title: Sleep disorders in systemic lupus erythematosus. Does vitamin D play a role?
abstract: OBJECTIVE
  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.
authors.affiliation: Poursina Hakim Research Institution, Isfahan, Iran gholamrezaei@med.mui.ac.ir.
authors.forename: A
authors.initials: A
authors.lastname: Gholamrezaei
authors.affiliation: Department of Internal Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Z Sayed
authors.initials: ZS
authors.lastname: Bonakdar
authors.affiliation: Medical Students' Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: L
authors.initials: L
authors.lastname: Mirbagher
authors.affiliation: Medical Students' Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: N
authors.initials: N
authors.lastname: Hosseini
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D005260:Female; D006304:Health Status; D006801:Humans; D016014:Linear Models; D008180:Lupus Erythematosus, Systemic / Q000097:blood / Q000150:complications* / Q000503:physiopathology; D008875:Middle Aged; D015999:Multivariate Analysis; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D012890:Sleep; D012893:Sleep Wake Disorders / Q000097:blood / Q000209:etiology* / Q000503:physiopathology; D014807:Vitamin D / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications* / Q000503:physiopathology
chemical_list: D015415:Biomarkers; D014807:Vitamin D
keywords: Systemic lupus erythematosus; sleep; sleep disorders; vitamin D deficiency