SummaryThe efficacy of zolpidem, a non benzodiazepine hypnotic agent with a short elimination half life, was reviewed, analysing more than 50 international clinical trials published since 1986. The hypnotic activity of zolpidem has been explored in different patient populations including normal volunteers, general practice outpatients and psychiatric out- or in-patients with varying sleep disorders; both transient and chronic. Assessment methods used have included objective and subjective measures of hypnotic efficacy for different treatment durations, with results confirming that 10 mg is superior to placebo. Zolpidem was shown to be superior in most trials on sleep parameters such as total sleep time, sleep onset latency and nocturnal awakenings, but total REM sleep and REM latency were usually unmodified. Zolpidem maintained normal sleep physiology as demonstrated by the preservation of slow wave stages and no, or minimal, effects on sleep architecture after abrupt discontinuation. Consequently, 10 mg is the recommended dose for the short-term treatment of insomnia in the non-elderly; in elderly patients 5 mg has been shown to be effective at inducing sleep whilst giving an optimum safety profile.