Hypnotics: an update.

This update reviews recent developments and advances in the therapeutic and side-effect profile of the benzodiazepine receptor agonists (BZRAs), the generally accepted drug class of choice for the symptomatic treatment of insomnia. All the approved BZRAs, depending on their pharmacokinetic profile, improve and maintain sleep. The major recent advance is in the enhanced diversity of the pharmacokinetic profiles of these drugs, and thus in the flexibility available to the clinician in treatment strategy. Also, during the past decade the nature and significance of the side effects associated with the BZRAs and their determinants, dose and half-life, have been identified and clarified. The important remaining question is whether, and how, the efficacy and safety of the BZRAs change with chronic use.