Antagonizing the effects of experimentally induced sleep disturbance in healthy volunteers by lormetazepam and zolpidem

The effects on sleep of two well known hypnotics, lormetazepam and zolpidem, during experimentally induced environmental noise were compared with placebo. In a double-blind, crossover study, 12 normal volunteers were subjected to prerecorded traffic noise with a mean noise level of 52 dB(A) and peaks to 77 dB(A) continuously for 8 hours in bed. Both hypnotics increased total sleep time, predominantly stage 2 sleep. A significant decrease in the number of sleep stage transitions, arousals, and awakenings longer than 3 minutes was found only with lormetazepam. No significant effects on rapid eye movement (REM) and slow wave sleep were observed. Latencies to persistent sleep and REM sleep onset were not different for either active treatment compared with placebo. Only after lormetazepam was performance on the morning reaction time test significantly affected. However, no differences were found in the subjective sleep quality and alertness ratings. Changes in the distribution of sleep stages throughout the night were related to the elimination half-life characteristics of the hypnotics, but few trends were detected. Both the protective properties against environmental noise of the hypnotics studied and the validity of the model of induced sleep disturbance in evaluating hypnotic agents are discussed.