title: Sleep duration and hypercholesterolaemia: Results from the National Health Interview Survey 2008.
abstract: BACKGROUND
  Previous studies have shown an inconsistent association between sleep duration and hypercholesterolaemia. This study examined the association between sleep duration and hypercholesterolaemia in a nationally representative sample of US adults.
  
  
  METHODS
  A cross-sectional study of 16,652 participants in the 2008 National Health Interview Survey (aged ⩾18years, 52.5% women) was conducted. Sleep duration was categorized as ⩽5, 6, 7, 8, or ⩾9h. Hypercholesterolaemia (n=5578) was assessed by questionnaire.
  
  
  RESULTS
  A significant gender difference was found in the association between sleep duration and hypercholesterolaemia (P interaction=0.003). Among women, sleep duration ⩽5h was positively associated with hypercholesterolaemia after adjusting for potential confounders and mediators including physical activity, psychological distress, body mass index, diabetes mellitus, and hypertension. Compared with a sleep duration of 7h (referent), the multivariate odds ratio (OR) of hypercholesterolaemia was 1.27 (95% confidence interval [CI] 1.04-1.54) for sleep duration ⩽5h. In contrast, among men, sleep duration ⩾8h was inversely associated with hypercholesterolaemia. Compared with a sleep duration of 7h (referent), the multivariate OR of hypercholesterolaemia was 0.80 (95% CI 0.69-0.94) and 0.78 (95% CI 0.60-1.00) for sleep durations of 8 and ⩾9h, respectively. In subgroup analyses, the positive association between sleep duration ⩽5h and hypercholesterolaemia in women, and the inverse association between sleep duration ⩾8h and hypercholesterolaemia in men, were more pronounced among those aged <60 years and race/ethnic groups other than non-Hispanic Whites.
  
  
  CONCLUSIONS
  Sleep duration ⩽5h was positively associated with hypercholesterolaemia in women, whereas sleep duration ⩾8h was inversely associated with hypercholesterolaemia in men.
authors.affiliation: Department of Community Medicine, West Virginia University School of Medicine, Morgantown, WV 26505-9190, USA.
authors.forename: Charumathi
authors.initials: C
authors.lastname: Sabanayagam
authors.forename: Anoop
authors.initials: A
authors.lastname: Shankar
mesh_terms: D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies / Q000706:statistics & numerical data; D005006:Ethnicity / Q000706:statistics & numerical data; D005260:Female; D006306:Health Surveys / Q000706:statistics & numerical data*; D006801:Humans; D006937:Hypercholesterolemia / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D017678:Sex Distribution; D012890:Sleep / Q000502:physiology*; D012893:Sleep Wake Disorders / Q000453:epidemiology*; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology; D055815:Young Adult