title: The U-shaped association between self-reported sleep duration and visual impairment in Korean adults: a population-based study.
abstract: This study aimed to investigate the association between self-reported sleep duration and visual impairment (VI) in Korean adults.
  
  
  
  This population-based, cross-sectional study examined ophthalmologic data of 16,374 Koreans aged 19 years and older from the 2010-2012 Korea National Health and Nutrition Examination Survey (KNHNES V). VI data (best-corrected distance visual acuity worse than 0.5 logMAR in the better-seeing eye) were obtained from direct ophthalmologic examinations, and data on self-reported sleep duration (≤5, 6, 7, 8, or ≥9 h/night) were obtained using questionnaires. Multiple logistic regression analysis was conducted to examine the association between self-reported sleep duration and VI, and we also adjusted for possible covariates.
  
  
  
  The weighted VI prevalences (95% CIs) were 1.23% (0.70-1.76), 0.40% (0.10-0.70), 0.18% (0.04-0.31), 0.42% (0.26-0.58), and 0.66% (0.25-1.07) for participants who slept ≤5, 6, 7, 8, and ≥9 h/night, respectively. Even after adjusting for demographic factors (age and sex), lifestyle factors (household income, occupation, smoking status, regular exercise, and suicidal thoughts), and medical factors (diabetes, hypertension, stroke, and history of ocular surgery), greater risk of VI was found in the ≤5 h/night (OR = 3.23, 95% CI: 1.43-7.31) and ≥9 h/night (OR = 2.56, 95% CI: 1.03-6.41) groups, compared to the 7 h/night group.
  
  
  
  In Korean adults, self-reported sleep duration and VI exhibited a U-shaped association. Both very short (≤5 h/night) and very long (≥9 h/night) sleep durations were significantly associated with increased VI.
authors.affiliation: Department of Ophthalmology and Catholic Institute for Visual Science, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Youngju
authors.initials: Y
authors.lastname: An
authors.affiliation: Department of Ophthalmology and Catholic Institute for Visual Science, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea. Electronic address: ckjoo@catholic.ac.kr.
authors.forename: Choun-Ki
authors.initials: CK
authors.lastname: Joo
mesh_terms: D000328:Adult; D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D015995:Prevalence; D012044:Regression Analysis; D056910:Republic of Korea / Q000453:epidemiology; D012307:Risk Factors; D057566:Self Report; D012890:Sleep / Q000502:physiology*; D013997:Time Factors; D014786:Vision Disorders / Q000453:epidemiology* / Q000209:etiology; D055815:Young Adult
keywords: Korean adults; Sleep duration; U-shaped association; Visual impairment