Zopiclone in insomniac shiftworkers. Evaluation of its hypnotic properties and its effects on mood and work performance.

Fifty adult insomniac shiftworkers (47 males and 3 females) between the ages of 22 and 55 participated in this two-week, double-blind comparative study of the hypnotic properties and effects on mood and work performance of zopiclone 7.5 mg and placebo. All subjects took inactive medication on the first night of the study and then received either zopiclone or placebo for the following 13 nights according to randomization. Pre-study variables included a demographic profile, medical history, physical examination, laboratory data, profile of insomnia and work shift pattern description. A sleep questionnaire along with mood and work performance questionnaires were filled out on Days 1, 2, 4, 9 and 12 of the study; on Days 7 and 14, adverse events were recorded. After the first placebo night, subjects assigned to receive zopiclone showed significantly improved sleep induction; from the second night on, a distinct pharmacological effect over placebo was observed and maintained since statistically significant increases in quantitative sleep induction and sleep soundness (qualitative and quantitative) were noted during the course of zopiclone treatment. Active hypnotic treatment did not interfere with morning awakening and functioning, nor did it affect mood or work performance. Zopiclone treatment produced significantly more taste disturbance and drowsiness. In summary, zopiclone was shown to be an effective, fast-acting hypnotic which maintained its efficacy over a two-week period in our sample of insomniac shiftworkers and did not produce mood changes or influence work performance.