Homeostatic sleep regulation in adolescents

Abstract

Study Objectives: To examine the effects of total sleep deprivation on adolescent sleep and the sleep electroencephalogram (EEG) and to study aspects of sleep homeostasis. Design: Subjects were studied during baseline and recovery sleep after 36 hours of wakefulness. Setting: Four-bed sleep research laboratory. Participants: Seven prepubertal or early pubertal children (pubertal stage Tanner 1 or 2 = Tanner 1/2; mean age 11.9 years, SD ± 0.8, 2 boys) and 6 mature adolescents (Tanner 5; 14.2 years, ± 1.4, 2 boys). Interventions: Thirty-six hours of sleep deprivation. Measurements: All-night polysomnography was performed. EEG power spectra (C3/A2) were calculated using a Fast Fourier transform routine. Results: In both groups, sleep latency was shorter, sleep efficiency was higher, non-rapid eye movement (NREM) sleep stage 4 was increased, and waking after sleep onset was reduced in recovery relative to baseline sleep. Spectral power of the NREM sleep EEG was enhanced after sleep deprivation in the low-frequency range (1.6-3.6 Hz in Tanner 1/2; 0.8-6.0 Hz in Tanner 5) and reduced in the sigma range (11-15 Hz). Sleep deprivation resulted in a stronger increase of slow-wave activity (EEG power 0.6-4.6 Hz, marker for sleep homeostatic pressure) in Tanner 5 (39% above baseline) than in Tanner 1/2 adolescents (18% above baseline). Sleep homeostasis was modeled according to the two-process model of sleep regulation. The build-up of homeostatic sleep pressure during wakefulness was slower in Tanner 5 adolescents (time constant of exponential saturating function 15.4 ± 2.5 hours) compared with Tanner 1/2 children (8.9 ± 1.2 hours). In contrast, the decline of the homeostatic process was similar in both groups. Conclusion: Maturational changes of homeostatic sleep regulation are permissive of the sleep phase delay in the course of adolescence.