Chlormezanone: its effects on subjective aspects of sleep and on skilled performance related to car driving.

A double-blind, crossover study compared chlormezanone 200 mg t.d.s., chlormezanone 400 mg nocte and placebo in twelve female volunteers. There was no obvious evidence of chlormezanone causing an impairment in early morning psychomotor performance, car driving ability or subjective ratings of early morning behaviour. Subjectively reported mood changes were consistent with those expected of a tranquillising drug and the sleep-inducing and improving properties of chlormezanone were confirmed. This volunteer study suggests that chlormezanone may well be a nocturnal sedative which does not have a morning hangover effect.