Adaptation of the 24-h growth hormone profile to a state of sleep debt

Abstract

In normal men, the majority of GH secretion occurs in a single large postsleep onset pulse that is suppressed during total sleep deprivation. We examined the impact of semichronic partial sleep loss, a highly prevalent condition, on the 24-h growth hormone profile. Eleven young men were studied after six nights of restricted bedtimes (0100-0500) and after 7 nights of extended bedtimes (2100-0900). Slow-wave sleep (SWS) was estimated as the duration of stages III and IV. Slow-wave activity (SWA) was calculated as electroencephalogram power density in the 0.5- to 3-Hz frequency range. During the state of sleep debt, the GH secretory pattern was biphasic, with both a presleep onset "circadian" pulse and a postsleep onset pulse. Postsleep onset GH secretion was negatively related to presleep onset secretion and tended to be positively correlated with the amount of concomitant SWA. When sleep was restricted, both SWS and SWA were increased during early sleep. Unexpectedly, the increase in SWA affected the second, rather than the first, SWA cycle, suggesting that presleep onset GH secretion may have limited SWA in the first cycle, possibly via an inhibition of central GH-releasing hormone activity. Thus neither the GH profile nor the distribution of SWA conformed with predictions from acute sleep deprivation studies, indicating that adaptation mechanisms are operative during chronic partial sleep loss.

Psychosocial stress and impaired sleep

“…Sleep loss also reduces glucose clearance (114,119,120), and blood sugar remains at a high level during sleep instead of falling as is normal during wakefulness. (121)(122)(123).…”

Quantification of sleep behavior and of its impact on the cross-talk between the brain and peripheral metabolism

“…Sleep loss also dysregulates counter-regulatory hormones in a manner consistent with the promotion of hyperglycemia and/or insulin resistance. Indeed, elevations of evening cortisol levels (48-51), increased release of growth hormone and ghrelin during daytime hours (52)(53)(54), and elevated daytime levels of epinephrine (55) have all been observed under sleep debt conditions. Orexins A and B, two peptides that are synthesized by neurons concentrated in the LH, constitute a molecular link between sleep-wake regulation and the neuroendocrine control of appetite.…”

Sleep and Circadian Rhythms in Humans

“…Six hours of time in bed per night for a week or two brings the average young adult to the same level of impairment as 24 hours of wakefulness, whereas 4 hours of time in bed per night rapidly induces a level of impairment comparable with 48 hours of wakefulness (i.e., two consecutive days and nights without sleep). Metabolic studies have demonstrated that such sleep curtailment has adverse effects on the metabolic and immune systems as well (Spiegel et al 2000(Spiegel et al , 2002(Spiegel et al , 2004a(Spiegel et al ,b, 2005Mander et al 2001;Van Cauter et al 2007). Moreover, sleep loss interferes with memory consolidation and learning (Stickgold et al 2000;Walker et al 2002;Huber et al 2004;Walker and Stickgold 2004;Stickgold 2005).…”