Polygraphical sleep recordings in insomniac patients under zopiclone or nitrazepam

Zopiclone, a new hypnotic with an original chemical structure, was compared in a sleep laboratory study with nitrazepam according to a double-blind, parallel group randomized design. Zopiclone (7.5 mg) and nitrazepam (5 mg) were each given for 14 nights to 5 insomniacs; a placebo washout period of 4 nights and a placebo withdrawal period of 10 nights were included in the design. Both drugs were found to be immediately and lastingly effective. Some slight insomnia rebound was found with nitrazepam, but not with zopiclone. Stage 2 was decreased, slow wave sleep (SWS) increased, and rapid eye movement unchanged by both drugs: however, only nitrazepam increased rapid eye movement latency. The differences between the effects of the drugs were quite limited. However, 3 out of 50 comparisons favoured zopiclone and none nitrazepam.