Restricted and disrupted sleep: Effects on autonomic function, neuroendocrine stress systems and stress responsivity

Exploring the Sleep Experience of Hospitalized Adult Patients

Interruptions in sleep for hospitalized patients have been correlated with decreases in immune function, changes in mental status, and increased stress levels. The purpose of this study was to explore patients’ perceptions of their sleep experiences during hospitalization. Structured interviews were conducted with a convenience sample of patients who had spent three consecutive nights in the hospital. Data was analyzed by content analysis; three themes emerged from the data. The findings from this pilot study will lead to further research in nursing practice as it relates to supporting sleep and rest in hospitalized patients.

Racial differences in sleep architecture: the role of ethnic discrimination

African Americans have been consistently shown to have less deep (slow wave sleep; SWS) and more light (Stages 1 and 2) sleep than Caucasian Americans. This paper explored whether discrimination, a stressor that uniquely impacts certain ethnic groups, contributes to differences in sleep architecture. The sleep of 164 African and Caucasian Americans was examined with laboratory based polysomnography (PSG). Experiences of perceived discrimination (The Scale of Ethnic Experience) and sociodemographic factors were also assessed. After adjusting for age, body mass index (BMI), socioeconomic status (SES) and smoking status, African Americans slept approximately 4.5% more total sleep time (TST) in Stage 2 sleep and 4.7% less TST in SWS than Caucasian Americans (ps<.05). Perceived discrimination was a partial mediator of ethnic differences in sleep architecture. Individuals who reported experiencing more discrimination slept more time in Stage 2 and less time in SWS (ps<.05). Results suggest that the impact of stress related to ethnic group membership plays a part in explaining differences in sleep architecture.

Influence of paradoxical sleep deprivation and sleep recovery on testosterone level in rats of different ages

This study was performed to assess serum testosterone alterations induced by paradoxical sleep deprivation (PSD) and to verify their attenuation during sleep recovery (SR) based on different durations and ages. Wistar male rats aged 12 weeks for the younger group and 20 weeks for the elder group were randomly distributed into one of the following groups: a control group (cage and platform), 3-day SD, 5-day SD, 7-day SD, 1-day SR, 3-day SR and 5-day SR groups. For PSD, the modified multiple platform method was used to specifically limit rapid eye movement (REM) sleep. Differences in the testosterone and luteinizing hormone levels between the younger group and the elder group according to duration of PSD and SR recovery were analysed. Testosterone continued to fall during the sleep deprivation period in a time-dependent manner in both the younger (P=0.001, correlation coefficient r=-0.651) and elder groups (P=0.001, correlation coefficient r=-0.840). The elder group showed a significantly lower level of testosterone compared with the younger group after PSD. Upon SR after 3 days of PSD, the testosterone level continued to rise for 5 days after sleep recovery in the younger group (P=0.013), whereas testosterone concentrations failed to recover until day 5 in the elder group. PSD caused a more detrimental effect on serum testosterone in the elder group compared to the younger group with respect to decreases in luteinizing hormone (LH) levels. The replenishment of serum testosterone level was prohibited in the elder group suggesting that the effects of SD/SR may be age-dependent. The mechanism by which SD affects serum testosterone and how age may modify the process are still unclear.

Sleep and immune function

Sleep and the circadian system exert a strong regulatory influence on immune functions. Investigations of the normal sleep–wake cycle showed that immune parameters like numbers of undifferentiated naïve T cells and the production of pro-inflammatory cytokines exhibit peaks during early nocturnal sleep whereas circulating numbers of immune cells with immediate effector functions, like cytotoxic natural killer cells, as well as anti-inflammatory cytokine activity peak during daytime wakefulness. Although it is difficult to entirely dissect the influence of sleep from that of the circadian rhythm, comparisons of the effects of nocturnal sleep with those of 24-h periods of wakefulness suggest that sleep facilitates the extravasation of T cells and their possible redistribution to lymph nodes. Moreover, such studies revealed a selectively enhancing influence of sleep on cytokines promoting the interaction between antigen presenting cells and T helper cells, like interleukin-12. Sleep on the night after experimental vaccinations against hepatitis A produced a strong and persistent increase in the number of antigen-specific Th cells and antibody titres. Together these findings indicate a specific role of sleep in the formation of immunological memory. This role appears to be associated in particular with the stage of slow wave sleep and the accompanying pro-inflammatory endocrine milieu that is hallmarked by high growth hormone and prolactin levels and low cortisol and catecholamine concentrations.

Psychosocial factors and sleep efficiency: discrepancies between subjective and objective evaluations of sleep

OBJECTIVES

Self-reported sleep efficiency may not precisely reflect objective sleep patterns. We assessed whether psychosocial factors and affective responses are associated with discrepancies between subjective reports and objective measures of sleep efficiency.

METHODS

Participants were 199 working women aged 20 to 61 years. Standardized questionnaires were used to assess psychosocial characteristics and affect that included work stress, social support, happiness, and depressive symptoms. Objective measures of sleep were assessed on one week and one leisure night with an Actiheart monitor. Self-reported sleep efficiency was derived from the Jenkins Sleep Problems Scale. Discrepancies between self-reported and objective measures of sleep efficiency were computed by contrasting standardized measures of sleep problems with objectively measured sleep efficiency.

RESULTS

Participants varied markedly in the discrepancies between self-reported and objective sleep measures. After adjustment for personal income, age, having children, marital status, body mass index, and negative affect, overcommitment (p = .002), low level of social support (p = .049), and poor self-rated heath (p = .02) were associated with overreporting of sleep difficulties and underestimation of sleep efficiency. Self-reported poor sleep efficiency was more prevalent among those more overcommitted at work (p = .009) and less happy (p = .02), as well as among those with lower level of social support (p = .03) and more depressive symptoms (p = .048), independently of covariates. Objective sleep efficiency was unrelated to psychosocial characteristics or affect.

CONCLUSIONS

The extent to which self-reported evaluations of sleep efficiency reflect objective experience may be influenced by psychosocial characteristics and affect. Unless potential moderators of self-reported sleep efficiency are taken into account, associations between sleep and psychosocial factors relevant to health may be overestimated.

Sleep and cardiovascular regulation

Normal sleep has a profound effect on the cardiovascular system, reducing cardiovascular activity throughout non-rapid eye movement sleep; changes that are modified and augmented by circadian system influence. There is also evidence that sleep-initiated changes in autonomic balance may in turn modify the development of sleep within a night, particularly the development of slow wave sleep. It is assumed that the cardiovascular changes that accompany sleep reflect a functional aspect of sleep, although the precise functional role has not been agreed upon. Nevertheless, there is good evidence that the cardiovascular changes that occur during normal sleep are beneficial for the cardiovascular system. Arousals from sleep, which are common even in normal sleep, are associated with a surge in activity in cardiorespiratory systems, with marked effects on the sleep-related pattern of cardiovascular activity when they occur frequently. Despite the importance of this aspect of sleep, controversy remains as to both the nature of the activation response and the circumstances under which it is elicited. The concept that sleep-related changes in cardiovascular activity are beneficial leads to the corollary that sleep disturbance would result in adverse cardiovascular consequences. While there is strong empirical evidence for such a relationship, it remains unclear whether this is a direct effect or, as has been suggested recently, the effect of disturbed sleep is mediated via stress-related modification of neuroendocrine systems.

Immune, inflammatory and cardiovascular consequences of sleep restriction and recovery

In addition to its effects on cognitive function, compelling evidence links sleep loss to alterations in the neuroendocrine, immune and inflammatory systems with potential negative public-health ramifications. The evidence to suggest that shorter sleep is associated with detrimental health outcomes comes from both epidemiological and experimental sleep deprivation studies. This review will focus on the post-sleep deprivation and recovery changes in immune and inflammatory functions in well-controlled sleep restriction laboratory studies. The data obtained indicate non-specific activation of leukocyte populations and a state of low-level systemic inflammation after sleep loss. Furthermore, one night of recovery sleep does not allow full recovery of a number of these systemic immune and inflammatory markers. We will speculate on the mechanism(s) that link(s) sleep loss to these responses and to the progression of cardiovascular disease. The immune and inflammatory responses to chronic sleep restriction suggest that chronic exposure to reduced sleep (<6 h/day) and insufficient time for recovery sleep could have gradual deleterious effects, over years, on cardiovascular pathogenesis with a heightened risk in women and in night and shift workers. Finally, we will examine countermeasures, e.g., napping or sleep extension, which could improve the recovery processes, in terms of alertness and immune and inflammatory parameters, after sleep restriction.

Prevalence of restless legs syndrome in North American and Western European populations: a systematic review

BACKGROUND

Restless legs syndrome (RLS) is a potentially debilitating sleep disorder that affects a significant percentage of North American and European adults. Although standardized RLS diagnostic criteria are now established and widely accepted, reported prevalence estimates have varied widely. In this paper, we review the literature regarding RLS prevalence in North American and Western European adult populations, examine potential sources of variation, briefly discuss the impact of RLS, and offer recommendations for future research.

METHODS

To identify qualifying studies, we searched 6 scientific databases and scanned bibliographies of relevant review papers and all identified articles. Studies including fewer than 300 participants, that did not use any of the 4 standard diagnostic criteria, were published prior to 1995 or targeted clinical populations were excluded.

RESULTS

Thirty-four papers detailing results of large, population-based studies in 16 North American and Western European countries met our inclusion criteria, including 5 multi-country studies (N=69,992 participants) and 29 single country studies (N=163,188 participants); all but one were cross-sectional. Reported general prevalence rates ranged from 4% to 29% of adults, averaging 14.5±8.0% across studies. Reported prevalence averaged higher in primary care populations than in populations derived from random sampling or geographically defined cohorts (19.5±7.9% vs. 12.3±7.2%). Diagnostic and severity criteria differed considerably among studies, as did inclusion criteria, with corresponding variation in prevalence estimates. Prevalence averaged higher in women and older adults; more limited data suggest race/ethnicity, parity, health status, and other factors may also contribute to the observed variation in prevalence. RLS has profound, negative effects on health, well-being, and quality of life, yet detection rates remain low.

CONCLUSIONS

Collectively, these studies indicate that RLS is a common disorder of major clinical and public health significance in the Western industrialized world, affecting between 4% and 29% of adults. The wide variation in reported prevalence likely reflects differences in demographic factors, health status, and other population characteristics; study population source and sampling frame; and inconsistencies in RLS diagnostic criteria and procedures. Prospective studies and corresponding incidence data on RLS are lacking, hindering the evaluation of both causal factors and sequelae.

No elevated plasma catecholamine levels during sleep in newly diagnosed, untreated hypertensives

The sympatho-adrenergic system is highly involved in regulating sleep, wake and arousal states, and abnormalities in this system are regarded as a key factor in the development and progression of arterial hypertension. While hypertension is associated with a hyperadrenergic state during wakefulness, the effect of hypertension on plasma-catecholamine levels during sleep is not yet known. Twelve young participants with newly diagnosed, untreated hypertension and twelve healthy controls slept for 7 hours in the sleep laboratory. Before and after sleep, subjects rested in a supine position for 3-h periods of wakefulness. We sampled blood at a fast rate (1/10 min) and monitored blood pressure and heart rate continuously. We show that plasma NE and E levels did not differ between hypertensives and normotensive during sleep as well as before and after sleep. Blood pressure was higher in hypertensives, reaching the largest group difference in the morning after sleep. Unlike in the normotensives, in the hypertensive participants the morning rise in blood pressure did not correlate with the rise in catecholamine levels at awakening. Our results suggest that hypertension in its early stages is not associated with a strong hyperadrenergic state during sleep. In showing a diminished control of blood pressure through sympatho-adrenergic signals in hypertensive participants, our data point towards a possible involvement of dysfunctional sleep-related blood pressure regulation in the development of hypertension.

Effects of body mass index on sleep patterns during pregnancy

The purpose of this study was to profile sleep patterns during pregnancy according to body mass index (BMI) and to correlate labour outcomes with both BMI and hours sleep. Data were collected from 200 postpartum women detailing sleep characteristics before and during pregnancy. A validated sleep questionnaire was employed, which comprised of questions about sleep apnoea, snoring, subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication and daytime dysfunction. Descriptive analyses were used. With advancing gestation, the mean (SD) number of hours sleep per night declined: pre-pregnancy 8.1 (SD 1.4); 1st trimester 8.3 (SD 1.8); 2nd trimester 7.7 (SD 1.7) and 3rd trimester 6.7 (SD 2.2). In the 18.5-24.9 BMI group, there was a marked difference in hours sleep per night from pre-pregnancy to 1st (8.6 h, p = 0.007), 2nd (7.9 h, p = 0.023) and 3rd (6.4 h, p = 0.000) trimesters in primiparous women. In the 25-29.9 BMI group, there was a difference from pre-pregnancy to 3rd trimester (p = 0.000). These changes were not reflected in a clinically significant difference in birth weight or mode of delivery.

Angiotensin I-converting enzyme (ACE) activity and expression in rat central nervous system after sleep deprivation

Proteases are essential either for the release of neuropeptides from active or inactive proteins or for their inactivation. Neuropeptides have a fundamental role in sleep-wake cycle regulation and their actions are also likely to be regulated by proteolytic processing. Using fluorescence resonance energy transfer substrates, specific protease inhibitors and real-time PCR we demonstrate changes in angiotensin I-converting enzyme (ACE) expression and proteolytic activity in the central nervous system in an animal model of paradoxical sleep deprivation during 96 h (PSD). Male rats were distributed into five groups (PSD, 24 h, 48 h and 96 h of sleep recovery after PSD and control). ACE activity and mRNA levels were measured in hypothalamus, hippocampus, brainstem, cerebral cortex and striatum tissue extracts. In the hypothalamus, the significant decrease in activity and mRNA levels, after PSD, was only totally reversed after 96 h of sleep recovery. In the brainstem and hippocampus, although significant, changes in mRNA do not parallel changes in ACE specific activity. Changes in ACE activity could affect angiotensin II generation, angiotensin 1–7, bradykinin and opioid peptides metabolism. ACE expression and activity modifications are likely related to some of the physiological changes (cardiovascular, stress, cognition, metabolism function, water and energy balance) observed during and after sleep deprivation.

Biological Consequences of Disturbed Sleep: Important Mediators of Health?

There is an extensive literature regarding the immunological and endocrinological consequences of illness, stress, and psychopathology. Yet only a modest literature is available regarding the potential unfavorable effects of chronic sleep loss/disruption on immune and endocrine pathways or on various aspects of health. Given that humans spend approximately 1/3 of their lives asleep, it seems pertinent to evaluate this necessary yet understudied behavior. The evidence overwhelmingly indicates that "excessive" sleep disruption or poor sleep quality/continuity may subsequently increase risk for adverse health outcomes, as well as mortality. This is thought to occur through dysregulation of biological pathways. While our information addressing the immunological or endocrinological consequences of poor sleep is mounting, the majority of evidence stems from epidemiologic and cross-sectional studies. The immune and endocrine systems are dynamic and constantly in flux. Thus, the methodologies and study designs used to understand how sleep affects these systems needs to be as dynamic. Experimental manipulations and longitudinal evaluations are needed to effectively understand sleep as a risk factor for health. Thus, this paper is a primer in which to highlight the immunological and endocrinological consequences of disrupted or disturbed sleep as well as describe how these relationships may impact overall health. It is also meant to spark an interest for future evaluations of how the behavior of sleep is relevant to health.

Do mice habituate to "gentle handling?" A comparison of resting behavior, corticosterone levels and synaptic function in handled and undisturbed C57BL/6J mice

STUDY OBJECTIVES

"Gentle handling" has become a method of choice for 4-6 h sleep deprivation in mice, with repeated brief handling applied before sleep deprivation to induce habituation. To verify whether mice do indeed habituate, we assess how 6 days of repeated brief handling impact on resting behavior, on stress, and on the subunit content of N-methyl-D-aspartate receptors (NMDARs) at hippocampal synapses, which is altered by sleep loss. We discuss whether repeated handling biases the outcome of subsequent sleep deprivation.

DESIGN

Adult C57BL/6J mice, maintained on a 12 h-12 h light-dark cycle, were left undisturbed for 3 days, then handled during 3 min daily for 6 days in the middle of the light phase. Mice were continuously monitored for their resting time. Serum corticosterone levels and synaptic NMDAR subunit composition were quantified.

RESULTS

Handling caused a ∼25% reduction of resting time throughout all handling days. After six, but not after one day of handling, mice had elevated serum corticosterone levels. Six-day handling augmented the presence of the NR2A subunit of NMDARs at hippocampal synapses.

CONCLUSION

Repeated handling induces behavioral and neurochemical alterations that are absent in undisturbed animals. The persistently reduced resting time and the delayed increase in corticosterone levels indicate that mice do not habituate to handling over a 1-week period. Handling-induced modifications bias effects of gentle handling-induced sleep deprivation on sleep homeostasis, stress, glutamate receptor composition and signaling. A standardization of sleep deprivation procedures involving gentle handling will be important for unequivocally specifying how acute sleep loss affects brain function.

A review of evidence for the claim that children are sleeping less than in the past

STUDY OBJECTIVES

The notion that children are sleeping less than they used to is widespread. This study examined the strength of the evidence for this idea by tracing a "scholarly genealogy" of the claims presented within the literature.

DESIGN

A systematic review of peer-reviewed literature was conducted to identify claims of a secular trend in children's sleep. For each identified claim, the references cited were reviewed.

MEASUREMENTS AND RESULTS

The review identified 51 studies. Of these, 17 evinced evidence (2 reported increases, 3 reported no change, 6 reported mixed trends, 6 reported decreases) and 34 provided statements without evidence. Although the evidence that sleep duration has declined is contested, all 34 studies reported a decline. Examination of the references cited revealed that 17 papers referred directly to studies which provided evidence, 4 papers referred indirectly to studies which provided evidence, 9 papers did not provide any evidence and 4 papers referred to studies which could not be located. Of the papers that did provide evidence, 85% referred to one of 3 sources of evidence, each of which was of moderate quality.

CONCLUSIONS

The genealogy of the notion of secular declines in children's sleep reveals a limited scientific basis. The apparent evidence base is inflated by repeated references to the same sources of evidence, reference to secondary sources, mis-referencing, and a failure to cite contrary evidence.

Sympathetic and angiotensinergic responses mediated by paradoxical sleep loss in rats

Introduction: Recent investigations over the past decade have linked the development of hypertension to sleep loss, although the mechanisms underlying this association are still under scrutiny. To determine the relationship between sleep deprivation and cardiovascular dysfunction, we examined the effects of paradoxical sleep deprivation on heart rate, blood pressure, sympathetic nerve activity (SNA) and their consequences in the blood renin—angiotensin system.

Materials and methods: Wistar-Hannover male rats were randomly assigned to three experimental groups: 1) control, 2) paradoxical sleep deprivation for 24 h and 3) paradoxical sleep deprivation for 96 h. Blood pressure and heart rate were recorded in awake, freely moving rats.

Results: Heart rate was higher in the 96 h paradoxical sleep deprivation group compared with the control group. Renal SNA was increased in all deprived groups. However, no significant statistical differences were observed in blood pressure or splanchnic SNA among groups. Paradoxical sleep deprivation (24 and 96 h) reduced plasma angiotensin II (Ang II) concentrations.

Conclusions: The results suggest that selective sleep deprivation produces an increase in SNA, preferentially in the kidney. Thus, alterations in the sympathetic system in response to sleep loss may be an important pathway through which hypertension develops.

Sleep deprivation increases blood pressure in healthy normotensive elderly and attenuates the blood pressure response to orthostatic challenge

STUDY OBJECTIVES

To determine how aging affects the impact of sleep deprivation on blood pressure at rest and under orthostatic challenge.

DESIGN

Subjects underwent a night of sleep and 24.5 h of sleep deprivation in a crossover counterbalanced design.

SETTING

Sleep laboratory.

PARTICIPANTS

Sixteen healthy normotensive men and women: 8 young adults (mean 24 years [SD 3.1], range 20-28 years) and 8 elderly adults (mean 64.1 years [SD 3.4], range 60-69 years).

INTERVENTIONS

Sleep deprivation.

MEASUREMENTS AND RESULTS

Brachial cuff arterial blood pressure and heart rate were measured in semi-recumbent and upright positions. These measurements were compared across homeostatic sleep pressure conditions and age groups. Sleep deprivation induced a significant increase in systolic and diastolic blood pressure in elderly but not young adults. Moreover, sleep deprivation attenuated the systolic blood pressure orthostatic response in both age groups.

CONCLUSIONS

Our results suggest that sleep deprivation alters the regulatory mechanisms of blood pressure and might increase the risk of hypertension in healthy normotensive elderly.

Evening preference is related to the incidence of depressive states independent of sleep-wake conditions

Although evening preference has recently been identified as a risk factor for depression, it has not been substantiated whether evening preference is a direct risk factor for depressive states, or if it is associated secondarily through other factors, such as delayed sleep timing and shortened sleep duration. The objective of this study is to investigate associations in Japanese adult subjects between evening preference and incidence of depressive states, adjusting for various sleep parameters related to depressive states. The Morningness-Eveningness Questionnaire (MEQ), the Pittsburgh Sleep Quality Index (PSQI), and the Center for Epidemiologic Studies Depression Scale (CES-D) were administered to 1170 individuals (493 males/677 females; mean and range 38.5 and 20-59 yrs) to assess their diurnal preferences, sleeping states, and presence of depression symptoms. Subjects were classified into five chronotypes based on MEQ scores. Evening preference was associated with delayed sleep timing, shortened sleep duration, deteriorated subjective sleep quality, and worsened daytime sleepiness. Logistic regression analysis demonstrated that the extreme evening type (odds ratio [OR] = 1.926, p = .018) was associated with increased incidence of depressive states and that the extreme morning type (OR = 0.342, p = .038) was associated with the decreased incidence of depressive states, independent of sleep parameters, such as nocturnal awakening (OR = 1.844, p < .001), subjective sleep quality (OR = 2.471, p < .001), and daytime sleepiness (OR = 1.895, p = .001). However, no significant associations were observed between the incidence of depressive states and sleep duration, sleep timing, and sleep debt (levels of insufficient sleep). Although the findings of this study do not demonstrate a causative relationship between evening preference and depression, they do suggest the presence of functional associations between mood adjustment and biological clock systems that regulate diurnal preference. They also suggest that evening preference might increase susceptibility to the induction of mood disorders.

Relationship of sleep quantity and quality with 24-hour urinary catecholamines and salivary awakening cortisol in healthy middle-aged adults

OBJECTIVES

a. Explore the stability in sleep/wake patterns of middle-aged adults over a 3-year follow-up period. b. Explore the relationship between objectively measured sleep indices, urinary catecholamines, and salivary cortisol.

DESIGN

Naturalistic follow-up for sleep/wake patterns (n = 114) by 2-week sleep log and cross-sectional design for objective sleep assessments and hormonal measures (n = 96) at follow-up period nearly 3 years after baseline measurements.

SETTING

Community

PARTICIPANTS

Healthy middle-aged adults

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

There were high correlations between baseline and follow-up period (2.6 ± 0.5 years) on sleep/wake patterns (r = 0.6-0.79) as measured by 2-week sleep log. For wave 2 cross-sectional study, objective poor sleepers (3-day actigraphy sleep efficiency < 85%) had a higher 24-h urinary norepinephrine (NE) level (205.7 ± 105 nmol/d vs 162.1 ± 55.6 nmol/d, P = 0.03) and a nearly significantly higher 24-h urinary epinephrine (E) level (P = 0.12) than good sleepers. There were no differences in 3-day mean salivary awakening cortisol and 24-h urinary catecholamines (NE and E) between short and normal/long sleepers. Linear regression results, however, showed that shorter time in bed and actual sleep time, longer sleep onset latency, and lower sleep efficiency were correlated with higher 24-h urinary E and NE (all P < 0.05) but not salivary cortisol. The effect of poor sleep quality on 24-h urinary catecholamines was stronger in males than females.

CONCLUSIONS

Increased sympathetic activity as measured by 24-h urinary catecholamines might play a critical role in the pathogenesis mediating the relationship of insufficient sleep (quantity and quality) with subsequent cardiovascular and metabolic complications. Salivary awakening cortisol was not associated with sleep quantity and quality in healthy middle-aged adults.

Sleep variability, health-related practices, and inflammatory markers in a community dwelling sample of older adults

OBJECTIVE

To explore relationships between wake- and sleep-related health behaviors and circulating concentrations of inflammatory markers (interleukin [IL]-6 and tumor necrosis factor [TNF]-α) in a cohort of community dwelling older adults. Low-grade chronic inflammation is an important risk factor for age-related morbidity. Health behaviors, including average aggregate measures of sleep, have been linked to increased inflammation in older adults. Variability in sleep timing may also be associated with increased inflammation.

METHOD

Participants were community dwelling older adults ≥ 60 years (n = 222: 39 bereaved, 55 caregivers, 52 with insomnia, and 76 good sleepers). Mean values and intraindividual variability in sleep, as well as caffeine and alcohol use, exercise, and daytime napping, were assessed by sleep diaries. Blood samples were obtained in the morning.

RESULTS

Several interactions were noted between sleep behaviors, inflammatory markers, and participant group. Greater variability in wake time and time in bed was associated with higher IL-6 among good sleepers relative to caregivers and older adults with insomnia. Good sleepers who consumed moderate amounts of alcohol had the lowest concentrations of IL-6 compared with the other three groups who consumed alcohol. Insomnia subjects, but not good sleepers, showed increased concentrations of IL-6 associated with caffeine use. Caregivers showed increased concentrations of TNF-α with alcohol use relative to good sleepers. Greater variability in bedtime, later wake times, and longer time in bed was associated with higher TNF-α regardless of group.

CONCLUSIONS

Moderation and regularity in the practice of certain health behaviors, including sleep practices, were associated with lower plasma levels of inflammatory markers in older adults. Life circumstances and specific sleep disorders may modify these associations.

Sleep-disordered breathing and pregnancy: potential mechanisms and evidence for maternal and fetal morbidity

PURPOSE OF REVIEW

This article reviews current data on pathophysiologic mechanisms by which sleep-disordered breathing during pregnancy may cause harm, and explores biological pathways for associated adverse maternal and fetal outcomes, especially pregnancy-induced hypertension and gestational diabetes.

RECENT FINDINGS

Accumulating data indicate that snoring and sleep apnea during pregnancy are likely to increase the risk for gestational hypertension and preeclampsia. Several new studies have observed that sleep-disordered breathing and short sleep duration also increase the risk of gestational diabetes, similar to observations in the general population. There are varying levels of emerging evidence for potential mechanisms, including oxidative stress, increased sympathetic activity and inflammation, adipokine levels and insulin resistance, linking sleep-disordered breathing events during pregnancy to adverse outcomes.

SUMMARY

Sleep-disordered breathing and adverse maternal-fetal outcomes such as preeclampsia and gestational diabetes share a number of mechanistic pathways, and growing data in pregnant women indicate that snoring and sleep apnea increase the risk of these and other complications for both the mother and the fetus. Nevertheless, direct evidence of the pathophysiologic mechanisms by which sleep-disordered breathing during pregnancy exerts negative effects remains sparse.

Deficiency of antinociception and excessive grooming induced by acute immobilization stress in Per1 mutant mice

Acute stressors induce changes in numerous behavioral parameters through activation of the hypothalamic-pituitary-adrenal (HPA) axis. Several important hormones in paraventricular nucleus of the hypothalamus (PVN) play the roles in these stress-induced reactions. Corticotropin-releasing hormone (CRH), arginine-vasopressin (AVP) and corticosterone are considered as molecular markers for stress-induced grooming behavior. Oxytocin in PVN is an essential modulator for stress-induced antinociception. The clock gene, Per1, has been identified as an effecter response to the acute stresses, but its function in neuroendocrine stress systems remains unclear. In the present study we observed the alterations in grooming and nociceptive behaviors induced by acute immobilization stress in Per1 mutant mice and other genotypes (wild types and Per2 mutant). The results displayed that stress elicited a more robust effect on grooming behavior in Per1 mutant mice than in other genotypes. Subsequently, the obvious stress-induced antinociception was observed in the wild-type and Per2 mutant mice, however, in Per1 mutant, this antinociceptive effects were partially-reversed (mechanical sensitivity), or over-reversed to hyperalgesia (thermal sensitivity). The real-time qPCR results showed that in PVN, there were stress-induced up-regulations of Crh, Avp and c-fos in all of genotypes; moreover, the expression change of Crh in Per1 mutant mice was much larger than in others. Another hormonal gene, Oxt, was up-regulated induced by stress in wild-type and Per2 mutant but not in Per1 mutant. In addition, the stress significantly elevated the serum corticosterone levels without genotype-dependent differences, and accordingly the glucocorticoid receptor gene, Nr3c1, expressed with a similar pattern in PVN of all strains. Taken together, the present study indicated that in acute stress treated Per1 mutant mice, there are abnormal hormonal responses in PVN, correlating with the aberrant performance of stress-induced behaviors. Therefore, our findings suggest a novel functional role of Per1 in neuroendocrine stress system, which further participates in analgesic regulation.

Chronic low back pain, sleep disturbance, and interleukin-6

OBJECTIVES

Sleep disturbance is a common comorbidity of chronic pain. Inflammatory processes are dysregulated in sleep disturbance and also contribute to pain sensitivity. Thus, inflammation may play an important role in bidirectional associations between pain and sleep. Little is known about concurrent relationships among chronic pain, sleep, and inflammation. The aim of our study was to examine associations between sleep disturbance and circulating levels of the inflammatory cytokine, interleukin-6 (IL-6), in individuals with and without chronic low back pain.

METHODS

Sex-matched and age-matched adults with chronic low back pain (CLBP; n=25) or without chronic pain (controls; n=25)completed measures of sleep quality in the past month and depressive symptoms in the past week, and provided a blood sample for IL-6. The next morning, participants reported their sleep quality the previous night and their current experience of morning pain.

RESULTS

Individuals with CLBP had more sleep disturbance than controls. Circulating IL-6 levels were similar for the 2 groups; however, in adults with CLBP, poorer sleep quality was associated with higher IL-6 levels, and both sleep and IL-6 related to pain reports. Unlike CLBP participants, controls showed normal, age-related increases in IL-6 levels, whereas sleep quality was unrelated to IL-6 levels. Depressive symptoms could not fully explain the observed associations.

DISCUSSION

Inflammatory processes may play a significant role in the cycles of pain and sleep disturbance. Clinical interventions that improve sleep and reduce concomitant inflammatory dysregulation hold promise for chronic pain management.

Does sleep promote false memories?

Memory is constructive in nature so that it may sometimes lead to the retrieval of distorted or illusory information. Sleep facilitates accurate declarative memory consolidation but might also promote such memory distortions. We examined the influence of sleep and lack of sleep on the cerebral correlates of accurate and false recollections using fMRI. After encoding lists of semantically related word associates, half of the participants were allowed to sleep, whereas the others were totally sleep deprived on the first postencoding night. During a subsequent retest fMRI session taking place 3 days later, participants made recognition memory judgments about the previously studied associates, critical theme words (which had not been previously presented during encoding), and new words unrelated to the studied items. Sleep, relative to sleep deprivation, enhanced accurate and false recollections. No significant difference was observed in brain responses to false or illusory recollection between sleep and sleep deprivation conditions. However, after sleep but not after sleep deprivation (exclusive masking), accurate and illusory recollections were both associated with responses in the hippocampus and retrosplenial cortex. The data suggest that sleep does not selectively enhance illusory memories but rather tends to promote systems-level consolidation in hippocampo-neocortical circuits of memories subsequently associated with both accurate and illusory recollections. We further observed that during encoding, hippocampal responses were selectively larger for items subsequently accurately retrieved than for material leading to illusory memories. The data indicate that the early organization of memory during encoding is a major factor influencing subsequent production of accurate or false memories.

Effect of crocetin from Gardenia jasminoides Ellis on sleep: a pilot study

Crocetin is a pharmacologically active carotenoid compound of Gardenia jasminoides Ellis used as a traditional herbal medicine and natural colorant. The present pilot study investigated the effect of crocetin on sleep. The clinical trial comprised a double-blind, placebo-controlled, crossover trial of 21 healthy adult men with a mild sleep complaint. It included two intervention periods of 2 weeks each, separated by a 2-week washout period. We measured objective sleep quality using an actigraph, and assessed the subjective symptoms using St Mary's Hospital Sleep Questionnaire. Actigraph data showed that after administration of crocetin, the number of wakening episodes was reduced compared to that of the placebo (p=0.025). Subjective data from St Mary's Hospital Sleep Questionnaire showed that crocetin tended to improve the quality of sleep compared to sleep before its intake. Additionally, no side effects from crocetin intake were observed. The results suggest that crocetin may contribute to improving the quality of sleep.

Long-term sleep disturbances in children: a cause of neuronal loss

Short-term sleep loss is known to cause temporary difficulties in cognition, behaviour and health but the effects of persistent sleep deprivation on brain development have received little or no attention. Yet, severe sleep disorders that last for years are common in children especially when they have neurodevelopmental disabilities. There is increasing evidence that chronic sleep loss can lead to neuronal and cognitive loss in children although this is generally unrecognized by the medical profession and the public. Without the restorative functions of sleep due to total sleep deprivation, death is inevitable within a few weeks. Chronic sleep disturbances at any age deprive children of healthy environmental exposure which is a prerequisite for cognitive growth more so during critical developmental periods. Sleep loss adversely effects pineal melatonin production which causes disturbance of circadian physiology of cells, organs, neurochemicals, neuroprotective and other metabolic functions. Through various mechanisms sleep loss causes widespread deterioration of neuronal functions, memory and learning, gene expression, neurogenesis and numerous other changes which cause decline in cognition, behaviour and health. When these changes are long-standing, excessive cellular stress develops which may result in widespread neuronal loss. In this review, for the first time, recent research advances obtained from various fields of sleep medicine are integrated in order to show that untreated chronic sleep disorders may lead to impaired brain development, neuronal damage and permanent loss of developmental potentials. Further research is urgently needed because these findings have major implications for the treatment of sleep disorders.

Work stress, worries, and pain interact synergistically with modelled traffic noise on cross-sectional associations with self-reported sleep problems

OBJECTIVES

To examine the risk of sleep problems associated with work stress (job strain, job demands, and decision authority), worries and pain and to investigate the synergistic interaction between these factors and traffic noise.

METHODS

Sleep problems and predictor variables were assessed in a cross-sectional public health survey with 12,093 respondents. Traffic noise levels were assessed using modelled A-weighted energy equivalent traffic sound levels at the residence. The risk of sleep problems was modelled using multiple logistic regression analysis.

RESULTS

With regard to sleep problems not attributed to any external source (general sleep problems), independent main effects were found for traffic noise (women), decision authority (women), job strain, job demands, suffering from pain or other afflictions, worries about losing the job, experiencing bullying at work, having troubles paying the bills, and having a sick, disabled, or old relative to take care of (women). Significant synergistic effects were found for traffic noise and experiencing bullying at work in women. With regard to sleep problems attributed to traffic noise, strong synergistic interactions were found between traffic noise and, respectively, job demands (men), having pain or other afflictions, taking care of a sick, old, or disabled relative, and having troubles paying the bills. Main effects were found for worries about losing the job, experiencing bullying at work, job strain (men), and decision authority (men). Synergistic interactions could potentially contribute with 10-20% of the sleep problems attributed to traffic noise in the population.

CONCLUSIONS

Work stress, pain, and different worries were independently associated with general sleep problems and showed in general no synergistic interaction with traffic noise. In contrast, synergistic effects between traffic noise and psychological factors were found with regard to sleep problems attributed to traffic noise. The synergy may contribute significantly to sleep problems attributed to traffic noise in the population.

Sleep homeostasis in the rat is preserved during chronic sleep restriction

Sleep is homeostatically regulated in all animal species that have been carefully studied so far. The best characterized marker of sleep homeostasis is slow wave activity (SWA), the EEG power between 0.5 and 4 Hz during nonrapid eye movement (NREM) sleep. SWA reflects the accumulation of sleep pressure as a function of duration and/or intensity of prior wake: it increases after spontaneous wake and short-term (3-24 h) sleep deprivation and decreases during sleep. However, recent evidence suggests that during chronic sleep restriction (SR) sleep may be regulated by both allostatic and homeostatic mechanisms. Here, we performed continuous, almost completely artifact-free EEG recordings from frontal, parietal, and occipital cortex in freely moving rats (n = 11) during and after 5 d of SR. During SR, rats were allowed to sleep during the first 4 h of the light period (4S(+)) but not during the following 20 h (20S(-)). During the daily 20S(-) most sleep was prevented, whereas the number of short (<20 s) sleep attempts increased. Low-frequency EEG power (1-6 Hz) in both sleep and wake also increased during 20S(-), most notably in the occipital cortex. In all animals NREM SWA increased above baseline levels during the 4S(+) periods and in post-SR recovery. The SWA increase was more pronounced in frontal cortex, and its magnitude was determined by the efficiency of SR. Analysis of cumulative slow wave energy demonstrated that the loss of SWA during SR was compensated by the end of the second recovery day. Thus, the homeostatic regulation of sleep is preserved under conditions of chronic SR.

Circadian rhythms and sleep in bipolar disorder

OBJECTIVE

Biological rhythm pathways are highlighted in a number of etiological models of bipolar disorder, and the management of circadian instability appears in consensus treatment guidelines. There are, however, significant conceptual and empirical limitations on our understanding of a hypothesised link between circadian, sleep, and emotion regulation processes in bipolar disorder. The aim of this article is to articulate the limits of scientific knowledge in relation to this hypothesis.

METHODS

A critical evaluation of various literatures was undertaken. The basic science of circadian and sleep processes, their involvement in normal emotion regulation, and the types of evidence suggesting circadian/sleep involvement in bipolar disorder are reviewed.

RESULTS

Multiple lines of evidence suggest that circadian and sleep-wake processes are causally involved in bipolar disorder. These processes demonstrably interact with other neurobiological pathways known to be important in bipolar disorder, but are unique in that they are open to behavioural manipulation.

CONCLUSION

Further research into biological rhythm pathways to bipolar disorder is warranted. Person-environment feedback loops are fundamental to circadian adaptation, and models of circadian pathogenesis (and treatment) should recognize this complexity.

Chronic sleep deprivation markedly reduces coagulation factor VII expression

Chronic sleep loss, a common feature of human life in industrialized countries, is associated to cardiovascular disorders. Variations in functional parameters of coagulation might contribute to explain this relationship. By exploiting the mouse model and a specifically designed protocol, we demonstrated that seven days of partial sleep deprivation significantly decreases (-30.5%) the thrombin generation potential in plasma evaluated upon extrinsic (TF/FVIIa pathway) but not intrinsic activation of coagulation. This variation was consistent with a decrease (-49.8%) in the plasma activity levels of factor VII (FVII), the crucial physiologicalal trigger of coagulation, which was even more pronounced at the liver mRNA level (-85.7%). The recovery in normal sleep conditions for three days completely restored thrombin generation and FVII activity in plasma. For the first time, we demonstrate that chronic sleep deprivation on its own reduces, in a reversible manner, the FVII expression levels, thus influencing the TF/FVIIa activation pathway efficiency.

Mortality associated with short sleep duration: The evidence, the possible mechanisms, and the future

This review of the scientific literature examines the widely observed relationship between sleep duration and mortality. As early as 1964, data have shown that 7-h sleepers experience the lowest risks for all-cause mortality, whereas those at the shortest and longest sleep durations have significantly higher mortality risks. Numerous follow-up studies from around the world (e.g., Japan, Israel, Sweden, Finland, the United Kingdom) show similar relationships. We discuss possible mechanisms, including cardiovascular disease, obesity, physiologic stress, immunity, and socioeconomic status. We put forth a social-ecological framework to explore five possible pathways for the relationship between sleep duration and mortality, and we conclude with a four-point agenda for future research.

Integrative dermatology for psoriasis: facts and controversies

Recommendations for changes in diet and lifestyle are not meant to supplant conventional therapy but to integrate with it and, hopefully, improve response to treatment. At the same time, integrative approaches permit the patient to depend less on more expensive and potentially harmful pharmaceutical and medical approaches. Manipulation of diet and lifestyle may actually diminish the effect of underlying predisposing or etiologic factors and simultaneously treat serious comorbidities. Topics include alcohol, smoking, body composition, sleep and stress, diet and nutrients, and exercise.

The ecological relevance of sleep: the trade-off between sleep, memory and energy conservation

All animals in which sleep has been studied express signs of sleep-like behaviour, suggesting that sleep must have some fundamental functions that are sustained by natural selection. Those functions, however, are still not clear. Here, we examine the ecological relevance of sleep from the perspective of behavioural trade-offs that might affect fitness. Specifically, we highlight the advantage of using food-caching animals as a system in which a conflict might occur between engaging in sleep for memory/learning and hypothermia/torpor to conserve energy. We briefly review the evidence for the importance of sleep for memory, the importance of memory for food-caching animals and the conflicts that might occur between sleep and energy conservation in these animals. We suggest that the food-caching paradigm represents a naturalistic and experimentally practical system that provides the opportunity for a new direction in sleep research that will expand our understanding of sleep, especially within the context of ecological and evolutionary processes.

Effects of Mindful Yoga on Sleep in Pregnant Women: A Pilot Study

Purpose: The purpose of this experimental pilot study was to measure the effects of a mindfulness-based yoga intervention on sleep in pregnant women. Methods: Fifteen healthy, nulliparous women in their second or third trimesters with singleton pregnancies attended weekly mindfulness meditation and prenatal Hatha yoga classes in the community for 7 weeks. Sleep variables, as estimated by 72 hr of continuous wrist actigraphy and the General Sleep Disturbance Scale (GSDS), were recorded at baseline (Time 1) and postintervention (Time 2). Control data were obtained by evaluating sleep in the third-trimester group at Time 1. Due to small sample size, data were analyzed using parametric and nonparametric statistics. Results: Women who began the intervention in the second trimester had significantly fewer awakenings, less wake time during the night, and less perceived sleep disturbance at Time 2 than at baseline. Those who began during the third trimester had poorer sleep over time in spite of the intervention. Women who began the intervention in their second trimester had less awake time at Time 2 compared to third-trimester controls at Time 1. Conclusions: Mindful yoga shows promise for women in their second trimester of pregnancy to diminish total number of awakenings at night and improve sleep efficiency and merits further exploration. Results from this pilot study provide the data to estimate sample size and design and implement powered and more controlled studies in the future.

Sleep, Hormones, and Circadian Rhythms throughout the Menstrual Cycle in Healthy Women and Women with Premenstrual Dysphoric Disorder

A relationship exists between the sleep-wake cycle and hormone secretion, which, in women, is further modulated by the menstrual cycle. This interaction can influence sleep across the menstrual cycle in healthy women and in women with premenstrual dysphoric disorder (PMDD), who experience specific alterations of circadian rhythms during their symptomatic luteal phase along with sleep disturbances during this time. This review will address the variation of sleep at different menstrual phases in healthy and PMDD women, as well as changes in circadian rhythms, with an emphasis on their relationship with female sex hormones. It will conclude with a brief discussion on nonpharmacological treatments of PMDD which use chronotherapeutic methods to realign circadian rhythms as a means of improving sleep and mood in these women.

Modulation of Sleep Homeostasis by Corticotropin Releasing Hormone in REM Sleep-Deprived Rats

Studies have shown that sleep recovery following different protocols of forced waking varies according to the level of stress inherent to each method. Sleep deprivation activates the hypothalamic-pituitary-adrenal axis and increased corticotropin-releasing hormone (CRH) impairs sleep. The purpose of the present study was to evaluate how manipulations of the CRH system during the sleep deprivation period interferes with subsequent sleep rebound. Throughout 96 hours of sleep deprivation, separate groups of rats were treated i.c.v. with vehicle, CRH or with alphahelical CRH(9-41), a CRH receptor blocker, twice/day, at 07:00 h and 19:00 h. Both treatments impaired sleep homeostasis, especially in regards to length of rapid eye movement sleep (REM) and theta/delta ratio and induced a later decrease in NREM and REM sleep and increased waking bouts. These changes suggest that activation of the CRH system impact negatively on the homeostatic sleep response to prolonged forced waking. These results indicate that indeed, activation of the HPA axis-at least at the hypothalamic level-is capable to reduce the sleep rebound induced by sleep deprivation.

Does mental health history explain gender disparities in insomnia symptoms among young adults?

BACKGROUND

Insomnia is the most commonly reported sleep disorder, characterized by trouble falling asleep, staying asleep, or waking up too early. Previous epidemiological data reveal that women are more likely than men to suffer from insomnia symptoms. We investigate the role that mental health history plays in explaining the gender disparity in insomnia symptoms.

METHODS

Using logistic regression, we analyze National Health and Nutritional Examination Survey (NHANES) III interview and laboratory data, merged with data on sociodemographic characteristics of the residential census tract of respondents. Our sample includes 5469 young adults (ages 20-39) from 1429 census tracts.

RESULTS

Consistent with previous research, we find that women are more likely to report insomnia symptoms compared to men (16.7% vs. 9.2%). However, in contrast to previous work, we show that the difference between women's and men's odds of insomnia becomes statistically insignificant after adjusting for history of mental health conditions (OR=1.08, p>.05).

CONCLUSIONS

The gender disparity in insomnia symptoms may be driven by higher prevalence of affective disorders among women. This finding has implications for clinical treatment of both insomnia and depression, especially among women.

Comorbidity of insomnia and depression

During the last decade, several studies have shown that insomnia, rather than a symptom of depression, could be a medical condition on its own, showing high comorbidity with depression. Epidemiological research indicates that insomnia could lead to depression and/or that common causalities underlie the two disorders. Neurobiological and sleep EEG studies suggest that a heightened level of arousal may play a common role in both conditions and that signs of REM sleep disinhibition may appear in individuals prone to depression. The effects of antidepressant drugs on non-REM and REM sleep are discussed in relation to their use in insomnia comorbid with depression. Empirical treatment approaches are behavioral management of sleep combined with prescription of a sedative antidepressant alone, co-prescription of two antidepressants, or of an antidepressant with a hypnotic drug.