Long term efficacy and withdrawal of zopiclone: a sleep laboratory study.

The purpose of this study was to evaluate the short, intermediate, and long-term (8 weeks) effectiveness, as well as the withdrawal effects of zopiclone 7.5 mg. Eleven chronic insomniacs participated in the study where both EEG sleep recordings and a subjective rating scale were used to evaluate drug effects. Zopiclone significantly decreased total wake time and nocturnal awakenings, and increased total sleep time and sleep efficiency. These effects were apparent from first treatment night and tolerance to the hypnotic effect did not develop over the 8 weeks of treatment. The subjective sleep questionnaire data showed significantly decreased sleep latency time but otherwise were consistent with the sleep laboratory findings. Zopiclone decreased the percentage of Stage 1 sleep but did not significantly alter the percentage of Stage 2 sleep, slow wave sleep or REM sleep. The withdrawal of zopiclone was associated with a return of sleep variables towards pre-treatment baseline values. Although 2 patients dropped out, 1 with a marked rebound insomnia and daytime anxiety during the first week of withdrawal, the other because of side-effects and poor hypnotic efficiency, no evidence of rebound insomnia was seen on the sleep EEG or subjective questionnaire data in the study population.