Objectives: Sleep disorders are common among patients with systemic lupus erythematosus (SLE) with unclear underlying mechanisms. We assessed the role of vitamin D in sleep quality of patients with SLE.
Methods: A retrospective study was conducted on women with SLE for whom the following data were available at the same time; sleep quality (Pittsburgh Sleep Quality Index (PSQI)), disease activity, cumulative disease damage, psychological state (Hospital Anxiety and Depression Scale (HADS)), and serum vitamin D level. Bivariate and regression analyses were computed to find contributors of sleep quality.
Results: In total, 63 women were studied. Serum vitamin D level was correlated with physical activity (r=0.310, p=0.015), season of assessment (r=-0.302, p=0.016), the PSQI global score (r=-0.262, p=0.043), anxiety score (r=-0.298, p=0.021), and non-significantly with depression score (r=-0.218, p=0.094). Including all variables into a linear regression model, vitamin D level was independently associated with the global PSQI score (beta=-0.364, p=0.042). Association of vitamin D level with psychological state disappeared after controlling for season of assessment (beta=-0.248, p=0.154).
Conclusions: We found a role for vitamin D in sleep quality of SLE patients. Further studies are warranted to confirm these results and to find possible mechanisms of action.
Keywords: Systemic lupus erythematosus; sleep; sleep disorders; vitamin D deficiency.
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