title: Sunlight exposure and cardiovascular risk factors in the REGARDS study: a cross-sectional split-sample analysis.
abstract: BACKGROUND
  Previous research has suggested that vitamin D and sunlight are related to cardiovascular outcomes, but associations between sunlight and risk factors have not been investigated. We examined whether increased sunlight exposure was related to improved cardiovascular risk factor status.
  
  
  METHODS
  Residential histories merged with satellite, ground monitor, and model reanalysis data were used to determine previous-year sunlight radiation exposure for 17,773 black and white participants aged 45+ from the US. Exploratory and confirmatory analyses were performed by randomly dividing the sample into halves. Logistic regression models were used to examine relationships with cardiovascular risk factors.
  
  
  RESULTS
  The lowest, compared to the highest quartile of insolation exposure was associated with lower high-density lipoprotein levels in adjusted exploratory (-2.7 mg/dL [95% confidence interval: -4.2, -1.2]) and confirmatory (-1.5 mg/dL [95% confidence interval: -3.0, -0.1]) models. The lowest, compared to the highest quartile of insolation exposure was associated with higher systolic blood pressure levels in unadjusted exploratory and confirmatory, as well as the adjusted exploratory model (2.3 mmHg [95% confidence interval: 0.8, 3.8]), but not the adjusted confirmatory model (1.6 mg/dL [95% confidence interval: -0.5, 3.7]).
  
  
  CONCLUSIONS
  The results of this study suggest that lower long-term sunlight exposure has an association with lower high-density lipoprotein levels. However, all associations were weak, thus it is not known if insolation may affect cardiovascular outcomes through these risk factors.
authors.forename: Shia T
authors.initials: ST
authors.lastname: Kent
authors.forename: Mary
authors.initials: M
authors.lastname: Cushman
authors.forename: George
authors.initials: G
authors.lastname: Howard
authors.forename: Suzanne E
authors.initials: SE
authors.lastname: Judd
authors.forename: William L
authors.initials: WL
authors.lastname: Crosson
authors.forename: Mohammad Z
authors.initials: MZ
authors.lastname: Al-Hamdan
authors.affiliation: Department of Biostatistics, 1665 University Blvd, University of Alabama at Birmingham, Birmingham 35294, Alabama. lmcclure@uab.edu.
authors.forename: Leslie A
authors.initials: LA
authors.lastname: McClure
mesh_terms: D000368:Aged; D001794:Blood Pressure / Q000502:physiology; D002097:C-Reactive Protein / Q000378:metabolism; D002318:Cardiovascular Diseases / Q000453:epidemiology*; D002784:Cholesterol / Q000097:blood; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007674:Kidney Diseases / Q000150:complications / Q000453:epidemiology; D008075:Lipoproteins, HDL / Q000097:blood; D008077:Lipoproteins, LDL / Q000097:blood; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009752:Nutritional Status; D012307:Risk Factors; D013472:Sunlight; D014807:Vitamin D / Q000378:metabolism
chemical_list: D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D014807:Vitamin D; D002097:C-Reactive Protein; D002784:Cholesterol