Power density in theta/alpha frequencies of the waking EEG progressively increases during sustained wakefulness.
Electroencephalogram (EEG) power density and self-rated fatigue were assessed in nine healthy women during a 40-hour period of sustained wakefulness under constant behavioral and environmental conditions (constant routine protocol). Waking EEG recordings were performed for 4 minutes after 3, 10, 27 and 34 hours of prior wakefulness. EEG power density in the 6.25- to 9.0-Hz frequency range progressively increased across the four recordings, suggesting an endogenous homeostatic component in the regulation of the theta/alpha frequencies under constant conditions. Subjective fatigue also exhibited an increasing component in the course of the constant routine protocol, with a clear circadian modulation. Fatigue ratings and the theta/ alpha power density of the waking EEG recorded at the same four time points during the constant routine 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.
Cajochen
C
C
Psychiatric University Clinic, Basel, Switzerland.
Brunner
D P
DP
Kräuchi
K
K
Graw
P
P
Wirz-Justice
A
A
D000328:Adult; D000368:Aged; D000513:Alpha Rhythm; D002940:Circadian Rhythm; D004569:Electroencephalography; D005221:Fatigue; D005260:Female; D006801:Humans; D008875:Middle Aged; D013826:Theta Rhythm; D014851:Wakefulness