Adverse Effects of Modest Sleep Restriction on Sleepiness, Performance, and Inflammatory Cytokines

TLDR

Sleep restriction is known to increase daytime sleepiness, impair performance, and disturb hormonal/metabolic processes, yet the impact of mild, real‑life chronic restriction remains unclear and raises concerns for health and safety. The study aimed to evaluate the effects of modest sleep restriction from 8 to 6 h per night for one week in healthy young adults. Participants were monitored over 12 consecutive nights in a sleep laboratory, with sleep limited to 6 h per night for one week. After one week of modest sleep restriction, participants showed increased daytime sleepiness, impaired psychomotor vigilance, elevated IL‑6 secretion in both sexes, heightened TNF‑α in men, and reduced cortisol peaks, confirming that even mild sleep loss triggers significant cognitive and inflammatory disturbances.

Abstract

Total sleep restriction in humans is associated with increased daytime sleepiness, decreased performance, and hormonal/metabolic disturbances. The effects of mild chronic sleep restriction that mimic real life are not known. To assess the effects of modest sleep restriction from 8 to 6 h/night for 1 wk, 25 young, healthy, normal sleepers (12 men and 13 women) were studied for 12 consecutive nights in the sleep laboratory. After 1 wk of sleep restriction, although subjects' nighttime sleep was deeper, subjects were significantly sleepier (multiple sleep latency test) and performed worse in four primary variables of psychomotor vigilance test (both P < 0.01). Furthermore, 24-h secretion of IL-6 was increased by 0.8 +/- 0.3 pg/ml (P < 0.05) in both sexes, whereas TNFalpha was increased only in men. Also, the peak cortisol secretion was lower after sleep restriction than at baseline, and this difference was stronger in men (55.18 +/- 24.83 nmol/liter; P < 0.05) than in women (35.87 +/- 24.83 nmol/liter; P < 0.16). We conclude that in young men and women, modest sleep loss is associated with significant sleepiness, impairment of psychomotor performance, and increased secretion of proinflammatory cytokines. Given the potential association of these behavioral and physical alterations with health, well-being, and public safety, the idea that sleep or parts of it are optional should be regarded with caution.