Sedatives are central nervous system (CNS) depressant drugs primarily used as sleep-inducing hypnotics, anxiolytics, muscle relaxants, and anticonvulsants. The most frequently prescribed sedatives include the benzodiazepines, non-benzodiazepine sedative hypnotics, barbiturates, and muscle relaxants. Other medications, such as the antihistamine diphenhydramine, can also be used for their general sedative properties. The use of sedatives often begins with a prescription to treat insomnia, anxiety, or muscular pain, and abuse develops for their sedative-hypnotic effects resulting in increased dosage without medical advice or continued use after the insomnia, anxiety, or pain has subsided.