Benzodiazepine hypnotic agents were the mainstream pharmacotherapy for insomnia from the 1960s to the 1980s, but their safety profile proved to be not quite as perfect as originally expected with regard to daytime performance and cognition, and above all the risk of dependence. These risks are substantially diminished in the non-benzodiazepine hypnotic agents developed and marketed during the past two decades, but the fears engendered by certain benzodiazepines still greatly influence the attitude of both physicians and the general public to the treatment of insomnia. For this reason, as well as in the interests of matching the pharmacotherapy of insomnia more closely to the often fluctuating nature of this disorder, the possibility of the discontinuous or 'as needed' use of hypnotic drugs has attracted increasing attention in recent years. Current recommendations strongly favour the use of hypnotic drugs for a limited period of time. However, some insomniac patients need sleep medication for longer periods in spite of a non-pharmacological approach, whereas other patients become dependent on drugs as a result of rebound insomnia, withdrawal symptoms, or the recurrence of insomnia. The pharmacological properties of zolpidem make it feasible for non-nightly use. A double-blind, randomized, parallel-group study of continuous treatment with either zolpidem or estazolam, followed by an observation of the discontinuation of drug treatments combined with the non-pharmacological management of primary insomnia, showed a carry-over benefit for zolpidem treatment.