title: Self-reported mental distress under the shifting daylight in the high north.
abstract: BACKGROUND
  The validity of the concept of seasonal affective disorder and the causal link to lack of daylight in winter is controversial. There is a need for investigations in large samples of the general population at different latitudes and within general research contexts to avoid selective response bias and sensitization of the population.
  
  
  METHODS
  During a study of health effects of the air pollution from Russia in a small community at 70 degrees north, a self-administered questionnaire was filled in by 3736 inhabitants, 60.8% of the total population between 18 and 69 years. Three questions concerned depression, sleeping problems and other problems related to the two contrasting seasons with regard to daylight.
  
  
  RESULTS
  Twenty-seven per cent reported to have some kind of problem in the dark period. Most frequently reported were sleeping problems during winter, in 19.9% of women and 11.2% of men. Self-reported depression in winter was found in 11.1% of women and 4.8%% of men. Sleeping problems increased with age, while depression was most often reported by middle-aged people. The only other reported problem in winter was fatigue. The adjusted relative risk (RR) for winter depression in women compared to men was 2.5 (95% confidence interval: 1.9-3.2). Very few had problems in summer.
  
  
  CONCLUSIONS
  In the high north, one-third of the women and one-fifth of the men experience problems with sleep, mood or energy related to season. The prevalence of self-reported depression was surprisingly low in winter considering the lack of daylight.
authors.affiliation: Institute of Community Medicine, University of Tromsø, Norway.
authors.forename: V
authors.initials: V
authors.lastname: Hansen
authors.forename: E
authors.initials: E
authors.lastname: Lund
authors.forename: T
authors.initials: T
authors.lastname: Smith-Sivertsen
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D016001:Confidence Intervals; D003430:Cross-Sectional Studies; D003863:Depression / Q000453:epidemiology; D005260:Female; D006306:Health Surveys; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D017440:Photoperiod; D015995:Prevalence; D012306:Risk; D012426:Russia / Q000453:epidemiology; D016574:Seasonal Affective Disorder / Q000453:epidemiology*; D012621:Seasons; D017678:Sex Distribution; D012893:Sleep Wake Disorders / Q000453:epidemiology*