The narcolepsy syndrome consists of excessive daytime somnolence, cata
plexy, hallucinations, and sleep paralysis. Data on the effects of tra
nylcypromine are scant. We report on a patient with severe narcolepsy
in whom administration of tranylcypromine led to freedom from hallucin
ations, nightmares, sleep paralysis, and rapid eye movements (REM), wi
th considerable amelioration of cataplexy and increased daytime alertn
ess. Muscle atonia and low-voltage desynchronized cortical activity du
ring REM sleep did not change. Tranylcypromine warrants further study
in narcolepsy.