Sedative

A sedative, or tranquilizer, is a substance that induces sedation by reducing irritability or excitement. They are central nervous system (CNS) depressants and interact with brain activity, causing its deceleration. Various kinds of sedatives can be distinguished, but the majority of them affect the neurotransmitter gamma-aminobutyric acid (GABA). Most sedatives produce relaxing effects by increasing GABA activity. This group is related to hypnotics. The term sedative describes drugs that serve to calm or relieve anxiety, whereas the term hypnotic describes drugs whose main purpose is to initiate, sustain, or lengthen sleep. Because these two functions frequently overlap, and because drugs in this class generally produce dose-dependent effects (ranging from anxiolysis to loss of consciousness), they are often referred to collectively as sedative–hypnotic drugs.