Dynamics of frontal EEG activity, sleepiness and body temperature under high and low sleep pressure

The impact of sleep deprivation (high sleep pressure) vs sleep satiation (l ow sleep pressure) on waking EEG dynamics, subjective sleepiness and core b ody temperature (CBT) was investigated in 10 young volunteers in a 40h cont rolled constant posture protocol. The differential sleep pressure induced f requency-specific changes in the waking EEG from 1-7 Hz and 21-25Hz. Fronta l low EEG activity (FLA, 1-7 Hz) during sleep deprivation exhibited a promi nent increase as time awake progressed, which could be significantly attenu ated by sleep satiation attained with intermittent naps. Subjective sleepin ess exhibited a prominent circadian regulation during sleep satiation, with virtually no homeostatic modulation. These extremely different sleep press ure conditions were not reflected in significant changes of the CBT rhythm. The data demonstrate that changes in FLA during wakefulness are to a large extent determined by the sleep-wake dependent process with little circadia n modulation, and reflect differential levels of sleep pressure in the awak e subject. NeuroReport 12:2277-2281 (C) 2001 Lippincott Williams & Wilkins.