title: Is there a negative impact of winter on mental distress and sleeping problems in the subarctic: the Tromsø Study.
abstract: BACKGROUND
  Prior studies have suggested that the darkness of winter impacts the level of mental distress and sleeping problems. Our study investigated whether people living in the sub-arctic had more sleeping problems or mental distress during winter.
  
  
  METHODS
  The cross sectional population Tromsø Study was conducted in Tromsø, North Norway, at 69.4 degrees North and above the Arctic Circle. The study included entire birth cohorts and random samples of the population aged 30 to 87 years. Data was collected continuously from 1 October 2007 to the end of December 2008 except July. 8951 persons completed questionnaires including the HSCL-10 and the MCTQ.
  
  
  RESULTS
  There were no significant differences in the reporting of current mental distress depending on season. Significantly more reported current sleeping problems in winter than in the other seasons, and less sleeping problems was found in spring.
  
  
  CONCLUSIONS
  In this sub-arctic population, insomnia was most prevalent in winter, but there were no significant seasonal differences in mental distress. Although some people in the sub-arctic clearly are mentally negatively affected by the darkness of winter, the negative impact of winter on mental distress for the adult population is not conclusive.
authors.affiliation: Department of Clinical Medicine, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway. maytrude@online.no
authors.forename: May Trude
authors.initials: MT
authors.lastname: Johnsen
authors.forename: Rolf
authors.initials: R
authors.lastname: Wynn
authors.forename: Trond
authors.initials: T
authors.lastname: Bratlid
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001110:Arctic Regions; D003624:Darkness; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D009664:Norway / Q000453:epidemiology; D015995:Prevalence; D012621:Seasons; D007319:Sleep Initiation and Maintenance Disorders / Q000453:epidemiology*; D013315:Stress, Psychological / Q000453:epidemiology*