Temporal EEG dynamics of non-REM sleep episodes in humans

The process of the human non-rapid eye movement (non-REM) sleep period has not been clarified. Time-based analysis on sleep EEG may provide an explanation. We focused on chronological aspects of initiation and termination of non-REM episodes, using spectral analysis of sleep EEG. The subjects were healthy male volunteers ( n=32, mean age±S.D.: 25.5±3.5 years). The rise latencies from non-REM sleep onset to the maximal power value and the decay latencies from the maximal power value to non-REM sleep offset were determined in the initial and final 21-min windows of individual non-REM episodes in each EEG band ranges. Low (12.1–13.7 Hz) and high (14.1–16.0 Hz) sigma ranges were analyzed separately. The rise and decay latencies were shorter in higher frequency ranges (>14 Hz) and longer in lower frequency ranges (