title: Associations of physical activity, screen time with depression, anxiety and sleep quality among Chinese college freshmen.
abstract: OBJECTIVE
  To investigate the independent and interactive associations of physical activity (PA) and screen time (ST) with depression, anxiety and sleep quality among Chinese college students.
  
  
  METHODS
  A cross-sectional study was conducted in Wuhan University, China from November to December 2011. The students reported their PA, ST and socio-economic characteristics using self-administered questionnaires. Sleep quality was measured by the Pittsburgh Sleep Quality Index (PSQI). Depression and anxiety were assessed using the Self-rating Depression Scale (SDS) and Self-rating Anxiety Scale (SAS), respectively. Multivariate logistic regression models were used to estimate the odds ratios (ORs) and 95% confidence intervals (CIs) of the independent and interactive relationships of PA and ST with depression, anxiety and sleep quality.
  
  
  RESULTS
  A total of 1106 freshmen (471 females and 635 males) aged 18.9±0.9 years were included in the study. After adjustment for potential confounders, high PA and low ST were independently associated with significantly lower risks for poor sleep quality (OR: 0.48, 95% CI: 0.30-0.78) and depression (OR: 0.67, 95%CI: 0.44-0.89), respectively. An interactive inverse association was observed for combined effects of PA and low ST on depression (OR: 0.62, 95%CI: 0.40-0.92) and sleep quality (OR: 0.51, 95%CI: 0.27-0.91). No statistically significant associations were found between PA, ST and anxiety among the participants.
  
  
  CONCLUSIONS
  These findings suggest an independent and interactive relationship of high PA and low ST with significantly reduced prevalence of depressive problems and favorable sleep quality among Chinese college freshmen.
authors: School of Public Health, Wuhan University, Wuhan, P. R. China.
authors: Qi
authors: Q
authors: Feng
authors: School of Public Health, Wuhan University, Wuhan, P. R. China.
authors: Qing-le
authors: QL
authors: Zhang
authors: School of Public Health, Wuhan University, Wuhan, P. R. China.
authors: Yue
authors: Y
authors: Du
authors: School of Public Health, Wuhan University, Wuhan, P. R. China.
authors: Yong-ling
authors: YL
authors: Ye
authors: School of Public Health, Wuhan University, Wuhan, P. R. China; Global Health Institute, Wuhan University, Wuhan, P. R. China.
authors: Qi-qiang
authors: QQ
authors: He
mesh_terms: D000293:Adolescent; D000328:Adult; D001008:Anxiety Disorders / Q000453:epidemiology* / Q000517:prevention & control; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D003866:Depressive Disorder / Q000453:epidemiology* / Q000517:prevention & control; D015444:Exercise / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008603:Mental Health; D015995:Prevalence; D057566:Self Report; D012893:Sleep Wake Disorders / Q000453:epidemiology* / Q000517:prevention & control; D013334:Students; D013997:Time Factors; D014495:Universities; D055815:Young Adult