Abstract Introduction Periodic limb movements of sleep (PLMS) are repetitive nocturnal leg movements typically occurring during non-rapid eye movement (NREM) sleep, though a subset of patients also display movements during rapid eye movement (REM) sleep. The physiological and clinical correlates of REM-related PLMS remain poorly understood. This objective of this study was to characterize the prevalence and predictors of PLMS during REM and NREM sleep in a clinically referred adult population undergoing polysomnography (PSG). Methods We conducted a cross-sectional analysis of 198 adults referred for diagnostic PSG. Demographic, clinical, and PSG data were extracted, and ridge-regression models identified predictors of PLMS separately for NREM and REM stages, adjusting for age, sex, comorbidities, and medication use. Results A total of 192 adults were analyzed for REM outcomes. The cohort included 47.4% men and 52.6% women. Hypertension was the most prevalent comorbidity (54.7%), followed by diabetes (24.0%) and hypothyroidism (17.7%). Elevated PLMS (PLMI 15) occurred in 19.5% of patients exclusively during NREM only, 7.8% during REM only, and 33.7% in both stages. In the NREM model, older age (β = 0.047, p 0.001) and male sex (β = 1.463, p = 0.020) predicted greater PLMS, whereas longer NREM duration was protective (β = –0.014, p = 0.008). In contrast, REM PLMS were inversely associated with hypothyroidism (β = –4.170, p 0.001) and positively with N1 sleep percentage (β = 0.368, p =0.024). Other morbidities and medication use were not significant. Conclusion Predictors of PLMS vary based on sleep stage. NREM PLMS are influenced by age and sex, while REM PLMS appear to be driven by sleep-stage dynamics and thyroid status. These findings suggest that REM-related PLMS may represent a distinct physiological phenotype, highlighting the need for further studies on their pathophysiological and clinical significance. Support (if any)
Vaddavalli et al. (2026) studied this question.