Rebound insomnia and rebound anxiety are clinical conditions related to withdrawal of certain benzodiazepine drugs. Numerous studies of benzodiazepine and nonbenzodiazepine hypnotics conducted in our sleep laboratory demonstrated that rebound insomnia developed following withdrawal from benzodiazepines with a rapid or intermediate elimination rate. Several studies conducted by other investigators also indicated the development of rebound insomnia under similar conditions. Rebound insomnia and rebound anxiety are discussed in terms of their interrelationship, clinical implications, and receptor mechanisms. Evidence suggests that drugs producing rebound insomnia and rebound anxiety also show a more rapid development of tolerance and greater potential for drug dependence than benzodiazepines where the parent compound or its metabolites have a long elimination half-life.