RLS severity is associated with poorer sleep quality in individuals with MS, both directly and indirectly through anxiety and fatigue, with these indirect associations varying as a function of disease duration.
Key Findings
Results
Greater RLS severity was significantly associated with poorer sleep quality in individuals with multiple sclerosis.
The direct association between RLS severity and sleep quality had a standardized coefficient of β = 0.31, p < 0.001.
The study used structural equation modeling to examine direct and indirect associations among variables.
The sample consisted of 110 individuals diagnosed with MS recruited from a governmental hospital outpatient clinic in Egypt.
Data were collected using validated self-report measures of RLS severity, sleep quality, anxiety, fatigue, and disease duration.
The study followed the STROBE checklist for reporting.
Results
Greater RLS severity was significantly associated with higher anxiety levels in individuals with MS.
The association between RLS severity and anxiety had a standardized coefficient of β = 0.42, p < 0.001.
This was the strongest direct association observed among the variables examined.
Anxiety was examined as an indirect correlate (mediator) in the moderated mediation model.
Cross-sectional design limits causal interpretation of this association.
Results
Greater RLS severity was significantly associated with greater fatigue in individuals with MS.
The association between RLS severity and fatigue had a standardized coefficient of β = 0.28, p = 0.001.
Fatigue was examined as an indirect correlate (mediator) alongside anxiety in the moderated mediation model.
Both anxiety and fatigue were theory-driven variables selected for the mediation model.
Results
Anxiety and fatigue statistically mediated a significant portion of the association between RLS severity and sleep quality.
Anxiety and fatigue 'statistically accounted for a significant portion of the association between RLS severity and sleep quality.'
The model tested a moderated mediation framework with anxiety and fatigue as indirect (mediating) variables.
Structural equation modeling was the primary analytic approach used to test these indirect associations.
The paper describes these as 'indirect correlates' rather than confirmed causal mediators, given the cross-sectional design.
Results
Disease duration moderated the indirect associations between RLS severity and sleep quality through anxiety and fatigue, with stronger associations among individuals with longer MS duration.
Conditional indirect associations indicated that the relationships were stronger among individuals with longer MS duration (>5 years).
Disease duration was examined as a moderating variable in the moderated mediation model.
This moderation suggests that the pathway from RLS through anxiety and fatigue to poor sleep quality becomes more pronounced as MS progresses.
The cross-sectional design limits conclusions about the direction or causality of this moderation effect.
Discussion
The study was cross-sectional and exploratory in nature, limiting causal inference.
The authors explicitly note the findings are 'exploratory and cross-sectional.'
A cross-sectional correlational design was used with 110 participants from a single governmental hospital outpatient clinic in Egypt.
Recruitment from a single site in Egypt may limit generalizability to other populations.
The authors acknowledged that despite these limitations, findings 'highlight the importance of comprehensive nursing assessment and integrated symptom management approaches.'
What This Means
This research suggests that restless legs syndrome (RLS) — a condition causing uncomfortable sensations and an urge to move the legs, especially at night — is connected to poorer sleep quality in people living with multiple sclerosis (MS). The study examined 110 MS patients in Egypt and found that more severe RLS symptoms were associated not only with worse sleep directly, but also with higher levels of anxiety and fatigue, which themselves were associated with worse sleep. In other words, RLS may worsen sleep both on its own and by contributing to anxiety and fatigue that then further disrupt sleep.
The study also found that how long a person has had MS matters: among people who had lived with MS for more than five years, the connections between RLS, anxiety, fatigue, and poor sleep appeared to be stronger. This suggests that as MS progresses, the interplay between these symptoms may become more complex and compounding.
Because this was a cross-sectional study — meaning it captured a snapshot in time rather than following patients over time — the findings cannot establish that RLS directly causes poor sleep or that anxiety and fatigue are the definitive reasons for this link. However, the results highlight that healthcare providers caring for people with MS may benefit from assessing and addressing RLS, anxiety, and fatigue together rather than in isolation, as these symptoms appear to be interconnected in ways that collectively affect sleep quality and overall well-being.
Hashem E, Mohammed Syam N, Ali Awad W, Ali Awad N, Mohammed N, Berdida D, et al.. (2026). Restless legs syndrome and sleep quality in patients with multiple sclerosis: A moderated mediation model of anxiety, fatigue, and disease duration.. Sleep medicine. https://doi.org/10.1016/j.sleep.2026.108790