Periodic Leg Movements Predict Total Sleep Time in Persons with Cognitive Impairment and Sleep Disturbance

To determine if periodic leg movements predict total sleep time at night in elders with cognitive impairment and sleep disturbance. Descriptive cross-sectional secondary analysis using data from an observational study and baseline data from a randomized, controlled clinical trial. Private homes, nursing homes, and assisted living facilities. One hundred and two persons with a mean age of 81.8 years, cognitive impairment, and sleep disturbance. N/A. We measured sleep variables using 1 night of attended polysomnography in each participant's usual sleep setting. We assessed 10 characteristics associated with sleep disturbance (periodic leg movement index, time in bed, apnea-hypopnea index, oxygen saturation nadir, age, sex, living arrangement, cognitive status, painful conditions, and depression) with multiple linear regression analyses to determine the predictors of total sleep time. Of the 102 participants, 56.9% were men, and 64.7% lived in nursing homes or assisted living facilities. Their mean Mini-Mental State Examination score was 17.3. In addition, 21.6% had 1 or more painful conditions, and 45.1% were diagnosed with depression. Participants' mean periodic leg movement index was 17.3 with 34 (33.3%) having a periodic leg movement index greater than 15. Time in bed at night exceeded 8 hours, yet participants averaged only 5.5 hours of sleep. They had a mean apnea-hypopnea index of 18.3, with a mean oxygen saturation nadir of 86.4%. Periodic leg movement index, time in bed, and age explained 43.6% of the variance in total sleep time. Frequent periodic leg movements, less time in bed, and older age are associated with less sleep at night in this population.