Sleep duration during the 24-hour day is associated with the severity of dementia in nursing home patients

Abstract

Study objectives: To describe the characteristics of 24-h sleep patterns in nursing home patients with dementia, and to determine whether various degrees of dementia have any influence on total sleep duration.

Design and setting: Cross-sectional study in a nursing home population (n = 23) consisting of patients with varying degree of dementia. Sleep was measured with actigraphy for a consecutive period of 14 days, based on individual bed and rising time, which was registered by nursing home staff.

Measurements and results: Mean age +/- standard deviation was 86.1 +/- 7.0 (range 72-96) and mean Mini-Mental Status Examination Score (MMSE) was 13.4 +/- 5.3 (range 1-21). Ten patients had MMSE < or = 12. Sleep was extremely fragmented, with frequent wake bouts during nighttime and frequent naps during daytime. During the 24-h period, patients spent nearly 13 h asleep, distributed as more than 9 h of nighttime sleep and more than 3 h of daytime sleep. Patients with severe degree of dementia (MMSE < or = 12) slept significantly longer during the 24-h day than patients with lesser degree of dementia (MMSE > 12). There was no significant difference in age between the dementia sub-groups.

Conclusion: Sleep duration during the 24-h day was positively correlated with the severity of dementia in nursing home patients. This is in contrast with total sleep time seen in healthy elderly, which shows a gradually decline with age. Changes in sleep patterns in dementia could be explained by co-morbid and environmental factors, as well as unknown pathological changes related to dementing illnesses.