sleeping pill, 1. (Informal) a prescription sedative taken for insomnia or for postoperative sedation. 2. an over-the-counter pill classified pharmaceutically as an aid to sleeping. Antihistamines, such as pyrilamine maleate, diphenhydramine, and doxylamine succinate, depend for sedative action on side effects, which may disappear with continued use of such agents. The use of all drugs that depress the central nervous system is contraindicated for pregnant and lactating women and for asthma, glaucoma, or prostatic hypertrophy patients.
