The Clinical Impact of Periodic Limb Movements During Sleep (PLMS): Under-Recognition in Sleep Disordered Breathing and Associations with Key Clinical Outcomes in 481,857 Patients

Study Objectives To evaluate periodic limb movements during sleep (PLMS) in a large sleep disorders cohort and explore associations with sleep-disordered breathing (SDB), demographics and key clinical comorbidities. Methods A retrospective analysis including 481,857 adults who completed overnight polysomnography (PSG) and a sleep/medical history questionnaire. Data collection spanned 240 sleep centers across 30 U.S. states. Periodic limb movement index (PLMI) was calculated from technician-scored PSGs, and all PSG measures were scored in accordance with American Academy of Sleep Medicine guidelines. Associations with PLMI were assessed using multivariable linear regression, with self-reported and objective measures analyzed separately, first in predictor-specific and then in simultaneous models. Results The sample included 54.1% males, with a mean age of 54.4 ± 14.4 years (range: 18–107), average PLMI of 10.3 ± 22.1 events/hour and average Apnea Hypopnea Index (AHI) of 14.7 ± 19.1 events/hour. PLMI was highest among White individuals; lower among Hispanic, Asian, and Black individuals. PLMI was strongly negatively associated with SDB measures, persisting even when stratified by CPAP usage. In both predictor-specific and simultaneous multivariable models, PLMI was associated with diagnosed depression, insomnia score, elevated blood sugar and anemia. Objectively, PLMI was associated with arousal index and lower sleep efficiency. Conclusions Our findings highlight the potential clinical relevance of PLMS across neuropsychiatric, cardiometabolic, and sleep domains. Racial disparities may reflect genetic and sociocultural factors. Most strikingly, in the setting of increased SDB, PLMS may be undercounted, potentially warranting further evaluation of scoring criteria. These results support further genetic and mechanistic investigations.