Serotonin inhibition and sleep.

Methysergide a clinically used blocker of serotonin receptors, was given for 48 hr to 11 normal adults, at a dose of 8 mg per 24 hr. Total REM sleep time was decreased, although total sleep time was unchanged. Stage 4 decreased and stage 3 increased, while total slow wave sleep remained constant. There was a tendency toward a decrease in the number of intact sleep cycles. The relationship of these data to published reports on p-chlorophenylalanine is discussed.