Can sleep deprivation make us sweeter?

International J. of Healthcare and Biomedical Research, Volume: 03, Issue: 03, April 2015, Pages 69-76
Original article
Can sleep deprivation make us sweeter?
Dr. Abeetha S1, Dr. Shiva Yogappa Teli2, Dr. Mitali Srivastava3, Dr. Divya R4, Dr. Ashok V5
1Post
graduate, Department of Physiology, SMVMCH, Pondicherry- 605107
2Associate
Professor, Department of Physiology, SMVMCH, Pondicherry- 605107
3Post
graduate, Department of Biochemistry, SMVMCH, Pondicherry- 605107
4Post
graduate, Department of Physiology, SMVMCH, Pondicherry- 605107
5Post
graduate, Department of Biochemistry, SMVMCH, Pondicherry- 605107
Corresponding author: Dr. Abeetha S
Abstract:
The events occurring in the human mind during sleep have kept many a researchers sleepless. This study aimed
to analyse the glycemic status among shift workers as well as to look for a relation between the age of the
subjects, duration of sleep and the years of shift work experience. We found a positive correlation between
fasting blood sugar and the age of the subject by Pearson’s correlation (r=0.660, p<0.001). Years of shift work
was also observed to be positively correlated to glycemic status (r=0.666, p<0.001). However, a negative
correlation was found between glycemic status and duration of sleep per day (r= -0.585, p<0.001).
The pathways responsible for this finding are complex and are yet to be clearly understood. These include- upregulation of the orexin neuron activity, reduced brain glucose utilisation after sleep loss, alteration of hormonal
activity of insulin, cortisol, growth hormone, leptin, ghrelin and cardiac sympatho - vagal balance due to sleep
deprivation, elevated levels of proinflammatory cytokines and low-grade inflammation which further cause
insulin and leptin resistance.
We concluded that glycemic status among sleep deprived is clearly associated with the age of the subjects, their
shift work experience but has an inverse relation with the duration of sleep. Which encourages us to further
affirm the role of a poor glycemic status in the development of numerous clinical and lifestyle hazards, like
cardio- metabolic risks, cognitive and behavioural disturbances, alcoholism all of which form a vicious cycle in
shift workers. This study asserts the importance of assessement of glycemic status in shift workers on a regular
basis to protect them from these preventable lifestyle disorders.
Introduction:
particularly in India. The revised international
Sleep refers to the reversible state of decreased
classification
responsiveness
with
recommended in 2005, and currently under
immobility. Inside the realm of sleep lies the
revision, classifies shift work sleep disorder
unknown. As research attempts to invade the on-
(SWSD) under circadian rhythm sleep disorders
goings of the human mind during sleep, the human
which is a subclass of dyssomnias. (1)
physiology offers some insight.
There is no specific definition for shift work, but it
Sleep
typically
deprivation
and
associated
sleep
loss
can
of
sleep
disorders
[ICSD-2],
be
is considered to be any work that is done outside of
conveniently studied among shift workers. Shift
normal daytime working hours. Shift work refers to
work sleep disorder is an understudied field,
work patterns that extend beyond the conventional
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International J. of Healthcare and Biomedical Research, Volume: 03, Issue: 03, April 2015, Pages 69-76
8-hour work day and that potentially disrupt
study mainly helps to identify the glycemic status
workers’ normal biological and/or social diurnal
among sleep deprived, particularly the security
rhythms.(2)Metabolic risk factors have been noted
staff, at a medical college hospital.
to be more frequent and more severe in night shift
Objective:
workers when compared to day time workers.(3)
To assess the glycemic status among sleep deprived
These occur because of the conflict between the
(security staff) working at a medical college
persistently changing work hours and output of the
hospital
biological clock.(4)
Methods:
Though mechanisms by which shift work causes
This cross-sectional study was conducted at Sri
metabolic and cardiovascular disorders are not
Manakula Vinayagar Medical College and Hospital
completely understood, it is suggested that the
(SMVMCH), Pondicherry, among 101 members of
major contributing factors include altered circadian
the security staff. The study included rotational
rhythm and confounding parameters such as
shift workers of both sex, aged between 25 and 45
smoking,
years, with a shift work experience of 6 months or
poor lifestyle choices,
and social
problems causing stress, which are common among
more.
shift workers.(2)
Subjects with any diagnosed non-communicable
Higher incidence of diseases such as coronary heart
disease
disease, metabolic syndrome, sleep disturbances,
Dyslipidemia, Endocrine disorders, Renal disease,
mental, emotional and behavioural disorders are
and Cardiovascular disease), blood dyscariases,
commonly found among shift workers and the
pregnant subjects and those with a work experience
sleep deprived.(5)It is already known that sleep
of less than 6 months were excluded.
duration influences the physical, emotional and
Data collection: Data collection was done between
mental well-being of an individual.(6)
7.00 and 9.00 AM after the night shift ended.
Multiple studies have found a poor glycemic status
Informed and written consent was obtained. A
to be associated with sleep deprivation. The
questionnaire
pathways relating serum glucose levels with sleep
information, duration of employment and duration
deprivation range from hormonal imbalance,
of sleep, was used to collect the data. Fasting blood
(involving cortisol, leptin and ghrelin) to the
samples were collected to measure the fasting
thermogenic responses to consumption of food,
blood glucose.
effect on insulin sensitivity and appetite. (7,8)The
Assessment of Fasting Blood Sugar: 1.5 ml of
American Heart Association has emphasised that
whole blood was collected from the study subjects
sleep of shorter duration may lead to a glycemic
after overnight fasting with dry disposable syringe
picture that trends towards diabetes.(9)
and needle by veni puncture under all aseptic
Though sleep deprivation has been considered as a
precaution. Serum was then separated after
risk factor for multiple morbidities, very limited
subjecting the collected blood to centrifugation at
data exists to show the relationship between
2500 rpm for 5min. Blood samples were analyzed
glycemic status and sleep deprivation among rural
using Cobas-Miras-Plus Automated Chemistry
population of India. This makes it essential to
Analyser (USA) at the college laboratory after
assess the glycemic status and to provide adequate
appropriate standardization in the lab.
(Diabetes
Mellitus,
requiring
Hypertension,
socio-demographic
management for the same in shift workers. This
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Ethical issues: Ethical principles such as respect for
Results:
the persons, beneficence and justice were adhered
The net sample size of this cross sectional study
to. Clearance from the Institutional Review Board
was 101, of which 68 subjects were male (67.3%),
was obtained prior to beginning the study. Blood
whereas 33 were females (32.7%). Evaluation of
samples collected for the study purpose were drawn
the collected data found an age range of 25 to 45
under strict aseptic precautions after obtaining
years. The total number of years of experience for
informed consent. No new information was
the study population was 1- 20 years. The sleep
withheld from the respondent.
duration, according to the received data was 3- 10
Analysis of quantitative and qualitative data: The
hours. The fasting blood sugar (FBS) was found to
data was entered and analysed by using Epi_info
have a range of 63- 120 mg/dl.
(version 6.04d) software package.
Table 1: Descriptive statistics for this study population
Parameter
Range
Mean ± S.D.
Age (years)
25 – 45
33.80 ± 6.417
Years of shift work (years)
1 – 20
10.47 ± 5.742
Duration of sleep (hours)
3 – 10
5.52 ± 1.540
Fasting blood sugar
63 – 120
90.41 ± 16.192
On further analysis, attempts were made to
the hours of sleep obtained in a day by the subject.
establish individual correlations between FBS and
Pearson’s correlation was used to analyse the
age of the subject, FBS and the total number of
desired data, as presented in table 2.
years since involvement in shift work and FBS and
Table 2: Correlation of parameters with FBS based on Pearson’s correlation.
Correlation of parameters with FBS
r
p
Age (years)
0.660
<0.001
Years of shift work (years)
0.666
<0.001
Duration of sleep (hours)
- 0.585
<0.001
P value <0.05 is considered significant
Pearson’s correlation demonstrated a positive
This study observes positive correlation between
relation of fasting blood sugar with the age of the
glycemic status and age as well as the total duration
subjects as well as the number of years of shift
of shift work experience. Meanwhile, the duration
work, both of which were highly significant
of sleep was found to be negatively correlated with
(p<0.001).
the fasting blood sugar.
A negative or inverse correlation was found
Discussion:
between the duration of sleep and the fasting blood
This study was done on shift workers and the
sugar of the subjects with r = -0.585, and p <0.001.
relationship between glycemic status and multiple
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factors pertaining to the study subjects was
tolerance appeared to be more frequent among shift
analysed. We found a positive correlation of FBS
workers as compared to day time workers. (11,12)
with increasing age and with a longer duration of
An Indian study, conducted by Sharma et al, stated
shift work experience. Subjects obtaining shorter
that presence of diabetes or poor glycemic status is
duration of sleep were found to have a poor
one of the most potential risk factors of
glycemic picture.
cardiovascular diseases, followed by hypertension
Dyssomnia is a constellation of disorders which
and coronary artery diseases. (13) It is an already
cause excessive sleepiness or else, difficulty
established fact that glycemic status is highly
initiating or maintaining sleep. Of the three types of
indicative of the cardio- metabolic risk in an
dyssomnias, shift work sleep disorder falls under
individual. Mosendane et al have offered a
circadian rhythm sleep disorders, the other two
systematic review of articles on shift work and its
classes’ being- intrinsic sleep disorders and
effect on cardiovascular system which concluded
extrinsic sleep disorders. Shift work sleep disorder
that long term effects result in cardio- metabolic
consists of insomnia or excessive sleepiness that
disturbances.(4)
occurs as transient phenomena with regard to the
The patho-physiology of this complex relation
work schedules. In such patients, the sleep period is
between shift work and glycemic status as well as
perceived as unsatisfactory. Security staff, with
propensity for cardiovascular risk development has
their duty rota of 6- 8 hours falls under shift work
been hypothesised by multiple studies.
and the sleep disorders in these individuals tends to
One of the pathways is the up-regulation of the
be shift work sleep disorder, more often than
orexin neuron activity which is said to be an
not.(10)
important mechanism relating sleep deprivation
According to the findings of this study, the duration
and metabolic abnormalities, as noted by Sakurai
of sleep or the number of hours of sleep, correlated
et al as well as de Lecea et al. (14,15)
negatively with the fasting blood glucose levels,
Also, as suggested by Thomas et al, the brain is a
while, conforming to this observation, a positive
major user of glucose, however, brain glucose
correlation was noted between the number of years
utilisation is reduced after sleep loss, which leads
of shift work experience and the glycemic picture.
to impaired glucose metabolism.(16)
Sleep of less than six hours is likely to have five
Morselli et al reviewed that duration of sleep
times the chance of developing abnormal fasting
affects various aspects of human physiology.
blood sugar levels as suggested by the American
Hormones like insulin, cortisol, growth hormone,
Heart Association. It is also hypothesised that
leptin, ghrelin and cardiac sympatho- vagal balance
impaired fasting blood glucose seen in these
can get altered due to sleep deprivation. These
individuals could be a potential precursor to type 2
alterations are proposed to be a result of alterations
diabetes. Moreover, a genetic basis is not
in the autonomic nervous system activity and in
speculated for this finding by the researchers,
those of counter-regulatory hormones.(7)
indicative of a non- genetic reason for this
Insulin
observation.(9)
activation and activated by para-sympathetic
Supporting our study, Boggild et al and Sookoian
stimulation.
et al have suggested that impaired glucose
compensatory hyperinsulinemia in response to the
release is
inhibited
However
the
by sympathetic
deficiency
of
reduced insulin sensitivity index, often found with
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International J. of Healthcare and Biomedical Research, Volume: 03, Issue: 03, April 2015, Pages 69-76
sleep loss can be related to abnormal autonomic
drug abuse. Alcoholism and drug dependency by
beta- cell regulation. (17,18)
itself is known to contribute to development of
Hormones regulating the appetite also have an
multiple lifestyle disorders like cardiovascular
impact on the metabolic consequences of sleep
diseases,
deprivation. Sympathetic activity inhibits leptin
(27,28)International
secretion while ghrelin secretion is inhibited by
Disorders-2 has also stated that the potential for
parasympathetic
development
hormonal
activity.
balance
is
This
physiological
interrupted
in
sleep
metabolic syndrome among others.
of
gastrointestinal
Classification
chronic
disorders
sleep
and
of
Sleep
disturbances,
cardiovascular
deprivation due to alteration in autonomic activity;
disease exists.(10)
which in turn leads to excessive production of
A meta- analysis of more than 27,000 people, by
ghrelin, (leading to increased appetite), and reduced
Karlsson et al found multiple aspects of metabolic
secretion of leptin, (causing poor satiety). (7,19,20)
syndrome to be associated with sleep deprivation.
Yet another pathway connecting sleep deprivation
(29)With increasing research in the field of sleep
to a poor metabolic picture is the presence of raised
studies, especially sleep deprivation and sleep loss,
levels of pro-inflammatory cytokines and low-
a multitude of disorders have been found to be
grade inflammation which may lead to insulin and
associated
leptin resistance. (21–24)
emotional and behavioural abnormalities, coronary
These proposed pathophysiological pathways may
artery disease,
not always conform to all studies, as seen in a study
gastrointestinal disorders, elevated risk of breast
conducted by Patel et al, among adolescents; no
cancer and unfavourable pregnancy outcomes.
relation between inadequate sleep and fasting blood
(4,30,29)
sugar was found in this particular research.(25)
According to established data by the International
Similarly, Ghiasvand et al and Ha et al observed a
Classification of Sleep Disorders-2, the age of
significant association of shift work only with lipid
onset of this type of dyssomnias is variable, in
profile alteration and not the blood glucose.
general, and depends on the age at which patient
(3,26)Despite not finding an association with
begins shift work.(10) Our findings stated that age
fasting blood sugar, the aforementioned study did
as well as the duration of shift work experience
find a significant association with lipid profile,
correlated positively with glycemic status in the
which is again indicative of cardio- metabolic risk
study subjects.
among the sleep deprived.
Karlsson et al, found a poor glycemic status to be
The interference and disruptions in social and
more frequent among 60 year old female shift
family life are common and may lead to drug and
workers.(29) While, Jermendy et al observed that
alcohol dependency exacerbated by attempts to
middle aged active shift workers, particularly
improve whatever sleep is obtainable and to reduce
women have a relatively poorer lifestyle and are
the wakefulness disruption produced by abnormal
more prone to cardio- metabolic risk. (5)
working hours. (10)
But, the International Classification of Sleep
Shift workers, by virtue of their prolonged and
Disorders-2, which is currently under review, stated
socially awkward working hours, have a higher
that there is no known difference of features on
tendency to indulge in poor lifestyle choices like
comparison between males and females. (10)
including-
cognitive
dysfunction,
metabolic syndrome,
obesity,
over-eating, smoking, alcoholism and at times,
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A general trend towards a decline in average sleep
Conclusion:
duration over the past 50 years expectedly overlaps
This study found a positive correlation between
with an increased incidence and prevalence of
fasting blood sugar and age of the subjects
obesity, along with other adverse effects on cardio-
(r=0.660, p<0.001) and also with duration of shift
metabolic and hormonal activities. (8)
work experience (r=0.666, p<0.001). While a
The unfortunate aspect of shift work is the
negative correlation was established between
persistence of sleep loss and deprivation throughout
fasting blood glucose and the duration of sleep (r= -
the duration of such a job. Adaptation has been
0.585, p<0.001). With the multitude of pre-
found to rarely occur, regardless of the number of
disposing factors to cardio- metabolic disorders
years of work experience. It has been suggested
already
that the reason for non- adaptability might be
occupational health check- ups can be provided.
resumption of full day time activities and night
History of shift work experience, duration of sleep,
time sleep during off- days, weekends and
smoking, alcoholism and other lifestyle choices,
vacations.(10)
assessment of blood pressure, body mass index,
The recently introduced ergonomic shift criteria
lipid profile and the glycemic status could be of use
which can intervene in shift work scheduling is one
in screening or monitoring the well- being of shift
of the methods to assess ill health at the earliest
workers.
present
in
shift
workers,
regular
which will augment the well-being of shift workers
with sleep deprivation.(31)
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