Effectiveness of yohimbine in treating narcolepsy.

Yohimbine was used in four men and four women ranging in age from 21 to 64 years with nocturnal polysomnography and multiple sleep latency test-verified narcolepsy. All achieved a stimulant response in doses ranging from 2.7 to 16.2 mg/day. The effective dose was defined as the amount of medication required to maintain subjective wakefulness for 8 consecutive working hours. The average effective dose was approximately 8 mg/day. While one subject became immediately tolerant, others maintained a response for several weeks. The first subject continued to have good control of sleepiness for 17 months. Mild and transient side effects were insomnia, diarrhea, dyspepsia, flushing, and tremor. Alpha-2 adrenergic receptor abnormalities are suspected in narcolepsy, which could explain the improvement in sleepiness for these patients.