Effect of zolpidem on sleep in healthy subjects: a placebo-controlled trial with polysomnographic recordings

The aims of this double-blind, placebo-controlled study, conducted in a group of healthy young adults with normal sleep patterns, were to ascertain the effect of various doses of zolpidem on polysomnographic variables and to determine whether zolpidem disrupts sleep architecture. Of the 15 subjects recruited, 8 were included in the final analysis. Subjects underwent four experimental sessions during three nights, of which the first night was used for adaptation, the second for zolpidem (10, 20, and 40 mg) or placebo administration, and the third for placebo administration. Sleep was assessed by conventional sleep parameters (latency, duration, wakefulness) and by subjective questionnaire. Polysomnographic recordings were analyzed for sleep stage, paradoxical sleep, graphic features, and longitudinally with reference to sleep stage. Zolpidem had little effect on polysomnographic variables, except for a trend toward a hypnotic effect and a slight, transient inhibition of paradoxical sleep at the highest dose. In particular, the clearcut reduction of stage 4 sleep and increase in spindle density often observed with benzodiazepine administration was not observed with zolpidem. Adverse effects were restricted to three reports of daytime drowsiness each after zolpidem 10 and 40 mg and placebo, and one amnesic episode after the highest dose (40 mg). There were no signs of ataxic symptomatology.