title: Physical activity, smoking, and the incidence of clinically diagnosed insomnia.
abstract: This study was designed to examine the independent and combined associations of physical activity and smoking on the incidence of doctor-diagnosed insomnia using a nationally representative sample over seven years, taking into account other relevant covariates.
  
  
  
  Participants aged 18 years or older in the 2005 Taiwan National Health Interview Survey (NHIS) with links to National Health Insurance (NHI) claim data between 2005 and 2012 and without diagnosed insomnia before 2005, were selected into this study (n = 12,728). Participants were classified as having insomnia with International Classification of Diseases, Ninth Revision (ICD-9) CM codes 307.41, 307.42, or 780.52. Self-reported smoking status and frequency, duration, and types of leisure-time and non-leisure-time physical activities were collected. Metabolic equivalent (MET) intensity levels for each activity were assigned, and weekly energy expenditure of each activity was calculated and summed.
  
  
  
  Inactive participants had a higher risk of incident insomnia [hazard ratio (HR) = 1.22, 95% confidence interval (CI) = 1.06-1.42, p = 0.007] than the active group, and ever-smokers were more likely to have incident insomnia than never smokers (HR = 1.45, 95% CI = 1.20-1.76, p < 0.001). Compared with the nonsmoker/active group, the ever-smoker/inactive group had a higher risk of incident insomnia (HR = 1.78, 95% CI = 1.41-2.25, p < 0.001). Sensitivity analyses excluding individuals diagnosed with other sleep disorders or mental disorders yielded similar results, with the ever-smoker/inactive group having the highest risk of insomnia.
  
  
  
  Inactive adults and smokers are at higher risk for incident insomnia, highlighting the importance of a healthy lifestyle and pointing to strategies such as encouraging smoking cessation and physical activity to avoid insomnia among adults.
authors.affiliation: Department of Exercise Health Science, National Taiwan University of Sport, Taichung City, Taiwan; Department of Epidemiology and Public Health, University College London, London, UK.
authors.forename: Li-Jung
authors.initials: LJ
authors.lastname: Chen
authors.affiliation: Department of Epidemiology and Public Health, University College London, London, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Steptoe
authors.affiliation: Department of Medical Research, Taichung Veterans General Hospital, Taichung City, Taiwan.
authors.forename: Yi-Huei
authors.initials: YH
authors.lastname: Chen
authors.affiliation: Department of Epidemiology and Public Health, University College London, London, UK; Graduate Institute of Sports and Health, National Changhua University of Education, Changhua City, Taiwan. Electronic address: powen.ku@gmail.com.
authors.forename: Po-Wen
authors.initials: PW
authors.lastname: Ku
authors.affiliation: Department of Medical Research, Taichung Veterans General Hospital, Taichung City, Taiwan. Electronic address: joelin99@gmail.com.
authors.forename: Ching-Heng
authors.initials: CH
authors.lastname: Lin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015444:Exercise; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D007319:Sleep Initiation and Maintenance Disorders / Q000453:epidemiology*; D012907:Smoking / Q000453:epidemiology*; D013624:Taiwan / Q000453:epidemiology; D055815:Young Adult
keywords: Cigarette; Exercise; Physical inactivity; Sleep disorder; Unhealthy behavior