title: Prevalence of excessive daytime sleepiness and associated factors in the adult population of Korea.
abstract: OBJECTIVE
  Information on the prevalence and correlates of excessive daytime sleepiness (EDS) is limited for Asians. We determined the prevalence of EDS and its associated factors in the adult population of Korea.
  
  
  METHODS
  The subjects consisted of 4405 Koreans aged 40-69 years from the Korean Genome Epidemiology Study, which is an ongoing prospective population-based study. Data were collected from a comprehensive health examination and a questionnaire at baseline.
  
  
  RESULTS
  The prevalence of EDS was 12.2% (10.7% for men and 13.7% for women). In multivariate models including sociodemographic, biochemical, clinical and sleep-related factors, age, physical activity, education, habitual snoring, waking up feeling unrefreshed, perceived insufficient sleep, and crawly feelings in the legs were significantly associated with EDS. Subjects aged 50-59 years had an excess risk of EDS by 1.42-fold (95% confidence interval [CI]=1.13-1.77) compared to those aged 40-49 years. In addition, the subjects with top quartile group of physical activity had a 1.80-fold (95% CI=1.18-2.73) higher risk of EDS than those with the lowest quartile group. A higher level of education was inversely associated with the risk of EDS. Furthermore, the subjects with habitual snoring had a 1.92-fold (95% CI=1.47-2.50) greater risk of EDS than non-snorers. Perceived insufficient sleep also increased the risk of EDS by 1.58-fold (95% CI=1.29-1.93) compared to perceived sufficient sleep. Subjects with crawly feelings in the legs had a 1.51-fold (95% CI=1.13-2.00) higher risk of EDS than those without crawly feelings in the legs. In addition, waking up feeling unrefreshed elevated a 1.24-fold (95% CI=1.01-1.53) risk of EDS compared to waking up feeling refreshed.
  
  
  CONCLUSIONS
  Our findings show that EDS is associated with a variety of factors in Korean adults, and habitual snoring or sleep-related problems increase the risk of EDS. Whether interventions to modify associated correlates can alter EDS warrants further study.
authors.affiliation: Institute of Human Genomic Study, Korea University Medical Center, Ansan Hospital, Gyeonggi-do, Republic of Korea.
authors.forename: Soonjae
authors.initials: S
authors.lastname: Joo
authors.forename: Inkyung
authors.initials: I
authors.lastname: Baik
authors.forename: Hyeryeon
authors.initials: H
authors.lastname: Yi
authors.forename: Kihwan
authors.initials: K
authors.lastname: Jung
authors.forename: Jehyeong
authors.initials: J
authors.lastname: Kim
authors.forename: Chol
authors.initials: C
authors.lastname: Shin
mesh_terms: D000328:Adult; D000368:Aged; D044466:Asian People / Q000706:statistics & numerical data*; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D006970:Disorders of Excessive Somnolence / Q000208:ethnology*; D005260:Female; D006801:Humans; D007723:Korea; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D012720:Severity of Illness Index; D017678:Sex Distribution; D012959:Socioeconomic Factors