Adverse effects of two nights of sleep restriction on the hypothalamic-pituitary-adrenal axis in healthy men.

Abstract

Insufficient sleep is associated with increased cardiometabolic risk. Alterations in hypothalamic-pituitary-adrenal axis may underlie this link. Our objective was to examine the impact of restricted sleep on daytime profiles of ACTH and cortisol concentrations. Thirteen subjects participated in 2 laboratory sessions (2 nights of 10 hours in bed versus 2 nights of 4 hours in bed) in a randomized crossover design. Sleep was polygraphically recorded. After the second night of each session, blood was sampled at 20-minute intervals from 9:00 am to midnight to measure ACTH and total cortisol. Saliva was collected every 20 minutes from 2:00 pm to midnight to measure free cortisol. Perceived stress, hunger, and appetite were assessed at hourly intervals by validated scales. Sleep restriction was associated with a 19% increase in overall ACTH levels (P < .03) that was correlated with the individual amount of sleep loss (rSp = 0.63, P < .02). Overall total cortisol levels were also elevated (+21%; P = .10). Pulse frequency was unchanged for both ACTH and cortisol. Morning levels of ACTH were higher after sleep restriction (P < .04) without concomitant elevation of cortisol. In contrast, evening ACTH levels were unchanged while total and free cortisol increased by, respectively, 30% (P < .03) and 200% (P < .04). Thus, the amplitude of the circadian cortisol decline was dampened by sleep restriction (-21%; P < .05). Sleep restriction was not associated with higher perceived stress but resulted in an increase in appetite that was correlated with the increase in total cortisol. The impact of sleep loss on hypothalamic-pituitary-adrenal activity is dependent on time of day. Insufficient sleep dampens the circadian rhythm of cortisol, a major internal synchronizer of central and peripheral clocks.