Sleep Cohort Links Periodic Limb Movements to Comorbidities and Possible Undercounting

A retrospective study published in SLEEP examined periodic limb movements during sleep in 481,857 adults evaluated at 240 sleep centers across 30 US states. Participants completed overnight polysomnography and a sleep/medical history questionnaire. Investigators used multivariable regression to assess associations between the periodic limb movement index (PLMI), sleep-disordered breathing, demographics and clinical comorbidities.

Participants had a mean age of 54.4 years, and 54.1% were male. Mean PLMI was 10.3 events/hour, while mean apnea–hypopnea index was 14.7 events/hour. PLMI was inversely associated with sleep-disordered breathing measures, including in analyses stratified by CPAP use. In both predictor-specific and simultaneous models, PLMI was associated with diagnosed depression, insomnia score, elevated blood sugar and anemia. Objective associations included arousal index and lower sleep efficiency. PLMI was highest among White participants and lower among Hispanic, Asian and Black participants.

The authors suggest that periodic limb movements may be undercounted when sleep-disordered breathing is more pronounced, potentially warranting evaluation of scoring criteria. This remains an interpretation rather than a demonstrated measurement error. The retrospective associations do not establish causality or treatment benefit, and the sleep-center population limits generalizability. Only the abstract was available; it did not report adjusted effect sizes or confidence intervals.