Sleep In Healthy Men Research Articles

Bone Turnover Markers After Six Nights of Insufficient Sleep and Subsequent Recovery Sleep in Healthy Men.

The goal of this study was to determine the bone turnover marker (BTM) response to insufficient and subsequent recovery sleep, independent of changes in posture, body weight, and physical activity. Healthy men (N = 12) who habitually slept 7-9h/night were admitted to an inpatient sleep laboratory for a baseline 8h/night sleep opportunity followed by six nights of insufficient sleep (5h/night). Diet, physical activity, and posture were controlled. Serum markers of bone formation (osteocalcin, PINP) and resorption (β-CTX) were obtained over 24 h at baseline and on the last night of sleep restriction, and on fasted samples obtained daily while inpatient and five times after discharge over 3weeks. Maximum likelihood estimates in a repeated measures model were used to assess the effect of insufficient and subsequent recovery sleep on BTM levels. There was no statistically or clinically significant change in PINP (p = 0.53), osteocalcin (p = 0.66), or β-CTX (p = 0.10) in response to six nights of insufficient sleep. There were no significant changes in BTMs from the inpatient stay through 3weeks of recovery sleep (all p [Formula: see text] 0.63). On average, body weight was stable during the inpatient stay (Δweight = - 0.55 ± 0.91kg, p = 0.06). No significant changes in serum BTMs were observed after six nights of insufficient or subsequent recovery sleep in young healthy men. Changes in weight and physical activity may be required to observe significant BTM change in response to sleep and circadian disruptions. Clinical Trials Registration Registered at ClinicalTrials.gov (NCT03733483) on November 7, 2018.

The sleep network organization during slow-wave sleep is more stable with age and has small-world characteristics more marked than during REM sleep in healthy men

Sleep plays an important role in cognitive functioning. However, few studies have investigated the sleep network organization. The aim of our study was to empirically investigate the presence and the stability with age of a small-world network organization during REM and slow-wave sleep using the effective connectivity measured by the Granger causality. Polysomnographic data from 30 healthy men recruited prospectively were analysed. To obtain the 19 × 19 connectivity matrix of all possible pairwise combinations of electrodes by the Granger causality method from our EEG data, we used the Toolbox MVGC multivariate Granger causality. The computation of the network measures was realised by importing these connectivity matrices into the EEGNET Toolbox. Even if all small-world coefficients obtained are compatible with a small-world network organization during REM and slow-wave sleep, slow-wave sleep seems to have a small-world network organization more marked than REM sleep. Moreover, the sleep network organization is affected greater by age during REM sleep than during slow-wave sleep. In healthy individuals, the highlighting of a sleep network organization during slow-wave sleep more stable with age and with small-world characteristics more marked than during REM sleep may help to better understand the global and local processing of information during sleep.

Influence of exogenous atrial natriuretic peptide on the nocturnal hypothalamic-pituitary-adrenal axis and sleep in healthy men

Atrial natriuretic peptide (ANP), originally found in the cardiac atria, is also widely distributed in the central nervous system (CNS) and has been predominantly found in the hypothalamus and the pituitary gland. Previous in vitro and in vivo studies have provided evidence for an inhibitory control of ANP at all regulatory levels of the hypothalamo-pituitary-adrenocortical (HPA) system. In vivo studies in man demonstrated that ANP inhibits stimulated pituitary-adrenal secretion during wakefulness. On the other hand, it has been reported that various neuropeptides not only influence the neuroendocrine compound of sleep, but also exert specific effects on the sleep electroencephalogram (EEG). To further characterize the role of ANP in the regulation of the nocturnal HPA axis activity and consecutive sleep regulation, we investigated sleep-endocrine effects of intravenously administered ANP in healthy men during nocturnal sleep. Eight volunteers underwent three trial conditions in random order and in a single-blind design receiving ANP infusion at the beginning of the 1st or the 2nd half of the night, or placebo. Sleep was assessed by polysomnography and blood samples were drawn in 30-min intervals for determination of adrenocorticotrophic hormone (ACTH) and cortisol during the entire night. While the ACTH and cortisol secretion during ANP infusions remained unchanged, an immediate increase of ACTH and cortisol secretion occurred after each infusion period for approximately 2h without changing basal levels and the circadian course of both hormones. Sleep EEG parameters were neither directly affected by ANP infusions nor by the following ANP-induced ACTH and cortisol secretion. The presence of such clear-cut enhancement of the pituitary-adrenal release indicates a rebound effect of ANP on HPA secretory activity and supports the idea that ANP acts as corticotropin-releasing hormone (CRH)-inhibiting factor.

Influence of exogenous ANP on the nocturnal HPA axis and sleep in healthy men

Influence of exogenous ANP on the nocturnal HPA axis and sleep in healthy men

Effects of hypoxia on genioglossus and scalene reflex responses to brief pulses of negative upper-airway pressure during wakefulness and sleep in healthy men

Hypoxia can depress ventilation, respiratory load sensation, and the cough reflex, and potentially other protective respiratory reflexes such as respiratory muscle responses to increased respiratory load. In sleep-disordered breathing, increased respiratory load and hypoxia frequently coexist. This study aimed to examine the effects of hypoxia on the reflex responses of 1) the genioglossus (the largest upper airway dilator muscle) and 2) the scalene muscle (an obligatory inspiratory muscle) to negative-pressure pulse stimuli during wakefulness and sleep. We hypothesized that hypoxia would impair these reflex responses. Fourteen healthy men, 19-42 yr old, were studied on two separate occasions, approximately 1 wk apart. Bipolar fine-wire electrodes were inserted orally into the genioglossus muscle, and surface electrodes were placed overlying the left scalene muscle to record EMG activity. In random order, participants were exposed to mild overnight hypoxia (arterial oxygen saturation approximately 85%) or medical air. Respiratory muscle reflex responses were elicited via negative-pressure pulse stimuli (approximately -10 cmH(2)O at the mask, 250-ms duration) delivered in early inspiration during wakefulness and sleep. Negative-pressure pulse stimuli resulted in a short-latency activation followed by a suppression of the genioglossus EMG that did not alter with hypoxia. Conversely, the predominant response of the scalene EMG to negative-pressure pulse stimuli was suppression followed by activation with more pronounced suppression during hypoxia compared with normoxia (mean +/- SE suppression duration 64 +/- 6 vs. 38 +/- 6 ms, P = 0.006). These results indicate differential sensitivity to the depressive effects of hypoxia in the reflex responsiveness to sudden respiratory loads to breathing between these two respiratory muscles.

Sex differences in cardiac sympathovagal balance and vagal tone during nocturnal sleep

Objective To analyze sex differences in nocturnal vagal tone and cardiac sympathovagal balance during sleep in healthy men and women. Methods In two groups of healthy, non-obese adults (15 men and 14 women), sleep was polygraphically recorded and heart rate variability was assessed during an awake period prior to sleep and during sleep. Vagal tone was estimated by the high-frequency (HF) power component of heart rate variability, and sympathovagal balance was indexed by the ratio of low-frequency (LF) power to HF power. Results As compared to women, men showed decreases in vagal tone and increases in sympathovagal balance. During rapid eye movement (REM) sleep, a withdrawal of vagal tone occurred with an increase in sympathetic dominance. Men showed a greater increase of sympathovagal balance during REM sleep than women. Secondary analyses covarying for differences in reproductive hormone levels, physical activity, and sleep measures did not alter the results. Conclusions The marked increase in cardiac sympathetic drive during REM sleep in men has implications for understanding sex differences in the risk of cardiovascular events. Additionally, these data offer a pathway to explain the peak in cardiac arrhythmias and sudden cardiac death seen more often in the morning hours.

Electroencephalogram characteristics of autonomic arousals during sleep in healthy men

Objective Many sleep disorders involve frequent, brief arousals, not appreciated during conventional sleep stage scoring due to lack of electroencephalogram (EEG) desynchronization. We evaluated the temporal relation between heart rate (HR) changes, an index of autonomic activation, and EEG in seven healthy subjects during sleep. Methods We identified bouts of tachycardia–bradycardia and performed spectral analysis of EEG during these. We also identified cortical arousals by the appearance of EEG alpha activity. This allowed us to dichotomize bouts of tachycardia–bradycardia by presence or absence of cortical arousal. Results During non-rapid eye movement (REM) sleep, bouts with or without cortical arousal occurred with approximately equal frequency. Those with cortical arousals usually preceded onset of EEG changes. Those without cortical arousals were followed by increases in delta but not alpha power. EEG did not change during bouts in REM sleep. Conclusions Capturing bouts of tachycardia–bradycardia is relatively easy via computerized algorithm. Bouts occur with cortical arousal or with slow wave synchronization suggestive of subcortical arousal. Thus, changes in HR may be useful index of arousal. Significance These brief bursts of tachycardia–bradycardia are consistent with autonomic arousal. Such a measure may be among the first in a continuum of arousal ending with frank awakening.

P456 Magnesium sulphate has GABA-agonistic effects on sleep in healthy men

P456 Magnesium sulphate has GABA-agonistic effects on sleep in healthy men

312. - Magnesium sulphate has GABA-Agonistic effects on sleep in healthy men

312. - Magnesium sulphate has GABA-Agonistic effects on sleep in healthy men

Effects of Intravenous Catheter on Sleep in Healthy Men and in Depressed Patients

The effects of intravenous catheter and nocturnal blood samplings at frequent intervals on sleep electroencephalogram (EEG) variables were investigated in 8 male healthy controls and 12 depressed patients, who were studied in the same experimental conditions. After one night of habituation, sleep was recorded during 4 consecutive nights in the sleep laboratory. A catheter was inserted around noon the day before the fourth night, and blood was sampled every 15 min for 25 h. The night-to-night comparison of sleep EEG variables did not show significant sleep continuity modifications in the control subjects, other than a weak trend toward an increase in nocturnal awakenings during the night with the catheter. A lengthening of sleep onset latency during the fourth night was found in the depressed patients. No significant changes were detected in percentage of rapid eye movement (REM) sleep in the two groups. However, a gradual increase in Stage 3 was observed across the 4 nights in the control subjects. These results indicate that intravenous blood sampling via a catheter can be performed without inducing significant disruption of sleep length and structure.