Effects of zolpidem 10 mg, zopiclone 7.5 mg and flunitrazepam 1 mg on night-time motor activity.

The effects of a single dose of zolpidem (10 mg), zopiclone (7.5 mg) and flunitrazepam (1 mg) on motor activity the following 3 nights were compared to those of a placebo in a double-blind, crossover study. Thirty-three healthy subjects received medication between 10.30 and 11.30 p.m. and were asked to rise between 7.30 and 8.30 a.m. During the night under treatment, flunitrazepam, zopiclone and zolpidem significantly reduced motor activity. Changes in motor activity are quantitatively compatible with the hypothesis of reduced light sleep and wakefulness after sleep onset. During the first or second post-drug night, for zolpidem and zopiclone the opposite effect was observed, i.e. increased activity compared with placebo. These modifications cannot be explained by modified sleep structure. This last result underlines our inadequate understanding of the underlying mechanisms of motor activity during sleep. However, being sensitive and easy to use, actigraphy is an ideal technique to assess the effect of hypnotics on large populations and for long duration studies.