Spectral Analysis of the Sleep Electroencephalogram During Adolescence

Abstract

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. After 10 nights on a fixed 10-hour sleep schedule without daytime naps, participants were studied during a 10-hour baseline night. Data were collected in a 4-bed sleep research laboratory. 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). Not applicable. 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. 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. 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.