Cortisol enhances non-REM sleep and growth hormone secretion in elderly subjects

Effects of melatonin on postoperative sleep quality: a systematic review, meta-analysis, and trial sequential analysis

PURPOSE

Postoperative sleep disturbances are common. Although several studies have examined the effect of melatonin on postoperative sleep disturbances, the results have not reached any definitive conclusion. We sought to conduct a systematic review to compare the effects of melatonin and melatonin agonists on postoperative sleep quality with those of placebo or no treatment in adult patients who underwent surgery under general or regional anesthesia.

METHODS

We searched MEDLINE, Cochrane Central Register of Controlled Trials, Embase, Web of Science, ClinicalTrials.gov, and the UMIN Clinical Trials Registry up to 18 April 2022. Randomized clinical trials examining the effects of melatonin or melatonin agonists in patients undergoing general or regional anesthesia with sedation for any surgery were eligible for inclusion. The primary outcome was sleep quality measured using a visual analog scale (VAS). The secondary outcomes were postoperative sleep duration, sleepiness, pain, opioid consumption, quality of recovery, and adverse events. A random-effects model was used to combine the results. We assessed study quality with the Cochrane Risk of Bias Tool version 2. We applied a trial sequential analysis to assess the precision of the combined results.

RESULTS

Eight studies (516 participants) were analyzed for sleep quality. Of those, four studies used only a short duration of melatonin, either on the night before and the day of surgery or only on the day of surgery. A random-effects meta-analysis showed that melatonin did not improve sleep quality measured by VAS compared with placebo (mean difference, -0.75 mm; 95% confidence interval, -4.86 to 3.35), with low heterogeneity (I2, 5%). Trial sequential analysis revealed that the accrued information size (n = 516) reached the estimated required information size (n = 295). We downgraded the certainty of the evidence because of the high risk of bias. The effect on postoperative adverse events was comparable between the melatonin and control groups.

CONCLUSION

Our results indicate that melatonin supplementation does not improve postoperative sleep quality measured with the VAS compared with placebo in adult patients (GRADE: moderate).

STUDY REGISTRATION

PROSPERO (CRD42020180167); registered 27 October 2022.

A Systematic Review, Meta-Analysis and Meta-Regression on the Effects of Carbohydrates on Sleep

This study aimed to assess the effects of quantity, quality and periodization of carbohydrates consumption on sleep. PubMed, SCOPUS and Cochrane Library were searched through October 2020. Data were pooled using random-effects meta-analysis. Eleven articles were included in the meta-analysis which consisted of 27 separate nutrition trials, resulting in 16 comparison data sets (sleep quantity n = 11; sleep quality n = 5). Compared to high carbohydrate (HCI), low carbohydrate intake (LCI) moderately increased duration and proportion of N3 sleep stage (ES = 0.37; 95% CI = 0.18, 0.56; p < 0.001 and ES = 0.51; 95% CI = 0.33, 0.69; p < 0.001, respectively). HCI prolonged rapid eye movement (REM) stage duration (ES = −0.38; 95% CI = 0.05, −8.05; p < 0.001) and proportion (ES = −0.46; 95% CI = −0.83, −0.01; p < 0.001), compared to LCI. The quality of carbohydrate intake did not affect sleep stages. Meta-regression showed that the effectiveness of carbohydrate quantity and quality in sleep onset latency was significantly explained by alterations of carbohydrate intake as a percentage of daily energy intake (R² = 25.87, p = 0.018) and alterations in the glycemic load (R² = 50.8, p = 0.048), respectively. Alterations in glycemic load partially explained the variance of the effectiveness of carbohydrate quality in sleep efficiency (R² = 89.2, p < 0.001) and wake after sleep onset (R² = 64.9, p = 0.018). Carbohydrate quantity was shown to affect sleep architecture, and especially N3 and REM sleep stages. Alterations in both quantity and quality of carbohydrate intake showed a significant effect on sleep initiation. Variations in carbohydrate quality significantly affected measures of sleep continuation. Further studies are needed to assess the effect of long-term carbohydrate interventions on sleep.

Sleep in pituitary insufficient patients compared to patients with depression and healthy controls at baseline and after challenge with CRH

Sleep disturbances are prevalent in both patients with pituitary insufficiency and with depression. The role of corticotropin releasing hormone (CRH), involved in sleep regulation, has not been fully clarified. Pituitary insufficiency is an ideal model for studying sleep-endocrine effects since no consecutive hormone releases and feedback effects occur after hormone administration. 11 male patients with a chronic insufficiency of the anterior pituitary gland (PI) and under stable hormonal substitution were studied during three consecutive nights in the sleep laboratory. The first night served for adapting to laboratory setting, during the second night placebo was administered and during the third night 4 × 50 μg CRH were injected in pulsatile fashion. Sleep parameters were additionally compared with those of 15 healthy male controls (C) and 15 male patients with depression (D). CRH administration was associated with a numerical increase of wake time (115 ± 15 to 131 ± 13 min) and a decrease of REM sleep (89 ± 8 to 80 ± 8 min), REM latency (69 ± 14 to 55 ± 9 min) and slow wave sleep (66 ± 16 to 57 ± 15 min). Yet, none of these changes reached statistical significance. PI showed a worse sleep profile as compared to both control groups, e.g. indicated by a significantly lower sleep efficiency index (PI:0.80 ± 0.03 vs. C:0.94 ± 0.01 vs. D:0.87 ± 0.03). In conclusion sleep-EEG changes after CRH in PI patients resemble those found in in part in patients with depression. Sleep in anterior pituitary insufficiency was impaired despite full hormonal substitution possibly suggesting an alteration of the receptor organisation of brain structures involved in sleep regulation.

The effect of evening cycling at different intensities on sleep in healthy young adults with intermediate chronobiological phenotype: A randomized, cross-over trial

This study investigated the effect of various cycling intensities on sleep-related parameters in healthy young adults with intermediate chronobiological phenotype. Ten recreationally trained male volunteers underwent an evening i) moderate-intensity continuous training (MICT; 45 min at 70% W_max), ii) high-intensity interval training (HIIT; 10 × 1 min at 90% W_max), iii) sprint interval training (SIT; 6 × 20 sec at 140% W_max) or iv) a non-exercise (CON) trial in randomized, counter-balanced and crossover order. At baseline, somatometric data, maximum oxygen uptake and chronotype were evaluated. Sleep-related indices and daily activity were recorded by a multi-sensor activity monitor. Total sleep time was longer after SIT compared to CON and MICT (p < 0.05). Sleep efficiency was higher in SIT than in CON (p < 0.05). Sleep onset latency did not differ among trials. Wake after sleep onset was decreased after SIT compared to CON (p= 0.049). No differences were found for bedtime among trials. Wake time was earlier in the MICT trial compared to CON (p = 0.026). Evening cycling exercise -independently of intensity- did not impair sleep of individuals with intermediate chronobiological phenotype. Furthermore, a single SIT session improved sleep quantity and continuation of individuals with this specific chronotype.

Copine-7 is required for REM sleep regulation following cage change or water immersion and restraint stress in mice

Sleep is affected by the environment. In rodents, changes in the amount of rapid eye movement sleep (REMS) can precede those of other sleep/wake stages. The molecular mechanism underlying the dynamic regulation of REMS remains poorly understood. Here, we focused on the sublaterodorsal nucleus (SLD), located in the pontine tegmental area, which plays a crucial role in the regulation of REMS. We searched for genes selectively expressed in the SLD and identified copine-7 (Cpne7), whose involvement in sleep was totally unknown. We generated Cpne7-Cre knock-in mice, which enabled both the knockout (KO) of Cpne7 and the genetic labeling of Cpne7-expressing cells. While Cpne7-KO mice exhibited normal sleep under basal conditions, the amount of REMS in Cpne7-KO mice was larger compared to wildtype mice following cage change or water immersion and restraint stress, both of which are conditions that acutely reduce REMS. Thus, it was suggested that copine-7 is involved in negatively regulating REMS under certain conditions. In addition, chemogenetically activating Cpne7-expressing neurons in the SLD reduced the amount of REMS, suggesting that these neurons negatively regulate REMS. These results identify copine-7 and Cpne7-expressing neurons in the SLD as candidate molecular or neuronal components of the regulatory system that controls REMS.

Corticotropin-releasing hormone induces depression-like changes of sleep electroencephalogram in healthy women

We reported previously that repetitive intravenous injections of corticotropin-releasing hormone (CRH) around sleep onset prompt depression-like changes in certain sleep and endocrine activity parameters (e.g. decrease of slow-wave sleep during the second half of the night, blunted growth hormone peak, elevated cortisol concentration during the first half of the night). Furthermore a sexual dimorphism of the sleep-endocrine effects of the hormones growth hormone-releasing hormone and ghrelin was observed. In the present placebo-controlled study we investigated the effect of pulsatile administration of 4×50μg CRH on sleep electroencephalogram (EEG) and nocturnal cortisol and GH concentration in young healthy women. After CRH compared to placebo, intermittent wakefulness increased during the total night and the sleep efficiency index decreased. During the first third of the night, REM sleep and stage 2 sleep increased and sleep stage 3 decreased. Cortisol concentration was elevated throughout the night and during the first and second third of the night. GH secretion remained unchanged. Our data suggest that after CRH some sleep and endocrine activity parameters show also depression-like changes in healthy women. These changes are more distinct in women than in men.

Target-based biomarker selection - Mineralocorticoid receptor-related biomarkers and treatment outcome in major depression

Aldosterone and mineralocorticoid receptor (MR)-function have been related to depression. We examined central and peripheral parameters of MR-function in order to characterize their relationship to clinical treatment outcome after six weeks in patients with acute depression. 30 patients with a diagnosis of major depression were examined 3 times over a 6 week period. Aldosterone and cortisol salvia samples were taken at 7.00 a.m. before patients got out of bed. Easy to use e-devices were used to measure markers of central MR function, i.e. slow wave sleep (SWS) and heart-rate variability (HRV). Salt-taste intensity (STI) and salt pleasantness (SP) of a 0.9% salt solution were determined by a newly developed scale. In addition, systolic blood pressure (SBP) and plasma electrolytes were determined as markers for peripheral MR activity. The relationship between the levels of these biomarkers at baseline and the change in clinical outcome parameters (Hamilton depression rating scale (HDRS)-21, anxiety, QIDS and BDI) after 6 weeks of treatment was investigated. A higher aldosterone/cortisol ratio (Aldo/Cort) (n = 17 due to missing values; p < 0.05) and lower SBP (n = 24; p < 0.05) at baseline predicted poor outcome, as measured with the HDRS, independent of gender. Only in male patients higher STI, lower SP, lower SWS (all n = 13) and higher HRV (n = 11) at baseline predicted good outcome p < 0.05). Likewise, in male patients low baseline sodium appears to be predictive for a poor outcome (n = 12; p = 0.05; based on HDRS-6). In conclusion, correlates of higher central MR-activation are associated with poorer clinical improvement, particularly in men. This contrasts with the finding of a peripheral MR-desensitization in more refractory patients. As one potential mechanism to consider, sodium loss on the basis of dysfunctional peripheral MR function and additional environmental factors may trigger increased aldosterone secretion and consequently worse outcome. These markers deserve further study as potential biological correlates for therapy refractory depression.

Sleep and hormonal changes in aging

Age-related sleep and endocrinometabolic alterations frequently interact with each other. For many hormones, sleep curtailment in young healthy subjects results in alterations strikingly similar to those observed in healthy old subjects not submitted to sleep restriction. Thus, recurrent sleep restriction, which is currently experienced by a substantial and rapidly growing proportion of children and young adults, might contribute to accelerate the senescence of endocrine and metabolic function. The mechanisms of sleep-hormonal interactions, and therefore the endocrinometabolic consequences of age-related sleep alterations, which markedly differ from one hormone to another, are reviewed in this article.

Delta wave power: an independent sleep phenotype or epiphenomenon?

Electroencephalographic (EEG) δ waves during non-rapid eye movement sleep (NREMS) after sleep deprivation are enhanced. That observation eventually led to the use of EEG δ power as a parameter to model process S in the two-process model of sleep. It works remarkably well as a model parameter because it often co-varies with sleep duration and intensity. Nevertheless there is a large volume of literature indicating that EEG δ power is regulated independently of sleep duration. For example, high amplitude EEG δ waves occur in wakefulness after systemic atropine administration or after hyperventilation in children. Human neonates have periods of sleep with an almost flat EEG. Similarly, elderly people have reduced EEG δ power, yet retain substantial NREMS. Rats provided with a cafeteria diet have excess duration of NREMS but simultaneously decreased EEG δ power for days. Mice challenged with influenza virus have excessive EEG δ power and NREMS. In contrast, if mice lacking TNF receptors are infected, they still sleep more but have reduced EEG δ power. Sleep regulatory substances, e.g., IL1, TNF, and GHRH, directly injected unilaterally onto the cortex induce state-dependent ipsilateral enhancement of EEG δ power without changing duration of organism sleep. IL1 given systemically enhances duration of NREMS but reduces EEG δ power in mice. Benzodiazepines enhance NREMS but inhibit EEG δ power. If duration of NREMS is an indicator of prior sleepiness then simultaneous EEG δ power may or may not be a useful index of sleepiness. Finally, most sleep regulatory substances are cerebral vasodilators and blood flow affects EEG δ power. In conclusion, it seems unlikely that a single EEG measure will be reliable as a marker of sleepiness for all conditions.

Circadian system, sleep and endocrinology

Levels of numerous hormones vary across the day and night. Such fluctuations are not only attributable to changes in sleep/wakefulness and other behaviors but also to a circadian timing system governed by the suprachiasmatic nucleus of the hypothalamus. Sleep has a strong effect on levels of some hormones such as growth hormone but little effect on others which are more strongly regulated by the circadian timing system (e.g., melatonin). Whereas the exact mechanisms through which sleep affects circulating hormonal levels are poorly understood, more is known about how the circadian timing system influences the secretion of hormones. The suprachiasmatic nucleus exerts its influence on hormones via neuronal and humoral signals but it is now also apparent that peripheral tissues contain circadian clock proteins, similar to those in the suprachiasmatic nucleus, that are also involved in hormone regulation. Under normal circumstances, behaviors and the circadian timing system are synchronized with an optimal phase relationship and consequently hormonal systems are exquisitely regulated. However, many individuals (e.g., shift-workers) frequently and/or chronically undergo circadian misalignment by desynchronizing their sleep/wake and fasting/feeding cycle from the circadian timing system. Recent experiments indicate that circadian misalignment has an adverse effect on metabolic and hormonal factors such as circulating glucose and insulin. Further research is needed to determine the underlying mechanisms that cause the negative effects induced by circadian misalignment. Such research could aid the development of novel countermeasures for circadian misalignment.

Ghrelin increases slow wave sleep and stage 2 sleep and decreases stage 1 sleep and REM sleep in elderly men but does not affect sleep in elderly women

Ghrelin increases non-REM sleep and decreases REM sleep in young men but does not affect sleep in young women. In both sexes, ghrelin stimulates the activity of the somatotropic and the hypothalamic-pituitary-adrenal (HPA) axis, as indicated by increased growth hormone (GH) and cortisol plasma levels. These two endocrine axes are crucially involved in sleep regulation. As various endocrine effects are age-dependent, aim was to study ghrelin's effect on sleep and secretion of GH and cortisol in elderly humans. Sleep-EEGs (2300-0700 h) and secretion profiles of GH and cortisol (2000-0700 h) were determined in 10 elderly men (64.0+/-2.2 years) and 10 elderly, postmenopausal women (63.0+/-2.9 years) twice, receiving 50 microg ghrelin or placebo at 2200, 2300, 0000, and 0100 h, in this single-blind, randomized, cross-over study. In men, ghrelin compared to placebo was associated with significantly more stage 2 sleep (placebo: 183.3+/-6.1; ghrelin: 221.0+/-12.2 min), slow wave sleep (placebo: 33.4+/-5.1; ghrelin: 44.3+/-7.7 min) and non-REM sleep (placebo: 272.6+/-12.8; ghrelin: 318.2+/-11.0 min). Stage 1 sleep (placebo: 56.9+/-8.7; ghrelin: 50.9+/-7.6 min) and REM sleep (placebo: 71.9+/-9.1; ghrelin: 52.5+/-5.9 min) were significantly reduced. Furthermore, delta power in men was significantly higher and alpha power and beta power were significantly lower after ghrelin than after placebo injection during the first half of night. In women, no effects on sleep were observed. In both sexes, ghrelin caused comparable increases and secretion patterns of GH and cortisol. In conclusion, ghrelin affects sleep in elderly men but not women resembling findings in young subjects.

Acute cortisol administration increases sleep depth and growth hormone release in patients with major depression

Acute administration of cortisol increases non-rapid-eye movement (non-REM) sleep, suppresses rapid-eye movement (REM) sleep and stimulates growth hormone (GH) release in healthy subjects. This study investigates whether cortisol has similar endocrine and electrophysiological effects in patients with depression who typically show a pathological overactivity of the hypothalamus-pituitary-adrenal (HPA) system. Fifteen depressed inpatients underwent the combined dexamethasone/corticotropin-releasing hormone test followed by three consecutive sleep EEG recordings in which the patients received placebo (saline) and hourly injections of cortisol (1mg/KG BW). Cortisol increased duration and intensity of non-REM sleep in particular in male patients and stimulated GH release. The activity of the HPA axis appeared to influence the cortisol-induced effects on non-REM sleep and GH levels. Stimulation of delta sleep was less pronounced in patients with dexamethasone nonsuppression. In contrast, REM sleep parameters were not affected by the treatment. These data demonstrate that the non-REM sleep-promoting effects of acute cortisol injections observed in healthy controls could be replicated in patients with depression. Our results suggest that non-REM and REM sleep abnormalities during the acute state of the disease are differentially linked to the activity of the HPA axis.

Ghrelin alone or co-administered with GHRH or CRH increases non-REM sleep and decreases REM sleep in young males

Ghrelin activates the somatotropic and the hypothalamic-pituitary-adrenal axes, being crucially involved in sleep regulation. Simplified, growth hormone releasing hormone (GHRH) increases slow-wave sleep and REM sleep in males, whilst corticotropin-releasing hormone (CRH) increases wakefulness and decreases REM sleep. Ghrelin's role in sleep regulation and particularly its interactions with GHRH and CRH are not entirely clear. We aimed to elucidate the interactions between ghrelin, GHRH and CRH in sleep regulation and the secretion of cortisol and GH. Nocturnal GH and cortisol secretion and polysomnographies were determined in 10 healthy males (25.7+/-3.0 years) four times, receiving placebo (A), ghrelin (B), ghrelin and GHRH (C), or ghrelin and CRH (D) at 22:00, 23:00, 00:00, and 01:00h, in this single-blind, randomized, cross-over study. Non-REM sleep was significantly (p<0.05) increased in all verum conditions (mean+/-SEM: B: 355.3+/-7.4; C: 365.4+/-8.1; D: 371.4+/-3.9min) compared to placebo (336.3+/-6.8min). REM sleep was decreased (B: 84.3+/-4.2 [p<0.1]; C: 74.2+/-7.0 [p<0.05]; D: 80.4+/-2.7min [p<0.05]) compared to placebo (100.9+/-8.3). CRH+ghrelin decreased the time spent awake and enhanced the sleep efficiency; furthermore, the REM latency was decreased compared to the other treatment conditions. CRH enhanced the ghrelin-induced cortisol secretion but had no relevant effect on GH secretion. In turn, GHRH enhanced the ghrelin-induced GH secretion but had no effect on cortisol secretion. In conclusion, ghrelin exhibited distinct sleep effects, which tended to be enhanced by both GHRH and CRH. CRH had sleep-improving and REM permissive effects when co-administered with ghrelin, being in contrast to the effect of CRH alone in previous studies.

Neurochemical regulation of sleep

This review summarizes recent developments in the field of sleep regulation, particularly in the role of hormones, and of synthetic GABA(A) receptor agonists. Certain hormones play a specific role in sleep regulation. A reciprocal interaction of the neuropeptides growth hormone (GH)-releasing hormone (GHRH) and corticotropin-releasing hormone (CRH) plays a key role in sleep regulation. At least in males GHRH is a common stimulus of non-rapid-eye-movement sleep (NREMS) and GH and inhibits the hypothalamo-pituitary adrenocortical (HPA) hormones, whereas CRH exerts opposite effects. Furthermore CRH may enhance rapid-eye-movement sleep (REMS). Changes in the GHRH:CRH ratio in favor of CRH appear to contribute to sleep EEG and endocrine changes during depression and normal ageing. In women, however, CRH-like effects of GHRH were found. Besides CRH somatostatin impairs sleep, whereas ghrelin, galanin and neuropeptide Y promote sleep. Vasoactive intestinal polypeptide appears to be involved in the temporal organization of human sleep. Beside of peptides, steroids participate in sleep regulation. Cortisol appears to promote REMS. Various neuroactive steroids exert specific effects on sleep. The beneficial effect of estrogen replacement therapy in menopausal women suggests a role of estrogen in sleep regulation. The GABA(A) receptor or GABAergic neurons are involved in the action of many of these hormones. Recently synthetic GABA(A) agonists, particularly gaboxadol and the GABA reuptake inhibitor tiagabine were shown to differ distinctly in their action from allosteric modulators of the GABA(A) receptor like benzodiazepines as they promote slow-wave sleep, decrease wakefulness and do not affect REMS.

Roles of peptides and steroids in sleep disorders

A bidirectional interaction exists between the electrophysiological and neuroendocrine components of sleep. The first is represented by the nonrapid eye movement sleep (NREMS) and rapid eye movement sleep (REMS) cycles, the latter by distinct patterns of the secretion of various hormones. Certain hormones (neuropeptides and steroids) play a specific role in sleep regulation. Changes in their activity contribute to the pathophysiology of sleep disorders. A reciprocal interaction of the peptides growth hormone-releasing hormone (GHRH) and corticotropin-releasing hormone (CRH) plays a key role in sleep regulation. GHRH promotes growth hormone secretion and, at least in males, NREMS, whereas CRH impairs NREMS, promotes REMS and stimulates the secretion of adrenocorticotropic hormone and cortisol. Changes in the CRH:GHRH ratio in favor of CRH contribute to impaired sleep, elevated cortisol secretion and blunted GH levels during depression and normal aging. However, in women, GHRH exerts CRH-like effects. Galanin, ghrelin and neuropeptide Y are other sleep-promoting peptides, whereas somatostatin impairs sleep. A decline of orexin activity causes narcolepsy. In addition to CRH overactivity, hypercortisolism appears to be involved in the pathophysiology of sleep- electroencephalogram (EEG) changes in depression. Various neuroactive steroids exert specific effects on sleep. The changes of sleep EEG in women after the menopause are related to the decline of estrogen and progesterone. Furthermore, sleep-EEG changes in dwarfism, acromegaly, Addison's disease, Cushing's disease, brain injury, sleep apnea syndrome, primary insomnia, prolactinoma and dementia appear to be related to changes in the activity of peptides and steroids.

Growth hormone-releasing hormone and corticotropin-releasing hormone enhance non-rapid-eye-movement sleep after sleep deprivation

The neuropeptides growth hormone (GH)-releasing hormone (GHRH) and corticotropin-releasing hormone (CRH) regulate sleep and nocturnal hormone secretion in a reciprocal fashion, at least in males. GHRH promotes sleep and GH and inhibits hypothalamo-pituitary-adrenocortical (HPA) hormones. CRH exerts opposite effects. In women, a sexual dimorphism was found because GHRH impairs sleep and stimulates HPA hormones. Sleep deprivation (SD) is the most powerful stimulus for inducing sleep. Studies in rodents show a key role of GHRH in sleep promotion after SD. The effects of GHRH and CRH on sleep-endocrine activity during the recovery night after SD are unknown. We compared sleep EEG, GH, and cortisol secretion between nights before and after 40 h of SD in 48 normal women and men aged 19-67 yr. During the recovery night, GHRH, CRH, or placebo were injected repetitively. After placebo during the recovery night, non-rapid-eye-movement sleep (NREMS) and rapid-eye-movement sleep (REMS) increased and wakefulness decreased compared with the baseline night. After GHRH, the increase of NREMS and the decrease of wakefulness were more distinct than after placebo. Also, after CRH, NREMS increased higher than after placebo, and a positive correlation was found between age and the baseline-related increase of slow-wave sleep. REMS increased after placebo and after GHRH, but not after CRH. EEG spectral analysis showed increases in the lower frequencies and decreases in the higher frequencies during NREMS after each of the treatments. Cortisol and GH did not differ between baseline and recovery nights after placebo. After GHRH, GH increased and cortisol decreased. Cortisol increased after CRH. No sex differences were found in these changes. Our data suggest that GHRH and CRH augment NREMS promotion after SD. Marked differences appear to exist in peptidergic sleep regulation between spontaneous and recovery sleep.

Neuroendocrine Regulation of Sleep Disturbances in PTSD

Studies that have conducted quantitative analysis of the sleep electroencephalogram (EEG) have demonstrated decreased delta sleep in PTSD. Elevations in both hypothalamic (neurohormonal) and extrahypothalamic (neurotransmitter) corticotropin releasing factor (CRF) release is associated with decreased delta sleep activity. We present data from several studies examining the effect of metyrapone administration on the sleep EEG in PTSD and control subjects. Plasma ACTH, cortisol, and 11-deoxycorticol were obtained the morning following polysomnographic sleep recordings before and after metyrapone administration. Delta sleep was measured by period amplitude analysis. The results demonstrate: a) decreased delta sleep in male subjects with PTSD; b) metyrapone administration resulted in an activation of the sleep EEG and a robust decrease in quantitative delta sleep; c) the sleep and endocrine (increase in ACTH) responses to metyrapone were significantly decreased in PTSD in two different study samples; and d) the metyrapone-related disruption to sleep in both samples was predicted by the increase in ACTH measured the following morning. These findings strongly suggest that the delta sleep response to metyrapone is a measure of the brain response to a hypothalamic CRF challenge. The attenuated delta sleep and endocrine response to metyrapone challenge in PTSD is consistent with a model of enhanced negative feedback regulation or downregulation of CRF receptors in an environment of chronically increased CRF activity.

Alpha-helical CRH exerts CRH agonistic effects on sleep-endocrine activity in humans

CRH is known to enhance wakefulness and to reduce SWS. In addition, some but not all, studies suggest that CRH promotes REM sleep. Alpha-helical CRH exerts CRH-antagonistic effects in various studies. We studied its effect on sleep EEG and nocturnal secretion of ACTH, cortisol, GH (n = 7) in young normal male subjects. After administering the substance cortisol and ACTH levels were enhanced during the total night compared to placebo. We found an increase of the time spent awake for the first half. ACTH (2nd half of the night) and cortisol (total night and 1st half of the night) increased. The results of the present study correspond to a mixture of agonistic and antagonistic effects of alpha-helical CRH.

Hypothalamic-pituitary-adrenal axis activity and sleep in posttraumatic stress disorder

Alterations of the hypothalamic-pituitary-adrenal (HPA) axis and sleep disturbances have been described separately in post-traumatic stress disorder (PTSD). It is not known if HPA alterations and sleep disturbances are associated in PTSD. This study examined sleep and HPA activity in 20 male medication-free subjects with PTSD and 16 matched healthy controls. Two nights of polysomnography were obtained and 24-h urinary cortisol was collected during day 2. Subjects self-administered a low-dose (0.5 mg) salivary dexamethasone test at home. Compared with controls, PTSD subjects had higher 24-h urinary microg cortisol/g creatinine (mean+/-SD 40+/-17 vs 28+/-12, p=0.03) but not significantly higher 24-h urinary cortisol (mean+/-SD 52+/-15 microg/day vs 43+/-23, p=0.19). PTSD subjects showed a trend towards less cortisol suppression after dexamethasone (73%+/-18 vs 83%+/-10, p=0.06). In the combined sample, delta sleep was significantly and negatively correlated with 24-h urinary cortisol (r=-0.36, p=0.04), and with 24-h urinary cortisol/g creatinine on a trend level (r=-0.34, p=0.06). Our results suggest that increased cortisol is negatively associated with delta sleep. This may contribute to sleep abnormalities in conditions associated with elevated cortisol, possibly including PTSD. Future studies should explore the temporal relationship between HPA activity, sleep disturbances, and psychopathology after a traumatic event.

Ultradian rhythms in pituitary and adrenal hormones: their relations to sleep

Sleep and circadian rhythmicity both influence the 24-h profiles of the main pituitary and adrenal hormones. From studies using experimental strategies including complete and partial sleep deprivation, acute and chronic shifts in the sleep period, or complete sleep-wake reversal as occurs with transmeridian travel or shift-work, it appears that prolactin (PRL) and growth hormone (GH) profiles are mainly sleep related, while cortisol profile is mainly controlled by the circadian clock with a weak influence of sleep processes. Thyrotropin (TSH) profile is under the dual influence of sleep and circadian rhythmicity. Recent studies, in which we used spectral analysis of sleep electroencephalogram (EEG) rather than visual scoring of sleep stages, have evaluated the temporal associations between pulsatile hormonal release and the variations in sleep EEG activity. Pulses in PRL and in GH are positively linked to increases in delta wave activity, whereas TSH and cortisol pulses are related to decreases in delta wave activity. It is yet not clear whether sleep influences endocrine secretion, or conversely, whether hormone secretion affects sleep structure. These well-defined relationships raise the question of their physiological significance and of their clinical implications.

Acute cortisol administration promotes sleep intensity in man

The neuronal mechanisms of sleep generation, in particular synchronization of brain activity in the process of non-rapid-eye movement (non-REM) sleep, has been elucidated in the past decade. A previous study of our group showed that acute administration of cortisol is known to increase slow-wave sleep and suppress rapid-eye movement (REM) sleep in man. To further elucidate the non-REM sleep-promoting effects of cortisol with respect to the synchronization of cortical activity, it is important to establish a sleep-state-specific quantitative EEG analysis. We therefore investigated the effects of repetitive injections of hydrocortisone on spectral composition of sleep EEG in 10 healthy male young volunteers. In addition, we performed high-frequency blood samplings to assess the relation between changes in the sleep EEG and sleep-associated secretion of growth hormone (GH). Cortisol administration resulted in a significant increase in highly synchronized EEG activity including delta and theta frequencies, according to a higher amount of slow-wave sleep. This effect predominated in the first few hours of night sleep. REM sleep was decreased, which appeared to be secondary to the lengthened first sleep cycle. The cortisol-induced stimulation of GH release did not occur in correspondence with the increased slow-wave activity. In view of the sleep impairing properties of corticotropin-releasing hormone (CRH) and the sleep-promoting function of GH-releasing hormone, it appears likely that a negative feedback inhibition of endogenous CRH was the key mechanism mediating the observed results. The cortisol-induced effects on sleep intensity and sleep-associated GH secretion appeared to be driven by different mechanisms.

Treatment with the CRH1-receptor-antagonist R121919 improves sleep-EEG in patients with depression

Well documented changes of sleep electroencephalogram (EEG) in patients with depression include rapid eye movement (REM) sleep disinhibition, decreases of slow-wave-sleep (SWS) and increase in wakefulness. Twenty-seven inpatients with major depression were admitted subsequently to a clinical trial with the CRH(1)-receptor-antagonist R121919 administered in two different dose escalation panels. A random subgroup of 10 patients underwent three sleep-EEG recordings (baseline before treatment, at the end of the first week and at the end of the fourth week of active treatment). SWS time increased significantly compared with baseline after 1 week and after 4 weeks. The number of awakenings and REM density showed a trend toward a decrease during the same time period. Separate evaluation of these changes for both panels showed no significant effect at lower doses, whereas in the higher doses after R121919 REM density decreased and SWS increased significantly between baseline and week 4. Furthermore positive associations between HAMD scores and SWS at the end of active treatment were found. Although these data might indicate that R121919 has a normalizing influence on the sleep EEG, the design of the study does not allow to differentiate genuine drug effects from those of clinical improvement and habituation to the clinical setting.

Delta sleep response to metyrapone in post-traumatic stress disorder

Metyrapone blocks cortisol synthesis, which results in the stimulation of hypothalamic cortiocotropin-releasing factor (CRF) and a reduction in delta sleep. We examined the effect of metyrapone administration on endocrine and sleep measures in male subjects with and without chronic PTSD. We hypothesized that metyrapone would result in a decrease in delta sleep and that the magnitude of this decrease would be correlated with the endocrine response. Finally, we utilized the delta sleep response to metyrapone as an indirect measure of hypothalamic CRF activity and hypothesized that PTSD subjects would have decreased delta sleep at baseline and a greater decrease in delta sleep induced by metyrapone. Three nights of polysomnography were obtained in 24 male subjects with combat-related PTSD and 18 male combat-exposed normal controls. On day 3, metyrapone was administered during normal waking hours until habitual sleep onset preceding night 3. Endocrine responses to metyrapone were measured in plasma obtained the morning following sleep recordings, the day before and after administration. Repeated measures ANOVAs were conducted to compare the endocrine and sleep response to metyrapone in PTSD and controls. PTSD subjects had significantly less delta sleep as indexed by stages 3 and 4, and total delta integrated amplitude prior to metyrapone administration. There were no differences in premetyrapone cortisol or ACTH levels in PTSD vs controls. PTSD subjects had a significantly decreased ACTH response to metyrapone compared to controls. Metyrapone caused an increase in awakenings and a marked decrease in quantitative measures of delta sleep that was significantly greater in controls compared to PTSD. The decline in delta sleep was significantly associated with the magnitude of increase in both 11-deoxycortisol and ACTH. The results suggest that the delta sleep response to metyrapone is a measure of the brain response to increases in hypothalamic CRF. These data also suggest that the ACTH and sleep EEG response to hypothalamic CRF is decreased in PTSD.

Depression-like changes of the sleep-EEG during high dose corticosteroid treatment in patients with multiple sclerosis

Acute exacerbations of multiple sclerosis (MS) are commonly treated with high doses of corticosteroids that can influence sleep regulation and hypothalamo-pituitary-adrenal (HPA) activity. We examined the sleep-EEG (including conventional and spectral EEG analysis) in 9 female patients with relapsing-remitting MS (and no psychiatric disorder) just prior to and on days 2 and 10 of high dose corticosteroid treatment (500 mg/day methylprednisolone given IV for 5 days, then PO taper down) and age-matched healthy female controls. Before treatment with corticosteroids, MS patients compared to controls showed few changes of the sleep EEG, namely a significant increase in slow wave sleep (SWS) and a decrease in stage 2 sleep. In contrast, on day 10, but not day 2 of treatment, MS patients showed a number of sleep-EEG changes typically observed in patients with depression, including a reduction in REM latency, an increase in REM density, a decrease in the SWS and delta sleep ratio and a decrease in sigma EEG activity. However, no concomitant effect of treatment on mood was noted. In summary, unlike acute treatment with methylprednisolone, prolonged treatment induces several changes of the sleep-EEG in MS patients, that are also observed in patients with an acute depressive episode. Further prospective studies with longer-term follow-up are needed to examine the clinical relevance of our preliminary data.

Sleep and endocrinology

A bidirectional interaction between sleep electroencephalogram and endocrine activity is well established in various species including humans. Various hormones (peptides and steroids) participate in sleep regulation. A key role was shown for the reciprocal interaction between sleep-promoting growth hormone-releasing hormone (GHRH) and sleep-impairing corticotropin-releasing hormone (CRH). Changes in the GHRH : CRH ratio result in changes of sleep-endocrine activity. It is thought that the change of this ratio in favour of CRH contributes to aberrations of sleep during ageing and depression (shallow sleep, blunted GH and elevated cortisol). Besides GHRH, ghrelin and galanin enhance slow wave sleep. Somatostatin is another sleep-impairing factor. Neuropeptide Y acts as a CRH antagonist and induces sleep onset. There are hints that CRH promotes rapid eye movement sleep (REMS). In animals prolactin enhances REMS. In humans vasoactive intestinal polypeptide (VIP) appears to play a role in the temporal organization of sleep as, after VIP, the non-REMS-REMS cycle decelerated. Cortisol appears to enhance REMS. Finally, gonadal hormones participate in sleep regulation. Oestrogen replacement therapy and CRH-1 receptor antagonism in depression are beneficial clinical applications of sleep-endocrine research.

Sleep and the hypothalamo-pituitary-adrenocortical system

The intention of this review is to summarize the current knowledge on the bidirectional interaction between sleep EEG and the secretion of corticotropin (ACTH) and cortisol. The administration of various hypothalamic-pituitary- adrenocortical (HPA) hormones and their antagonists exerts specific sleep-EEG changes in several species including humans. It is well documented that corticotropin releasing hormone (CRH) impairs sleep and enhances vigilance. In addition, it may promote REM sleep. Changes in the growth hormone-releasing hormone (GHRH):CRH ratio in favour of CRH appear to contribute to shallow sleep, elevated cortisol levels and blunted GH in depression and ageing. On the other hand, in women GHRH appears to exert CRH-like effects on sleep. Acute cortisol administration increases slow-wave sleep (SWS) and GH, probably due to feedback inhibition of CRH, and inhibits REM sleep. With the mixed glucocorticoid and progesterone receptor antagonist mifepriston sleep is disrupted. Subchronic administration of the glucocorticoid agonist methylprednisolone desinhibited REM sleep. A synergism of elevated CRH and cortisol activity may contribute to REM disinhibition during depression. Also ACTH and vasopressin modulate sleep specifically but their physiological role remains unclear. For example acute icv vasopressin enhances wakefulness in rats, whereas its long-term administration increases SWS in the elderly. In various studies the interaction of sleep EEG and HPA hormones has been investigated at the baseline, after manipulation of sleep-wake behaviour and after environmental changes. Most studies agree that the circadian pattern of cortisol is relatively independent from sleep and environmental influences. Some data suggest a major effect of light on cortisol secretion. Sleeping is widely associated with blunting and awakenings are linked with increases of HPA hormones.

Effect of the GABAA agonist gaboxadol on nocturnal sleep and hormone secretion in healthy elderly subjects

Aging is associated with a dramatic decrease in sleep intensity and continuity. The selective GABA(A) receptor agonist gaboxadol has been shown to increase non-REM sleep and the duration of the non-REM episodes in rats and sleep efficiency in young subjects and to enhance low-frequency activity in the electroencephalogram (EEG) within non-REM sleep in both rats and humans. In this double-blind, placebo-controlled study, we investigated the influence of an oral dose of 15 mg of gaboxadol on nocturnal sleep and hormone secretion (ACTH, cortisol, prolactin, growth hormone) in 10 healthy elderly subjects (6 women). Compared with placebo, gaboxadol did not affect endocrine activity but significantly reduced perceived sleep latency, elevated self-estimated total sleep time, and increased sleep efficiency by decreasing intermittent wakefulness and powerfully augmented low-frequency activity in the EEG within non-REM sleep. These findings indicate that gaboxadol is able to increase sleep consolidation and non-REM sleep intensity, without disrupting REM sleep, in elderly individuals and that these effects are not mediated by a modulation of hormone secretion.

The GABA uptake inhibitor tiagabine promotes slow wave sleep in normal elderly subjects

Aging is associated with a dramatic decrease in slow wave sleep (SWS) and sleep consolidation. Previous studies revealed that various GABA(A) agonists and the GABA uptake inhibitor tiagabine augment slow frequency components in the EEG within non-REM sleep, and thus promote deep sleep in young individuals and/or rats. In the present double-blind, placebo-controlled study, we assessed the effect of a single oral dose of 5 mg tiagabine on nocturnal sleep in ten healthy elderly volunteers (6 females). During the placebo night the subjects displayed a low sleep efficiency, due to high amounts of intermittent wakefulness, and little SWS. Tiagabine significantly increased sleep efficiency, tendentially decreased wakefulness and prominently increased both SWS and low-frequency activity in the EEG within non-REM sleep. The present findings demonstrate that tiagabine increases sleep quality in aged subjects. Moreover, the effects of tiagabine closely match those evoked by the GABA(A) agonist gaboxadol in young subjects and indicate that such compounds may have prospects in the treatment of sleep disturbances, particularly of those commonly occurring in the elderly.

Non-linear changes of electrocortical activity after antenatal betamethasone treatment in fetal sheep

We determined the effects of betamethasone on the fetal sheep electrocorticogram (ECoG) using linear (power spectral) and non-linear analysis. For non-linear analysis we used an algorithm based on the Wolf algorithm for the estimation of the leading Lyapunov exponent which calculates a prediction error based on the course of the time series in the phase space. A high prediction error stands for low predictibility or low regularity and vice versa. After 48 h of baseline recordings, vehicle (n = 6) or betamethasone (n = 7) at 10 microg h(-1) was infused over 48 h to the sheep fetus at 128 days gestational age (0.87 of gestation). ECoG spectral analysis revealed no difference in power spectrum between vehicle- and betamethasone-treated fetuses. The prediction error of the ECoG during REM sleep was higher than during non-REM or quiet sleep in both groups (P < 0.0001) revealing lower causality of brain activity during REM sleep. During REM sleep, prediction error significantly decreased 18-24 h after onset of betamethasone treatment (P < 0.05) and returned to baseline values within the following 24 h of continued betamethasone treatment. No ECoG changes were found during quiet sleep. Non-linear ECoG changes during metabolically active REM sleep accompanied the previously described decrease in cerebral blood flow. These results suggest that betamethasone in doses used in perinatal medicine acutely alters complex neuronal activity.

Modelling and exploring human sleep with event history analysis

In this paper we propose the use of statistical models of event history analysis for investigating human sleep. These models provide appropriate tools for statistical evaluation when sleep data are recorded continuously over time or on a fine time grid, and are classified into sleep stages such as REM and nonREM as defined by Rechtschaffen and Kales (1968). In contrast to conventional statistical procedures, event history analysis makes full use of the information contained in sleep data, and can therefore provide new insights into non-stationary properties of sleep. Probabilities of or intensities for transitions between sleep stages are the basic quantities for characterising sleep processes. The statistical methods of event history analysis aim at modelling and estimating these intensities as functions of time, taking into account individual sleep history and assessing the influence of factors of interest, such as hormonal secretion. In this study we suggest the use of non-parametric approaches to reveal unknown functional forms of transition intensities and to explore time-varying and non-stationary effects. We then apply these techniques in a study of 30 healthy male volunteers to assess the mean population intensity and the effects of plasma cortisol concentration on the transition between selected sleep stages as well as the influence of elapsed time in a current REM period on the intensity for a transition to nonREM. The most interesting findings are that (a) the intensity of the nonREM-to-REM transitions after sleep onset in young men shows a periodicity which is similar to that of nonREM/REM cycles; (b) 30-45 min after sleep onset, young men reveal a great propensity to pass from light sleep (stages 1 or 2) into slow-wave sleep (SWS) (stages 3 or 4); (c) high cortisol levels imposed additional impulses on the transition intensity of (i) wake to sleep around 2 h after sleep onset, (ii) nonREM to REM around 6 h later, (iii) stage 1 or stage 2 sleep to SWS around 2, 4 and 6 h later and (iv) SWS to stage 1 or stage 2 sleep about 2 h later. Moreover, high cortisol concentrations at the beginning of REM periods favoured the change to nonREM sleep, whereas later their influence on a nonREM change became weak and weaker. As sleep data are also available as event-oriented data in many studies in sleep research, event history analysis applied additionally to conventional statistical procedures, such as regression analysis or analysis of variance, could help to acquire more information and knowledge about the mechanisms behind the sleep process.

Enhanced slow wave sleep in patients with prolactinoma

Bidirectional interactions between nocturnal hormone secretion and sleep regulation are well established. In particular, a link between PRL and rapid eye movement (REM) sleep has been hypothesized. Short-term administration of PRL and even long-term hyperprolactinemia in animals increases REM sleep. Furthermore, sleep disorders are frequent symptoms in patients with endocrine diseases. We compared the sleep electroencephalogram of seven drug-free patients with prolactinoma (mean PRL levels 1450 +/- 1810 ng/mL; range between 146 and 5106 ng/mL) with that of matched controls. The patients had secondary hypogonadism but no other endocrine abnormalities. They spent more time in slow wave sleep than the controls (79.4 +/- 54.4 min in patients vs. 36.6 +/- 23.5 min in controls, P < 0.05). REM sleep variables did not differ between the samples. Our data suggest that chronic excessive enhancement of PRL levels exerts influences on the sleep electroencephalogram in humans. Our result, which seems to be in contrast to the enhanced REM sleep under hyperprolactinemia in rats, leads to the hypothesis that both slow wave sleep and REM sleep can be stimulated by PRL. These findings are in accordance with reports of good sleep quality in patients with prolactinoma, which is in contrast to that of patients with other endocrine diseases.

Pulsatile cortisol secretion and EEG delta waves are controlled by two independent but synchronized generators

We have previously described a temporal relationship between plasma cortisol pulses and slow-wave sleep and, more recently, an inverse significant cross-correlation between cortisol secretory rates and delta wave activity of the sleep electroencephalogram (EEG). The aim of this study was to observe ACTH, cortisol, and sleep delta wave activity variations throughout 24 h to get a better insight into their initiating mechanisms. Two groups of 10 subjects participated in a 24-h study, one group with a night sleep (2300-0700) and the other with a day sleep (0700-1500). Cortisol secretory rates were calculated by a deconvolution procedure from plasma levels measured at 10-min intervals. Delta wave activity was computed during sleep by spectral analysis of the sleep EEG. When delta waves and cortisol were present at the same time at the end of the night sleep as well as during the daytime sleep, they were negatively correlated, cortisol changes preceding variations in delta wave activity by approximately 10 min. Increases in delta wave activity occurred in the absence of cortisol pulses, as observed at the beginning of the night. Cortisol pulses occurred without any concomitant variations of sleep delta wave activity, as observed during wakefulness and intrasleep awakenings. In no case did delta wave activity increase together with an increase in cortisol secretory rates. In conclusion, cortisol secretion and delta wave activity have independent generators. They can oscillate independently from each other, but when they are present at the same time, they are oscillating in phase opposition.