Insomnia can cause impaired productivity and absenteeism from work, increased risk of accidents, and impaired quality of family and social life. Thus, it can compromise quality of life in affected individuals and result in costs to society as a whole. The nonbenzodiazepine hypnotic zopiclone is effective and well tolerated in the treatment of insomnia. Importantly, it also has minimal effects on next-day performance and psychological function. 458 patients treated with zopiclone for 14 days showed significantly greater improvement compared with placebo recipients in sleep evaluation questions and scores for activity, social and professional quality-of-life aspects. After 8 weeks, the improvement in scores for sleep, activity and social questions remained significantly higher in patients who had received zopiclone compared with placebo recipients. No significant differences were observed between 167 patients who had been taking zopiclone for at least 12 months and a control group of 381 persons with no sleep problems in virtually all of the 5 aspects of the quality-of-life questionnaire. Some important aspects such as relationships and professional life were not modified by zopiclone. When insomnia is treated appropriately, compared with no treatment, patients' feelings about their quality of life are improved and, furthermore, do not appear to differ significantly from perceptions of quality of life in those without sleep-related problems.