Effects of sleep deprivation
SHORT PAPER
Effects of sleep deprivation on neuroendocrine hormones in servicemen
Xin-Yang SUN,1*Hong-Tao SONG,2*Ting-shu YANG,3*Li-Yi ZHANG,4Lin ZHAO,5Jia-Lin YANG 3and Jing BAI 3
1
Departement of Psychology,The Second Military Medical University,Shanghai,2Clinical Medical School,Jiangsu University,Zhenjiang,Jiangsu,3Department of Cardiology,General Hospital of Chinese People’s Liberation Army,Beijing,4Prevention and Treatment Center of Psychological Diseases,No.102Hospital of Chinese People’s Liberation Army,Changzhou,and 5Clinical Medical School,Xuzhou Medical College,Xuzhou,Jiangsu,China
Abstract
This study aimed to investigate the effects of 24h total sleep deprivation on serum rennin,angiotensin II,cortisol,dopamine,epinephrine and norepinephrine in servicemen.A total of 223servicemen had blood drawn before and after deprivation for serum rennin,angiotensin II and cortisol measurements.Altogether 60participants were randomly selected from all the participants as a subsample for serum dopamine,epinephrine and norepinephrine measurements.The results revealed that the levels of all six hormones after sleep deprivation were signi?cantly higher than those before.We conclude that sleep deprivation probably serves as an endogenous stressor via complex pathways.
Key words:angiotensin II,catecholamine,cortisol,dopamine,rennin,sleep deprivation.
INTRODUCTION
Sleep is an instinctive biological phenomena to maintain normal function,1which is constantly regulated through complex interactions between multiple brain regions,neurotransmitters and https://www.wendangku.net/doc/9314646170.html,ura et al .conducted partial sleep deprivation on 31healthy male subjects and found that sleep loss may serve to decrease nocturnal interleukin-6(IL-6)levels with effects on the integrity of immune system functioning and may have implications for in?ammatory disease risk.2Dettoni
et al .carried out partial sleep deprivation on 13healthy male subjects,concluding that sleep deprivation might promote vein endothelial dysfunction,which might play a role in precipitating cardiovascular diseases.3A recent study revealed that a great variety of hormones secre-tion,stress hormones in particular,namely cortisol,epi-nephrine and norepinephrine,soared in the course of sleep deprivation.4Currently ,some of the sleep depri-vation studies took animals as subjects,the conclusions of which could hardly apply to humans.The sleep deprivation studies with a human sample size of more than 30are scarce in general population groups,let alone special population groups.In this study ,a total of 223servicemen were selected to undergo 24h total sleep deprivation,before and after which six horm-ones,including cortisol,epinephrine,norepinephrine,rennin,dopamine and angiotensin II based on relevant research results,3–5were measured.Our hypothesis that if sleep deprivation should serve as an endogenous stressor,it would exert impact on all of these six
Correspondence:Dr Li-yi Zhang,Prevention and Treatment Center of Psychological Diseases,No.102
Hospital of Chinese People’s Liberation Army ,North Peace Road 55,Changzhou 213003,Jiangsu,China.Email:zly102@https://www.wendangku.net/doc/9314646170.html,
*These authors have contributed equally to this paper and agreed to share the ?rst authorship position together.Accepted 28July 2013.
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Sleep and Biological Rhythms 2013;11:274–277doi:10.1111/sbr.12027
274
?2013The Authors
hormones,would shed light on,if validated,interven-tion methodology of reducing harm and injury induced by sleep deprivation,providing valuable evidence for enhancing mental and physical health of sleep-deprived servicemen and the general population. METHODS
Participants
A total of223servicemen were selected as a convenient sample by random cluster sampling from a military unit whose title could not be disclosed due to military con?dentiality consideration based upon the following inclusion criteria:physically and mentally healthy, no history of mental illnesses,recent sleep shortage, fatigue,or any traumatic life events one month before testing;no smoking or over-drinking alcohol or coffee or tea at least48h before testing;currently not on any medication.
Procedures
Three trained research fellows(one clinical chief doctor, one an attending doctor and one professional laboratory technician)were involved in the procedure.The pro-cedure was carried out in an exclusive sleep laboratory in the General Hospital of the People’s Liberation Army (PLA)in Beijing.All participants were instructed to col-lectively stay in the laboratory and its controlled vicinity for7days of baseline preparation.During this prepara-tion period,all the participants were served with stand-ard meals three times a day without content of alcohol or tea or coffee or chocolate,and allowed to be active within a certain limit.No vigorous activity or smoking was allowed.Sleep diaries were kept by simple reviews for all participants every morning including information on sleep duration,sleep quality,awakening time and any abnormal events during sleep the night before.After 7days of normal sleep as baseline preparation,the procedure started at8AM on Day8and ended at8AM on Day9,during which a total of218out of the223 participants underwent24h total sleep deprivation. Four participants who found the procedure insufferable and one participant who complained of blood with-drawal procedure were allowed to quit prematurely.All participants had blood drawn at8AM on Day8and Day 9.During the24h,all participants were con?ned to an exclusive large lobby,spending time reading,watching TV or movies(with lights on),playing poker or chess, or walking outside for a short span of time under close surveillance.All laboratory conditions were kept the same as the preparation period.Three research fellows had been monitoring by paying close attention to each and every one of them,preventing dozing off or naps.When a subject appeared drowsy,a research fellow would engage him in leisurely conversation. Also,in order to guarantee the representative power of our sample to the most extent,and derail the military routine training schedule to the least extent,we deter-mined to select60participants by systematic random sampling from the total sample for serum dopamine, epinephrine and norepinephrine measurements at8AM on Day9.However,6of the60participants who were assigned emergent military tasks were removed from this subsample,leaving54for further study.The proto-col for this study was approved by the Human Research Medical Ethics Committee at No.102Hospital of PLA. Informed consents were obtained from all participants. Measurements
Radioimmuneassay(RIA)was used by the Endocrine Laboratory of General Hospital of Chinese People’s Liberation Army to measure all six hormones using commercial kits(instrument speci?cations:XH6080; agent company:DIAsouce Immunoassays s.s.Belgium) with intra-and interassay coef?cients of variations of less than10%.All measurements were run in parallel. Statistical analysis
All data were processed in SPSS version17.0.All the hormone level data were analyzed using matched pair t-test,which was recommended for an identical sample before and after intervention.P-values less than0.05 were considered statistically signi?cant. RESULTS
A total of182of the subjects were soldiers(81.61%), and41were of?cers(18.39%);service duration aver-aged1.19(SD=1.62,ranging from1to13)years; average age20.77(SD=2.08,from17to30)years;52 of the total from urban areas(23.32%)and171from rural areas(76.68%);214unmarried(95.96%)and nine married(4.04%).Matched pair t-test results indicated that serum rennin,angiotensin II and cortisol levels after sleep deprivation were signi?cantly higher than those before sleep deprivation(P<0.05).See Table1. Matched pair t-test results revealed that serum dopa-mine,epinephrine and norepinephrine levels after sleep Sleep deprivation and neuroendocrine hormones
deprivation were signi?cantly higher than those before sleep deprivation(P<0.05),see Table2. DISCUSSION
Con?icting results of studies on cortisol lead to inde?-nite conclusions.Eun et al.found signi?cantly elevated serum concentrations of stress hormones,including cor-tisol,epinephrine,and norepinephrine.4Another study by Mullington et al.demonstrated elevations in cortisol during total acute sleep deprivation in the late afternoon and into the early nighttime hours.5This result was replicated by Spiegel et al.in a partial sleep deprivation study.6On the other hand,some studies did not detect elevated effects of cortisol7or even found decreased effects.8A potential explanation of these results is that the maintenance of slow wave sleep(SWS)after sleep restriction might have prevented signi?cant cortisol changes to a certain degree.In our study,the results exhibited that the serum cortisol level after sleep deprivation was signi?cantly higher than that before.
A possible explanation is that maintenance of continued wakefulness activates hypothalamo-pituitary-adrenal (HPA)axis,which in turn induces an increase of serum cortisol,a dominant component of glucocorticoid.In addition to methodological factors,these studies with inconsistent results imply that stress hormone changes induced by sleep deprivation probably involved multiple pathways,which would better explain its endocrinological effects than a unitary pathway.Also, catecholamine results of sleep deprivation studies have been con?icting,and studies on sleep deprivation effects on dopamine in human subjects are rarely reported.In this study,the levels of serum dopamine,epinephrine and norepinephrine after the sleep deprivation were signi?cantly higher than those before.This result advocates the hypothesis that as a typical endoge-nous stressor,sleep deprivation could activate locus coeruleus-noradrenergic neurons/sympathetic-adrenal medulla axis,leading to signi?cant increases of serum dopamine,norepinephrine,and epinephrine levels.In addition,relevant studies have shown that norepine-phrine(NE)is one of the main neurotransmitters involved in arousal.The neurotransmitter NE,through its involvement in the ascending arousal system,might be active in the wake-promoting pathway,9thus demon-strating another stress pathway besides HPA axis.10All of these studies combined suggest that catecholamine changes induced by sleep deprivation presented uncer-tainty,which might result from different methodolo-gies,laboratory conditions,and arti?cial factors.Rennin and angiotensin II are rarely seen in sleep deprivation studies.As we were trying to verify sleep deprivation to be an endogenous stressor,we hypothesize that rennin and angiotensin II would also increase after sleep dep-rivation.The results revealed signi?cant increases of rennin and angiotensin II level after deprivation than those before,which was a clear sign of rennin-angiotensin system activation.
Limitations
We had blood drawn for measurements only once, making it impossible to establish a dynamic chart of targeted hormone levels.Second,we had no female subjects for comparison.
Table1Comparison between cortisol,rennin and angiotensin II levels before and after sleep deprivation
Variables Sample
(n)
Before sleep
deprivation x±
()S
After sleep
deprivation x±
()S t-value P-value
Rennin(ng/mL.h)218 2.152±1.187 3.018±1.9827.2040.000 Angiotensin II(pg/mL)21862.23±14.98665.648±21.289 2.1730.031 Cortisol(nmol/L)218486.587±102.062508.788±89.467 2.3720.019 Table2Comparison between dopamine,epinephrine and norepinephrine levels before and after sleep deprivation
Variables Sample
(n)
Before sleep
deprivation x±
()S
After sleep
deprivation x±
()S t-value P-value
Dopamine(nmol/24h)547.870±2.1538.820±2.891 2.2140.031 Epinephrine(nmol/24h)5425.802±7.48031.035±10.717 3.8780.000 Norepinephrine(nmol/24h)54 1.456±0.646 2.260±1.213 5.9930.000 X-Y Sun et al.
276?2013The Authors
ACKNOWLEDGMENTS
We sincerely thank the military personnel for their participation,and all the medical staff involved in the whole procedure.
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Sleep deprivation and neuroendocrine hormones