Sleep disturbances and related daytime complaints are frequent in rheumatoid arthritis (RA). The aim of the current study was therefore to evaluate the effect of a newer hypnotic on sleep structure and clinical parameters in RA. Forty outpatients were randomized to a two week treatment regimen with either 7.5 mg zopiclone or placebo at bedtime. Clinical examinations were performed before and after treatment and the degree of pain, fatigue, sleepiness, morning stiffness, and activities of daily living were assessed. Two sleep questionnaires were also completed weekly. Polysomnography was performed before the study and after 14 days of treatment. Recordings were evaluated using conventional sleep scoring as well as frequency analysis of the electroencephalography (EEG). Patients in the zopiclone group had subjective improvement of sleep, but otherwise no differences in pain score or the other clinical parameters were found. Conventional sleep assessments showed only minor changes during treatment, but frequency analysis demonstrated a shift from the lower towards the higher EEG frequencies in the active treatment group. Although the modulation of the EEG can represent a non-specific pharmacologic epiphenomenon, it might also reflect a disturbance of sleep microstructure. In conclusion, treatment with zopiclone may be of value for subjective sleep complaints in selected patients with RA, but it is doubtful whether hypnotics improve daytime symptoms in this patient group.