This study was undertaken in order to analyse sleep in a group of patients who were operated on for cataract. All patients (n=328) undergoing cataract surgery at the Department of Ophthalmology, Sundsvall Hospital during a 4-month period were asked to complete a questionnaire on the state and change of sleep and sleepiness 1 month after the operation. Twelve persons were unable or declined to participate. The response rate was 97.2%. The mean ages of the participating men and women were 74.5 and 76.3 years, respectively. Pre-operative visual acuity in the operated eye was 0.16 in men and 0.18 in women. After cataract extraction sleep was improved in 12.0% of the men and in 26.3% of the women. Nevertheless poor sleep 1 month post-operatively was reported by 29.3% of the men and 42.6% of the women (P<0.05). There was no age-related increase in sleep complaints. The results indicate that in elderly persons with cataract sleep is impaired, and that 1 month after cataract extraction improved sleep may be experienced.