The term “sedative”, or “sedative-hypnotic” refers to a class of substances that depress the central nervous system (C.N.S.), which induces a state of calmness, relaxation, reduction of anxiety, sleepiness, and slowed breathing.

Sedative-hypnotics may be also be referred to as tranquilizers, depressants, anxiolytics, soporifics, or sleeping pills.