Weeks Of Sleep Restriction Research Articles

Vascular response to 1 week of sleep restriction in healthy subjects. A metabolic response?

BackgroundSleep loss may induce endothelial dysfunction, a key factor in cardiovascular risk. We examined the endothelial function during one week of sleep restriction and a recovery period (from 3-to-13days) in healthy subjects, and its link to autonomic, inflammatory and/or endocrine responses. Methods12 men were followed at baseline (B1, 8-h sleep), after 2 (SR2) and 6 (SR6) days of SR (4-h sleep: 02:00–06:00) and after 1 (R1) and 12 (R12) recovery nights (8h sleep). At 10:00, we assessed changes in: arm cutaneous vascular conductance (CVC) induced by local application of methacholine (MCh), cathodal current (CIV) and heat (44°C), finger CVC and skin temperature (Tfi) during local cold exposure (5°C, 20-min) and passive recovery (22°C, 20-min). Blood samples were collected at 08:00. ResultsCompared with baseline (B1), MCh and heat-induced maximal CVC values (CVCpeak) were decreased at SR6 and R1. No effect of SR was observed for Tfi and CVC during immersion whereas these values were lower during passive recovery on SR6 and R1. From SR2 to R12, plasma concentrations of insulin, IGF-1 (total and free) and MCP-1 were significantly increased while those of testosterone and prolactin were decreased. Whole-blood blood mRNA concentrations of TNF-α and IL-1β were higher than B1. No changes in noradrenaline concentrations, heart rate and blood pressure were observed. ConclusionsThese results demonstrate that SR reduces endothelial-dependent vasodilatation and local tolerance to cold. This endothelial dysfunction is independent of blood pressure and sympathetic activity but associated with inflammatory and metabolic pathway responses (ClinicalTrials-NCT01989741).

Chronic sleep restriction causes a decrease in hippocampal volume in adolescent rats, which is not explained by changes in glucocorticoid levels or neurogenesis

Sleep loss strongly affects brain function and may even predispose susceptible individuals to psychiatric disorders. Since a recurrent lack of sleep frequently occurs during adolescence, it has been implicated in the rise in depression incidence during this particular period of life. One mechanism through which sleep loss may contribute to depressive symptomatology is by affecting hippocampal function. In this study, we examined the effects of sleep loss on hippocampal integrity at young age by subjecting adolescent male rats to chronic sleep restriction (SR) for 1 month from postnatal day 30 to 61. They were placed in slowly rotating drums for 20 h per day and were allowed 4 h of rest per day at the beginning of the light phase. Anxiety was measured using an open field and elevated plus maze test, while saccharine preference was used as an indication of anhedonia. All tests were performed after 1 and 4 weeks of SR. We further studied effects of SR on hypothalamic-pituitary-adrenal (HPA) axis activity, and at the end of the experiment, brains were collected to measure hippocampal volume and neurogenesis. Behavior of the SR animals was not affected, except for a transient suppression of saccharine preference after 1 week of SR. Hippocampal volume was significantly reduced in SR rats compared to home cage and forced activity controls. This volume reduction was not paralleled by reduced levels of hippocampal neurogenesis and could neither be explained by elevated levels of glucocorticoids. Thus, our results indicate that insufficient sleep may be a causal factor in the reductions of hippocampal volume that have been reported in human sleep disorders and mood disorders. Since changes in HPA activity or neurogenesis are not causally implicated, sleep disturbance may affect hippocampal volume by other, possibly more direct mechanisms.

Effect of 1 Week of Sleep Restriction on Testosterone Levels in Young Healthy Men

To the Editor: Chronic sleep curtailment is endemic in modern societies. The majority of the daily testosterone release in men occurs during sleep.1 Sleep fragmentation and obstructive sleep apnea are associated with reduced testosterone levels.2 In older men, morning testosterone levels are partly predicted by total sleep time.3 Testosterone is critical in male sexual behavior and reproduction, but also has important beneficial effects on muscle mass and strength, adiposity, bone density, and vigor and well-being.4 We investigated the effect of 1 week of sleep restriction on testosterone levels in young healthy men.

Sleep Restriction Therapy and Hypnotic Withdrawal versus Sleep Hygiene Education in Hypnotic Using Patients with Insomnia

Insomnia is a common problem that affects 9% to 15% of the population chronically. The primary objective of this study was to demonstrate that 8 weekly sessions of sleep restriction therapy of insomnia combined with hypnotic reduction instructions following a single session of sleep hygiene education would result in greater improvements in sleep and hypnotic use than sleep hygiene education alone. Forty-six men and women were recruited from a sleep medicine practice and randomly assigned to sleep hygiene education plus 8 weeks of sleep restriction and hypnotic withdrawal (SR+HW; n = 24), or a sleep hygiene education alone (SHE; n = 22) condition. Pre-randomization, all patients received a single session of instruction in good sleep habits (sleep hygiene education). The SR+HW condition had greater improvements in hypnotic medication usage, sleep onset latency, morning wake time, sleep efficiency, and wake time after sleep onset (trend), than the SHE condition. Continued improvement was seen in TST in the SR+HW group at 6-month follow-up, and gains on all other variables were maintained at 6- and 12-month follow-up. These results provide evidence that more intensive treatment of insomnia (i.e., 8 sessions of SR+HW plus hypnotic withdrawal instructions) results in better outcomes than SHE alone.