Effect of diphenhydramine on subjective sleep parameters and on motor activity during bedtime.

The effect of a single oral dose of diphenhydramine (Benocten) (50 mg or 75 mg) on subjective sleep parameters and motor activity during bedtime was investigated in 10 young, healthy adults. A placebo-controlled, double-blind crossover design was used. Although the self-ratings of sleep latency were consistent with a mild hypnotic action of the drug, none of the subjective sleep parameters differed significantly from placebo. Motor activity tended to be increased in the drug nights. Diphenhydramine caused neither an impairment of psychomotor performance in the morning, nor a rebound insomnia in the following night.