title: Population study on the prevalence of insomnia and insomnia-related factors among Japanese women.
abstract: BACKGROUND
  To identify the effect of certain factors on insomnia in the general population.
  
  
  METHODS
  A self-reported questionnaire survey was conducted among 648 Japanese women living in the residential area of a city. Age of participants ranged from 20 to 80 s.
  
  
  RESULTS
  The crude prevalence of insomnia was 8.8%. Multivariate logistic regression analysis with control for many confounding variables revealed that experiencing a major life event (OR=4.4, 95% CI=1.7-11.4, P<0.01), depressive state (OR=1.2, 95% CI=1.1-1.3, P<0.01), and 'relatively poor or poor' self-rated health (OR=3.2, 95% CI=1.0-10.1, P<0.05) were risk factors for insomnia. By contrast, there was no dose-response relationship between the distance of our subjects from a major road and prevalence of insomnia.
  
  
  CONCLUSIONS
  The authors assume that depressive state by a major life event is closely associated with insomnia and that relatively poor self-rated health is also associated with stressful event and psychological distress. Although the noise from vehicles such as cars or motorcycles can affect the quality of sleep for subjects who live near a major road, in general the prevalence of insomnia did not increase significantly in this study.
authors: Department of Public Health, Gunma University School of Medicine, Showa 3, Maebashi 371-8511, Japan. kawada@nms.ac.jp
authors: Tomoyuki
authors: T
authors: Kawada
authors: Sasazawa
authors: S
authors: Yosiaki
authors: Kiryu
authors: K
authors: Yasuo
authors: Shosuke
authors: S
authors: Suzuki
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003863:Depression / Q000523:psychology*; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008016:Life Change Events; D016015:Logistic Models; D008875:Middle Aged; D009622:Noise; D011159:Population Surveillance; D015995:Prevalence; D007319:Sleep Initiation and Maintenance Disorders / Q000453:epidemiology / Q000208:ethnology*; D011795:Surveys and Questionnaires