ORIGINAL RESEARCH article
Front. Neurol.
Sec. Sleep Disorders
Lower Fat-Free Mass is Independently Linked to Restless Legs Syndrome in Men: A Cross-Sectional PSG–BIA Study
1. Inje University Ilsan Paik Hospital, Goyang-si, Republic of Korea
2. Samsung Medical Center, Gangnam-gu, Republic of Korea
3. University of California San Francisco, San Francisco, United States
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Abstract
Objective: Restless legs syndrome (RLS) is a common sensorimotor disorder that disrupts sleep and quality of life. Sarcopenia—reduced skeletal muscle mass and function—has been linked to sleep disturbances, but its relationship with RLS remains unclear. We examined whether sarcopenia is associated with RLS, with a focus on sex-specific effects. Methods: We conducted a cross-sectional analysis of 5,752 adults who underwent both type-I polysomnography (PSG) and bioelectrical impedance analysis (BIA) at a tertiary sleep center. RLS was diagnosed by IRLSSG criteria. Sarcopenia was defined using skeletal muscle index (SMI) and fat-free mass index (FFMI) thresholds. Multivariable models adjusted for age, physical activity, caffeine/alcohol intake, and apnea–hypopnea index (AHI). Results: RLS prevalence was 6.6% in females and 2.9% in males. Sarcopenia was more frequent in the RLS group than in non-RLS (10.6% vs. 6.8%), particularly among males (8.7% vs. 3.2%). In males, lower SMI and FFMI were independently associated with higher odds of RLS; sex interaction for FFMI was significant. Conclusions: Reduced muscle mass is independently associated with RLS in men, suggesting a male-specific muscle phenotype relevant to RLS pathophysiology. Incorporating BIA-based screening and muscle-preserving interventions may benefit the management of male patients with RLS.
Summary
Keywords
bioelectricalimpedance analysis, Fat-free mass index, Restless Legs Syndrome, Sarcopenia, Skeletal muscle index
Received
20 November 2025
Accepted
17 February 2026
Copyright
© 2026 Bae, Park, Kim and JOO. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: EUN YEON JOO
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