POWER-DENSITY IN THETA ALPHA FREQUENCIES OF THE WAKING EEG PROGRESSIVELY INCREASES DURING SUSTAINED WAKEFULNESS/

Electroencephalogram (EEG) power density and self-rated fatigue were a ssessed in nine healthy women during a 40-hour period of sustained wak efulness under constant behavioral and environmental conditions (const ant routine protocol). Waking EEG recordings were performed for 4 minu tes after 3, 10, 27 and 34 hours of prior wakefulness. EEG power densi ty in the 6.25- to 9.0-Hz frequency range progressively increased acro ss the four recordings, suggesting an endogenous homeostatic component in the regulation of the theta/alpha frequencies under constant condi tions. Subjective fatigue also exhibited an increasing component in th e course of the constant routine protocol, with a clear circadian modu lation. Fatigue ratings and the theta/alpha power density of the wakin g EEG recorded at the same four time points during the constant routin e protocol correlated significantly. Our data demonstrate the presence of a homeostatic component in the control of EEG power density in the 6.25- to 9.0-Hz range.