Background: Sleep problems are common in people with intellectual disabilities (ID), but the knowledge on the natural course of sleep-wake rhythms and sleep problems in elderly persons with ID is limited. In the current study, objectively measured sleep-wake rhythms and the prevalence and severity of sleep problems of elderly persons with ID was compared to that of healthy elderly persons from a large representative sample from the general population. Methods: Actigraphy data of 501 elderly persons with ID (age 62.02 ± 8.02 years, 48% female) from the Healthy Ageing and Intellectual Disabilities study was compared to the data of 1734 elderly persons from the general population (age 62.24 ± 9.34 years, 53% female) from the Rotterdam Study. Main outcome variables were Interdaily stability (IS) and Intradaily variablitiy (IV), total sleep time (TST), Waking after sleep onset (WASO), Short sleep (TST<6 h), Night waking (WASO >90 min). Results: Elderly persons with ID had less stable sleep wake rhythms than elderly persons from the general population (IS = 0.70 ± 0.17, vs 0.80 ± 0.10 z = −8.00). Their sleep-wake rhythm was also more fragmented (IV = 0.56 ± 0.26 vs 0.42 ± 0.13 respectively, z = 8.00). Elderly persons with ID slept on average 60.09 min longer than elderly persons from the general population, and lay awake 48.28 min longer after sleep onset. Short sleep in elderly persons with ID was less prevalent (20.7% vs 30.2%) but more severe (TST in Short sleep; 5.13 ± 0.80 h vs 5.39 ± 0.50 h, z = −2.76) then in elderly persons from the general population. Night waking was more prevalent (63.0% vs 17.7%) and more severe in elderly persons with ID (WASO in Night waking; 150.39 ± 54.72 min vs 111.60 ± 17.95 min, z = 7.06). Conclusion: The differences in sleep-wake rhythms, prevalence and severity of sleep problems between elderly persons with and without ID are marked and possibly explained by medical, psychiatric conditions and lifestyle in elderly persons with ID. Better understanding of sleep in elderly with ID is needed to improve the quality of sleep in this population and to diminish health problems related to a disruption of sleep.