Spectral analysis of the sleep electroencephalogram during adolescence

Abstract

Objectives: To describe developmental changes of the human sleep electroencephalogram (EEG) during adolescence using EEG spectral analysis and specifically to compare the nocturnal dynamics of slow-wave activity (EEG spectral power 0.6-4.6 Hz, a marker for sleep homeostatic pressure) in prepubertal and mature adolescents. Design: After 10 nights on a fixed 10-hour sleep schedule without daytime naps, participants were studied during a 10-hour baseline night. Setting: Data were collected in a 4-bed sleep research laboratory. Participants: Eight prepubertal children (pubertal stage Tanner 1; mean age 11.3 years, SD ± 1.2, 4 boys) and 8 mature adolescents (Tanner 5; mean age 14.1 years, ± 1.3, 3 boys). Interventions: Not applicable. Measurements: All-night polysomnography was performed. Sleep stages were scored according to conventional criteria. EEG power spectra (of derivation C3/A2) were calculated using a fast Fourier transform routine. Results: A reduction of non-rapid eye movement (NREM) sleep stage 4 (by 40.1%) and greater amounts of stage 2 sleep (19.7%) were found in mature compared to prepubertal adolescents. NREM sleep EEG power was lower in the frequency ranges < 7 Hz, 11.8 to 12.6 Hz, and 16.2 to 16.8 Hz in mature adolescents. A reduction of rapid eye movement sleep spectral power was present in the frequency ranges < 8.6 Hz and 9.6 to 15 Hz for mature compared to prepubertal adolescents. Slow-wave activity showed identical dynamics within individual NREM sleep episodes and across the night in both developmental groups. Conclusions: The homeostatic recuperative drive during sleep remains unchanged across puberty. The decline of slow-wave sleep during adolescence may reflect developmental changes of the brain rather than changes of sleep regulatory processes.