Human EEG slow-wave sleep increased by a serotonin antagonist.

Serotonin has been held to play a necessary role in EEG slow-wave sleep. A central serotonin antagonist, known as FU 29-245, 200 mg, was taken nightly for 6 nights by 10 volunteers, mean age 59 years. Compared with baseline sleep the drug significantly increased the duration of slow-wave sleep, with a significant rebound decrease below baseline after withdrawal. The drug also caused fewer transitions into stage 1 and less time in stage 1 and less time in stage 2. There were significant tolerance effects by the fifth and sixth nights. No subjective effects were present.