This study was undertaken to analyze sleep development in a group of patients during the first 9 months after cataract extraction. Men and women (n=407) undergoing cataract surgery at the Department of Ophthalmology, Sundsvall Hospital during two periods in 2000-2002 were asked to complete a questionnaire on the state and change of sleep and sleepiness 1 and 9 months after the operation. The response rate was 90.8%. The mean ages of the participating men and women were 74.5 and 75.6 years, respectively. One week after cataract extraction the visual acuity in the treated eye was 0.67 (+/-0.31) in men and 0.69 (+/-0.28) in women (NS), and showed an inverse relationship to age in both men (P<0.01) and women (P<0.0001). One month after cataract extraction 28.3% of the men and 37.5% of the women experienced poor sleep, and after 9 months the figures were 15.8 and 31.4%, respectively. Frequent awakenings and difficulty in falling asleep after nocturnal awakenings improved correspondingly. Being well rested in the morning increased and daytime sleepiness decreased. The results indicate that in elderly persons with cataract sleep is improved 1 month after cataract extraction and further improvement during the first 9 months may be experienced.