title: Vitamin D, race, and excessive daytime sleepiness.
abstract: OBJECTIVE
  First, to determine whether serum vitamin D levels were correlated with excessive daytime sleepiness (EDS) in patients with or without vitamin D deficiency (VitDd). Second, to assess whether race affected the relation between vitamin D levels and EDS.
  
  
  METHODS
  Serum 25-hydroxyvitamin D (25OHD) was measured by immunoassay in a consecutive series of 81 sleep clinic patients who complained of sleep problems and nonspecific pain (25OHD < 20 ng/mL ' VitDd). Sleepiness was determined using the Epworth Sleepiness Scale score ([ESSs] ESSs ≥ 10 ≡ EDS). Correlations were assessed using Pearson r.
  
  
  RESULTS
  In patients without VitDd (25OHD ≥ 20 ng/mL), ESSs was inversely correlated with vitamin D concentration (r = 0.45, p < 0.05). The group consisted of 6% black patients, compared with 35% for the entire cohort. Among the patients who had VitDd (25OHD < 20 ng/mL), ESSs was directly correlated with 25OHD in black (r = 0.48, p < 0.05) but not white patients. In black patients, mean ESSs in patients with VitDd were higher and 25OHD levels were lower p < 0.05).
  
  
  CONCLUSIONS
  The results suggested the novel possibility that VitDd-related disease has a yet-to-be-identified mechanistic role in the presentation of sleepiness, sleep disorders, or both. Further research is needed to clarify the mechanism(s) involved in producing the complex relationships noted.
authors.affiliation: Division of Sleep Medicine, Department of Neurology, Louisiana State University Health Sciences Center, Shreveport, LA 71130-3932, USA. dmcca1@lsuhsc.edu
authors.forename: David E
authors.initials: DE
authors.lastname: McCarty
authors.forename: Aronkumar
authors.initials: A
authors.lastname: Reddy
authors.forename: Quinton
authors.initials: Q
authors.lastname: Keigley
authors.forename: Paul Y
authors.initials: PY
authors.lastname: Kim
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Marino
mesh_terms: D001741:Black or African American; D015415:Biomarkers; D016022:Case-Control Studies; D015897:Comorbidity; D006970:Disorders of Excessive Somnolence / Q000208:ethnology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D014481:United States / Q000453:epidemiology; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000208:ethnology*
chemical_list: D015415:Biomarkers; D014807:Vitamin D; C104450:25-hydroxyvitamin D