Physostigmine alters onset but not duration of REM sleep in man.

Physostigmine (1.0mg) or placebo were administered intravenously over 1-h period to seven male normal volunteers beginning 35 min after sleep onset. The results indicate that physostigmine induced the onset of REM sleep but did not significantly alter the duration of individual REM sleep periods. Physostigmine significantly shortened the REM latency and the duration of the second nonREM period. After inducing the onset of the first REM period(s); physostigmine also appeared to advance succeeding REM-nonREM sleep cycles relative to sleep onset even when the duration of each cycle was unaffected.