Bedtime flurazepam and the human circadian rhythm of spontaneous motility.

Sixteen male students received bedtime placebo and flurazepam 30 mg at home in a counter-balanced double-blind, crossover design. For 24 h after each treatment the subjects' spontaneous motor activity was recorded each 15 min with an unobtrusive actometer, worn as the subjects attended classes. The circadian activity curves were submitted to cosinor analyses. The 24 h post-flurazepam activity was a mean of 15.1% lower than post-placebo activity (P less than 0.025). On the average, both the nocturnal through and the daytime peak of motility dropped; the latter change was greater, reducing by a mean of 19.4% the amplitude of the circadian rhythm of activity (P greater than 0.01). the timing, or phase, of the rhythm was not shifted. Although the drug did not consistently modify reports of subjective feelings on the Profile of Mood States (POMS), 13 subjects correctly discriminated drug from placebo sessions (P less than 0.05). A bedtime dose of 30 mg of flurazepam appears to significantly reduce spontaneous human motility that night and during the next day. Activity recording revealed an important residual, behavioral effect of the drug which was not reflected in POMS reports of subjective feelings, suggesting that activity recording may provide a more sensitive measure for psychotropic drug effects.