In a double-blind controlled study, an oral dose of diphenhydramine hydrochloride (12.5, 25, or 50 mg), methapyrilene fumarate (36, 72, or 144 mg), or placebo was administered to 1295 post-partum patients if they complained of, or anticipated, a sleep problem. Hypnotic activity was assessed clinically by subjective and objective techniques. Methapyrilene and diphenhydramine, at all doses, were found to be effective hypnotics in comparison to placebo, based on sleep latency, sleep duration, awakening in the night, global evaluation, and morning alertness. Increasing the dose of these drugs, in the range studied, produced a minimal increase in effectiveness.