The dose-dependent, acute effects of transdermal nicotine (7 and 14 mg) and placebo, applied 2 hours before bedtime, on sleep and mood were determined in 12 nonsmoking normal volunteers. Compared with placebo patch, transdermal nicotine was associated with early morning awakening and reduced total rapid eye movement (REM) sleep time and REM% in a dose-dependent fashion. On the recovery night after the administration of an active nicotine patch, REM latency and stage 2% were significantly reduced, whereas REM sleep time and REM% increased compared with the active patch. Mood and subjective recall of dreaming were not significantly affected in this study. Although one subject vomited about 10.5 hours after the 14-mg dose, reported side effects were generally mild.