title: [Association between time spent on physical exercise, sleep, homework and suspected myopia among students].
abstract: OBJECTIVE
  To investigate the prevalence of suspected myopia among students and to examine the relationship between time spent on physical exercise, sleep, homework and suspected myopia.
  
  
  METHODS
  A total of 8 030 primary and secondary school students from 4(th) to 12(th) grades were selected from the National Student Constitution and Health Survey (NSCHS) in Anhui province in 2014. Time spent on exercise, sleep and homework per day were collected using a self-administrated questionnaire. Visual acuity was examined using the Standard Logarithmic Visual Acuity Chart.
  
  
  RESULTS
  The overall prevalence of suspected myopia was 69.03%. Prevalence rates of suspected myopia appeared higher in girls, in urban students, with the highest in the 16 to 18 year-old groups. RESULTS from the multiple logistic regression analysis showed that the amount of time spent on physical exercise, sleep and homework per day were all significantly associated with suspected myopia. Suspected myopia was associated with longer time on physical exercise among students aged 8 to 12 years (OR=0.80, 95%CI: 0.64-0.99), and longer sleep time among students in the age groups of 13 to 15 years and 16 to 18 years (OR=0.73, 95% CI: 0.56-0.94;OR=0.38, 95% CI: 0.21-0.68, respectively). Longer time spent on homework significantly increased the risk of suspected myopia among students in the age groups of 8 to 12 years and 13 to 15 years (OR=1.41, 95%CI: 1.11-1.79; OR=1.74, 95% CI: 1.36-2.23, respectively).
  
  
  CONCLUSIONS
  Suspected myopia appeared common among students. Comprehensive intervention programs focusing on sufficient physical exercise and sleep but less homework might help to prevent myopia among students at different ages.
authors.affiliation: Anhui Provincial Key Laboratory of Population Health & Aristogenics, Department of Maternal, Child and Adolescent Health Care, School of Public Health, Anhui Medical University, Hefei 230032, China.
authors.forename: S J
authors.initials: SJ
authors.lastname: Xu
authors.forename: Y H
authors.initials: YH
authors.lastname: Wan
authors.forename: Z H
authors.initials: ZH
authors.lastname: Xu
authors.forename: H
authors.initials: H
authors.lastname: Zhang
authors.forename: L
authors.initials: L
authors.lastname: Xu
authors.forename: B
authors.initials: B
authors.lastname: Wang
authors.forename: F B
authors.initials: FB
authors.lastname: Tao
mesh_terms: D000293:Adolescent; D002648:Child; D002681:China / Q000453:epidemiology; D015444:Exercise; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D009216:Myopia / Q000453:epidemiology*; D015995:Prevalence; D012890:Sleep; D013334:Students / Q000706:statistics & numerical data*; D013997:Time Factors