Impact of sleep and its disturbances on hypothalamo-pituitary-adrenal axis activity

Sleep duration and patterns in Chinese patients with diabetes: A meta-analysis of comparative studies and epidemiological surveys

PURPOSE

A meta-analysis on sleep duration and patterns in patients with diabetes in China.

DESIGN AND METHODS

Two investigators independently carried out a systematic literature search in both international and Chinese databases.

FINDINGS

A total of 47 studies with 98 911 patients were included. The pooled mean sleep duration was 7.15 hours/day in patients with diabetes and 7.49 hours/day in healthy controls. The estimated percentage of short sleep duration of less than 6 hours/day was 23.0% in patients with diabetes and 12.3% in healthy controls, while the proportion of short sleep duration of less than 7 hours/day was 38.0% in patients with diabetes and 14.1% in healthy controls.

PRACTICE IMPLICATIONS

Short sleep duration was common in Chinese patients with diabetes.

Prenatal alcohol exposure and sleep-wake behaviors: exploratory and naturalistic observations in the clinical setting and in an animal model

INTRODUCTION

Clinical research and studies using animal models have revealed a complex and relatively under-explored interaction between prenatal alcohol exposure (PAE) and alterations in sleep-wake behaviors.

OBJECTIVES

To utilize a structured naturalistic observation-based methodology, consisting of descriptive elements, to provide insight into possible links between altered sleep and disruptive daytime presentations in children and adolescents with fetal alcohol spectrum disorder (FASD). To apply a similar structured behavioral observation protocol in a PAE animal model to compare outcomes from the experimental and clinical studies utilizing naturalistic observational methodology.

METHODS

Forty pediatric patients with FASD (1.8-17.5 yrs, median age 9.4 yrs) and chronic sleep problems were assessed. In the PAE animal model, male offspring from PAE, Pair-Fed (PF), and ad libitum-fed Control (C) groups (n = 8/group) were assessed in the juvenile/preadolescent (23-25 days of age) and adolescent/pubertal (35-36 days of age) periods.

RESULTS

In the clinical setting, we found that 95% of children with FASD showed disruptive or externalizing behaviors, 73% showed internalizing behaviors, 93% had circadian rhythm sleep disorders, all had chronic insomnia, and 85% had restless sleep, often with tossing/turning/kicking movements indicative of non-restorative sleep with hypermotor events. In the daytime, individuals showed excessive daytime sleepiness as well as hyperactive/hyperkinetic behaviors, an urge-to-move, and involuntary movements suggestive of hyperarousability. Alterations in sleep/wake behaviors in the PAE animal model paralleled the clinical data in many aspects, demonstrating greater sleep latencies, less total time asleep, more total time awake and longer awake bouts, more position changes, more time in transition, and longer transition bouts in PAE compared to PF and/or control animals.

CONCLUSIONS

Thus, our findings provide support for the power and validity of naturalistic observational paradigms in revealing dysregulated sleep-wake behaviors and their association and/or exacerbating relationship with day and nighttime behavioral problems, such as disruptive behaviors, externalizing and internalizing disorders, and daytime sleepiness.

Sleep and type 1 diabetes in children and adolescents: Proposed theoretical model and clinical implications

Youth with type 1 diabetes mellitus (T1D) experience more sleep disturbances and shorter sleep durations compared to their healthy peers. Researchers have now uncovered the negative mental health and physical health outcomes associated with poor sleep in youth with T1D. The field of T1D sleep research currently operates under the broad notion that sleep behaviors impact treatment adherence, which ultimately lead to worse long-term health outcomes. This model however does not explain how behavior influences T1D management and sleep outcomes on a day-to-day basis, leading to difficulties in providing tailored treatment recommendations. In this review, we present a theoretical framework that describes the recursive cycle between sleep behaviors, T1D outcomes, and symptoms of negative affect/stress over a 24-hour period. This model is guided by the sleep literature, showing a clear relationship between poor sleep and negative affect, and the T1D literature demonstrating a link between poor sleep and disease management for youth with T1D. Further, emerging literature indicates a need for additional parent sleep assessment considering that T1D management and fear of hypoglycemia negatively impact parent sleep behaviors. Recommendations are provided to move the field toward effective intervention studies and new areas of research to evaluate and modify the proposed model.

Chronic stress influences attentional and judgement bias and the activity of the HPA axis in sheep

INTRODUCTION

Environmental challenges are part of everyday life for most domestic animals. However, very little is known about how animals cope emotionally and physiologically with cumulative challenges. This experiment aimed to determine the impact of long-term exposure to environmental challenges on the affective state and hypothalamic-pituitary-adrenal (HPA) axis responses to a subsequent additional acute shearing challenge.

METHODS

Sheep were exposed to either a long-term environmental challenge (rest disruption and individual housing) in order to induce chronic stress (chronic stress group) or control conditions (group housing in a field with low stress handling and daily feed rewards, control group). Judgement and attention bias were assessed as measures of the emotional state following several days of the challenge or control treatment (pre-shearing tests). In addition, the responsiveness of the HPA-axis was evaluated using a combined Corticotropin Releasing Hormone and Arginine Vasopressin (CRH/AVP) challenge. Finally, all animals were exposed to an acute shearing challenge, then judgement bias (post-shearing test), HPA-axis and internal body temperature responses were determined.

RESULTS

In the pre-shearing judgement bias test, the chronic stress group slightly increased optimism compared to the control treatment. In the attention bias test, the chronic stress group showed reduced vigilance behaviour towards a predator threat and a quicker approach to the food compared to the control treatment. The chronic stress group also had lower plasma ACTH concentrations in response to the CRH/AVP challenge compared to the control group, no differences in cortisol concentrations were found. In the post-shearing judgement bias test, differences in optimism were no longer evident between the chronic stress and control groups. Plasma ACTH concentrations and body temperatures showed a greater increase in response to shearing in the chronic stress group compared to the control group.

CONCLUSION

Our results suggest that long-term exposure to challenges biased cognitive measures of the affective state towards an increased expectation of a reward and reduced attention towards a threat. The exaggerated ACTH responses in the chronic stress group may be indicative of HPA-axis dysregulation. Despite a period of challenge exposure in the chronic stress group, judgement bias responses to the shearing challenge were similar in the chronic stress and control groups; the reasons for this need further investigation. The altered affective state together with signs of HPA-axis dysregulation may indicate an increased risk of compromised welfare in animals exposed to long-term environmental challenges.

The Effects of Deep-Breathing Exercises on Postoperative Sleep Duration and Quality in Patients Undergoing Coronary Artery Bypass Graft (CABG): a Randomized Clinical Trial

Introduction: Disordered sleep occurs frequently in patients who have undergone coronary bypass graft surgery, and it contributes to increased morbidity, mortality, and resource utilization. The present study aimed to determine the effects of deep-breathing exercises on postoperative sleep duration and quality in patients undergoing coronary artery bypass graft.

Methods: This study was a clinical trial. The study sample included 64 patients who were coronary artery bypass graft hospitalized from January 2015 to April 2015 in Qazvin Booali-Sina hospital. The patients were selected by convenient sampling and then the participants were randomly allocated to the intervention and control groups. The baseline and postoperative (day 7) sleep duration and quality metrics were measured. The St Mary's Hospital Sleep Questionnaire was used to evaluate sleep quality in two groups.

Results: Baseline night sleep duration was 5.72 (1.63) hours in the control group and 5.58 (1.07) hours in the intervention group. The initial findings showed that the mean of sleep quality score of patients in the intervention and control groups were 19.72 (2.68) and 18.22 (3.81) respectively. These measurements did not decline postoperatively in the intervention group while night sleep duration and quality declined in the control group. Deep breathing exercise program had a significant effect on sleep quality score in the intervention group compared to the control group.

Conclusion: The results indicated that deep breathing exercises prevent decline in sleep quality postoperatively. It seems to be a safe method with no side effects for these patients. Furthermore, it is a simple method to implement and does not impose a high cost.

Association of sleep problems with neuroendocrine hormones and coagulation factors in patients with acute myocardial infarction

Background

Obstructive sleep apnea (OSA) and insomnia are frequent sleep problems that are associated with poor prognosis in patients with coronary heart disease. The mechanisms linking poor sleep with an increased cardiovascular risk are incompletely understood. We examined whether a high risk of OSA as well as insomnia symptoms are associated with neuroendocrine hormones and coagulation factors in patients admitted with acute myocardial infarction.

Methods

We assessed 190 patients (mean age 60 years, 83% men) in terms of OSA risk (STOP screening tool for the assessment of high vs. low OSA risk) and severity of insomnia symptoms (Jenkins Sleep Scale for the assessment of subjective sleep difficulties) within 48 h of an acute coronary intervention. Circulating concentrations of epinephrine, norepinephrine, cortisol, fibrinogen, D-dimer, and von Willebrand factor were measured the next morning. The association of OSA risk and insomnia symptoms with neuroendocrine hormones and coagulation factors was computed using multivariate models adjusting for demographic factors, health behaviors, somatic and psychiatric comorbidities, cardiac disease-related variables, and OSA risk in the model for insomnia symptoms, respectively, for insomnia symptoms in the model for OSA risk.

Results

High OSA risk was identified in 41% of patients and clinically relevant insomnia symptoms were reported by 27% of patients. Compared to those with low OSA risk, patients with high OSA risk had lower levels of epinephrine (p = 0.015), norepinephrine (p = 0.049) and cortisol (p = 0.001). More severe insomnia symptoms were associated with higher levels of fibrinogen (p = 0.037), driven by difficulties initiating sleep, and with lower levels of norepinephrine (p = 0.024), driven by difficulties maintaining sleep.

Conclusions

In patients with acute myocardial infarction, sleep problems are associated with neuroendocrine hormones and coagulation activity. The pattern of these relationships is not uniform for patients with a high risk of OSA and those with insomnia symptoms, and whether they contribute to adverse cardiovascular outcomes needs to be established.

Trial registration

ClinicalTrials.gov NCT01781247.

The serotonin transporter polymorphism (5-HTTLPR) and cortisol stress responsiveness: preliminary evidence for a modulating role for sleep quality

The short (S) allele of a functional polymorphism (5-HTTLPR) within the promoter region of the serotonin transporter gene (SLC6A4) is found to predispose the risk for stress-related affective disorders relative to the long (L) allele. Evidence suggests that elevated stress reactivity of the hypothalamic-pituitary-adrenal (HPA) axis might underlie this association although there is little understanding about the origin of inconsistent findings. Since inadequate sleep is commonly known to promote HPA stress reactivity, it might well play an important modulating role. The present study tested this hypothesis by investigating whether sleep quality moderates the relationship between 5-HTTLPR and cortisol stress responsiveness. From a large 5-HTTLPR database (n = 771), a sample of healthy male and female participants homozygous for either the 5-HTTLPR S-allele (n = 25) or L-allele (n = 25) were assessed for sleep quality and salivary cortisol secretion during acute laboratory stress. Diminished sleep quality was found to exclusively potentiate cortisol stress reactivity in the homozygous L-allele genotype. Accounting for this 5-HTTLPR-dependent influence enhanced the predictive value of 5-HTTLPR on cortisol stress responsiveness, revealing greater HPA reactivity in S-allele relative to L-allele carriers. Current findings suggest that variations in sleep quality may serve as a confounding factor in the search for genetic differences in stress sensitivity and related affective disorders.

Obesity and sleep disturbance: the chicken or the egg?

Epidemiological studies suggested an association between obesity and sleep disturbances. Obstructive sleep apnea is the most prevalent type of obesity-related sleep disorder that lead to an increased risk for numerous chronic health conditions. In addition the increased visceral adipose tissue might be responsible for the secretion of inflammatory cytokines that could contribute to alter the sleep-wake rhythm. Unhealthy food characterized by high consumption of fat and carbohydrate seems to negatively influence the quality of sleep while diet rich of fiber is associated to more restorative and deeper sleep. Although obesity could cause through several pathogenetic mechanisms an alteration of sleep, it has been reported that subjects suffering from sleep disorders are more prone to develop obesity. Experimental laboratory studies have demonstrated that decreasing either the amount or quality of sleep increase the risk of developing obesity. Experimental sleep restriction also causes physiological, hormonal and food behavioral changes that promote a positive energy balance and a compensatory disproportionate increase in food intake, decrease in physical activity, and weight gain. Thus, the aim of this review is to provide observational evidence on the association of obesity with sleep disturbances and viceversa with emphasis on possible pathophysiological mechanisms (hormonal and metabolic) that link these two pathological conditions.

Does sleep deprivation increase the vulnerability to acute psychosocial stress in young and older adults?

Sleep loss and psychosocial stress often co-occur in today's society, but there is limited knowledge on the combined effects. Therefore, this experimental study investigated whether one night of sleep deprivation affects the response to a psychosocial challenge. A second aim was to examine if older adults, who may be less affected by both sleep deprivation and stress, react differently than young adults. 124 young (18-30 years) and 94 older (60-72 years) healthy adults participated in one of four conditions: i. normal night sleep & Placebo-Trier Social Stress Test (TSST), ii. normal night sleep & Trier Social Stress Test, iii. sleep deprivation & Placebo-TSST, iv. sleep deprivation & TSST. Subjective stress ratings, heart rate variability (HRV), salivary alpha amylase (sAA) and cortisol were measured throughout the protocol. At the baseline pre-stress measurement, salivary cortisol and subjective stress values were higher in sleep deprived than in rested participants. However, the reactivity to and recovery from the TSST was not significantly different after sleep deprivation for any of the outcome measures. Older adults showed higher subjective stress, higher sAA and lower HRV at baseline, indicating increased basal autonomic activity. Cortisol trajectories and HRV slightly differed in older adults compared with younger adults (regardless of the TSST). Moreover, age did not moderate the effect of sleep deprivation. Taken together, the results show increased stress levels after sleep deprivation, but do not confirm the assumption that one night of sleep deprivation increases the responsivity to an acute psychosocial challenge.

Altered ultradian cortisol rhythmicity as a potential neurobiologic substrate for chronic insomnia

Chronic insomnia is highly prevalent and associated with significant morbidity (i.e., confers risk for multiple psychiatric and medical disorders, such as depression and hypertension). Therefore, it is essential to identify factors that perpetuate this disorder. One candidate factor in the neurobiology of chronic insomnia is hypothalamic-pituitary-adrenal-axis dysregulation, and in particular, alterations in circadian cortisol rhythmicity. Cortisol secretory patterns, however, fluctuate with both a circadian and an ultradian rhythm (i.e., pulses every 60-120 min). Ultradian cortisol pulses are thought to be involved in the maintenance of wakefulness during the day and their relative absence at night may allow for the consolidation of sleep and/or shorter nocturnal awakenings. It is possible that the wakefulness that occurs in chronic insomnia may be associated with the aberrant occurrence of cortisol pulses at night. While cortisol pulses naturally occur with transient awakenings, it may also be the case that cortisol pulsatility becomes a conditioned phenomenon that predisposes one to awaken and/or experience prolonged nocturnal awakenings. The current review summarizes the literature on cortisol rhythmicity in subjects with chronic insomnia, and proffers the suggestion that it may be abnormalities in the ultradian rather than circadian cortisol that is associated with the pathophysiology of insomnia.

From pillow to podium: a review on understanding sleep for elite athletes

Sleep is considered vital to human health and well-being, and is critical to physiological and cognitive functioning. Elite athletes experience high training and competition demands, and are often exposed to various factors, situations, and environments that can cause sleep impairments. Previous research has shown that athletes commonly experience sleep loss in the lead up to and following competition, which could have significant impacts on their preparation, performance, and recovery. In particular, the results from previous research show significant reductions in total sleep time (~1:40 h:min) and significant increases in sleep latency (~45 minutes) following evening competition. Napping is common in both the training and competition setting in athletes; however, research on the effect of napping on physiology and performance is limited. In contrast, research on strategies and interventions to improve sleep are increasing in the athletic population, with sleep hygiene research resulting in significant improvements in key sleep indices. This review investigates the physiological importance of sleep in athletes, current tools to monitor athletes' sleep, the role of sleep for cognitive functioning and athletic performance, the prevalence of sleep disturbances and the potential mechanisms causing sleep disturbances, the role of napping, and different intervention strategies to improve sleep.

Association between Sleep Duration and Body Composition Measures in Korean Adults: The Korea National Health and Nutrition Examination Survey 2010

Background

The association between sleep duration and body composition measures in Korean adults remains unclear.

Methods

This cross-sectional study included 3,532 subjects aged ≥40 years (1,542 men and 1,990 women) who participated in the 2010 Korea National Health and Nutrition Examination Survey V-1. Self-reported sleep duration and anthropometric data were collected. Appendicular skeletal muscle mass (ASM) was quantified via dual-energy X-ray absorptiometry. Obesity was defined according to the body mass index and waist circumference. Sarcopenia was defined as the muscle mass percentage (ASM/weight) below the lowest quintile computed for the study population. Multivariate logistic regressions with or without adjustment for sociodemographic and lifestyle factors were used to evaluate the association of sleep duration with obesity and sarcopenia for participants who slept ≤5, 6–8, and ≥9 h/d. The results were expressed as odds ratios (ORs) with 95% confidence intervals (95% CIs).

Results

In women, the association between sleep duration and sarcopenia was stronger for individuals who slept ≥9 h/d than for those who slept 6–8 h/d (unadjusted OR, 1.99; 95% CI, 1.19–3.34; adjusted OR, 1.77; 95% CI, 1.06– 2.96).

Conclusion

Longer sleep duration is associated with a significantly higher incidence of sarcopenia in Korean women aged ≥40 years.

Glucocorticoid and inflammatory reactivity to a repeated physiological stressor in insomnia disorder

Despite known associations of insomnia disorder with alterations in cytokine and glucocorticoid (GC) production, neither the sensitivity of immune cells to a GC signal nor the reactivity of the hypothalamus-pituitary-adrenal (HPA) axis and inflammatory system to stress, or adaptation of these systems to repeated stress have been assessed in patients with insomnia. To investigate potential dysregulation in stress reactivity and adaptation to repeated exposure, a physiological stressor (the cold pressor test; CPT) was repeatedly administered to N = 20 participants with insomnia disorder (based on DSM-V, 18 females, age 30 ± 2.5 years) and N = 20 sex-matched healthy controls following an at-home actigraphy and in-laboratory PSG. HPA and inflammatory markers (serum cortisol, plasma interleukin [IL]-6) were measured at baseline/resting levels and following each of the three CPTs. In addition, sensitivity of monocytes to the synthetic GC dexamethasone was assessed in-vitro at baseline levels in order to examine the cortisol-IL-6 interplay at the cell level. Compared to healthy controls, individuals with insomnia disorder exhibited shorter sleep duration as assessed by actigraphy and PSG (p ≤ 0.05). HPA, but not inflammatory reactivity to the repeated CPT challenge was greater in insomnia disorder (p ≤ 0.05 for group effect), due to greater cortisol responses to the initial CPT (p ≤ 0.05). There were no between-group differences in the ability of the HPA to adapt to stress repetition nor in basal/resting levels of cortisol, IL-6, and GC sensitivity. These findings suggest that insomnia disorder potentiates HPA axis reactivity to initial/novel stressors, which may constitute a pathway underlying adverse health consequences in the long term.

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Insomnia disorder potentiates HPA, but not inflammatory reactivity to a novel stressor.

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The ability of the HPA axis to adapt to the repeated exposure to the same stressor is unchanged in insomnia.

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Basal/resting levels of cortisol, IL-6, and their interplay at cell level (i.e., GC sensitivity of monocytes) are unchanged in insomnia.

An earlier time of scan is associated with greater threat-related amygdala reactivity

Time-dependent variability in mood and anxiety suggest that related neural phenotypes, such as threat-related amygdala reactivity, may also follow a diurnal pattern. Here, using data from 1,043 young adult volunteers, we found that threat-related amygdala reactivity was negatively coupled with time of day, an effect which was stronger in the left hemisphere (β = -0.1083, p-fdr = 0.0012). This effect was moderated by subjective sleep quality (β = -0.0715, p-fdr = 0.0387); participants who reported average and poor sleep quality had relatively increased left amygdala reactivity in the morning. Bootstrapped simulations suggest that similar cross-sectional samples with at least 300 participants would be able to detect associations between amygdala reactivity and time of scan. In control analyses, we found no associations between time and V1 activation. Our results provide initial evidence that threat-related amygdala reactivity may vary diurnally, and that this effect is potentiated among individuals with average to low sleep quality. More broadly, our results suggest that considering time of scan in study design or modeling time of scan in analyses, as well as collecting additional measures of circadian variation, may be useful for understanding threat-related neural phenotypes and their associations with behavior, such as fear conditioning, mood and anxiety symptoms, and related phenotypes.

A Transcriptional Circuit Filters Oscillating Circadian Hormonal Inputs to Regulate Fat Cell Differentiation

Glucocorticoid and other adipogenic hormones are secreted in mammals in circadian oscillations. Loss of this circadian oscillation pattern correlates with obesity in humans, raising the intriguing question of how hormone secretion dynamics affect adipocyte differentiation. Using live, single-cell imaging of the key adipogenic transcription factors CEBPB and PPARG, endogenously tagged with fluorescent proteins, we show that pulsatile circadian hormone stimuli are rejected by the adipocyte differentiation control system. In striking contrast, equally strong persistent signals trigger maximal differentiation. We identify the mechanism of how hormone oscillations are filtered as a combination of slow and fast positive feedback centered on PPARG. Furthermore, we confirm in mice that flattening of daily glucocorticoid oscillations significantly increases the mass of subcutaneous and visceral fat pads. Together, our study provides a molecular mechanism for why stress, Cushing's disease, and other conditions for which glucocorticoid secretion loses its pulsatility may lead to obesity.

Perceived Discrimination and Adolescent Sleep in a Community Sample

Sleep is a key restorative process, and poor sleep is linked to disease and mortality risk. The adolescent population requires more sleep on average than adults but are most likely to be sleep deprived. Adolescence is a time of rapid social upheaval and sensitivity to social stressors including discrimination. This study uses two weeks of daily e-diary measures documenting discrimination exposure and concurrent objective sleep indicators measured using actigraphy. We assess associations between daily discrimination and contemporaneous sleep with a diverse sample of adolescents. This novel study shows youth with higher average discrimination reports have worse average sleep relative to their counterparts. Interestingly, youth reporting daily discrimination have better sleep the day of the report than youth who do not.

A systematic review of cortisol, thyroid-stimulating hormone, and prolactin in peripartum women with major depression

Pregnancy and postpartum are periods of high susceptibility to major depression (MD) and other mood disorders. The peripartum period is also a time of considerable changes in the levels of hormones, including cortisol, thyroid-stimulating hormone (TSH), prolactin, gonadotropins, and gonadal steroids. To investigate the relationship between mood and hormonal changes during and after pregnancy, we reviewed published reports of hormonal measures during this time frame, searched via PubMed and Web of Science. Studies were included if women in the antepartum or postpartum periods were clinically diagnosed with MD, and if there were repeated measures of cortisol, TSH, or prolactin. For these three hormones, the numbers of human studies that met these criteria were 15, 7, and 3, respectively. Convergent findings suggest that morning cortisol is reduced in pregnant and postpartum women with MD. Evidence did not support changes in TSH as a marker of MD during the peripartum period, and evidence for changes in prolactin in peripartum MD was equivocal. Aside from reduced morning cortisol in peripartum women with MD, definitive evidence for an association between specific hormonal fluctuations and mood disorders in the peripartum period remains elusive.

Sleep architecture, insulin resistance and the nasal cycle: Implications for positive airway pressure therapy

Background: The global pandemic of metabolic disease is worsening. The metabolic theory of obesity proposes that hormonal changes, especially hyperinsulinaemia, precede metabolic disease development. Although quality sleep is recognised as a key factor for good health, less is known about disrupted sleep as a risk factor for hyperinsulinaemia. Aim: To explore the relationship between sleep, especially sleep architecture and the nasal cycle, on insulin secretion in obstructive sleep apnoea (OSA) with comorbid metabolic disease. This review includes a discussion of the potential role of Rest-Activity-Cycler positive airway pressure (RACer-PAP), a novel non-pharmacological OSA treatment strategy. Methods: A narrative review of all the relevant papers known to the authors was conducted. This review also included results from a polysomnographic sleep clinic pilot study (n = 3) comparing sleep efficiency of RACer-PAP to nasal continuous positive airways pressure (n-CPAP) in OSA patients.  Results: Metabolic disease is strongly associated with disturbed sleep. Sleep architecture influences cerebral hormonal secretion, lateral shifts in the autonomic nervous system and nasal airflow dominance. Disturbed sleep shortens short-wave sleep periods, decreasing insulin sensitivity and glucose tolerance. Improvements to metabolic function during n-CPAP treatment are inconsistent. If RACer-PAP demonstrates superior effects on sleep architecture and autonomic function, it may offer advantages in OSA patients with comorbid metabolic disease. Conclusion: Improving sleep architecture by maintaining the nasal cycle proposes a novel non-pharmacological treatment paradigm for treating OSA with comorbid metabolic disease. Research is required to demonstrate if RACer-PAP therapy influences whole night sleep architecture, sympathovagal balance and markers of metabolic disease.

The Relationship between Alcohol Drinking Patterns and Sleep Duration among Black and White Men and Women in the United States

In the United States, racial minorities generally experience poorer cardiovascular health compared to whites, and differences in alcohol consumption and sleep could contribute to these disparities. With a nationally representative sample of 187,950 adults in the National Health Interview Survey from 2004 to 2015, we examined the relationship between alcohol-drinking patterns and sleep duration/quality by race and sex. Using Poisson regression models with robust variance, we estimated sex-specific prevalence ratios for each sleep duration/quality category among blacks compared to whites within categories of alcohol-drinking pattern, adjusting for socioeconomic status and other potential confounders. Across alcohol drinking patterns, blacks were less likely than whites to report recommended sleep of 7-<9 h/day. Short (PR = 1.30 [95% CI: 1.22-1.39]) and long (PR = 1.30 [95% CI: 1.07-1.58]) sleep were 30% more prevalent among black-male infrequent heavy drinkers compared to white-male infrequent heavy drinkers. Short (PR = 1.27 [95% CI: 1.21-1.34]) sleep was more prevalent among black-female infrequent heavy drinkers compared to white-female infrequent heavy drinkers, but there was no difference for long sleep (PR = 1.09 [95% CI: 0.97-1.23]). Black female infrequent moderate drinkers, however, had a 16% higher (PR = 1.16 [95% CI: 1.01-1.33]) prevalence of long sleep compared to their white counterparts. Environmental, social, and biological factors contributing to these findings, along with their impact on disparate health outcomes, should be studied in greater detail.

Unpredictable chronic mild stress differentially impairs social and contextual discrimination learning in two inbred mouse strains

Alterations in the social and cognitive domain are considered important indicators for increased disability in many stress-related disorders. Similar impairments have been observed in rodents chronically exposed to stress, mimicking potential endophenotypes of stress-related psychopathologies such as major depression disorder (MDD), anxiety, conduct disorder, and posttraumatic stress disorder (PTSD). Data from numerous studies suggest that deficient plasticity mechanisms in hippocampus (HC) and prefrontal cortex (PFC) might underlie these social and cognitive deficits. Specifically, stress-induced deficiencies in neural plasticity have been associated with a hypodopaminergic state and reduced neural plasticity persistence. Here we assessed the effects of unpredictable chronic mild stress (UCMS) on exploratory, social and cognitive behavior of females of two inbred mouse strains (C57BL/6J and DBA/2J) that differ in their dopaminergic profile. Exposure to chronic stress resulted in impaired circadian rhythmicity, sociability and social cognition in both inbred strains, but differentially affected activity patterns and contextual discrimination performance. These stress-induced behavioral impairments were accompanied by reduced expression levels of brain derived neurotrophic factor (BDNF) in the prefrontal cortex. The strain-specific cognitive impairment was coexistent with enhanced plasma corticosterone levels and reduced expression of genes related to dopamine signaling in hippocampus. These results underline the importance of assessing different strains with multiple test batteries to elucidate the neural and genetic basis of social and cognitive impairments related to chronic stress.

Sleep duration and progression to diabetes in people with prediabetes defined by HbA1c concentration

AIMS

To evaluate the association between sleep duration and the risk of progression to diabetes among people with prediabetes, defined by HbA_1c values.

METHODS

We conducted a cohort study in 17 983 adults who underwent health check-up examinations, including assessments of sleep duration and quality. Diabetes was defined as either HbA_1c ≥48 mmol/mol (6.5%), or the use of antidiabetic medication. Time-dependent proportional hazards models were used to evaluate the association between sleep duration and the risk of progression to diabetes.

RESULTS

During 31,582 person-years of follow-up, 664 incident cases of diabetes were identified; the incidence rate was 21.0 per 1000 person-years. The multivariate adjusted hazard ratios for progression to diabetes in people with sleep durations of ≤5, 6 and ≥8 h compared with 7 h were 1.68 (95% CI 1.30-2.16), 1.44 (95% CI 1.17-1.76) and 1.23 (95% CI 0.85-1.78), respectively (P for quadratic trend <0.001). This association was partially mediated by biomarkers of adiposity, fatty liver and insulin resistance.

CONCLUSION

In this large study in young and middle-aged adults with prediabetes, we found an association between short sleep duration and the risk of progression to diabetes. Our findings suggest that sufficient sleep duration is important for delaying or preventing the progression of prediabetes to diabetes.

Sleep duration partially accounts for race differences in diurnal cortisol dynamics

OBJECTIVE

Emerging research demonstrates race differences in diurnal cortisol slope, an indicator of hypothalamic-pituitary-adrenocortical (HPA)-axis functioning associated with morbidity and mortality, with African Americans showing flatter diurnal slopes than their White counterparts. Sleep characteristics are associated with both race and with HPA-axis functioning. The present report examines whether sleep duration may account for race differences in cortisol dynamics.

METHOD

Participants were 424 employed African American and White adults (mean age = 42.8 years, 84.2% White, 53.6% female) with no cardiovascular disease (Adult Health and Behavior Project-Phase 2 [AHAB-II] cohort, University of Pittsburgh). Cortisol slope was calculated using 4 salivary cortisol readings, averaged over each of 4 days. Demographic (age, sex), psychosocial (socioeconomic status [SES], affect, discrimination), and health behaviors (smoking, alcohol use, physical activity) variables were used as covariates, and sleep (self-report and accelerometry) was also assessed.

RESULTS

African Americans had flatter slopes than Whites (F(1, 411) = 10.45, B = .02, p = .001) in models adjusting for demographic, psychosocial, and health behavior covariates. Shorter actigraphy-assessed total sleep time was a second significant predictor of flatter cortisol slopes (F(1, 411) = 25.27, B = -.0002, p < .0001). Total sleep time partially accounted for the relationship between race and diurnal slope [confidence interval = .05 (lower = .014, upper .04)].

CONCLUSIONS

African Americans have flatter diurnal cortisol slopes than their White counterparts, an effect that may be partially attributable to race differences in nightly sleep duration. Sleep parameters should be considered in further research on race and cortisol. (PsycINFO Database Record

Investigating the effect of acute sleep deprivation on hypothalamic-pituitary-adrenal-axis response to a psychosocial stressor

The hypothalamic-pituitary-adrenal (HPA) axis has been previously identified as one potential mechanism that may explain the link between sleep deprivation and negative health outcomes. However, few studies have examined the direct association between sleep deprivation and HPA-axis functioning, particularly in the context of stress. Therefore, the aim of the current study was to investigate the relationship between acute sleep deprivation and HPA-axis reactivity to a psychosocial stressor. Participants included 40 healthy, young adults between the ages of 18-29. The current protocol included spending two nights in the laboratory. After an adaptation night (night 1), participants were randomized into either a sleep deprivation condition (29 consecutive hours awake) or a control condition (night 2). Following the second night, all participants completed the Trier Social Stress Test (TSST). Salivary cortisol was collected before, during, and after the TSST. Results indicated that there were significant group differences in cortisol stress reactivity. Specifically, compared to participants in the control condition, participants in the sleep deprivation condition had greater baseline (i.e., pre-stress) cortisol, yet a blunted cortisol response to the TSST. Taken together, a combination of elevated baseline cortisol (and its subsequent effect on HPA-axis regulatory processes) and a relative 'ceiling' on the amount of cortisol a laboratory stressor can produce may explain why participants in the sleep deprivation condition demonstrated blunted cortisol responses.

Sleep duration and quality in relation to chronic kidney disease and glomerular hyperfiltration in healthy men and women

Background

It is unclear whether sleep duration and quality are associated with chronic kidney disease (CKD) and glomerular hyperfiltration. The aim of this study was to examine the association of sleep duration and quality with CKD and glomerular hyperfiltration in young and middle-aged adults.

Methods

We conducted a cross-sectional study of men and women who underwent a health checkup examination, including assessment of sleep duration and quality (n = 241,607). Chronic kidney disease (CKD) was defined as an estimated glomerular filtration rate (eGFR) less than 60 ml/min/1.73 m², and glomerular hyperfiltration was defined as eGFR above the age-/sex-specific 95^th percentile.

Results

In a multinomial logistic regression analysis adjusting for relevant confounders, the adjusted prevalence ratios for CKD (95% confidence interval) comparing sleep durations of ≤ 5, 6, 8, and 9 hours with 7 hours were 1.22 (0.95–1.55), 0.93 (0.75–1.14), 0.97 (0.75–1.26), and 1.56 (1.06–2.30) in men and 0.98 (0.68–1.43), 1.03 (0.72–1.46), 1.39 (0.97–2.00), and 1.31 (0.78–2.22) in women, respectively. The corresponding prevalence ratios (95% confidence interval) for glomerular hyperfiltration were 1.00 (0.93–1.08), 0.97 (0.91–1.03), 1.03 (0.94–1.13), and 1.39 (1.13–1.72) in men and 1.04 (0.95–1.14), 0.96 (0.90–1.04), 1.11 (1.02–1.20), and 1.28 (1.14–1.45) in women, respectively. Poor subjective sleep quality was associated with glomerular hyperfiltration in men and women.

Conclusion

In this large study of young and middle-aged adults, we found that long sleep duration was associated with CKD and glomerular hyperfiltration. Additionally, poor subjective sleep quality was associated with increased prevalence of glomerular hyperfiltration, suggesting the importance of adequate quantity and quality of sleep for kidney function.

The Functional and Clinical Significance of the 24-Hour Rhythm of Circulating Glucocorticoids

Adrenal glucocorticoids are major modulators of multiple functions, including energy metabolism, stress responses, immunity, and cognition. The endogenous secretion of glucocorticoids is normally characterized by a prominent and robust circadian (around 24 hours) oscillation, with a daily peak around the time of the habitual sleep-wake transition and minimal levels in the evening and early part of the night. It has long been recognized that this 24-hour rhythm partly reflects the activity of a master circadian pacemaker located in the suprachiasmatic nucleus of the hypothalamus. In the past decade, secondary circadian clocks based on the same molecular machinery as the central master pacemaker were found in other brain areas as well as in most peripheral tissues, including the adrenal glands. Evidence is rapidly accumulating to indicate that misalignment between central and peripheral clocks has a host of adverse effects. The robust rhythm in circulating glucocorticoid levels has been recognized as a major internal synchronizer of the circadian system. The present review examines the scientific foundation of these novel advances and their implications for health and disease prevention and treatment.

Stress-Related and Circadian Secretion and Target Tissue Actions of Glucocorticoids: Impact on Health

Living organisms are highly complex systems that must maintain a dynamic equilibrium or homeostasis that requires energy to be sustained. Stress is a state in which several extrinsic or intrinsic disturbing stimuli, the stressors, threaten, or are perceived as threatening, homeostasis. To achieve homeostasis against the stressors, organisms have developed a highly sophisticated system, the stress system, which provides neuroendocrine adaptive responses, to restore homeostasis. These responses must be appropriate in terms of size and/or duration; otherwise, they may sustain life but be associated with detrimental effects on numerous physiologic functions of the organism, leading to a state of disease-causing disturbed homeostasis or cacostasis. In addition to facing a broad spectrum of external and/or internal stressors, organisms are subject to recurring environmental changes associated with the rotation of the planet around itself and its revolution around the sun. To adjust their homeostasis and to synchronize their activities to day/night cycles, organisms have developed an evolutionarily conserved biologic system, the "clock" system, which influences several physiologic functions in a circadian fashion. Accumulating evidence suggests that the stress system is intimately related to the circadian clock system, with dysfunction of the former resulting in dysregulation of the latter and vice versa. In this review, we describe the functional components of the two systems, we discuss their multilevel interactions, and we present how excessive or prolonged activity of the stress system affects the circadian rhythm of glucocorticoid secretion and target tissue effects.

Work duration does not affect cortisol output in experienced firefighters performing live burn drills

Work duration may affect firefighters' stress responses. Forty-two firefighters (38 males) performed either 2 (SWD) or 3 (LWD) bouts of simulated fire suppression activity. Salivary cortisol, self-reported fear and anxiety, and perceptual thermal responses were measured. Cortisol was evaluated using area-under-the-curve calculations (Pruessner et al., 2003). Affective responses between the two conditions were compared using T-tests. Pearson product moment correlations were used to analyze the relationships between affect and change in thermal load perception. Cortisol decreased across the protocol in both groups, and no difference was found in cortisol or affect between the groups. Cortisol decreased (F4,36 = 3.43, p < 0.05) in the SWD group from a mean concentration of 40.93 ± 11.41 nmol/L to 25.07 ± 9.88 nmol/L at the end of the protocol. In the LWD group, the mean cortisol concentration decreased from 42.89 ± 11.83 to 25.07 ± 8.82 at the end of the protocol (F5,50 = 14.77, p < 0.01). Anxiety increased in the LWD (F4,72 = 5.11, p = 0.001) but not the SWD group. Fear increased in the SWD (F3,48 = 14.15, p < 0.001) and LWD group (F4,60 = 4.47, p < 0.01). The present findings suggests a moderate fear load with firefighting, which appears not to be associated with duration of work bout. Examination of more varied work bout lengths may reveal an association between anxiety and work duration. However, the work bout durations investigated in the current study comprise the range of what is practical from an occupational standpoint and the physiological capabilities of the firefighters.

Insomnia and the risk of depression: a meta-analysis of prospective cohort studies

BACKGROUND

Observational studies suggest that insomnia might be associated with an increased risk of depression with inconsistent results. This study aimed at conducting a meta-analysis of prospective cohort studies to evaluate the association between insomnia and the risk of depression.

METHODS

Relevant cohort studies were comprehensively searched from the PubMed, Embase, Web of Science, and China National Knowledge Infrastructure databases (up to October 2014) and from the reference lists of retrieved articles. A random-effects model was used to calculate the pooled risk estimates and 95 % confidence intervals (CIs). The I ² statistic was used to assess the heterogeneity and potential sources of heterogeneity were assessed with meta-regression. The potential publication bias was explored by using funnel plots, Egger's test, and Duval and Tweedie trim-and-fill methods.

RESULTS

Thirty-four cohort studies involving 172,077 participants were included in this meta-analysis with an average follow-up period of 60.4 months (ranging from 3.5 to 408). Statistical analysis suggested a positive relationship between insomnia and depression, the pooled RR was 2.27 (95 % CI: 1.89-2.71), and a high heterogeneity was observed (I ²  = 92.6 %, P < 0.001). Visual inspection of the funnel plot revealed some asymmetry. The Egger's test identified evidence of substantial publication bias (P <0.05), but correction for this bias using trim-and-fill method did not alter the combined risk estimates.

CONCLUSIONS

This meta-analysis indicates that insomnia is significantly associated with an increased risk of depression, which has implications for the prevention of depression in non-depressed individuals with insomnia symptoms.

Sleep Duration and Diabetes Risk: Population Trends and Potential Mechanisms

Sleep is important for regulating many physiologic functions that relate to metabolism. Because of this, there is substantial evidence to suggest that sleep habits and sleep disorders are related to diabetes risk. In specific, insufficient sleep duration and/or sleep restriction in the laboratory, poor sleep quality, and sleep disorders such as insomnia and sleep apnea have all been associated with diabetes risk. This research spans epidemiologic and laboratory studies. Both physiologic mechanisms such as insulin resistance, decreased leptin, and increased ghrelin and inflammation and behavioral mechanisms such as increased food intake, impaired decision-making, and increased likelihood of other behavioral risk factors such as smoking, sedentary behavior, and alcohol use predispose to both diabetes and obesity, which itself is an important diabetes risk factor. This review describes the evidence linking sleep and diabetes risk at the population and laboratory levels.

Repeating patterns of sleep restriction and recovery: Do we get used to it?

Despite its prevalence in modern society, little is known about the long-term impact of restricting sleep during the week and 'catching up' on weekends. This common sleep pattern was experimentally modeled with three weeks of 5 nights of sleep restricted to 4h followed by two nights of 8-h recovery sleep. In an intra-individual design, 14 healthy adults completed both the sleep restriction and an 8-h control condition, and the subjective impact and the effects on physiological markers of stress (cortisol, the inflammatory marker IL-6, glucocorticoid receptor sensitivity) were assessed. Sleep restriction was not perceived to be subjectively stressful and some degree of resilience or resistance to the effects of sleep restriction was observed in subjective domains. In contrast, physiological stress response systems remain activated with repeated exposures to sleep restriction and limited recovery opportunity. Morning IL-6 expression in monocytes was significantly increased during week 2 and 3 of sleep restriction, and remained increased after recovery sleep in week 2 (p<0.05) and week 3 (p<0.09). Serum cortisol showed a significantly dysregulated 24h-rhythm during weeks 1, 2, and 3 of sleep restriction, with elevated morning cortisol, and decreased cortisol in the second half of the night. Glucocorticoid sensitivity of monocytes was increased, rather than decreased, during the sleep restriction and sleep recovery portion of each week. These results suggest a disrupted interplay between the hypothalamic-pituitary-adrenal and inflammatory systems in the context of repeated exposure to sleep restriction and recovery. The observed dissociation between subjective and physiological responses may help explain why many individuals continue with the behavior pattern of restricting and recovering sleep over long time periods, despite a cumulative deleterious physiological effect.

Daily family stress and HPA axis functioning during adolescence: The moderating role of sleep

The present study examined the moderating role of sleep in the association between family demands and conflict and hypothalamic-pituitary-adrenal (HPA) axis functioning in a sample of ethnically diverse adolescents (n=316). Adolescents completed daily diary reports of family demands and conflict for 15 days, and wore actigraph watches during the first 8 nights to assess sleep. Participants also provided five saliva samples for 3 consecutive days to assess diurnal cortisol rhythms. Regression analyses indicated that sleep latency and efficiency moderated the link between family demands and the cortisol awakening response. Specifically, family demands were related to a smaller cortisol awakening response only among adolescents with longer sleep latency and lower sleep efficiency. These results suggest that certain aspects of HPA axis functioning may be sensitive to family demands primarily in the context of longer sleep latency and lower sleep efficiency.

Obstructive sleep apnoea and dementia: is there a link?

OBJECTIVE

Obstructive sleep apnoea is a common sleep disturbance in people of all ages, while dementia is an increasing entity among the ageing population of the world. Recent studies have established a link between sleep apnoea and cognitive decline. This literature review explores this relationship and examines the mechanisms, neurobiology and treatment modalities.

DESIGN

The study was conducted with the use of narrative literature overview.

RESULTS AND CONCLUSIONS

While there are numerous studies that establish a clear relationship between obstructive sleep apnoea, cognitive decline and dementia, more work is needed in understanding the mechanism and processes involved. A detailed understanding of pathophysiology of sleep and the relationship with cognitive decline will be vital in addressing the possibility of averting a likely reversible cause of dementia or cognitive decline.

Possible Contribution of PTSD to Altered Cortisol Activity in Young Adult Obese African-American Women

OBJECTIVE

African-Americans have been found to experience increased rates of post-traumatic stress disorder (PTSD), obesity, and flatter diurnal cortisol slopes compared to other demographic groups. Further exploration, however, is needed to understand how PTSD impacts diurnal cortisol activity in obese African-American women. The purpose of the current study is to examine the relationship between salivary cortisol levels and PTSD in a sample of obese young adult African-American women and to examine how depression and insomnia influence the relationship.

METHODS

Thirty-four young adult African-American women (mean age = 24.0 years; mean BMI = 37.4 kg/m(2), 6/34 of the sample had a score of 40 or above on the PTSD Checklist (PCL) representing clinically significant PTSD) filled out questionnaires assessing PTSD, lifetime exposure to traumatic events, insomnia severity, and depression. A home-based assessment of salivary cortisol was provided upon awakening at 30 min and 1, 3, 6, and 12 h.

RESULTS

There was a significant interaction between PTSD status and diurnal cortisol activity (p < 0.04). There were trends for higher cortisol levels at awakening (p < 0.051) and 30 min post-awakening (p < 0.059) with PTSD. The significance of the interaction between PTSD and cortisol was attenuated by co-varying for depression and insomnia (p > 0.05).

CONCLUSION

PTSD, influenced by depression and insomnia symptoms, has an impact on diurnal cortisol activity in obese young adult African-American women.

Interactions between sleep, stress, and metabolism: From physiological to pathological conditions

Poor sleep quality due to sleep disorders and sleep loss is highly prevalent in the modern society. Underlying mechanisms show that stress is involved in the relationship between sleep and metabolism through hypothalamic–pituitary–adrenal (HPA) axis activation. Sleep deprivation and sleep disorders are associated with maladaptive changes in the HPA axis, leading to neuroendocrine dysregulation. Excess of glucocorticoids increase glucose and insulin and decrease adiponectin levels. Thus, this review provides overall view of the relationship between sleep, stress, and metabolism from basic physiology to pathological conditions, highlighting effective treatments for metabolic disturbances.

Social support moderates the relationship between sleep and inflammation in a population at high risk for developing cardiovascular disease

Poor sleep and low social support have each been associated with mortality and morbidity from chronic illness, and a small body of research suggests that the two interact to influence systemic inflammation whereby good social relationships may buffer the relationship between poor sleep and increased inflammation. The current study investigated interactions between sleep and social support in the prediction of inflammation in a clinical population (prehypertensive and hypertensive individuals) at high risk for the development of cardiovascular disease. Using a standardized subjective measure of sleep quality, we found that social support moderated the association between sleep and circulating levels of both IL-6 and CRP, such that poor sleep appeared to confer a risk of increased inflammation only in those participants who also reported low social support. In women, the same relationship was observed for TNF-α. These results extend previous findings into a clinical population and also demonstrate that sleep quality and social support interact in the prediction of two previously uninvestigated clinically relevant inflammatory markers (CRP and TNF-α). High levels of perceived social support may compensate for the negative health impact of poor sleep quality and vice versa.

Poor sleep as a pathophysiological pathway underlying the association between stressful experiences and the diurnal cortisol profile among children and adolescents

Recent evidence suggests that poor sleep is a potential pathway underlying the association between stressful experiences and the diurnal cortisol profile. However, existing findings are largely limited to adults. The present study examines whether poor sleep (duration, quality) mediates the relation between stressful experiences and the diurnal cortisol profile in children and adolescents. Children and adolescents (N = 220, M(age) = 12.62) provided six saliva samples over two days to derive cortisol indices (bedtime, AUCAG, AUCTG, slope(MAX)). Perceived stress, stressful life events, self-reported sleep duration, and sleep quality were measured. Using bootstrapping analyses, sleep quality mediated the relation between perceived stress and AUCTG (R(2) = 0.10, F(7, 212) = 3.55, p = .001; 95% BCI[0.09, 1.15]), as well as the relation between stressful life events and AUCTG (R(2) = 0.11, F(7, 212) = 3.69, p = .001; 95% BCI[0.40, 3.82]). These mediation models remained significant after adjusting for sleep duration, suggesting that poor sleep quality underlies the association between stressful experiences and the diurnal cortisol profile in children and adolescents. Longitudinal data combined with objectively-measured sleep is essential to further disentangle the complex association between sleep and stress.

Overnight suppression of HPA axis after mineraolocorticoid receptor stimulation: A sleep endocrine study

Nocturnal hyperactivity of hypothalamic-pituitary-adrenal axis (HPA) indicates decreased feedback inhibition with stress-related conditions such as major depression and sleep disorders. To characterize the role of mineralocorticoid (MR) in regulation of HPA axis activity during nocturnal sleep and involvement in sleep architecture, we investigated sleep endocrine effects of the MR agonist fludrocortisone in healthy men after pretreatment with metyrapone to minimize the impact of endogenous cortisol. Subjects (n=8) were treated on three occasions in a single-blinded design in random order with a) metyrapone, b) fludrocortisone after metyrapone, and c) placebo. Polysomnography was recorded and blood samples were drawn for determination of adrenocorticotropic hormone (ACTH) and cortisol during the entire night. After metyrapone administration ACTH was significantly enhanced, while overall nocturnal cortisol secretion remained largely unchanged. Whereas administration of fludrocortisone induced a significant inhibitory effect on basal ACTH and cortisol secretion, no considerable effects on sleep pattern were detectable. While the involvement of MR in sleep regulation needs further study, endocrine findings underline the role of MR in tonic regulation of HPA axis during nocturnal sleep and demonstrate the ability of fludrocortisone to further suppress HPA axis activity overnight. Additional studies would be required to evaluate endocrine and clinical fludrocortisone effects in depressive patients showing HPA hyperactivity.