Dual electroencephalogram markers of human sleep homeostasis: Correlation between theta activity in waking and slow-wave activity in sleep

To investigate the relationship between markers of sleep homeostasis during waking and sleep, the electroencephalogram of eight young males was recorded intermittently during a 40-h waking episode, as well as during baseline and recovery sleep. In the course of extended waking, spectral power of the electroencephalogram in the 5-8 Hz band (theta activity) increased. In nonrapid eye movement sleep, power in the 0.75-4.5 Hz band (slow-wave activity) was enhanced in the recovery night relative to baseline. Comparison of individual records revealed a positive correlation between the rise rate of theta activity during waking and the increase in slow-wave activity in the first non-rapid eye movement sleep episode. A topographic analysis based on 27 derivations showed that both effects were largest in frontal areas. From these results, we suggest that theta activity in waking and slow-wave activity in sleep are markers of a common homeostatic sleep process. (C) 2000 IBRO. Published by Elsevier Science Ltd. All rights reserved.