Psychotropics affect the regulation of sleep and wake by influencing brain stem neurotransmitter systems. The monoaminergic systems are active during wake but diminish their activity when transitioning to sleep in response to increased gamma-aminobutyric acid activity. The cholinergic system is active both during wake and during rapid eye movement sleep. According to their mode of action, different classes of psychotropics can be understood to act differently on sleep continuity and sleep architecture. This review outlines the differences. Increased knowledge of the detailed sleep effects of psychotropics may improve the perceived subjective quality of sleep.