BACKGROUND: Insomnia is the subjective complaint of poor sleep or an inadequate amount of sleep that adversely affects daily functioning. For the past 4 decades, treatment of insomnia has shifted away from the use of barbiturates toward the use of hypnotic agents of the benzodiazepine class. However, problems associated with the latter (eg, next-day sedation, rebound insomnia, dependence, and tolerance) have prompted development of other agents. OBJECTIVE: This review describes the recently approved nonbenzodiazepine agent, zaleplon. METHODS: Studies of zaleplon were identified through a search of English-language articles listed in MEDLINE and International Pharmaceutical Abstracts, with no limitation on year. These were supplemented by educational materials from conferences. RESULTS: The efficacy and tolerability of zaleplon have been documented in the literature. Zaleplon has been shown to improve sleep variables in comparison with placebo. Like most hypnotic agents, zaleplon can be used for problems of sleep initiation at the beginning of the night, but its short duration of clinical effect may also allow patients to take it later in the night without residual effects the next morning. Zaleplon can be taken < or = 2 hours before awakening without "hangover" effects. It is generally well tolerated, with headache being the most commonly reported adverse event in clinical trials (15%-18%). Compared with flurazepam, a long-acting benzodiazepine sedative-hypnotic agent, zaleplon causes significantly less psychomotor and cognitive impairment (P < 0.001). Zaleplon has not been studied in pregnant women or children. The dose of zaleplon should be individualized; the recommended daily dose for most adults is 10 mg. CONCLUSIONS: Insomnia has a substantial impact on daily functioning. If pharmacologic treatment is indicated for insomnia, the choice of an agent should be guided by individual patient characteristics.