The purpose of this presentation is to provide a survey of the clinical use of hypnotics. To this end, we shall first discuss the relation of pharmacokinetic properties and the clinical effects of hypnotics. The second part will present some guidelines for hypnotic use based on current knowledge of sleep disorders medicine. There is much confusion over the definition of a sedative/hypnotic. For the purpose of the present overview, a sedative/hypnotic is defined as any compound that promotes

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... p (sleepiness-drowsiness, falling asleep, and staying asleep) and inhibits wakefulness (awakening, maintaining wakefulness, and functioning while awake). Many different groups of drugs (e.g., barbiturates, tricyclics, antihistamines, benzodiazepines) can be and are used as hypnotics. Of the various drug classes, benzodiazepines are the most commonly used compounds (1) and, therefore, will be discussed more extensively than other classes. To understand the effects of hypnotics, one must first recognize that hypnotic drugs do not simply affect rapidity of falling asleep and time of waking. In fact, they have multiple effects. Those biological processes currently known to be affected by hypnotics are: (a) sleep architecture, (b) sleep physiology, (c) sleep pathophysiology, and (d) sleep efficiency. Effects on Sleep Architecture. Virtually all psychotropic drugs affect sleep stages, suppressing stage 3-4, the rapid eye movement (REM) stage, or both. A thorough review of the effects of psychotropics on sleep stages is beyond the scope of this paper, and can be found in an article by Kay et aL (2). Benzodiazepines were once thought to have no effect on REM sleep; however, it is well documented that benzodiazepines, like all other sedative hypnotics, suppress REM sleep. Overall, benzodiazepines have dose-related effects on virtually all sleep stages (3). They decrease stages 1,3 -4, and REM. In comparison with other psychotropics, they suppress delta sleep (stage 3-4) as much as any other drug group. On the other hand, they are mild REM suppressants as compared with tricyclic antidepressants (4). Although the clinical effect of increasing or decreasing sleep stages is currently not well understood, the effect of drugs on sleep Address correspondence and reprint requests to Thomas Roth, Ph.D., Sleep Center, 512 NCP, Henry Ford Hospital, 2799 w. Grand Boulevard, Detroit, Michigan 48202.