Study objectives: Periodic limb movements of sleep (PLMS) are common in the elderly. However, no large polysomnographic study has closely examined the relationship of PLMS to sleep architecture and arousals from sleep. We investigated the prevalence and correlates of PLMS in a community-based sample of older women.
Design: Observational study, cross-sectional analyses.
Setting: Two clinical sites participating in the Study of Osteoporotic Fractures (SOF).
Participants: 455 older community-dwelling women (mean age 82.9 years) who completed in-home polysomnography at SOF visit 8.
Interventions: N/A.
Measurements and results: In-home 12 channel polysomnography was performed with measurement of leg movements by bilateral piezo sensors. Measures of PLMS included the number of leg movements per hour of sleep (PLMI) and the number of leg movements causing EEG-documented arousals per hour of sleep (PLMA). An elevated PLMI was common, with 66% showing PLMI > or =5 and 52% showing PLMI > or =15. A PLMA > or =5 and > or =15 were observed in 124 (27%) and 26 (6%) participants respectively. After adjustment for the potential confounders of antidepressant medication use, age, race, body mass index, and apnea-hypopnea index, participants with a higher PLMA had a significantly higher arousal index, lower sleep efficiency, higher percentages of sleep stages 1 and 2 and lower percentages of stages 3-4 and REM (p < .001). An increased PLMI was associated with a higher arousal index, but not with other indices of sleep quality. Neither PLMI or PMLA was associated with subjective sleepiness or other known comorbidities.
Conclusions: Periodic leg movements are very common in older community-dwelling women. PLMS which were associated with EEG arousals had a strong and consistent association with markers of disturbed sleep. PLMS associated with arousals thus appear to be more clinically relevant and should be considered when examining health outcomes associated with PLMS.