabetes, impaired glucose metabolism, and
development of metabolic syndrome. In the present study we
compared self-reported indices of cardiometabolic function from a
convenience sample of shiftworkers and non-shiftworkers.
Methods: Participants were approached during random breath
test stops on one of three highways in Central Queensland, and
asked if they were interested in completing a questionnaire by
phone in the days following this stop. Of 1,180 drivers invited to
participate, n = 649 drivers completed the phone interview, and
n = 525 had compete cardiometabolic data and were included in
the present analysis. Of the total sample, n = 286 were dayworkers
(mean age = 44.4 ± 12.9) and n = 239 were shiftworkers (mean age
41.4 ± 11.4).
62
Results: Compared to dayworkers, shiftworkers worked longer
hours per week, reported shorter sleep durations per 24 hours,
including in the previous 24 hours, and were more likely to have an
evening chronotype. In addition, there was a trend for shiftworkers
to report a higher prevalence of snoring relative to dayworkers.
There was no significant difference in BMI, or risk for sleep apnea
between the groups. There was an age by work type interaction,
with a higher rate of obesity in older shiftworkers relative to older
dayworkers. The strongest contributors to increased BMI were a
high risk for sleep apnea, snoring, weekly work hours and age.
Conclusions: Although in the present study there was no significant
difference between dayworkers and shiftworkers for BMI or sleep
apnea risk, assessed using the Berlin Questionnaire, there was a
trend for more shift workers to be snorers than day workers; in
addition shiftworkers worked significantly longer hours per week
than dayworkers. Consequently, two of the strongest contributors
to having high BMI, which is a risk factor for development of
cardiometabolic disorders were more prevalent in shiftworkers
relative to dayworkers, suggesting potential targets for reducing the
risk of cardiometabolic diseases in shiftworkers.
PD 46
SHIFT WORK AND SLEEP QUALITY OF THE
NURSING TEAM IN A INTENSIVE CARE UNIT
Santos TCMM1,2, De Faria AL2, Feitosa MS2, Silva GTCA2,
Ferreira LC2, De Martino MMF1
Department of Nursing of the Medical Sciences School of the State
University of Campinas, Brazil.
2
University of Taubaté, Brazil.
[email protected]
1
Introduction: The scales of nursing work staff are usually
organized in shifts of eight or 12 hours duration followed by 36
hours off. Thus, the duration of each shift start and end of several
shifts, regular working hours, flexibility of the system, and the
distribution of free time may lead these professionals to present
changes to habitual sleep patterns, cognitive and physiological
functions which are expressed in a rhythmic manner.
Objective: To analyze the sleep quality of nursing staff working in
an Intensive Care Unit.
Methods: Prospective, descriptive, quantitative approach research.
The population consisted of 17 employees of the nursing staff.
The instruments used for data collection were the identification
form and Quality Index, Pittsburgh Sleep - PSQI - through out
the months of June and July 2011, after the approval of the Ethics
Committee of the University of Taubaté, Protocol N. 075/11. Data
were tabulated by the program Microsoft Excel 2007.
Results: This study showed the predominance of 14 (82.35%)
females, and. age group 7 (41.18%) between 30-49 years old. As
the training the predominance was of the nursing technicians 8
(47.06%). Regarding the shift work is 12 x 36 a total, 10 (58.83%).
As sleep quality, 15 (88.24%) of the professionals surveyed had
scores greater than five, indicating poor sleep quality. Among them,
9 (52.95%) sleep six to eight hours for day and 8 (47.5%) sleep
less than six hours. It was observed that 12 (70.60%) had problems
staying awake to perform other activities.
Conclusion: The results showed a poor sleep quality of nurses
who participated in the research. Workers, for having irregular
hours of sleep, can not reestablish and restore themselves for the
next day, which impairs their work performance, and thus, it may
contribute to situations of negligence and recklessness.
Keywords: Sleep; Nursing team; Intensive care units.
PD 47
ROTATING NIGHT SHIFT WORK AND PHYSICAL
ACTIVITY OF NURSES AND MIDWIVES
Pepłońska B, Bukowska A, Sobala W
Department of Environmental Epidemiology, Nofer Institute of Occupational
Medicine, Lodz, Poland.
[email protected]
Introduction: The benefits of exercising for one’s health have
been well established, with reported inverse association between
physical activity and all-cause mortality, coronary heart disease,
diabetes, and benefits in cancer prevention and weight control.
Shift work has been thought to restrict participation in leisure time
activities, however epidemiological data in this subject are sparse.
Also, it is not known whether rotating night shift work affects
physical activity (PA) among women. We used the data from the
cross-sectional study on nurses and midwives in Lodz, Poland to
explore this understudied topic.
Methods: The study included 354 nurses and midwives (aged
40-60) currently working on rotating night shifts and 371 ones
working days only. The information on the work characteristics and
potential covariates was collected via a personal interview. PA was
assessed according to the international questionnaire on physical
activity - IPAQ, covering 7 days before the interview, with the data
collected on four PA domains: work, active transportation, domestic
and garden, and leisure time. MET hrs per week were calculated.
Women who reported no leisure time activity were classified as
“recreationally inactive”. The medians were predicted with multiple
linear models adjusted for age, smoking, marital status, number of
births, sleep quality, BMI and season of the year. Associations for
“recreational inactivity” were calculated with the multiple logistic
regression model.
Results: The work-related PA domain was the major component
of the total PA and the recreational PA contributed the least. Current night shift work was associated positively with
occupational PA, with increasing MET scores according to the night shifts frequency and duration of the night shift work (median
MET * hrs per week: night shift nurses (≥ 8 night duties/month):
190, 95% CI: 164-217, and > 25 years of the night shift work: 170,
95% CI: 156-185 - vs. day nurses: 131, 95% CI: 122-140). Current night shift work was associated with “recreational inactivity”
(OR: 1.6, 95% CI: 1.1-2.2), in particular in women with ≥ 8 night
shifts/m.: OR = 2.5, 95% CI: 1.3-4.9), and > 25 yrs of night shift
work (OR = 2.6, 95% CI: 1.4-4.9). Other statistically significant
determinants (p < 0.05), out of these tested in multivariate models
of PA, were: for the work domain - age (β = -1.7 per 1 yr), for
active transportation - calendar season: (β = -2.3 - from October
to April), for domestic - number of children (β = + 5.7 - for ≥
3 children), calendar season (β = -2.7 - from October to April)
and marital status (β = -5.6 - for widows), and for recreational number of children (β = -7.5 - for ≥ 3 children), and sleep quality
(β = -0.38 - for 1 p. score).
Conclusion: Rotating night shift work of nurses and midwives
is associated with higher work-related physical activity, and
recreational inactivity.
Support: The project is supported by grants from the
Polish-Norwegian Research Fund (Grant No: PNRF-243-A1-1/07
and Grant: CLOCKSHIFT).
63
PD 48
PHYSICAL AND MENTAL FITNESS OF SHIFT
WORKERS IN PRODUCTION COMPANIES
Goudswaard A, Zwieten MV
TNO Work and Employment, Hoofddorp, The Netherlands.
[email protected]
Introduction: Companies that are dependent on continuous
production systems and therefor have employees working in
continuous shift systems face major challenges in keeping their
workforce productive and healthy. An ageing workforce and a
higher retirement age, mean that they have to find new solutions
that go beyond the ‘old’ policy that spare the elderly workers in case
of night shifts, early retirement schemes or the award of additional
days off. One of the interventions might be the implementation of
less demanding work rosters or more tailor made individual work
schedules. But in most cases, an intervention in the work schedules
is simply not enough. Interventions should take all kind of
work-related and personal factors into account, including working
conditions, work processes, life style issues. The question is what
types of interventions are most suitable in a specific situation and
how the different interventions are related.
Methods: This study aimed to explore associations between
factors that contribute to physical and mental fitness of employees
working shifts, including nights. We examined the contributing
factors with both MARVEL (Method to Analyse Relations between
Variables using Enriched Loops) and a systematic literature search.
MARVEL, a Group Model Building method, is a process that
consisted of several group meetings designed to co-create a system
dynamic model with experts on the topic at stake. This method
gives insight into the associations of relevant factors. A systematic
literature search was conducted to identify articles containing
information on factors that contribute to physical and mental
fitness of employees working shifts, including nights. Relevant
articles published between 2002 en 2013 that were listed on the
database SCOPUS were selected. The literature research gives
support to the with MARVEL constructed model and defines what
is not known yet. As a follow up to this method, we will validate
the research model in production companies in the metals and
electrical engineering sector. This validation will take place in 2013.
Results: The result of the MARVEL - method and literature
review is an integrated model that gives insight into work-related
as well as personal factors that contribute to physical and mental
fitness of employees working shifts, as well as the interrelationship
between these factor. This paper, on the one hand, presents the
research model and the state of the art in literature, and will show
the gaps in knowledge. On the other hand, the paper describes the
practical application of the research model and the way in which
the model helps companies to understand the interrelationship
between factors and choose their priorities in interventions. The
result of the validation process will be a dashboard that can be used
by employers and employees in companies working in shifts.
PD 49
NURSING SCHEDULES AND CIRCULATION OF
PATHOGENS WITHIN AN INTENSIVE-CARE UNIT:
A MODELING STUDY
Salomon M1, Ferrer J2, Folkard S3, Salomon J2, Temime L2
Robert Koch Institut, Germany.
Conservatoire national des Arts et Métiers, France.
3
Université Paris Descartes, France.
[email protected]
1
2
Introduction: Observational studies in hospitals suggest first,
that some nursing schedule characteristics influence the fatigue of
health-care workers (HCWs), and second, that the hygiene behavior
of HCWs is altered through fatigue, leading to an increased risk of
nosocomial pathogen transmission between patients and HCWs.
Here, we explored how nursing schedules may influence the
prevalence of colonization with vancomycin-resistant entorocci
(VRE) in intensive-care unit (ICU) patients.
Methods: To this aim, we proposed a three-step approach.
First, a wide array of nursing schedules was generated using the
commercial software Shift Plan Assistant© developed by Ximes®.
Second, the impact of these schedules on nurse performance was
examined using the previously validated Fatigue and Risk Index.
Finally, the values for nurse performance were fed into NosoSim,
an agent-based model of VRE spread in the ICU developed by our
team, as a factor modifying the individual per-contact probability
of VRE transmission.
Results: Both univariate and multivariate analysis were performed
on model predictions for over 350 different nursing schedules. The
factors we found most strongly associated with VRE colonization
prevalence in patients were work organization (higher prevalence in
2 x 12 versus 3 x 8 organizations), working time (higher prevalence
when increasing per-week working hours), length of work blocks
(higher prevalence in longer blocks of consecutive working days)
and the length of rest blocks (higher prevalence in split versus
joined days-off).
Conclusions: Our study allowed the exploration of the hypothetical
links between HCW schedules, fatigue and at-risk behaviors of
operating nurses, which may afford a better understanding of
the impact of nursing schedules on patient safety. This approach
may prove useful when crossing ICU administrative information
with infection surveillance data, and with measurements of nurse
performance, such as compliance with hand hygiene.
Support: This work was supported by the French agency for Food,
Environmental and Occupational Health Safety (Anses; MOTILIS
contract EST-2011/1/069).
PD 50
DIABETES CONTROL IN SHIFT WORKERS
Knutsson A1, Kempe A2
Mid Sweden University, Sundsvall, Sweden.
Öbackakliniken, Härnösand, Sweden.
[email protected]
1
2
Introduction: Diabetes mellitus is a metabolic disease which is
characterized by increased blood glucose levels due to insufficient
production of insulin and/or insulin resistance. Both prevalence
and incidence are increasing. One reason for this is the increasing
trend of obesity. Some evidence exists that shift work might be
a risk factor for diabetes. There is lack of knowledge of how
individuals with diabetes to manage their diabetes in relation to
work schedules and varying levels of physical activity. The problem
is both hyper - and hypoglycemia. The aim of this abstract was
to review the literature on (1) the control of blood glucose in
subjects with diabetes in relation to shift work, (2) advice provided
by current guidelines on treatment and prevention of diabetes in
shift workers.
Methods: A systematic literature review was carried out. Search
terms were: shift, night, work, shiftwork, nightwork, diabetes,
diabetic, hypoglycaemia, hypoglycemia, guidelines, control.
Results: We found only three studies on blood glucose control in
shift workers. A study of Chalernvanichakorn et al. (J Med Assoc
Thai 2008;91:1093-6) reported that day workers more often had
good blood sugar control than shift workers. In another study
64
shift - and day workers, who were diagnosed with diabetes type
1, were compared. The results showed that the shift workers had
higher HbA1c levels than the day workers (Young et al. Occup
Med (Lond) 2013;63:70-2). HbA1c is a measure of the mean level
of blood glucose during the last 6 weeks. A small study on nurses
investigated the effect of shift schedules on blood glucose and
HbA1c. The results showed that both shift - and day working nurses
had poor diabetic control. No statistically significant differences
existed between shift and day working (Poole et al. Br J Ind Med
1992;49:513-5). Current guidelines do not address the problem of
shift work and diabetes.
Conclusion: The literature on how shift workers should keep
their diabetes in order to get a good blood sugar control is quite
insignificant. In current guidelines the problems associated with
diabetes and shift work are not addressed. Therefore, more research
is needed in order to provide a scientific basis for advice.
PD 51
SLEEPINESS AND CARBOHYDRATE CONSUMPTION AMONG TRUCK DRIVERS
Martins AJ, Lemos LC, Silva LG, Moreno CRC
[email protected]
Introduction: There is evidence that increased consumption of
carbohydrates is associated with sleepiness. When performed at
night, carbohydrate intake might be a factor that affects alertness.
Paradoxically, night work could lead to increased intake of
carbohydrate-rich foods as a result of sleep deprivation.
Objectives: To verify whether there is a correlation between
carbohydrate intake and sleepiness in truck drivers.
Methods: The first phase of this study included 71 truck drivers
with a mean age of 41 years (SD = 9.5), divided into two groups: long
haul drivers (irregular shift work) and short haul drivers (day shift). In
this phase, a questionnaire about socio demographic aspects, lifestyle,
food intake and work was filled out. In the second phase, 49 drivers
(24 long haul drivers with a mean age of 41 years SD = 8.3 and 25
short haul drivers with a mean age of 39 years SD = 11.4) responded
to a 24hr food intake recall (for two working days and one day off)
and the Karolinska Sleepiness Scale (KSS). The workers also filled
out an activity diary and wore actigraphs for 10 consecutive days.
Results: About 70% of the drivers were overweight or obese.
The Kruskal Wallis test showed that long haul drivers had a mean
consumption of carbohydrates in the meal preceding the work onset
(91.8 g ; SD = 53.7) significantly higher than the short haul drivers
(mean = 51.3 g ; SD = 32.6) (p < 0.05). A repeated measurement
ANOVA, revealed an effect of time (p < 0.001) and an interaction
effect of time and work area (p < 0.05) on sleepiness. The Spearman
correlation test, between the consumption of carbohydrates in the
meal prior to work onset and the sleepiness levels immediately after
this meal, was not significant for both groups.
Conclusion: Although it was not possible to establish an association
between carbohydrate intake and sleepiness, it was observed that, the
long haul drivers consume more carbohydrates than the short haul drivers. This occurs in the meal that precedes the work onset. In conclusion, truck drivers have distinct patterns of sleepiness, whose expression seems to vary according to the social pressure of working hours.
Support: CAPES.
PD 52
CIRCADIAN RHYTHMS AND ACUTE CORONARY
SYNDROMES: A RETROSPECTIVE OBSERVATIONAL
STUDY IN A GREEK POPULATION
Nikolaidou E, Korompeli A, Katsoulas Th, Zidianakis V,
Kosta NE, Fildissis G
Faculty of Nursing, University of Athens, Greece.
[email protected]
Introduction: Cardiovascular diseases (CVD) remain a major
public health problem(1).There is a conceptual model, in which three
main pathways to CVD are postulated-social problems, behavioural
change, and disturbed circadian rhythm.
Objectives: Tο describe the circadian, weekly and seasonal rhythms
of incidence of Acute Myocardial Infarction (AMI) and Unstable
Angina (UA) events in relation to age, gender and diagnosis.
Methods: A retrospective observational study was carried out from
January 2000 to December 2005 in a general hospital of Athens,
Greece.
Patients admitted to the Cardiac Coronary Unit (CCU) with
AMI and UA were included in the study. Admission rates were
calculated according to the hour of the day (circadian rhythm),
day of the week (weekly rhythm), and month of the year (seasonal
rhythm).
Results: A total number of 1118 patients with ΑΜΙ (905) and UΑ
(213) were included in the study, who met the inclusion criteria.
72.6% of the sample were men with mean age of 64.5 years
(SD ± 12.0) and 73.8 years (SD ± 9.9) for women.
There was found two phases of increased frequency of admissions during the 24 hour (p < 0.001), a strong increase at 1:00
pm to 2:00 pm, followed by a second, shorter evening at 22:00
to 23:00. Also, patients < 65 years are the ones most often suffer
from AMI on Friday, and are the main population of the sample
employed. Finally, the admissions’ frequency was greater during
the winter months of January and March.
Conclusion: The results for the first phase of the increased
frequency of admissions is not in accordance with other studies,
as it has been found that increased admissions occur from 6:00
to 12:00(2). Also, the impaired function of the cardiovascular
system in previous days seems to contribute to the emergence of more episodes of AMI on Friday, the last working day
of the week. This is in contrast with other studies which have
found that more episodes of AMI occur on Monday(3). Finally,
the knowledge of the seasonal distribution of events will enable
nurses to inform patients about what they should avoid at that
time of the year.
REFERENCES
1. Esquirol Y, Perret B et al. 2011 Shift work and cardiovascular risk factors: New knowledge from the past decade. Archives of Cardiovascular
Disease, 104, 636-668.
2. Savopoulos C, Ziakas A. et.al. 2006 Circadian rhythm in sudden cardiac
death: A retrospective study of 2,665 cases.Angiology;57:197-204.
3. Herlitz J, Eek M et al. 2002 Diurnal, weekly and seasonal rhythm of out
of hospital cardiac arrest in Sweden. Resuscitation; 54:133-138.
65
PD 53
THE SHIFT WORK AND THE COMMON MENTAL
DISORDERS
Baptista PCP, Tito RS
School of Nursing, University of São Paulo, Brazil.
[email protected]
Introduction: The working conditions of nursing workers described
in the nursing work process show that times of work are in disagreement with the biological rhythms of individuals, causing illnesses.
The mismatch in the usual schedule of nursing needs investigation,
since health data show changes in physical and psychological health of
nursing working after being at work in shifts, day or night. This study
aims to identify the presence of common mental disorders in nursing
workers of a intensive care skilled in children with heart disease.
Methods: This is an exploratory, transversal and quantitative study
with 92 nursing workers of a children intensive care in a university
hospital of Sao Paulo, skilled on cardiology. The data were collect by
Self-Reporting Questionnaire, SRQ-20. The project was submitted
to the Ethics Committee of the School of Nursing. The data were
analysed statistically and were presented in graphs and tables.
Results: Considering the cutoff score ≥ 7 for “suspicion” of
common mental disorders, it was observed that most workers
55.40% (51) has a score < 7, which means “suspicion” of common
mental disorders. In relation to age, we found that 82.93% (34)
have between 20-40 years, 46.10% (19) belong to the nocturnal
period, followed by 31.90% (13)% in the afternoon with common
mental disorders. In the group of somatic symptoms, it was found
that 52.20% (48) reported headache, 48.90% (45) bad sleepers,
41.30% (38) have unpleasant sensations in the stomach and 39.10%
(36) dyspepsia. Regarding the group of “vital energy decrease,”
observed complaints of tiring easily in 48.90% (45) of workers,
43.50% (40) reported feeling tired all the time, 39.10% (36) have
difficulties in performing daily activities with satisfaction, 26.10%
(24) reported difficulty making decisions, 22.80% (21) reported
difficulty in thinking clearly and finally, 18.50% (17) claim that work
causes them suffering.
Regarding the group of symptoms such as depressed mood,
anxiety, 65.90% (60) reported feeling nervous, tense or worried,
42.40% (39) sadness, 25.00% (23) have been crying more than the
custom and 34.80% (32) scares easily. Furthermore, 26.10% (24)
report having lost interest in things, 6.52% (6) express feelings of
being unable to play a useful role in life and feel worthless and
1.10% (1) expressed the idea of ending life.
Conclusion: These data suggest that shift work impacts the quality
of life of this population, since living with physical and psychological
changes, which may also influence the quality of nursing care. Therefore, it’s necessary to recreate the work process with the implementation of protective measures the health of nursing.
PD 54
SLEEP INERTIA IN A SIMULATED 8-HOUR
ON/8-HOUR OFF ROTATING SHIFT SCHEDULE
Hilditch CJ1, Short MA1,2, Centofanti SA1, van Dongen HPA3,
Kohler MJ1, Banks S1
Centre for Sleep Research, University of South Australia, Adelaide, SA,
Australia.
2
Bushfire CRC, Melbourne, VIC, Australia.
3
Sleep and Performance Research Center, Spokane, WA, USA.
[email protected]
1
Introduction: Sleep inertia refers to a brief period of cognitive
impairment typically experienced upon waking. Sleep inertia is of
concern to on-call emergency service personnel and others required
to perform safety-critical tasks soon after waking. This study
examined sleep inertia in an 8h on/8h off rotating shift schedule.
Methods: As part of a larger study, eight healthy subjects (ages 2133; 4 females) participated in a 9-day laboratory study with two baseline nights (BL1, BL2; 10h time-in-bed (TIB) per day, 2200h-0800h),
four 24h periods (SS1-SS4) of an 8h on/8h off rotating shift schedule, and two recovery nights (10h TIB per day, 2200h-0800h). Each
8h ‘off ’ period included 1h 20 min for simulated domestic activities
and commuting, and 6h 40 min TIB - such that each 24h period
contained a total of 10h TIB. At 2, 17, 32 and 47 min after scheduled
awakening, subjects completed an 8 min sleep inertia test bout, which
included a 3min Psychomotor Vigilance Task (PVT-B) and the Samn
-Perelli (SP) Fatigue Scale. Tests were performed at a computer adjacent to each subject’s bed, and subjects remained seated at the computer throughout the sleep inertia testing period. Repeated-measures
ANOVA was used to compare between days BL2 and SS4 the effect
of time (2, 17, 32, 47 min) after scheduled awakening (at 0800h) on
PVT-B fastest 10% reaction times (F10-RT), PVT-B lapses (defined
as reaction times > 355 ms), and SP fatigue scores.
Results: There were significant effects of time after scheduled
awakening for PVT-B F10-RT (p = 0.003), PVT-B lapses (p = 0.038),
and SP fatigue (p = 0.011). Across days, F10-RT was 182.2 ms ± 2.5
ms (mean ± SE) at 2 min after scheduled awakening and dropped to
172.7 ms ± 3.1 ms at 47 min; total lapse count was 2.7 ± 0.5 at 2 min
and dropped to 1.0 ± 0.5 at 47 min; and SP fatigue was 4.5 ± 0.5 at
2 min and dropped to 3.4 ± 0.3 at 47 min. There was a trend for an
effect of day (p = 0.058) on SP fatigue scores, with subjects reporting
higher overall fatigue during the sleep inertia testing period on SS4
compared to BL2. There were no significant effects of day for PVT-B F10-RT or lapses. There were no significant interaction effects.
Conclusion: Sleep inertia, measured as objective performance
impairment and subjective fatigue, was similar after awakening at
0800h from a 10h baseline sleep opportunity, and from a 6h 40
min sleep opportunity after four days on an 8h on/8h off rotating
shift schedule. In future analyses in a larger sample, we will extend
our analyses to sleep opportunities at different times of day, and
compare the 8h on/8h off schedule to a 6h on/6h off schedule.
Support: Bushfire Cooperative Research Centre.
PD 55
DIFFERENCES IN FATIGUE DEVELOPMENT
UNDER 12-HOUR SHIFTS: AGE, TIME-OF-DAY AND
TIME-ON-DUTY EFFECTS ON CARDIOVASCULAR
SYSTEM ACTIVITY IN CONTROL ROOM WORKERS
Bobko N, Chernyuk V, Apykhtin K
State Institution “Institute for Occupational Health of the National Academy
of Medical Sciences of Ukraine”, Ukraine.
[email protected]
Objectives: To reveal the age, time-of-day and time-on-duty effects
on cardiovascular system activity in control room shiftworkers
under fatigue development during 12 hour shifts.
Methods: Blood pressure and heart rate were tested in electricity
distribution network controllers (204 human-shifts), holter
monitoring of heart activity was performed in engineers-electronics
maintaining the air traffic control systems (52 human-shifts). Data
were analyzed at p < 0.05.
Results: Persisting decrease in the heart part of bloodcirculation
selfregulation accompanied with the compensatory increase in its
vascular part was found after 8 hours of time-on-duty - the same
time on shift when the accident risk increases due to the literature
data (T. Akerstedt, 1995, K. Hanecke et al., 1998, S. Folkard,
1996, F. Nachreiner, 2000). With ageing fatigue at the night shifts
66
brakes the sympathetic-vagal balance in nervous regulation of
bloodcirculation, while at the day shifts - changes to the little extent.
The power of both the sympathetic (LF) and parasympathetic
(HF) branches of vegetative nervous regulation of heart activity
decreased in the older age group (40 y.o. +) that corresponds to the
literature data on the ageing decrease in nervous regulation of heart
activity. In the older age group compared to the younger one there
were found the increase in LF/HF reflecting the relative increase in
sympathetic regulation of heart activity; decrease in triangle index
and increase in AMo reflected the increase in centralizing of the
heart rate regulation. Age-experience increase in the ventricular
extrasystols frequency (VEF) was found in the older engineers at
the periods of the limits of the body possibilities: the lowest ones
- in the early morning (to the most considerable extent - VEF was
4-6 times higher compared to the other hours of day or younger
workers) (at 5-7 a.m. - the worst human-operator reliability period)
and midnight (at 0-1 a.m. - the second decrease in human-operator
reliability), the highest ones - at the late morning (at 9-11 a.m. the better cognitive performance period) and early evening (at 4-7
p.m. - the second circadian increase in performance) evidencing
the additional stimulation nidi appearance within the heart muscle
owing to the body weakening to resist the strong activation. Heart
rate variability that reflects mainly parasympathetic regulation of
cardiac activity (RMSSD, pNN50) decreased with ageing that was
more pronounced at the night shifts compared to the day shifts
and also became more pronounced towards the end of the working
shifts reflecting age caused and fatigue induced weakening in
parasympathetic regulation of cardiac activity.
Conclusion: Ageing, night working and long working hours
strengthen the unfavorable changes in cardiovascular system activity
of control room shiftworkers under connection with cognitive
performance changes that manifests the increase in both the
physiological price of working and risk of pathology development.
was 3.2 years (range; 0.1-40) in the same type of occupation. The
proportion of precarious workers was 22.5%. Night work was
defined more than 8 hours work per week between 22:00 to 06:00.
Ten percent of respondents were engaged in night work. The
proportion of workers working 52-59 hours per week was 12.2%
and that of workers more than 60 hours was 11.8%. The prevalence
of definite depression was 21.2% when defined the score was 25
and over. After controlling for related factors by logistic regression,
the odds ratio (OR) of workers working 60 hours and over per
week was 1.45 (95% confidence interval (CI); 1.03-2.02) compared
to workers working less than 40 hours per week. OR of workers
working 52-59 hours per week was 1.15 (95% CI; 0.82-1.60) and
that of workers 40-51 hours per week was 0.99 (95% CI; 0.77-1.27).
The risk was the highest in the restaurant workers OR 4.17 (95%
CI; 1.03-16.81).
Conclusion: Long working hours have impact on workers health,
not only in male workers but also in female workers. Furthermore,
married female workers have to take care of their children and to
do their house chores after coming back home. Because of these
physical and mental burden, it may cause depression in female
workers. Further studies are needed to investigate other health
effects in female workers associated with long working hours.
PD 57
NIGHT SHIFT WORK AND COLORECTAL CANCER
RISK IN A POPULATION-BASED CASE-CONTROL
STUDY IN SPAIN
Papantoniou K1, Martin Sanchez V2, Pollán M3, Llorca J4,
Moreno V5, Tardón A6, Alguacil J7, Kogevinas M1,8
1
Centre for Research in Environmental Epidemiology (CREAL), Hospital de
Mar Medical Research Institute (IMIM); CIBER Epidemiologia y Salud Publica
(CIBERESP); Universitat Pompeu Fabra (UPF), Spain.
2
Universidad de Leon, Spain.
3
Centro Nacional de Epidemiología-Instituto de Salud Carlos III, Spain.
4
Universidad de Santander, Spain.
5
Instituto Catala de Oncologia (ICO), Spain.
6
Universidad de Oviedo, Spain.
7
Universidad de Huelva, Spain.
8
National School of Public Health, Greece.
[email protected]
Introduction: The health effects of long working hours and shift
work have been well known. Average annual working hours per
Korean worker was the longest until 2007 by OECD statistics.
According to recent data, Korean worker have worked 2,193 hours
in 2010. However, health effects were not investigated extensively in
female workers. In this study, we explored the association between
depression and long working hours and night work in female workers
in one community in Korea through self administered questionnaire.
Methods: Five thousands and twenty-one female workers were
participated. We divided workers by five categories; office workers
2,426 (49.4%), manual workers 478 (9.7%), sales workers 580 (11.8%),
call center workers 716 (14.6%), others (workers in restaurants,
cleaning workers, and etc) 709 (14.5%). Basic characteristics, health related behaviors, and work related characteristics were assessed
by a questionnaire. We applied CES-D (Center for Epidemiological
Studies - Depression Scale) to evaluate depression in previous week.
Results: We analyzed 4,909 (97.8%) surveyed questionnaires.
Median age of study subjects was 32 years (range; 13-71) and
workers in twenties were the largest (39.5%). Median work duration
Objectives: Recent animal data indicate that exposure to light at
night is carcinogenic. In humans shift work that involves circadian
disruption has been associated with a higher risk of different types
of cancer. Most epidemiological studies up to date have focused
on breast cancer risk and evidence on other tumors is limited. We
evaluated colorectal cancer risk in relation to permanent night and
rotating shift work in a population based case-control study in
Spain, the Multi Case-Control study (MCC-Spain).
Methods: In this analysis 1134 male and 613 female incident
colorectal cancer cases and 3484 randomly selected population
controls of both sexes, enrolled in 11 regions of Spain, were
included. Information was collected on socio-demographic factors,
environmental exposures, occupation, lifestyle factors - smoking,
alcohol consumption, physical activity, others -, medication use,
personal and family medical history and was assessed by face-to-face
interviews. Lifetime occupational history including questions on
daily time schedule of each job, day/night/rotating shifts, light at
night exposure, and duration of different jobs, was used for the
exposure assessment. We estimated the risk of permanent night
and rotating shift work separately using unconditional logistic
regression analysis adjusting for potential confounders.
Results: Among the study population 5% of males and 2% of
females had ever worked in permanent night shifts and 26% of
males and 13% of females in rotating shifts for ≥ 1 year. Having
PD 56
THE ASSOCIATION BETWEEN DEPRESSION AND
LONG WORKING HOURS IN FEMALE WORKERS IN
ONE COMMUNITY IN KOREA
Lim S1, Kang Ht2, Lee JW3, Kim HJ4
Department of Occupational and Environmental Medicine, Kyung Hee
University Hospital, Seoul, Korea.
2
Wonju College of Medicine, Yonsei University.
3
Soonchunhyang University Hospital.
4
Ewha Womans University School of Medicine.
[email protected]
1
67
ever performed rotating shift work was associated with an increased
risk for colorectal cancer among males (Odds Ratio (OR) 1.40; 95%
Confidence Interval (CI) 1.18-1.67), but not among females (OR
1.15; 95% CI 0.85-1.56) as compared to permanent day workers,
after adjusting for confounders (age, centre, educational level). ORs
tended to increase with increasing number of lifetime cumulative
years of rotating shift work in both sexes. For each year worked
in rotating shifts, colorectal cancer risk increased by 1% (OR 1.01;
95% CI 1.004-1.02). Having ever worked in permanent night shift
was not associated with colorectal cancer risk in males (OR 0.77;
95% CI 0.57-1.03) nor in females (OR 1.15; 95% CI 0.68-1.94).
Conclusion: In this large population based study we found an
increase in colorectal cancer risk associated with rotating shift work
in males. The study is ongoing and at the conference results will
be presented for more detailed exposure classifications of night
shift workand lifetime cumulative exposure. (Additional authors:
Castaño-Vinyals G, Barcelona, Spain; Ardanaz E, Navarra, Spain;
Jimenez Moleón JJ, Granada, Spain; Altzibar JM, Guipuzkoa, Spain;
Peiro R, Valencia, Spain).
PD 58
MINOR PSYCHIATRIC DISORDERS AMONG
DAY AND IRREGULAR SHIFT WORKING TRUCK
DRIVERS
Ulhôa MA, Marqueze EC, Moreno CRC
[email protected]
Introduction: Studies have found that mental health status can
increase cortisol levels. Then, higher levels of cortisol are associated
to changes in metabolic parameters, as dyslipdemias, for instance.
In this context, this study aimed to analyze minor psychiatric
disorders and metabolic parameters in truck drivers working day
shifts (n = 26) compared to those working irregular shifts (n = 31).
Methods: Participants were 57 truck drivers of a transportation
company that work in day shift (39.7 YO, SD ± 5.8) and irregular
shift (39.9 YO, SD ± 7.2). The day workers worked from 8:00h
to 18:00 h Monday to Friday, with 1 hour for lunch. The irregular
shift workers usually start driving at 22:30 and had no fixed time
to finish their duty. The participants filled in questionnaires about
sociodemographic data, health, sleep, life style and work conditions.
Minor psychiatric disorder was assessed using the Brazilian version
of the Self-Report Questionaire (SQR-20). The drivers wore
actigraphs per 7 days and had measured their anthropometric data,
blood pressure, besides biochemical blood tests. Data analyses were
performed using qui-square for categorical variables and mean
difference tests were performed for continuous variables.
Results: The prevalence of minor psychiatric disorder (MPD)
was 7.7% e 6.5%, for day and irregular shift workers, respectively.
The irregular shift workers had higher BMI, cholesterol, LDL and
VLDL cholesterol and reported higher tiredness after working,
compared to day workers (p < 0.05). Sleep duration was 399.9
min (SD ± 89.1) and 414.9 min (SD ± 77.3) for day workers and
irregular shift workers, respectively (p = 0.54). DPM was not
associated to sleep duration and metabolic parameters, however
was associated to poor sleep quality only for those who work in
day shift (p = 0.007).
Conclusion: The irregular shift workers had worst physical health
profile compared to day workers. However, there was no association
between minor psychiatric disorders and metabolic parameters or
sleep duration in the studied population. Poor sleep quality among
day workers could be related to sleep debts. Future studies are
important to search causes and consequences of shift on mental
health problems.
PD 59
MATERNITY PROBLEMS ASSOCIATED WITH
NIGHT AND SHIFTWORK AMONG SUDANESE
NURSES
Modawi S1, Sulaiman S2
Occupational Health Department, Federal Ministry of Health, Khartoum,
Sudan.
2
Nile College, Khartoum, Sudan.
[email protected]
1
Introduction: Shift work among women was a public health issue
about a century ago. In 1877, shift work became forbidden among
women in Switzerland, and by the end of 1914, it was also forbidden
in 10 different countries (Harma, 2008). This prohibition was
revoked later for mostly political reasons. The Sudanese legislation
specifically states that women night work is forbidden except for
women in essential services like hospitals. For a long time nurses
were among the only women working at night. While night work
affects the health and social life of both men and women, women
are more vulnerable to the adverse effects.
After almost 100 years shift work among women has again become
a new health issue in occupational health. Under occupational
health and safety (OHS) legislation, the employer has a duty of care
to provide a healthy and safe workplace and safe systems of work.
Methods: This cross - sectional study was done using a self
administered questionnaire filled by randomly selected nurses. An additional section concerning maternity problems was added to the Standard Shiftwork Index (SSI). Total coverage was done by including all
nurses registered for shiftwork and excluding those who are exempted
from night work e.g. head nurses. The sample size was 310 nurses. The
data were analyzed with Statistical Package Social Science (SPSS).
Results: The percentage of participants having regular menstruation
dropped to almost half after shiftwork (from 73% to 38%). The
percentage of participants that have normal amount of blood
dropped from 70% to 45%. On the other hand, the percentage of
those having heavy blood amount increased from 25% to 44%. The
percentage of participants who suffer from backache increased from
48% to 67% also, the percentage of participants who suffer from headache increased from 29% to 45%. The percentage of participants
who take one day off for menstruation decreased from 87% before
shiftwork, to 78% after shiftwork, whereas the percentage of those
who take more than one day increased from13% to 22%. A 19% of
the participants had miscarriage before shiftwork. After shiftwork,
the percentage increased to 31%, combined with this the decrease
in the incidence of early delivery which decreased from 16% before
shiftwork to 5% after shiftwork. Results of cross tabulation did not
show consistency.
Conclusion: The impact of night and shift work on women’s
health especially menstruation, is very obvious as the results of this
study showed. These disturbances can be most likely caused by the
disruption of circadian rhythms, and the resulting desynchronization
of cyclic physiological function especially hormonal activity.
PD 60
BARRIERS TO AND PREFERENCES FOR PHYSICAL
ACTIVITY IN FEMALE SHIFTWORKERS
Neil SE1, Muñoz C2, Beauchamp MR3, Campbell KC4, Gotay CC1,2
School of Population and Public Health, University of British Columbia.
UBC-CCS Cancer Prevention Centre.
3
School of Kinesiology, University of British Columbia.
4
Department of Physical Therapy, University of British Columbia.
[email protected]
1
2
68
Introduction: Shiftworkers are at a higher risk for a variety of
chronic diseases such as cardiovascular disease, diabetes, and
cancer, as well as short-term health effects such as sleep deprivation.
Although the mechanisms underlying these risks are not completely
understood, several biological changes due to exposure to light at
night have been suggested. Shift work has also been associated
with poor lifestyle habits such as decreased physical activity and
poor nutrition. In non-shiftworkers, physical activity has been
used as a preventative measure to reduce the long-term risk of a
variety of negative health outcomes, as well as to improve sleep
and quality of life. Understanding the barriers to and preferences
for physical activity programming is an important first step in the
development of physical activity interventions targeted at this
high-risk population. The purpose of this study was to identify the
main barriers to and preferences for physical activity programming
in shift workers.
Methods: Participants (n = 17) included female, age 40-65, currently
employed in an occupation with high circadian disruption (rotating
or permanent night shift) at least 3 times per month for at least two
years. Data were collected as part of a larger ongoing sleep hygiene
intervention study. All participants completed additional online
physical activity questionnaires at baseline to determine barriers
to participating in physical activity, and to identify preferences for
physical activity programming.
Results: Participants were on average 47.4 years of age (range
41-54), and included mostly rotating (n = 16), and one permanent
night shift worker. The most common barriers to participation in
physical activity were work schedule interference (76%), lack of
time (59%), lack of self-discipline (41%), and lack of interest (35%).
The most important components of the physical activity program
were flexible hours (88%), that exercise not be boring (76%),
that individuals were able to see results (71%), that individuals be
able to choose their exercise mode (59%), and that parking was
convenient (59%). Overall, individuals indicated a preference for
outdoor exercise (41%) compared to at-home (29%) or gym-based
(12%) exercise. More participants desired face-to-face advice (82%)
vs. written (6%) or online (6%) advice. A combination of aerobic
and strength training was preferred (75%), and flexible or drop-in
sessions (82%) were preferred over scheduled exercise times (6%).
Individuals reported a preference for activities with others/in a
group (65%) rather than alone (35%). All participants surveyed
indicated that they would rather exercise on their days off than
before or after day or night shifts.
PD 61
SHIFTWORK AND NURSES’ HEALTH OUTCOMES
IN CANADA
McGillis Hall L
Kathleen Russell Distinguished Professor, Bloomberg Faculty of Nursing,
University of Toronto, Canada.
[email protected]
Introduction: Little or no work had been conducted on nurses work
hours (shiftwork) in Canada and how these contribute to nurse and
patient safety. The objectives of this study were to identify nursing
work schedules/shiftwork patterns in different health care settings
in Canada; to determine if relationships exist between nursing work
schedules/shiftwork patterns on both nurses’ health and work
outcomes and examine the moderating effects of individual nursing
characteristics on both nurses’ health and work outcomes.
Methods: A mixed method research design was used in this study
involving surveys of nurses across acute and long-term care sectors
in the province of Ontario, Canada and secondary data related
to clinical health outcomes. This included 4 health care regions
participating in a clinical health outcomes data collection initiative
and 3 that were not yet part of it. The sample was comprised of
primary survey data collected from 2,825 registered nurses (45.1%
response rate).
Results: Almost half of the study participants (48.7%) reported
having no control over their shifts or schedules worked. Close to
half of the respondents identified working between four and twelve
hours of paid overtime in addition to their regular work schedule,
while 70% identified working the same amount of hours unpaid.
Participants also identified concern with health outcomes including
sleep disturbances and fatigue.
Conclusion: Shiftwork is known to have a detrimental effect on
workers - gastrointestinal problems, cardiovascular disorders, stress,
sleep disturbances, and decreased work performance. Given the
hectic health care work environments, it is important to explore
factors in the organization of nursing work that may have a negative
impact on nurse’s work.
Support: Funded by the Canadian Institutes of Health Research
(CIHR) peer reviewed operating grants program.
PD 62
SHIFT WORK AND THE NURSES IN A SURGICAL
CENTER
Baptista PCP1, Goncalves PS2
Professor of School of Nursing, University of São Paulo, Brazil.
Nurse, School of Nursing, University of São Paulo, Brazil.
[email protected]
1
2
Introduction: In the current way of life, occupational stress has
become a major source of concern and is recognized as one of the
most serious risks psychosocial well-being of the individual. The
main factors causing stress present in the workplace involve aspects
of organization, administration and system of work and the quality
of human relationships. Nurses who work in surgical center have
a work process which specific characteristics, shift work, different
interpersonal relationship; it appears especially susceptible to the
phenomenon of occupational stress. My objective was to know the
impact of stress in the lives of nurses who work in surgical center.
Methods: This is an exploratory, qualitative study, conducted in the
surgical center of a university hospital, located in the western region
of São Paulo. The study subjects were 11 nurses from all shifts that
agreed to participate after the clarification by signing the consent
form. To preserve anonymity, the speeches are presented identifying
nurses with numbering from 1 to 11 as the temporal sequence of
interviews. Prior to data collection, this study was submitted to the
Ethics Committee in Research of the School of Nursing and the
hospital. The interviews were analyzed according to the Minayo with
steps: transcription in full, pre-analysis, material exploration, processing and interpretation of results. The transcripts were subjected to
thorough reading and rereading and after setting the record units in
the text, identify and name the themes or meaning units, associated
with the object of study. Then were defined and named two categories: “The meaning nurse work stress on Surgical Center”; “The
impact of stress in the lives of nurses Surgical Center.”
Results: When mean stress in the work process in the Surgical
Center, workers recognize that the work itself is not the generator
of stress can even be a health enhancer in that it stimulates and
motivates the workers, however, the very peculiarities of Working
in shifts, with casters, contributes to wear. The discourses revealed
that the consequences are not restricted to the physical dimension,
but also psychic, highlighting the presence of tiredness, fatigue,
insomnia, musculoskeletal symptoms, headache and immunological
changes. It became clear that, despite the symptoms, workers
remain on the job, configuring, presenteeism.
Conclusion: The nurses who work in surgical center recognize
the work process as stressful and they feel effects of work on the
physical and mental body.
69
PD 63
LOWER SICKNESS RATES AFTER REDUCING
WORKING HOURS
Gaertner J1, Cygan D1, Akerstedt T2, Arlinghaus A3, Folkard S4,
Kundi M5
XIMES GmbH & Vienna University of Technology, Austria.
Stockholm, Sweden.
3
GAWO e.V., Germany.
4
Université Paris Descartes, France & Swansea University, UK.
5
University of Vienna, Austria.
[email protected]
1
2
A large European steel company reduced working hours for some of
its employees. We examined the consequences for employees’ health.
The original (O) shift-schedule built upon a MMMEEENNN--- rhythm (3 Morning, 3 Evening, 3 Night, 3 days off). Each shift had a
length of 8 hours (with 30’ of paid break). Additional days off were
given in order to reach the working hours agreed (38.5h). Employees
worked - incl. vacations etc. - approx. 250 days a year.
The new schedule (C) built upon a MMEENN---- rhythm (2224)
with additional shifts to reach the new working hours agreed
(approx. 34.4h), leading to approx. 224 days a year. The timing and
duration of the shifts remained unchanged.
The reduction of working hours was accompanied by a temporary
additional allowance that kept income constant in nominal terms until pay raises would again result in an increase in income after some
years. This was made possible by public grants and by the company
helping to ease the change. As the overall number of employees increased only slightly as a result of the change to a 5 group-schedule
in the long run such a system may prove cheaper for the company.
We compared sickness rates (days scheduled for work but being spent
absent because illness) in order to control for different numbers of
working days a year between workers in the old and new shift systems.
We controlled for age (C employees on average slightly older), change
of working conditions (no major change, no strong differences).
We included employees who worked continuously between 2006
and 2012/04 (04 being the last month we got data). We distinguished
between employees that would continue to work in the original shift
schedule (O_4) and employees who were going to change to the
new shift schedule, but were still working the old shift schedule
(C_4). Between 2006/04-2009/12, sickness rates of O_4 were
slightly lower than for C_4.
Those units that changed into the new shift system did so at
different times and only when the vast majority of employees of
the unit opted for change. Sickness rates of persons that changed
into the new schedule (C_5) were roughly equal in 2007/2008 and
slightly higher in 2009 than for O_4, C_4. It is unclear whether
this was caused by the economic crisis or the transition. Later
on, while sickness rates increased substantially both for O_4 and
C_5, the increase for O_4 was significantly higher than that for
C_5 (sickness rate 6.7(StDev 1.5) versus 5.5 (1.2); significance, p =
0.003 for the last 24 months). Thus, the new shift system (C_5) was
associated with a relative improvement in sickness rates.
Further research is needed to better understand the mechanisms of
this positive change.
PD 64
SHIFTWORK AND EARLY ALTERATIONS OF
CARDIAC FUNCTION IN HEALTH CARE WORKERS
Meloni M, Lecca L, Del Rio A, Setzu D, Campagna M, Cocco P
CENTRALABS, University of Cagliari, Italy.
[email protected]
Introduction: The evaluation of early negative effect of
desynchronization due to shift work in health care workers, having
also an important component of work-related stress, has become
an important topic of discussion in the performance of duties of
the occupational physician.
Methods: The aim of our study was to evaluate the change of Heart
Rate Variability (HRV) in shift workers through a short-term Holter
ECG performed during the different shifts (morning, afternoon,
night), in order to deduce the adaptability of the cardiovascular
system to different shifts. The sample is composed of 39 healthcare
workers of the University Hospital of Cagliari, 24-58 years old (13
male, 26 female), of which 11 are doctors and 28 nurses working on
3 shifts (07-14, 14-22 and 22-07). Each subject in question has been
examined by Holter ECG recording (60 minutes) both during the
work shift and in performing normal activities of the department.
ECG data were compared on the type of shift, the recording time
(day and night), cigarette smoking, Body Mass Index (BMI) and
age. We evaluated the following HRV parameters: average heart
rate, maximum heart rate, minimum heart rate, standard deviation
of normal-to-normal RR intervals (DSNN), triangular index and
standard deviation of the averaged normal-to-normal RR intervals
(DSaNN). For each parametric variable considered for the purposes
of this study, we calculated the measures of central tendency (mean
and median) and dispersion (standard deviation). Comparisons
between the medians of the HRV parameters associated with
the type of shiftwork and smoking habits were performed using
Mann-Whitney test (for nonparametric data).
Results: A SDNN comparison between shift workers and day care
workers showed that SDNN values are significantly lower in shift
workers (81.2) compared with the day workers (100.8). There were
no statistically significant differences as regards the registration
period between different shifts within the group of shift workers
(p-value = 0.94). We compared medians of SDNN in smokers and
non-smokers. The differences were highly significant: lower in
smokers (74.1) compared with non smokers (91.7) with p < 0.005.
The Kruskal Wallis test showed values of SDNN significantly
lower among smokers (74.1) and former smokers (73.5) compared
with non-smokers (95.5), with a value of p < 0.05.
Conclusion: We found values of SDNN significantly lower in
shift workers (day and night) compared with workers engaged
solely on day shifts. The adaptability of the cardiovascular system is
disrupted by desynchronization of the biological rhythm secondary
to the organization of shiftwork and night work. Shift work is an
important factor of social and biological stress influencing the
adaptability of the cardiovascular system to stimuli and demands
of work organization.
PD 65
FACTORS ASSOCIATED WITH WORK ABILITY
AND SLEEPINESS AMONG WORKERS FROM THE
CENTRAL SUPPLY OF CAMPINAS
Masson V, Monteiro I, Vedovato T
Faculty of Nursing, University of Campinas, São Paulo, Brazil.
[email protected]
The early start of the working day in the fruit and vegetables selling
area at five o’clock in the morning can provide a sleep deficit to
workers from the Central Supply of Campinas. In general, sleep
problems can cause negative impacts on the work ability of workers
who need to wake up very early in the morning to work.
The aim of this study was to evaluate the work ability and sleepiness
among young people and women who worked in Campinas Ceasa.
This study is a quasi-experimental time-series design and was
conducted by collecting data pre-and post-intervention in the
workplace, in micro and small businesses of Campinas Ceasa. The
70
sample was intentional and composed by 90 subjects in the pre
-intervention and 70 subjects in the post-intervention, carried out
six months after the intervention.
The intervention was based on health promotion strategies
and distribution educational brochures to individuals based on
educational activities to raise awareness and change habits for
healthier lifestyles. Strategies for health promotion were based on
guidelines on hygiene sleep and relaxation techniques.
Statistical analyses were performed and Chi-square, Wilcoxon and
linear regression in the post-intervention to test the WAI with some
variables. Most participants were female, married, with children and
with over 11 years of study.
With respect to lifestyle, 13% of workers were smokers, 38%
reported use of alcohol and 54% physical inactivity and was
overweighed in the pre-intervention. Linear regression results in
the post-intervention showed significant increase in WAI score
among young and women workers which presented higher degree
of education, without reporting pain in the last six months and last
week and without reporting use of medicine.
The average sleeping time reported by workers remained between
the pre-and post-intervention was less than six hours per night.
Most subjects reported evaluating the education al brochures on
sleep positively. The comparative analysis of the average points
of the Epworth sleepiness scale presented statistically significant
difference in pre-and post-intervention with decrease in mean
drowsiness only among younger workers from 9.9 to 8.1 points
(p-value 0.04). For women, although there was a slight decrease
from 7.5 to 6.9 points, it was not statistically significant. The present
study was of great importance to the workers health as the first
interventional study conducted in Campinas Ceasa and their results
showed the need for continued interventions, to maintain the work
ability of young people and women in the course of years reducing
the problems caused by sleep deprivation.
Totally disagree to Totally agree. Mental distress was measured using
The Hospital Anxiety and Depression Scale (HADS) (Zigmond &
Snaith, 1983). The 14 items were measured on a four-point scale.
Results: Four different shift schedule groups were identified and
analyzed: Day time only (n = 99), both day and evening (n = 304),
nights only (n = 82) and revolving shift (day, evening and night,
n = 701). The results showed no statistical significant difference in
terms of mental distress between the four shift schedule groups,
neither at baseline nor at follow-up. Skill discretion at baseline
predicted less mental distress at follow-up among daytime working
nurses. Role conflict at baseline predicted more mental distress at
follow-up among revolving shift working nurses, whereas social
support was associated with less mental distress for this group. We
also tested for reversed causality. Mental distress at baseline generally
predicted less role clarity, less fair leadership and less social support
at follow up. Mental distress at baseline also predicted more role
conflict at follow-up.
Conclusion: Working shift does not seem to be related to more
mental health problems than working day time. However, in further
analysis we will test night work as a potential moderator between
work factors and mental health. We will also conduct structural equation modelling to determine which model is the most potent indicator of casual associations - between work factors and mental distress.
PD 67
ASSESSMENT OF BREAST CANCER RISK BY USE
OF THE DANISH WORKING HOUR DATABASE AND
OCCUPATIONAL EXPOSURE TO LIGHT AT NIGHT
Vistisen HT1, Garde AH2, Hansen J3, Hansen AM2,
Christiansen P4, Kolstad HA5
Danish Ramazzini Center.
National Research Center for the Working Enviroment; Denmark.
3
Institute of Cancer Epidemiology.
4
Department of Public Health.
5
Danish Ramazzini Center; Aarhus University Hospital.
[email protected]
1
2
PD 66
SHIFT WORK AND MENTAL HEALTH: THE
INTERACTION BETWEEN SHIFT SCHEDULE AND
WORK FACTORS ON MENTAL HEALTH IN NURSES
Berthelsen M1, Knardahl S1, Pallesen S2, Moen B2, Bjorvatn B2,
Magerøy N2
National Institute of Occupational Health, Oslo, Norway.
University of Bergen, Bergen, Norway.
[email protected]
1
2
Introduction: Shift work may have a number of effects on workers
health. These effects may depend on shift schedules, shift duration
and on interaction with psychological and social factors at work as
well as exposure to chemical and physical factors. In spite of many
years of research on effects of shift work, knowledge of effects on
health is still inadequate. Few previous studies have controlled for
basic work-related factors, when investigating the effects of shift
work on health.
Methods: A survey sample (N ¼ 6000) comprised of five strata,
each containing 1200 nurses maintaining at least a 50% work
position, was randomly selected from the member register of the
Norwegian Nurses Organization. Data were collected both by
paper and pencil and questionnaire. A total of 2059 completed and
returned the questionnaire at wave 1, thereby yielding a response
rate of 38.1%. The response rate for wave 2 was about 80%.
Psychological and social work exposures were measured using the
following scales from the QPSNordic: Role clarity, Role conflict
and Fair leadership. The items were measured on a five-point rating
scale. Job demands, job control and social support were measured
using Karasek & Theorells (1990) job-demand and support model.
The items were measured on a five-point Likert scale, ranging from
Introduction: In 2007, the International Agency for Research on
Cancer classified nightshift work that involves circadian disruption
as probably carcinogenic to humans, based partly on an increased
risk of breast cancer among long-term nightshifts workers. Since
then, several epidemiologic studies have examined this relation.
Despite these efforts, confounding and bias regarding the exposure
assessment can not be eliminated and is a methodologic Achilles
heel in the studies leading to persisting uncertainty regarding
causality. The aim of the present study is to investigate the
association between night-work and risk of breast cancer by use of
the newly established Danish Working Hour Database (DWHD)
and a job exposure matrix (JEM) with information about light at
night (LAN) exposure in different occupations.
Methods: Employees in the Central Denmark Region having
night-work (permanently or rotating) were recruited from May
2012 to May 2013. Over a 7-day study period including at least
one nightshift, each participant wore a light data logger (Actiwatch
Spectrum). These data will be used to form a JEM with information
about light exposure (intensity, spectrum, and duration) and will be
combined with DWHD to provide individual information about
exposure. DWHD is a large, national cohort of public health care
professionals with a high prevalence of night shift work. The
majority of Danish health care professionals are employed by the
Danish Regions. For every employee, the Danish Regions keep
information regarding the personal identification number, sex, date
of birth, position, absence and reasons therefore, e.g. vacation,
sickness and maternity leave, and seniority, in addition to date, hour,
and minute for the beginning and end of every work duty. DWHD
was established in 2012 and encompasses data as of 2007. The data
71
are updated on an annual basis. Data from DWHD will be linked
with national cancer registers.
Results: Approximately 200 persons were included in the 7-day
light-measurement study period. The distributions of occupations
among the 200 participants and the light-measurements have not
yet been analyzed. DWHD encompasses for 2007 102.487 female
employees of which 36.419 work nightshifts. During the 6 year
follow-up period 2007-2012, we expect a total of 300 breast cancer
cases among these female employees. The age group from 50 to 59
is expected to account for nearly 50 percent of those cases. This
age group encompasses 7.274 nightshift workers with a mean of
2.5 nightshifts per month.
Conclusion: The Danish Working Hour Database provides
high-quality data on working hours that in combination with the JEM
with information about light exposure (intensity, spectrum, duration)
and national health register information will form a unique resource
for assessing potential health effects of nightshift work.
PD 68
ADIPOKINE LEVELS OF RESIDENTS PHYSICIANS
OF BOTH GENDER
Mota MC1, Rossato LT1, Silva CM1, Tufik S2, Melo MT3, Crispim CA1
Federal University of Uberlandia, Brazil.
Department of Psychobiology, Sleep Institute, Federal University of São
Paulo, Brazil.
3
Department of Psychobiology, Federal University of São Paulo, Brazil.
[email protected]
1
2
Introduction: Studies have showed that medical residency
provides an ideal model for studying how work schedules can
affect a healthy lifestyle. In addition, other classes of shiftwork are
often associated with metabolic diseases, and in the past few years,
several adipokines have been postulated to contribute to these
diseases. However, few studies have investigated the metabolic
profile of residents physicians. The objective of the study was to
evaluate the concentrations of leptin, adiponectin, tumor necrosis
factor-α (TNF-α) and interleukin-6 (IL-6) in residents physicians
of both gender working in shift schedules, and compares these
concentrations according to the different levels of sleepiness.
Methods: The study included 72 resident physicians (52
women and 20 men) who underwent the following assessments:
fasting adipokine levels [leptin, adiponectin, TNF-α and IL-6],
anthropometric variables (height, weight, body mass index and
waist circumference), sleep quality (Pittsburgh Sleep Quality Index
- PSQI) and sleepiness (Epworth Sleepiness Scale - ESS).
Results: It was observed a high frequency of residents who were
overweight or obese (65% for men and 21% for women, p = 0.004).
Men displayed significantly greater body mass index (BMI) values
(p = .002) and self-reported weight gain after the beginning
of residency (p = 0.008) than women. The PSQI global scores
indicated significant differences between genders (5.9 vs. 7.5 for
women and men, respectively, p = 0.01). Women had a higher levels
of adiponectin than men (p = .04). The levels of leptin, TNF-α
and IL-6 did not differ significantly between genders. Women with
excessive sleepiness showed lower leptin levels when compared
with non-sleepy women (p = 0:04). Leptin levels did not differ
between men with different levels of sleepiness.
Conclusion: These results indicate that resident physicians are
susceptible to alterations in the secretion of adipokines, and the
level of sleepiness of these individuals seem to influence the
concentration of adipokines. It was also identified high rates of
overweight in residents, especially among men. It is necessary to
review the work schedule of doctors-in-training to improve their
working conditions and to prevent future health problems.
Support (if any): This study was supported: by FAPEMIG
(Grant no. CDS-APQ-04643-10), AFIP, Sleep Institute, CEDIP/
FAPESP (no. 998/14303-3), CEPE, UNIFESP, FADA, CAPES
and CEMSA.
PD 69
NUTRITIONAL STATUS AND EATING HABITS OF
DAY AND NIGHT BUS DRIVERS
Mota MC, Balieiro LCC, Rossato LT, Paim SL, Crispim CA
Faculty of Medicine of the Federal University of Uberlandia, Minas Gerais,
Brazil.
[email protected]
Introduction: Recent studies have demonstrated that shift work
is associated with poor diet and sedentary behavior. In addition,
overweight, obesity, dyslipidemia, type 2 diabetes and metabolic
syndrome are more prevalent in shift workers than day workers.
The aim of this study was to evaluate the nutritional and metabolic
profile of day and night bus drivers.
Methods: One hundred volunteers (80 night and 20 day workers)
participated of the study. Dietary intake was assessed using a validated
semiquantitative food frequency questionnaire. Measurements of
height, weight and waist circumference were obtained. Data such as
blood glucose and lipid profile were analyzed through information
obtained by periodical check-up of the company.
Results: A significant difference was observed for waist
circumference mean values between groups (96.5 cm ± 11.8
day versus 103.3 cm ± 9.7 night workers; p = 0.009). Night shift
workers showed higher frequencies values for body index mass
(BMI) and waist circumference (WC) than day workers (65% day
versus 90% night and 60% day versus 86.2% night, respectively).
No significant differences were found between shifts for food
intake. However, both groups had inadequate intake values when
compared with recommended values. The night group had a higher
frequency of inadequate intake of beans in relation to the day
workers (70% versus 45%, p = 0.04). Metabolic markers analyzed
were not significant between shifts for any variables. However, it
was observed a high prevalence of dyslipidemia in both groups.
Conclusion: Nutritional profile of shift workers seems to be affected
by work schedule, with a higher prevalence of overweight and abdominal obesity in the night drivers. Dietary intake of both groups
analyzed showed to be inadequate in several respects. This demonstrates the need of lifestyle intervention programs in these workers.
Support (if any): This work was supported by Fundação de
Amparo à Pesquisa do Estado de Minas Gerais (PIBIC Grant/
FAPEMIG, nº: 2012-SAU002).
PD 70
SLEEP HOURS, WORK ABILITY AND LIFE STYLE
AMONG POULTRY INDUSTRY WORKERS
Monteiro I, Goes EP
Work and Health Research Group, Faculty of Nursing, University of
Campinas. Brazil.
[email protected]
Poultry industry is an important branch in agribusiness currently
for Brazilian exportation. A cross-sectional study was carried
out in Brazil South region in poultry industry with the objective
of to identify the workers profile and self-referred sleep hours,
self-referred health and the work ability.
72
The sample was composed by 1567 workers and the response rate
was 77%. The mean age was 29 years (SD 7.7) and 54.1% was male,
54.8% was married, with kids (55.5%) and the Body Mass Index
average was 23.9 kg/m2 (SD 3.4).
The sleep duration average during week days was 6.2 hours (SD
1.4) and 8.2 hours (SD 1.7) during weekend. 21.1% performed shift
work and the work schedule begin between 3-6:59am for 60.6%
of the workers and between 2-4:00pm for 28.2%. The majority
received low wage (less than US$ 260).
Turnover occurred in this company because the mean of work in
this place was only 1.7 years (SD 2.2). The work journey was 44
hours per week and they h ad overtime on Saturday. In relation to life
style 15.8% use tobacco, 28.7% referred alcohol intake, 69.4% had
physical activities out of work and 60.6% referred house activities.
Duration of physical activity out of the work and work ability score was analyzed with ANOVA and the p-value = 0.0013. Tiredness
at work had significance to decrease the work ability score
(p-value < 0.0001). According to these results the company needs to review work organization and to implement workplace health promotion.
PD 71
ASSOCIATION BETWEEN LONG WORKING HOURS
AND SUBJECTIVE HEALTH STATUS, QUALITY OF
LIFE AND MENTAL HEALTH
Kim T1, Mo-Yeol K1, Min-sang Y1, Soo-Hun C1,2, Yun-Chul
H1,2
Department of Preventive Medicine, Seoul National University College of
Medicine.
2
Institute of Environmental Medicine, Seoul National University Medical
Research Center.
[email protected]
1
Objectives: This study was conducted to investigate the relationship
of long working hours and self-reported health status, quality of
life and mental health through data from a national representative
survey in the general population.
Methods: We evaluated data from the Korean National Health and
Nutrition Examination Survey for 2007-2009. This cross-sectional
study included basic health information such as occupation,
working hours, incomes, and health behaviors. It also contained
questionnaire about subjective health perception, quality of life
estimated by EuroQol (EQ5D), depressive mood, and suicidal
idea and attempt. We studied 8,972 full-time workers, divided into
6 groups from < 30 to ≥ 80 hours/week by 10 hours. The relationships between working hours and subjective health perception,
quality of life and mental health were analyzed using Chi-square
test, ANOVA and multivariate logistic regression. Multivariate
logistic regression was used to adjust for sex, age, education,
income, and occupation.
Results: The subjects worked 50.05 (± 16.81 SD) hours in
average and the number of overtime workers was 3,405 (37.99%).
Subjective health perceptions including subjective health status,
discomfort days, activities limitation frequency and sleeping hours
were significantly worsening as working hours increasing more than
40 hours. Quality of life and mental health including perception of
strong mental stress, depressive mood, and suicidal idea and attempt
were also significantly worsening as working hours increasing more
than 40 hours.
Conclusion: Long working hours is significantly associated with
deterioration of subjective health perception, quality of life and
mental health.
PD 72
THE RELATIONSHIP BETWEEN NIGHT WORK
AND TYPE 2 DIABETES: THE ELSA-BRASIL COHORT STUDY
Silva-Costa A1, Rotenberg L2, Chor D1, Griep RH2
National School of Public Health - ENSP/FIOCRUZ, Brazil.
Foundation, Brazil.
[email protected]
1
2
Introduction: Night work is associated to higher risk of
cardiometabolic diseases due to circadian misalignment. However,
there is controversy about the relationship between work schedule
and diabetes. This study aimed to investigate the association
between night work and the prevalence of type 2 diabetes in a
cohort of Brazilian civil servants.
Methods: The study population is comprised of 15,105 employees
(active and retired) of ELSA-Brazil (Brazilian Longitudinal Study
of Adult Health), a multicenter cohort of six public institutions of
education and research, aged between 35 and 74 years. This population
was included in the baseline examination (2008-2010) which was based on detailed interviews, clinical and anthropometric examinations
as well as an oral glucose tolerance test. The participants were classified into (i) those working during the day (reference group), (ii) those
working night shifts, and (iii) former night shift workers. Classification
of type 2 diabetes was based on reporting a clinical diagnosis prior to
the study or fasting glucose ≥ 126 mg/dl or glucose after 2 hours >
200 mg/dl (test solution glycosylated) or glycated hemoglobin (A1C)
≥ 6.5%. Multiple logistic regression analysis was carried out. Analyses
were adjusted by age, sex, education and income. Associations were
estimated through odds ratio and respective 95% CI. The software R,
version 2.15 (R Development Core Team, Vienna, Austria) was used.
Results: The study group consisted of 8105 women (55%), 11,985
participants (80.8%) were classified as day workers, 854 (5.8%) worked
night shifts, and 1984 (13.4%) were former night workers; 18% were
classified as diabetic. Mean age was 43.2 (SD = 10.7 years); mean professional work hours was 52.2 (SD = 9.1) hours/week. An association between night work and the prevalence of diabetes was identified
(OR = 1.23, 95% CI = 1.02-1.49). Moreover, among those who had
worked night shifts in the past (former night workers) the association
observed was not significant (OR = 1.09, 95% CI = 0.97-1.24).
Conclusion: Results indicate that night shift work is associated with
the prevalence of type 2 diabetes. Considering the inconsistency of
findings in the literature on the association between night work and
diabetes, a second wave of ELSA Brazil will allow the investigation
of this association on a longitudinal basis.
PD 73
ASSOCIATION OF REPORTED MUSCULOSKELETAL
LOW BACK PAIN WITH PSYCHOPHYSIOLOGICAL
FACTORS IN TRUCK DRIVERS
Lemos LC, Marqueze EC, Moreno CRC
[email protected]
Introduction: Low back pain is common in many work activities,
and particularly affects professional drivers due to work-related
factors predisposing them to musculoskeletal pain.
Objectives: To evaluate the association between musculoskeletal low
back pain complaints and psychophysiological factors in truck drivers.
73
Methods: The study population comprised male truck drivers
(n = 460) with a, mean age of 39.8 years (SD ± 9.8 ys) from a cargo
transportation company. The truck drivers filled out a questionnaire
on sociodemographic, lifestyle and work-related psychosocial
factors, and sleep characteristics.
Musculoskeletal low back pain was reported using the short version
of the Nordic Musculoskeletal Questionnaire. Logistic regression
analysis was performed, adopting a significance level of 0.05 on the
multiple model.
Results: The prevalence of musculoskeletal low back complaints
reported over the last 12 months was 28%. Predictive factors for
low back pain were poor sleep quality (OR = 2.48; p < 0.01), habit
of skipping naps (OR = 2.83; p < 0.01), fear of being robbed,
death, falling ill or having an accident at work (OR = 1.19; p = 0.05).
Conclusion: These findings indicated an association of psychophysiological and sleep- related factors with the occurrence of
musculoskeletal low back pain among truck drivers.
PD 74
INTERRELATIONS BETWEEN SHIFT WORK, SOCIO-DEMOGRAPHIC AND HEALTH CONDITIONS
IN NURSING WORKERS
Siqueira K1, Silva-Costa A1,2, Fonseca M1, Griep R2, Rotenberg L2
National School of Public Health, ENSP/FIOCRUZ, Brazil.
Foundation, Brazil.
[email protected]
1
2
Introduction: Shift work, especially night work, is associated
with inadequate health behavior and increase in weight. Statistical
techniques for the simultaneous exploration of the relationship of
night work and a large set of variables can subsidize prevention
strategies based on characteristics of the evaluated groups. The aim
of this study is to explore joint relationships between shift work,
work-related variables, socio-demographic status, body mass index
and health behavior among nursing workers.
Methods: Cross-sectional study with 1,182 participants from
nursing staff of a public hospital in Rio de Janeiro, Brazil. Data
were collected by structured questionnaire.
The correspondence analysis, a statistical method for descriptive
exploratory analysis of large matrices, was conjugated to cluster
analysis. The most important relations among a large pool of
variables were plotted graphically as a dendrogram.
Results: The results showed four different groups. The first one
includes those workers who have never worked at night, women, skin
color brown, secondary education, lower per capita income, previous
poor economic status, maternal education up to primary education,
nursing assistants, domestic work hours higher than eleven hours/
week, eutrophics, non-smokers and ex-smokers, no physical activity, self-perception of good health status and without self-reported
hypertension. The second group, which included former and present
night workers with up to five nights per fortnight, had the following
characteristics: men, older (45-70 years old), divorced, separated or
widowed, working up to 40 hours/week, permanent employment
status, overweight, smoker and regularly exercising. The third group
includes night workers with more than five nights per fortnight, skin
color white, younger (16-44 years old), unmarried, childless, higher
education level, higher per capita income, previous rich/average economic status, maternal education of high school or college, nurses,
working time more than 40 hours/week, non permanent jobs and
domestic work hours up to 11 hours/week.
The fourth group consisted of those with skin color black, primary
education, very poor previous economic status, mother without
any school education, obese, self-perceived poor health status and
self-reported diagnosis of hypertension.
Conclusion: More favorable behaviors and health status were
associated to workers with no experience on night work. Although
previous and present better socio-demographic conditions going
along with a high load of night work more than five times per
fortnight, younger age and non permanent work suggest that night
work is a consistent factor in the early career when chronic health
problems have not yet been manifested. The group of former
night workers or with a smaller load of night work includes more
unfavorable health conditions. Finally, the group with the most
unfavorable previous and present socio-economic status and
with hypertension, is not inter-related with any category of work
schedule, suggesting that social determinants of health appear to
have a greater impact on health in this group of workers.
PD 75
SELECTION INTO SHIFT AND NIGHT WORK
Axelsson J1, Kecklund G2, Gustavsson P1, Rudman A1
Dept of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
Stress Research Institute, Stockholm University, Sweden.
[email protected]
1
2
Objectives: Selection factors may be an important mediator of the
relationship between shift and night work and impaired health. The
aim was to investigate if factors already during higher education (e.g.
demographical and health behavioral factors) are more prevalent
amongst individuals working shift-work or permanent night work
one year after graduation.
Methods: Three national cohorts of nursing students (n = 1155,
1702, and 1459) filled out a questionnaire before graduating and
after one year in work life. The sampling frame constituted the total
population of last semester nursing students from all 26 universities
in Sweden (2002, 2004 and 2006, respectively). At baseline, the
response rate varied between 68 and 73%. At follow up, one year
post-graduation the response rate was 92% for the 2002 and 2004
cohorts, and 78% for the 2006 cohort. Data from the baseline
questionnaires was used to predict future work schedules of 3-shift
(including night, 26%), and permanent night (5%). Other work
schedules were: day shift (Mon-Fri, 8%), 2-shift (morning/evening,
54%), other schedules (6%). All p’s are < .05.
Results: The typical 3-shift worker was a single, healthy male nurse.
More specifically, socio-demographic predictors for working 3-shift
one year post graduation were being male, living alone, having no
children, regular alcohol consumption, being a non-smoker, having
ideal BMI, and high self-rated health. With respect to choosing
permanent night work one year post graduation, the characteristic
nurse had more often children, smoked, had high BMI and lower
self-rated health as measured at the time of graduation.
Conclusion: We found that selection into shift- and night work was
mainly related to demographical variables and to some degree to life
-style and health factors. While selection into 3-shift work was related
to a wide range of ‘positive’ health factors, the opposite was true for
those starting to work permanent night work, largely supporting and
extending on recent work. Thus, selection into 3 shift-work seem to
largely relate to factors that also promote health while the opposite
seem true for selection into permanent night work.
PD 76
BREAST CANCER AND NIGHT SHIFT WORK: RESULTS OF A META-ANALYSIS
Costa G1, Ijaz S2, Verbeek J2, Seidler A3, Lindbohm M-L4,
Ojajärvi A4, Orsini N5, Neuvonen K2
1
University of Milano, Italy.
74
FIOH, Kuopio, Finland.
Technical University of Dresden, Germany.
4
FIOH, Helsinki, Finland.
5
Karolinska Institute, Stockholm, Sweden.
[email protected]
2
3
Introduction: It has been recently postulated that night work can
result in a higher risk of breast cancer. Several new studies have
become available since the IARC review in 2007. Being uncertainty
in evidence from previous research, a systematic review has been
carried out to assess the strength of association between exposure
to night shift work and breast cancer incidence.
Methods: Multiple databases and non-electronic sources were
systematically searched to identify case control and cohort studies
involving females in night shift work. The comparison was
non-shift or day work and the outcome was incident breast cancer.
We assessed studies for risk of bias using a content specific piloted
checklist on 10 domains of interest. We performed random effects
meta-analysis and meta-regressions of study-specific incremental
relative risks to determine the risk of cancer associated with a 5 year
and 300 night shift increases in exposure. Sensitivity analyses were
performed to test model assumptions.
Results: We included 16 studies (12 case control and four cohorts).
Ten studies were conducted in Western Europe, four in USA and
two in China. Almost half of the studies were on nurses. None
of the 16 studies was at low risk of bias and six studies were at
moderate risk of bias. Studies with appropriate exposure assessment
were lacking, with only one measuring exposure in an objective
way prospectively. Twelve studies (nine case controls and three
cohorts) provided data for the random effects meta-regression
of dose response using generalized least square estimates. There
was a 9% risk increase per five years of night shift work exposure
in case-control studies (RR 1.09; 95% Confidence Interval (CI)
1.02 to 1.20; I2 = 37%, 9 studies), but not in cohort studies (RR
1.01; 95% CI 0.97 to 1.05; I2 = 53%, 3 studies). Heterogeneity
was significant overall (I2 = 55%, 12 studies). Results for 300 night
shifts were similar (RR 1.04 (95% CI 1.00 to 1.10; I2 = 58%, 8
studies). Sensitivity analysis using various exposure transformations
such as cubic splines, a fixed effect model, or including only better
quality studies did not change the results.
Conclusion: Based on the low quality of exposure data and the
difference in effect by study design, our findings indicate insufficient
evidence for a link between nightshift work and breast cancer. Objective prospective exposure measurement is needed in future studies.
Support: The study has been funded by The Danish Work and
Environment Fund.
PD 77
WORK-RELATED STRESSORS AND WORK ABILITY:
A 4-YEAR FOLLOW UP OF HOSPITAL WORKERS
Fischer FM1, Martinez MC2
Hospital Samaritano, Brazil.
[email protected]
1
2
Introduction: Mental and physical demands that characterize
hospital jobs are associated with negative outcomes, eventually
earlier reduction in work ability. We aim to evaluate the exposure to
work-related stressors associated with work ability.
Methods: The study was conducted in a philanthropic hospital in
São Paulo, Brazil. It is a 300-bed medium-size hospital, where highly
complex procedures are performed. We conducted a 4-year cohort
study (2009-2012). A comprehensive questionnaire was yearly answered to obtain data on sociodemographics, lifestyles, working conditions, health symptoms. The questionnaire also included the Brazilian
versions of the following scales: the Job Stress Scale (JSS), Effort
-Reward Imbalance (ERI), Work-Related Activities That May Contribute To Job-Related Pain and/or Injury (WRAPI) and Work Ability
Index (WAI). The study population was initially 1,226 employees
(87.9% of the total hospital workers). Those who reported reduced
work ability according to Tuomi et al. (1996) and Kujala (1990) criteria, and those who did not yearly participated were excluded from the
present analyses. The final number of participants during the 4-year
cohort totalized 268 workers. Spearman correlations were performed
to compare yearly (short-term exposure) to ERI, JSS and WRAPI
and the yearly WAI outcomes.
Results: Females were 73.3%, 30.6% had 40 years old and more.
Occupational features: 53.4% were nursing personnel, 28.4%
were fixed night workers, 21.6% were 11 years and longer on
the job; 14.6% and 12.7% reported a second job respectively at
the beginning and at the end of the 4 year study time. The work
ability index showed a small but progressive reduction over the
years (44.0 in 2009; 44.0 in 2010; 43.5 in 2011 and 42.3 in 2012).
All investigated work stressors increased during this 4-year time.
Significant correlations with all work stressors but work control and
reduction of the work ability were observed.
Conclusion: This study confirms the theoretical framework that
psychosocial factors at work and other environmental stressors
are consistently associated with work ability. Given that many
hospital workers are shift workers, managers and workers should
be attentive to the combined effects of the work organization and
working conditions and health consequences upon those workers.
Acknowledgments: The hospital team who supported the study,
and the participants.
PD 78
SLEEP DEPRIVATION-ASSOCIATED HYPERALGESIA IS NOT RELATED TO MEASURES OF SLEEPINESS
Matre D1, Viken LA1,2, Hjelle IB1,2, Andersen MR1,2, Stuenaes
J1, Nilsen KB1,3,4
National Institute of Occupational Health, Dept. of Work psychology and
physiology, Norway.
2
Norwegian University of Life Sciences, Ås, Norway.
3
Norwegian University of Science and Technology, Department of Neuroscience, Norway.
4
Oslo University Hospital - Ullevål, Department of Neurology, Section for
Clinical Neurophysiology, Norway.
[email protected]
1
Introduction: Sleep deprivation is reported to increase pain
sensitivity. However, the mechanisms are not clear. We hypothesized
that the increased pain sensitivity after sleep restriction would be
related to changes in objectives measures of sleepiness.
Methods: Twenty-two healthy subjects (14 females) received
experimental pain stimuli in the laboratory twice; after 2 nights with
normal sleep and after 2 nights of 50 % sleep deprivation. The order
of the sleep conditions was randomized. The experimental pain
stimuli were electrical pain and heat pain delivered to the forearm
and the pressure pain threshold (PPT) assessed from the trapezius
muscle. Subjective sleepiness was measured with the Karolinska
sleepiness scale (KSS). The response speed, defined as 1/reaction
time, was found using a standardized psychomotor vigilance test.
The effect of sleep deprivation on subjective pain was analyzed
using a linear mixed model (LMM) with sleep (50% vs. normal) as
the independent factor and with sleepiness and response speed as
covariates. Subjective pain was rated on 0-10 visual analog scales or
numerical rating scales.
Results: The PPT was lower (p = 0.007), electrical pain was rated
higher (p = 0.019) and heat pain was rated higher (p < 0.001),
75
after sleep deprivation vs. after normal sleep. KSS score was
higher (p < 0.001) and response speed was lower (p = 0.007) after
sleep deprivation vs. after normal sleep. No interactions were
found between the response speed (p > 0.19) and any of the pain
measures. There was a tendency towards an interaction between
KSS score and heat pain scores (p = 0.08).
Conclusion: Sleep deprivation leads to lower PPT and higher
ratings of electrical pain and heat pain, interpreted as sleep
deprivation-associated hyperalgesia. Sleep-deprivation associated
hyperalgesia is however not related to changes in neither objective
nor subjective measures of sleepiness. One interpretation may
be that sleep deprivation-associated hyperalgesia is not caused by
increased sleepiness.
PD 79
BACK MUSCULOSKELETAL SYMPTOMS AND
THEIR ASSOCIATION WITH FATIGUE SCORE
Araujo LG, Moreno CRC
[email protected]
Introduction: Exposure to unusual work schedules, as occurs in
shift work, has been associated with deleterious effects on health
such as sleep loss, fatigue, disrupted circadian rhythms, decreased
productivity, and increased risk of developing several chronic
diseases. The aim of this study was to estimate the prevalence and
factors associated with reported musculoskeletal symptoms among
workers.
Methods: A cross-sectional study was conducted involving a total
of 123 assembly line workers and forklift operators, comprising
56 day workers (mean age 31.8 ± 7.8 years) and 67 night workers
(mean age 34.3 ± 8.8 years) who filled out a questionnaire collecting
data on demographic characteristics, working and living conditions,
including educational level, number of children in the household,
smoking, alcoholic beverage consumption, use of medication,
difficulty falling asleep, environment for sleep, snoring, sleep apnea;
work organization conditions, such as work shift satisfaction, feeling tired upon waking and during waking hours, dozing off at
work, presence of comorbidities, complaints of musculoskeletal
symptoms, and fatigue. After testing for normality with the
Kolmogorov-Smirnov test, continuous variables of the groups
were compared by applying Student’s t test or the Chi-square test.
Logistic regression analysis was conducted to verify associations,
with the self-reported back musculoskeletal symptoms considered
the dependent variable. For all statistical tests, a test power of 80%
and level of significance of α ≤ 0.05 were adopted.
Results: A total of 20.3% reported back musculoskeletal symptoms,
with symptoms more prevalent in the thoracic (13.8%) than lumbar
(14.6%) region. On the general model, most of the variables cited
were entered but only the fatigue score was retained (OR 1.048)
when tested in the final model, using the sleep variables, fatigue and
anxiety as independent variables.
Conclusion: Variables related to living, leisure and working
conditions and organization were not associated with the occurrence
of back musculoskeletal symptoms among production line workers
and machine operators, but the fatigue score represented a risk factor
for this complaint. Further studies with biological measurements,
such as inflammation cytokine, would involve additional elements
to help identify factors associated with musculoskeletal symptoms.
Support: Fundação de Amparo à Pesquisa do Estado de São Paulo
- FAPESP Process N°: 2011/12379-9.
Keywords: nightshift, musculoskeletal symptoms, fatigue, disease.
PD 80
ANALYSIS OF SALIVARY CORTISOL AS INDICATOR OF STRESS AND THE RELATION WITH THE
SLEEP QUALITY IN NURSES
Rocha MCP1, De Martino MMF1, Grassi-Kassisse DM2, Souza
AL3
Faculty of Nursing. State University of Campinas. São Paulo, Brazil.
Laboratory of Stress Study, Department of Biophysics and Physiology,
Institute of Biology; State University of Campinas. São Paulo, Brazil.
3
Department of Internal Medicine, Faculty of Medical Sciences. State
University of Campinas. São Paulo, Brazil.
[email protected]
1
2
Introduction: the nurse accomplishes a job with great demand
of attention and executes activities with high degree of difficulty
and responsibility, constituting factors that condition the presence
of stress at work. The physical tension of work can generate
highly harmful effects to the sleep. This study was based on the
knowledge of physiology to understand how stress can interfere
with the circadian rhythm and sleep quality of nurses.
Methods: quantitative, comparative and cross-sectional study with a
sample group of RN nurses (n = 57) from one of the main hospital
institutions in the city of Campinas, Sao Paulo, Brazil. The information
was obtained through a social-demographic identity card from October 2011 to march 2012. The research includes nurses that work
morning, afternoon and night shifts. The Inventory Stress in Nurses
(IEE) is an instrument that allows the identification and classification
of the nurses’ stress and the stressors origins in some activities executed by the nurses in the hospitals. The Pittsburgh Sleep Quality Index
Brazil (PSQI-BR) questionnaire evaluates the characteristics of the
sleep standards and quantifies the sleep quality. The questionnaire for
identification individuals’ morning and evening adapted from Östeberg
and Horne (1976) for Brazil by Benedito-Silva et al. (1990) and salivary
cortisol. The samples of saliva were made by the worker himself four
times and always before meals: from 6:00 am to 7:00 a.m., from 12:00
to 13:00 a.m., from 7:00 to 8:00 p.m. and from 10:00 to 11:000 p.m.
This procedure was performed on a workday and a day off.
Results: 80.7% was female, with 37.07 years old (SD = 8.49). Using
an analysis of the area under curve (AUC), was found significant
negative correlation between salivary cortisol and age of nurses in
the work day (Spearman correlation, r = -0.27579, p = 0.0435). It
was observed that the day shifts were setting the parameters of the
circadian rhythm of salivary cortisol in 24 hour period, while for
the night shift nurses, no adjustment to Cosinor model. 25% of RN
nurses had stress, and 74% of showed poor sleep quality.
Conclusion: the results of the measures of salivary cortisol in the
evening nurses demonstrated the absence of 24 hours in the work
day in and day off, and was demonstrated interference shift in daily
rhythmicity of salivary cortisol. Analysis of Cosinor of 24 hours
on days off results showed significant values for salivary cortisol
for day and night shifts, and confirms the importance of the day
off for the normalization adjustment of circadian rhythms to the
recovery of the cortisol indices.
PD 80
ANALYSIS OF SALIVARY CORTISOL AS INDICATOR OF STRESS AND THE RELATION WITH THE
SLEEP QUALITY IN NURSES
Rocha MCP1, De Martino MMF1, Grassi-Kassisse DM2, Souza AL3
76
Faculty of Nursing. State University of Campinas. São Paulo, Brazil.
Laboratory of Stress Study, Department of Biophysics and Physiology,
Institute of Biology; State University of Campinas. São Paulo, Brazil.
3
Department of Internal Medicine, Faculty of Medical Sciences. State
University of Campinas. São Paulo, Brazil.
[email protected]
1
2
Introduction: the nurse accomplishes a job with great demand
of attention and executes activities with high degree of difficulty
and responsibility, constituting factors that condition the presence
of stress at work. The physical tension of work can generate
highly harmful effects to the sleep. This study was based on the
knowledge of physiology to understand how stress can interfere
with the circadian rhythm and sleep quality of nurses.
Methods: quantitative, comparative and cross-sectional study
with a sample group of RN nurses (n = 57) from one of the main
hospital institutions in the city of Campinas, Sao Paulo, Brazil. The
information was obtained through a social-demographic identity card
from October 2011 to march 2012. The research includes nurses that
work morning, afternoon and night shifts. The Inventory Stress in
Nurses (IEE) is an instrument that allows the identification and classification of the nurses’ stress and the stressors origins in some activities executed by the nurses in the hospitals. The Pittsburgh Sleep
Quality Index Brazil (PSQI-BR) questionnaire evaluates the characteristics of the sleep standards and quantifies the sleep quality. The
questionnaire for identification individuals’ morning and evening
adapted from Östeberg and Horne (1976) for Brazil by Benedito-Silva et al. (1990) and salivary cortisol. The samples of saliva were made
by the worker himself four times and always before meals: from 6:00
am to 7:00 a.m., from 12:00 to 13:00 a.m., from 7:00 to 8:00 p.m.
and from 10:00 to 11:000 p.m. This procedure was performed on a
workday and a day off.
Results: 80.7% was female, with 37.07 years old (SD = 8.49). Using
an analysis of the area under curve (AUC), was found significant
negative correlation between salivary cortisol and age of nurses in
the work day (Spearman correlation, r = -0.27579, p = 0.0435). It
was observed that the day shifts were setting the parameters of the
circadian rhythm of salivary cortisol in 24 hour period, while for
the night shift nurses, no adjustment to Cosinor model. 25% of RN
nurses had stress, and 74% of showed poor sleep quality.
Conclusion: the results of the measures of salivary cortisol in the
evening nurses demonstrated the absence of 24 hours in the work
day in and day off, and was demonstrated interference shift in daily
rhythmicity of salivary cortisol. Analysis of Cosinor of 24 hours
on days off results showed significant values for salivary cortisol
for day and night shifts, and confirms the importance of the day
off for the normalization adjustment of circadian rhythms to the
recovery of the cortisol indices.
Session II - November 6th
16:30- 18:30 h
E - New trends in working hours
PE 81
SHIFTWORK AND WORKING HOURS OF WOMEN
MANUFACTURING WORKERS IN GLOBALIZED
LABOUR PRODUCTION
Lu, JL
Institute of Health Policy and Development Studies, National Institutes of
Health, University of the Philippines, Philippines.
[email protected]
Objectives: The study looked into the occupational hazards and
injuries among 500 workers in 10 semiconductor industries in
Cavite Export Processing Zone in the Philippines.
Methods: The subjects included only those who were doing
extended shiftwork beyond 8 hours, specifically 12 hours.
Industries were classified as either small, medium or large scale
industries based on the number of workers in the company. This
is a parametric study using stratified sampling where instruments
included workplace ambient monitoring, safety investigation,
medical records review, survey questionnaires and interviews.
Results: For the 500 workers given questionnaires, problems
cited for work conditions included poor housekeeping, slippery
floors, uneven floors, no machine guard, insufficient work area,
and insufficient warehouse/storage area. These conditions may
predispose a worker to accidents and injuries. The top five most
frequent stressors for both males and females were overtime,
fast-paced work, repetitive work, mental fatigue and visual strain.
The most prevalent injury was cuts and bruises at 65.5%. When
hazards and injuries were associated for this group of extended
shiftworkers, the results showed significant association between
the following: noise with hearing loss (p = 0.19), poor illumination
with eye strain (p = 0.007), muscle injury with vibration (p = 0.46),
excessive work with low back injury (p = 0.00), slipping with poor
housekeeping (p = 0.021), slippery floor with falls (p = 0.32), and
with uneven floors (p = 0.003). The injury data from the medical
clinic for one year indicated 27 cases of laceration, 25 cases of
punctures, 9 cases of chemical burns, 4 cases of fractures, and
3 cases each of amputation and eye injuries. All these injuries
occurred in the workplace due to lack of machine guards, improper
use of tools, non-ergonomically designed tools, fast workplace and
unsafe conditions. Three amputations of the middle crease of the
hand extending to all fingers were also noted.
Conclusion: The study has shown that extended shiftwork may be
contributory to occupational injuries and unsafe conditions.
PE 82
WORK-TIME STRESSES OF WOMEN WORKERS IN A
DEVELOPING COUNTRY
Lu SF1, Lu JL2
College of Social Sciences and Philosophy, University of the Philippines,
Philippines.
2
Institute of Health Policy and Development Studies, National institutes of
Health, University of the Philippines, Philippines.
[email protected]
1
Objectives: In the light of global industrialization, much attention
has been focused on working time of workers and its influence on
the health and welfare of workers.
Methods: This was a cross sectional study using stratified sampling
technique located in export zones in the country. This study was
done in an export processing zone.
Results: The establishment of export processing zones (EPZs)
is seen as a sub regional response to globalization. Transnational
companies that forge merges and strategic alliances are major
employers in export zones. In this economic enclave, economic
activities are coordinated so as to produce globally competitive commodities. The activities are micro regional and cross border strategies
for zonal development across the globe. Export zones have been
created to cope with the demands of globalization in sub regional
areas, or to take advantage of investment incentives offered by host
Taiwan, Brazil, the Philippines and India in the late 1960s. The study
sampled 24 industries, 6 were small scale industries and 9 each for
medium and large scale industries. From the 24 industries, a total
77
of 500 respondents for the questionnaire were taken. Among the
500 respondents, majority were female (88.8%), single (69.6%) and
worked in the production or assembly-line station (87.4%). Sickness
absenteeism was relative high among the workers in this study accounting for almost 54% among females and 48% among males. Many
of the workers also reported of work overtime, nightshift work, and
poor performance at work, boredom, tardiness and absenteeism. Organizational stress was associated with fatigue from overtime work
and overwork, lack of skills training lack of promotions, job insecurity, and poor relationship with employers (p = 0.05).
Conclusion: From the data generated, important issues that must
be dealt with in work organizations that include the quality of work
life, and health and safety issues are affected by work time schedule.
There must be an active campaign for favorable and healthful work
time schedules for workers that remain to be indispensable in the
industrial economy.
Keywords: Work time schedule, organizational stress, export
processing zones, quality of work life.
PE 83
BOUNDARY MANAGEMENT STRATEGIES AND
WORK-LIFE BALANCE IN KNOWLEDGE INTENSE,
FLEXIBLE WORK
Mellner C1, Aronsson G2, Kecklund G3
Department of Work and Organizational Psychology, Stockholm University,
Sweden.
2
Department of Work and Organizational Psychology, Stockholm University,
Sweden.
C Stress-research Institute, Stockholm University, Sweden
[email protected]
1
Introduction: Boundary strategies, segmentation and integration, were
explored in knowledge intense, flexible work. Socio-demographic, work
-related and individual factors were investigated in relation to strategy
choice, and further, which of these factors that discriminated between
succeeding or not with the chosen strategy. Moreover, work-life balance
was studied in relation to strategy choice.
Methods: A web-questionnaire was sent to all employees at a work unit
(n = 1238, response rate 65%) at an international telecom company in
Sweden in 2010.
Results: A majority, 82 percent, chose segmentation. More integrators
as compared to segmenters perceived their strategy as non-successful.
Integrators further reported higher time-spatial flexibility in terms of
higher working time per week, working evenings and weekends as well
as at different places than the workplace, especially from home, more
often than segmenters. However, these aspects of time-spatial flexibility were only related to not succeeding with one´s strategy among
segmenters. Especially, co-habiting women with children choosing segmentation perceived their strategy as non-successful. In contrast, male
segmenters that were co-habiting and having children succeeded more
often. Discriminating factors for succeeding or not with one´s preferred
strategy that emerged in both strategy groups reflected the capacity for
self-regulation, i.e., being able to say no and set limits, organizing work
efficiently, and work independently. As for work-life balance, those who
succeeded with the integration strategy, in particular integrating women,
reported a higher degree of work-life balance, irrespective of their family
situation, as compared to others. Female segmenters that were co-habiting and having children perceiving their strategy as non-successful instead reported poorer work-life balance than all other groups.
Conclusion: Self-regulation seems a crucial competence in a working
life characterized by boundarylessness. Results are of value for health
promotion in flexible work organizations in supporting employees
achieving successful boundary management based on individual strategy preference and hence, subsequent work-life balance. Results needs to
be confirmed in other work settings and associations between boundary
management and stress and health established.
PE 84
TRUCK DRIVERS’ WORKING HOURS AND IMPACT
ON SOCIAL AND FAMILY LIFE
Silva LG, Moreno CRC
[email protected]
Introduction: Long and irregular working hours are typical working
conditions of truck drivers. The interference of work schedules on
family and social dynamics may contribute to impaired quality of
life and health among this group of workers.
Aim: To identify the effects of working hours on the family and
social life of truck drivers.
Methods: A qualitative study was conducted based on group
interviews. Four meetings were held during which drivers reported
their activities. The descriptions collected were used to build
the following categories: work, health, employment contracts,
occupational accidents and impact of work on social and family
life. For this study was prioritized the category impact of work on
social and family life. Results were validated by the workers.
Results: Working hours were characterized as both a positive and
negative aspect, considering two periods: when away from home
and when back at home. During deliveries, driver s considered the
time away from home as a negative aspect of the job, with majority
of time spent at work and less time on private and family activities.
Truck drivers reported working away from home for one to two
months at a time, removing them from daily family issues. Thus,
when truck drivers were back at home they faced changes in the
family dynamics.
Conclusions: Paradoxically, although truck drivers miss their
families, being away from home became routine, and consequently
time spent at home sometimes led to family conflicts. The family
appears to represent an important social function for these workers.
On the other hand, long working hours and nighttime work affect
the social and family life of truck drivers, having a serious negative
impact on family and social.
Support: Conselho Nacional de Desenvolvimento Científico e
Tecnológico (CNPq).
PE 85
DEVELOPMENT OF A METHOD TO EVALUATE
CHARACTERISTICS OF WORKING HOURS OBJECTIVELY
Härma M, Ropponen A, Hakola T, Puttonen S, Koskinen A,
Sallinen M, Bohle P
Working Hours, Alertness and Professional Traffic Team, FIOH, Finland.
Statistics and Health Economics Team, FIOH, Finland.
Work and Health Research Team, The University of Sydney, Australia.
[email protected]
Introduction: Epidemiologic evidence on the effects of night
and shift work on health has been rather inconsistent. Exposure
assessment in epidemiological studies on working hours has mostly
been based on self-reported and discontinuous data prone to bias
and inaccuracy offering limited possibilities for categorization.
The aim of the current study was to develop a method to evaluate
the different characteristics of working hours objectively. The
method will be used in the Finnish Public Sector study, an on-going
prospective study including biannual questionnaires on health for
about 40,000 persons since 2008 and wide register data on health
of about 250,000 workers.
78
Methods: Objective daily working hour data (used for payroll) from
20 wards of Social Services and Health Department (n = 1332,
13% male, 87% female) of a large city were analysed from 20082012. The working hour data were retrieved from a shift scheduling
programme (Titania) including both planned and realized working
hours and shift preferences.
The data was averaged for each year to calculate 26 individual
working hour characteristics under the following dimensions: 1.
length of the working hours (6 items related to the average weekly
working hours and the length of individual shifts), 2. Consecutive
working days (3 items), 3. shift work (4 items, % of different shifts),
4. Recovery between shifts (4 items), 5. social aspects of working
hours (3 items including annual leave, week-ends and single free
days), 6. variability of working hours (mean absolute deviation
of shift starting and ending times and shift lengths (3 items), 7.
predictability of working hours (realization % of the planned shifts)
and 8. work-time control (% of realized shift preferences and %
of realized preferences/annual working days). The frequencies and
distributions of the variables were studied to evaluate the statistical
properties and possible outliers. The internal consistency of each
hypothesized main dimension was assessed with Cronbach’s alpha.
Stability was studied between subsequent years.
Results: No missing data or any significant outliers were observed
(no individual value was theoretically impossible). Based on 2011
data, the calculated internal consistencies of most of the working
hours main dimensions were low (Cronbach’s alpha .23-.48), except
for shift work (.82) and the variability of working hours (.84).
Comparison between different years showed high stabilities of
most working hour characteristics, correlation coefficients being
from .70 to .90 in within-individual comparisons.
Conclusion: The developed method can be used for multidimensional and accurate estimation of shift work exposure. The method
itself is reliable but the individual characteristics of working hours
should be combined cautiously.
Support: This study was supported by a grant from the Finnish
Work Environment Fund (no 112065).
PE 86
FINANCIAL REGULATIONS MAY FOSTER OR REINFORCE NON-OPTIMAL WORKING TIMES
Gaertner J1, Popkin St2, Lockley St3
XIMES GmbH & Vienna University of Technology, Austria.
U.S. Department of Transportation Volpe Center, USA.
3
Harvard, USA.
[email protected]
1
2
Ability to influence one’s income influences workers’ resistance/
acceptance of when and how much they work. Typically, employees
resist change if it reduces their income.
Besides the hourly rate there are several financial rules that influence
actual income of employees: number of hours of overtime; timing
of the work; premiums, e.g. for night work; taxation; social security
payments; insurance costs, etc. Such financial rules may foster bad
working times:
• In some countries their socio-political system compensates for
unhealthy hours by not including them as part of the tax base/
social security base (e.g., premiums for night and weekend work
are not always taxed in Germany - a rule that was introduced in
fascist Germany to appease workers). By this, the government
incentivises unhealthy/unsocial work. Similarly in the USA, it is
often the case that pensions are calculated based on the last 3 or 5
years of employment. When there is a shift or overtime differential,
those employees who are often the oldest and less likely resilient to
working shifts, are incentivized to work those hours.
• Insurance and other staff benefits often are an incentive for
creating overtime work. If insurance costs are fixed (e.g. per head)
or with an upper limit per head (e.g., up to an upper-limit of
approx. 4.500 Euro employers and employees pay a percentage to
social security in Austria) then overtime becomes more attractive
for employers as well as for employees. E.g., 10 persons working
60 hours a week each may be cheaper than 15 persons working 40
hours each a week.
This near-term calculus, however, does not take into account longerterm morbidity and mortality of working these scheduled for many
years. In such cases, overtime/work, night/work, and weekend work
sometimes is done not due to actual needs but to preserve/increase
income, often concentrated to just a few persons.
The result is more unhealthy/unsocial hours are worked than
necessary by a small number of persons, creating a financial prison
which they cannot easily escape. From an ergonomics point of view,
well designed shift systems typically offer little or no overtime. To facilitate adoption of better working times, premiums should be small
in respect to wages or better substituted by time off instead of additional money. Furthermore, tax/social security incentives for unhealthy hours’ premiums would be better used for programs that increase
health; a small tax dis-incentive for unhealthy/unsocial work might
help to move in that direction. Insurance would be best organized in
a way that is neutral to the number of working hour’s resp. income or
even progressive to make shorter hours more attractive. In the presentation we will present cases from US and Europe from different
industries (e.g. health, transport, industry) to substantiate the claim.
PE 87
HEALTH, SLEEP, AND WORK-LIFE BALANCE OF
EMPLOYEES WORKING SHIFTS WITH OVERTIME:
A PROSPECTIVE STUDY OF CHANGE IN WORKTIME CONTROL
Takahashi M1, Kubo T1, Liu X1, Togo F2, Shimazu A2, Tanaka
K3, Uchiyama T4
National Institute of Occupational Safety and Health, Japan.
The University of Tokyo, Japan.
3
Kitasato University, Japan.
4
Kakogawa Works, Kobe Steel, Ltd.
[email protected]
1
2
Introduction: Employees are expected to gain benefits of worktime
control (WTC) for many aspects of working life. Evidence available
is not sufficient to determine the role of WTC in shift work, though
reported in some cross-sectional and intervention research (e.g.,
self-rostering). Effects of WTC are also unclear when shift work
is coupled to overtime. This prospective study investigated how
change in WTC was associated with health, sleep, and work-life
balance among shift workers who worked overtime.
Methods: A three-wave study was conducted at a manufacturing
worksite with an interval of approximately 6 months. A total of
2,206 to 2,345 employees responded to the questionnaire (response
rate = 83 to 87%). This study selected 1,028 shift workers who
continued to work shifts across the follow-up period (1,020 men, 8
women; mean age 39+/-15 yrs).
The questionnaire measured WTC, health, sleep, work-related, and non
-work-related variables. WTC was assessed as the extent of influencing
five aspects of working times (1 = very little, 5 = very much): (i) length
of a workday, (ii) starting and finishing times of a workday, (iii) taking
of breaks during the workday, (iv) scheduling of vacations and paid
days off, and (v) taking of unpaid leave. The total score at each wave
was divided into two categories (low, high) by median at baseline (T1).
Participants were classified into four groups according to the WTC category principally at baseline and T3: low-low (LL, n = 366), low-high
(LH, n = 167), high-low (HL, n = 131), high-high (HH, n = 364).
79
Outcomes included subjective symptoms of fatigue, psychological
distress (K6), sleep (Pittsburg Sleep Quality Index, PSQI),
and work-self interference. Linear mixed models were used to
examine the main effects of WTC change and wave and also their
interaction separately by weekly work hours (-40, 41-50, 50-60, 61
+ hours). Covariates included age, cohabitation status, occupation,
psychosocial work characteristics (quantitative job overload, job
control, social support at work).
Results: (1) Up to 40 hours: Fatigue in LH decreased significantly
from T1 to T2 and leveled off thereafter, whereas fatigue in LL
and HL showed the greater levels. Psychological distress in HL
increased significantly from T1 to T3, with the highest at T3. The
PSQI global score in LH decreased significantly from T1 to T2
and reached the lowest during the follow-up period. Work-self
interference showed a similar pattern as psychological distress. (2)
41-50 hours: The PSQI global score in HH decreased significantly
from T1 to T2 and remained lower than LL or HL. Work-self
interference in LH and HH was consistently smaller than LL. (3)
Beyond 50 hours: No results were significant.
Conclusion: Positive change in WTC and persistently high WTC
are associated with favourable outcomes in shift workers working
by 50 hours a week.
PE 88
WORKING HOURS IN THE DANISH PUBLIC
HEALTH CARE SECTOR - THE DANISH WORKING
HOUR DATABASE (DWHD)
Garde AH1, Johnni Hansen J2, Hansen ÅM1,3, Kolstad H4
National Research Centre for the Working Environment, Denmark.
The Danish Cancer Society, Denmark.
3
University of Copenhagen, Denmark.
4
Danish Ramazini Centre, Aarhus University Hospital.
[email protected]
1
2
Introduction: Shift work and night work has become very frequent
in the modern world and such working time arrangements have an
impact on health and well-being. Despite decades of intense research
on shift work and health, especially the epidemiological evidence is
still limited. One epidemiologic problem is exposure assessment i.e.
lack of exact information of working hours over longer periods of
time. The aim of the present study is to describe working hours related to gender based on exact working hours by use of the newly
established Danish Working Hour Database (DWHD).
Methods: The present analyses all public employees from all five
regions in Denmark in 2008 (n = 174.269; 22.9 % men). They were
employed at hospitals (79 %), specialized handicap homes (15 %)
and regional administration (6 %). We used administrative data on
working hours from DWHD, which contains information on daily
starting and ending times for all employees in the cohort from
2007-2011. The database was approved for research use by The
Danish Data Protection Agency (ref no: 2011-41-7046). Gender
was assessed from the personal ID-number. Estimated working
hour variables were: Number of day, evening (ends between
19:00 and 01:00), night (at least 3 hours between 00:00 and 5:00),
weekend (starting on Saturday or Sunday) shifts and quick returns
(< 9 hours between two shifts); number of short (≤ 4 hours), long
(≥ 9 hours), or very long (≥ 12 hours) shifts. All working hour
data is per year. Wilcoxon Two-Sample Test (two-sided) was used
to test for differences between groups. Analyses were not adjusted
for absence due to sickness, maternity leave, family related sickness,
work-related injury or periods of not being employed in the regions.
Results: Distributions between men and women differed for all
working hour variables (p < 0.0001).
Conclusion: The results demonstrate that work schedules differ
according to gender in the Danish public health care sector and
that DWDH is useful for detailed description of working hours.
Data from DWHD will be updated yearly and may be coupled with
information from registers on e.g. hospital admissions and use of
prescription medicine. We currently work on studies on shiftwork
and breast cancer, sickness absence, mental health and pregnancy
complications, and welcome new research projects within the
database.
PE 89
THE EFFECT OF THE CONTINUOUS LONG
WORKING HOURS ON WORKERS’ LIFESTYLE
Okubo Y, Kuroda R
Division for Environment, Health and Safety, University of Tokyo, Japan.
[email protected]
Objectives: The long working hours is one of the causes of
fatigue and health problems. Actually, the long working hours
among software programmers and engineers engaged in research
and development are commonly observed. However the effects
of the continuous long working hours on the lifestyle are still
unclear. Thus we retrospectively investigated the relationships of
the continuous long working hours and activity on holiday, drinking
habit or changes of weight and appetite.
Methods: The subjects were record of medical interviews for male
engineers in electronic equipment manufacturing company. Total
number of workers was 1,058. The records of medical interview
including blood pressure, drinking habit, activity on holiday,
changes of appetite and weight. The monthly working hours was
collected every month for each worker. The periods of continuous
long working hours were classified into 5 categories; 1 month,
2-3 months, 4-6 months, 7-12 months and more than 13 months.
If the monthly extra working hours were less than 40 hours per
month, we defined that the continuous long working hours was
interrupted. We adopted the logistic regression analysis and general
linear model in analyses.
Results: The odds ratios of decreasing the activity on holiday were
elevated with the prolonging of period of long working hours.
However, significant differences in blood pressure, drinking habit,
changes in weight and appetite were not observed.
Conclusion: We reported that the risks of sleep related symptom,
physical symptom, burn out and fatigue were elevated with
prolonging the period of the long working hours in ISSWT 2011.
In this study, drinking habit, appetite and weight were not changed
with the period of continuous long working hours. However
workers who engaged in continuous long working hours took
the rest on holiday, such as taking a nap, interruption of habitual
physical activity and restraining themselves from going on a trip
or to play, to recover from their exhaustion. This result suggested
that prolonging the period of the long working hours also worsen
quality of life.
80
PE 90
SHIFTWORK ISSUES OF INDUSTRIAL MULTINATIONAL AND TRANSNATIONAL ESTABLISHMENTS
Lu JL
National Institutes of Health, University of the Philippines, Philippines.
[email protected]
Objectives: This is an investigation of the working time schedule
and occupational health issues of workers and supervisors in
manufacturing industries in the Philippines that export their
manufactures to other countries. These industries are owned by
multinational companies.
Methods: Sample consisted of 23 establishments, 613 workers,
and 47 supervisors for the survey, and 10 focus group discussions
(FGDs) for workers, and 5 FGDs for supervisors. Workers
and supervisors alike reported long working hours and job
dissatisfaction.
Results: Survey showed that the most prevalent issues among
workers were the need to upgrade skills (77.6%), pressure in
intensified working time (60.4%), fast paced work (60.4%), repetitive work (63%), and that work entailed both physically tiring
tasks (59.6%). Logistic regression showed that large industries were
more exposed to hazardous environment and work time pressure
compared to the medium industries. Workers tended to have low
physical health when they were subjected to close monitoring, work
time pressure, and lack of job autonomy. Focus group discussions
showed that workers and supervisors were confronted with stress,
overtime work, extended working time, night shift work, fast-paced
work, the need to upgrade skills due to accommodation of information technology into the work production, and fatigue.
Conclusion: This study was able to show the nature of working
time schedule in manufacturing work that support global markets.
Keywords: Work time schedule, occupational health issues, workers
and supervisor sin manufacturing, global market, globalization.
5
AUTHOR INDEX
A
Akerstedt T
Albertsen K
Alexander M
Alguacil J
Andersen MR
Anelli MM
Anmarkrud K
Anttila T
Apostolopoulos Y
Apykhtin K
Araujo LG
Arlinghaus A
Aronson JK
Aronsson G
Axelsson J
TS 3.3, PA 09, S 5, S 4, OS 2.8
TS 3.1
PA 10
PD 57
PD 78
OS 3.5
PA 05
OS 1.3, PC 36, OS 3.4
PC 34
PD 55
PD 79
OS 1.2, PD 63, PB 18, OS 2.2, PD 63
TS 4.2
TS 3.3, PE 83
PD 75
B
Baisch C
Balieiro LCC
Baltopoulos G
Banks S
Baptista PCP
Barger LK
Barnes-Farrell J
Barnett M
Barreto A
Bastos LS
Beauchamp MR
Bejerot E
Benedito-Silva AA
Berthelsen M
Birks RB
Bjorvatn B
Blettner M
Bobko N
Bochkarev M
Bohle P
Boivin DB
Boot CRL
Boudjeltia KM
Boudreau P
Brauch H
Brenner B
TS 4.3
PD 69
PB 21
PD 54, PB 15
PD 62, PD 53
TS 1.1, TS 1.3
OS 3.4
S5
PC 37
TS 6.3
PD 60
TS 3.3
OS 2.7
PD 66
PC 38
OS 2.1, PD 66, OS 2.3
TS 4.3
PD 55
OS 4.4
TS 3.4, PE 85
TS 5.2
S1
TS 5.5
TS 5.2
TS 4.3
OS 3.2
Brouwer S
Brown S
Brüning T
Bukowska A
Bültmann U
Burch JB
Burch K
W 3, PA 07
PC 35
TS 4.3
PD 47
W 3, PA 07
TS 4.1, PA 10
OS 3.4
C
Cade BE
Calonga SMS
Campagna M
Campbell KC
Carvalho ANS
Carvalho RJM
Castaño-Vinyals G
Castellini G
Cavicchia P
Centofanti SA
Cherniack M
Chernyuk V
Chor D
Chouliara A
Christiansen P
Clarkson L
Cocco P
Cohrs CR
Coplen M
Costa G
Courtney TK
Crispim CA
Cvirn M
Cygan D
Czeisler CA
TS 1.1
PB 20
PD 64
PD 60
PC 40, PC 39
PC 29
TS 5.3
OS 3.5
PA 10
PD 54, PB 15
OS 3.4
PD 55
PD 72
PB 21
PD 67
PB 14
PD 64
PC 27
OS 1.5
PD 76, OS 3.5
OS 2.2
PD 69, PD 68
PB 22
PD 63
TS 1.1
D
Dahlgren A
Darwent D
Davies-Schrils K
Dawson D
De Faria AL
de Looze MP
Del Rio A
De Martino M
S5
PC 43, PB 14, OS 4.4
OS 3.4
PC 43, PB 14, OS 4.4, OS 2.6
PD 46
W 3, PA 07
PD 64
PC 27
6
De Martino MMF PD 80
Demers PA
PA 04
Di Milia L
PD 45, OS 2.3
Dohi S
TS 6.2
Drake CL
TS 1.3
Duboutay F
TS 5.5
Dumont M
TS 2.2
Durand P
OS 3.1
E
Eastman CI
Emrich K
Epstein LJ
Espinosa A
Esteves AM
TS 2.4
TS 4.3
TS 1.1
TS 5.3
PC 37
F
Feitosa MS
Ferguson S
Fernandes-Junior SA
Fernandes PACM
Ferreira LC
Ferrer J
Figueiro MG
Fildissis G
Fischer D
Fischer FM
Fischer MF
Flo E
Folkard S
Fonseca M
Fonseca MJM
Fustinoni S
PD 46
PB 22, OS 2.6
PC 40, PC 39
PA 01
PD 46
PD 49
TS 2.3
PD 52, PB 21
TS 5.4, PA 03, OS 4.5
PD 77, PC 42, PC 31, PC 30, PB 25,
PA 11, PA 01
PC 32
OS 2.1, OS 2.3
TS 6.4, PD 63, PD 49, OS 2.2
PD 74
TS 6.3, PD 74, PD 72, PC 44, OS 2.7
OS 3.5
G
Gaertner J
Gamble LK
Garde AH
Garefelt J
Gavala Al
Gignac M
Goes EP
Goncalves PS
Gordijn MCM
Gotay CC
PD 63, W 4, PE 86
TS 5.1
TS 3.1, PE 88, PD 67
PA 11, PA 09, OS 4.2
PB 21
OS 1.4
PD 70
PD 62
PA 07
PD 60, PA 04
Goudswaard A
Grassi-Kassisse DM
Griep RH
Griffie JT
Guess J
Gustavsson P
W 3, PD 48
PD 80
TS 6.3, PD 72, PC 44, OS 2.7
TS 5.1
PA 10
PD 75
H
Hakola T
Halson SL
Hamann U
Hammer PG
Hampton S
Hansen AM
Hansen J
Hare D
Härmä M
Harth V
Hartikainen A
Haubruge D
Haugen A
Hébert JR
Hege A
Heinze E
Hidalgo PM
Hilditch CJ
Hinson JM
Hjelle IB
Hlobil H
Hopsu L
Hosaka T
Howard M
Howarth H
Ho Yu C
Hublin C
Hurley TG
Hursh SR
Hvid H
Hyvärinen HK
PE 85, PB 17, PA 06
OS 2.4
TS 4.3
TS 4.3
TS 5.5
PD 67, TS 3.1, PE 88
PD 67, OS 4.1
TS 1.2
PB 13, PA 01, OS 2.5, TS 1.4, PE 85
TS 4.3
OS 1.3, OS 3.4
TS 5.5, PA 08
PA 05
PA 10
PC 34
TS 4.3
K2
PD 54, PB 15
S7
PD 78
S1
PB 17
OS 1.6
TS 1.2
OS 1.5
PC 34
TS 1.4, PB 13, OS 2.5
PA 10
S6
TS 3.1
PB 19
I
Ijaz S
Imai T
Imamura S
Ingre M
PD 76
TS 6.2
OS 1.6
S 4, OS 2.8
7
J
Jackson ML
Jackson P
Jay S
Jin K
Johansson M
John A
Johnni Hansen J
Johnson A
Johnson LR
Justenhoven C
S7
S3
PB 22
OS 2.2
OS 3.6, OS 3.6
OS 1.5
PE 88
PC 34
TS 5.1
TS 4.3
K
TS 6.2
PD 56
TS 5.5, PA 08
PB 13
PD 52
TS 3.3, PE 83, PD 75, S 5, S 4,
OS 2.8
Keller Celeste R
OS 1.1
Kempe A
PD 50
Keren A
OS 3.2
Kerkhofs M
TS 5.5, PA 08
Kiilian M
PC 27
Kim HJ
PD 56
Kim T
PD 71
Kircher A
S5
Kivimäki M
PB 13
Kjaerheim K
PA 05
Kjuus H
PA 05
Knardahl S
PD 66
Knutsson A
PD 50
Kochi T
TS 6.2
Kogevinas M
TS 5.3, PD 57
Kogi K
OS 1.6
Kohler MJ
PD 54, PB 15
Kolstad HA
PE 88, PD 67
Konttinen J
PB 17
Korompeli A
W 1, PD 52, PB 21
Koskinen A
PE 85
Kosmadopoulos A PC 43, OS 4.4
Koolhaas W
W3
Kosta NE
PD 52
Ko Y
TS 4.3
Kabe I
Kang Ht
Kantermann T
Karhula K
Katsoulas Th
Kecklund G
Koyama RG
Kubo T
Kundi M
Kuroda R
Kuwahara K
PC 41, PC 40, PC 39
PE 87
PD 63
PE 89
TS 6.2
L
Landrigan CP
Lastella M
Lecca L
Lederle K
Lee JW
Lehrer A
Leite CMG
Lemos LC
Lennernäs M
Levandovski R
Liang Y
Licati P
Lie Sigstad J-A
Lim S
Lindbohm M-L
Liu X
Llorca J
Lockley St
Lockley SW
Lombardi DA
Loudon R
Loudoun R
Lowden
Lowden A
Lu JL
Lund H
Lu SF
Lützhöft M
Luz AA
TS 1.1
OS 2.4
PD 64
S3
PD 56
PB 24, S 2
PC 29
PD 73, PD 51
OS 3.6, OS 3.6
K2
OS 2.2
PB 25
PA 05
PD 56
PD 76
PE 87
PD 57
PE 86
TS 1.1
OS 2.2
TS 3.5
PB 23
PA 11
PC 32, PA 09, OS 4.2
PE 90, PE 82, PE 81
TS 3.1
PE 82
S5
PC 42, PC 30
M
PD 66
Marchand A
OS 3.1
Marcos J
TS 5.3
Marqueze E
PC 32
Marqueze EC
TS 6.1, PD 73, PD 58, PA 11
Markus RP
PA 01
Martin Sanchez V PD 57
Martins AJ
PD 51
Magerøy N
8
Martinez MC
Matre D
Matsagas P
Masson V
McGillis Hall L
Mehlmann JL
Mellner C
Mello MT
Meloni M
Menna-Barreto L
Merikanto I
Michinaga M
Middleton B
Min-sang Y
MiyamotoT
Mizoue T
Modawi S
Moen BE
Moen EM
Monteiro I
Moreno CRC
Moreno V
Morgan PL
Mota MC
Mo-Yeol K
Müller K
Muñoz C
Murray G
Mustard C
Mutanen P
Muurlink O
Myriantheas P
PD 77
PD 78
PC 35
PD 65
PD 61
TS 5.4, PA 03, OS 4.5
OS 1.1, PE 83
PD 68, W 2, PC 41, PC 40, PC 39,
PC 37
PD 64
PC 31, PC 30, PB 25
TS 1.4
OS 1.6
TS 5.3, PA 08
PD 71
TS 6.2
TS 6.2
PD 59
PD 66, OS 2.3
OS 2.1
PD 70, PD 65
TS 6.1, PE 84, PD 79, PD 73, PD 58,
PD 51, PC 32, PC 31, PC 30, PA 11
PD 57
PA 08
PD 69, PD 68
PD 71
TS 1.4
PD 60
PB 23, TS 3.5
OS 1.4
PB 19
PB 23, TS 3.5
PB 21
N
Nachreiner F
Nadir Y
Nag A
Nag PK
Nakagawa T
Narciso FV
Nasterlack M
Nätti J
Neil SE
OS 1.2, PB 18
OS 3.2
PB 16
PB 16
TS 6.2
PC 39, PC 37
TS 4.3
OS 1.3, PC 36, OS 3.4
PD 60, PA 04
Neuvonen K
Ng KT
Niemelä P
Nikolaidou E
Nilsen KB
Nishihara A
Nyberg M
PD 76
TS 1.3
PA 06, OS 2.5
PD 52
PD 78
TS 6.2
OS 3.6, OS 3.6
O
Oberlin D
O’Brien CS
Ogeil RP
Oinas T
Ojajärvi A
Okubo Y
Orsini N
PC 34
TS 1.1, TS 1.3
TS 1.3
OS 1.3, PC 36, OS 3.4
PD 76
PE 89
PD 76
P
Pahwa M
Paim SL
Pallesen S
Papantoniou K
Paterson JL
Paterson L J
Peetz D
Pepłońska B
Perry MJ
Pesch B
Pinheiro F
Pisarski A
Pitts C
Pollán M
Popkin S
Portela L F
Pozo OJ
Psallida V
Puttonen S
Pylkkönen M
PA 04
PD 69
OS 2.1, PD 66, OS 2.3
TS 5.3, PD 57
PC 26
PB 14
PB 23, TS 3.5
PD 47
OS 2.2
TS 4.3
PC 31, PC 30
PB 12
TS 3.4
PD 57
OS 1.5, PE 86, PB 24, S 2
TS 6.3
TS 5.3
PB 21
PE 85, PB 17, PB 13, TS 1.4, PE 85,
PB 17, PB 13, OS 2.5
PB 19
Q
Qadri S
TS 1.1
R
Rabstein S
Ragozin O
Rajaratnam SM
TS 4.3
OS 4.4
TS 1.1, TS 1.3
9
Raso V
Rea M
Reinhardt EL
Roach G
Roach GD
Rocha MCP
Roenneberg T
Rogers N.L
Ropponen A
Rossato LT
Rotenberg L
Rousseau
Rudman A
Ruiz FS
PC 37
TS 2.1
PA 01
OS 2.6
PC 43, OS 4.4, OS 2.4
PD 80
K2, TS 5.4, PA 07, PA 03, OS 4.5
PD 45
PE 85
PD 69, PD 68
TS 6.3, PD 74, PD 72, PC 44, OS 2.7
PA 08
PD 75
PC 41, PC 39, PC 37
S
Saba A
Saharov G
Sallinen M
Salomon J
Salomon M
Santos TCMM
Sargent C
Sasaki T
Schiffermann M
Schmidt-Trucksäss A
Seidler A
Setzu D
Shattuck N
Shaw WS
Shea SA
Sheffield D
Shimazu A
Shivappa N
Schlangen LJM
Shochat T
Short MA
Sihvola M
Silva CM
Silva GTCA
Silva LG
Silva-Vasconcellos PR
Simonov V
Siqueira K
Skene DJ
Smid T
Smith B
PC 41, PC 40, PC 39
OS 3.2
TS 1.4, PE 85, PB 19, PB 13, OS 2.5
PD 49
PD 49
PD 46
PC 43, OS 4.4, OS 2.6, OS 2.4
PC 33
TS 4.3
TS 5.5
PD 76
PD 64
PC 35
W3
TS 1.1
S3
PE 87
PA 10
PA 08
PC 28, OS 3.2
PD 54, PB 15
PB 19
PD 68
PD 46
PE 84, PD 51
PC 44
OS 4.4
PD 74
K 1, TS 5.3, TS 5.5, PC 32, PA 11, PA 08
S1
PB 22
Smith C
Smith P
Snow JZ
Soares-Junior RC
Sobala W
Sofianopoulos S
Sönmez S
Soo-Hun C
Sourtzi P
Souza AL
Souza JC
Steck SE
Stetner LA
Stuenaes J
Sulaiman S
Sullivan JP
Swann P
PC 35
OS 1.4
OS 1.5
PC 37
PD 47
PC 26
PC 34
PD 71
PB 21
PD 80
PC 37
PA 10
PC 41, PC 40
PD 78
PD 59
TS 1.1
TS 1.2
T
Takahashi M
Tanaka K
Tardón A
Teixeira LR
Temime L
Thomson BS
Tieves D
Tito RS
Togo F
Toivanen S
Toivanen T
Tucker P
Tufik S
PE 87
PE 87
PD 57
PC 31, PC 30, PB 20
PD 49
TS 5.1
TS 3.2
PD 53
PE 87
TS 6.3, OS 1.1, PA 02,
PA 02
TS 3.3, TS 6.4
PD 68, PC 41, PC 40, PC 39, PC 37
U
Uchiyama T
Ulhôa MA
PE 87
PD 58
V
Vahtera J
Valente D
Vancini CR
Vandenbossche E
van der Beek AJ
van der Klink JJL
van de Ven HA
van Dongen H
van Dongen HPA
PB 13
PB 20
PC 27
PA 08
S1
W 3, PA 07
W 3, PA 07
S7
PD 54, PB 15
10
van Drongelen A
van Leeuwen W
van Leeuwen WMA
Vanttola P
Vasconcelos S
Vedovato T
Verbeek J
Vetter C
Viitasalo K
Viken LA
Virkkala J
Vistisen HT
S1
S4
S5
TS 1.4, OS 2.5
PC 32, PA 11
PD 65
PD 76
TS 5.4, PA 07, PA 03, OS 4.5, OS 2.2
PA 06, OS 2.5
PD 78
TS 1.4, PB 13, OS 2.5
PD 67
Wideman L
Wilkinson V
Williams
Winnebeck E
Wong I
Wright Jr. PK
OS 2.1, OS 2.3
PC 35
TS 1.1
OS 3.6, OS 3.6
PC 31, PC 30, PB 25
TS 1.1
S7
Z
W
Waage S
Waggoner L
Wang W
Wetterstrand M
Wey D
White DP
Whitney P
PC 34
TS 1.2
PC 26
K2
OS 1.4
PC 38
Y
Yun-Chul H
Yong M
Yoshikawa T
Young EM
Young R
Zhang H
Zhou X
Zidianakis V
Zienolddiny S
Zion N
Zwieten MV
PD 71
TS 4.3
OS 1.6
TS 5.1
PC 35
PA 10
PC 43, OS 4.4, OS 2.6
PD 52
PA 05
PC 28
PD 48
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