The sedative hypnotic drugs represent a variety of chemical agents that depress central nervous system activity. They have many clinical uses in medicine including treatment of anxiety and insomnia, epilepsy, as muscle relaxants, and for induction of anesthesia. Some members of the class also possess significant abuse potential and a hazard of overdose fatalities, especially when combined with alcohol or other drugs. The focus of this chapter will be on benzodiazepines and nonbenzodiazepine hypnotics (colloquially called the Z-drugs). The use of barbiturates has become more limited with the introduction of the benzodiazepines, which have lower risk of death in overdose, fewer drug drug interactions, and less risk for addiction.