title: Seasonal variation in specific methods of suicide: a national register study of 20,234 Finnish people.
abstract: BACKGROUND
  Previous studies have suggested differences in seasonal variation of violent and non-violent suicides, but seasonal distribution of the specific methods of suicide is less clear.
  
  
  METHODS
  We investigated the seasonal distribution of the specific suicide methods for both genders during a 16-year period. The seasonal effect was explored by monthly ratio statistics from the large population-based data including all suicides in Finland during years 1980-1995 (n=20,234).
  
  
  RESULTS
  Hanging peaked in spring among both genders. In summer, the significant peaks were occurred in suicides by drowning, jumping and gassing among males. The bimodality in female suicides with autumn peaks was explained by poisoning and drowning. Traffic suicides showed substantial winter-troughs for both genders.
  
  
  CONCLUSIONS
  The results suggested that specific violent and nonviolent methods of suicides grouped into their traditional clusters on the basis of their seasonality, except suicides by gassing and shooting. The seasonal distribution in specific suicide methods should take into account in suicide prevention at clinical work and also it should be considered while determining which methods of suicides are regarded as violent or non-violent methods in research.
authors.affiliation: Department of Psychiatry, University of Oulu, Peltolantie 5, FIN-90220 Oulu, Finland. pirkko.rasanen@oulu.fi
authors.forename: Pirkko
authors.initials: P
authors.lastname: Räsänen
authors.forename: Helinä
authors.initials: H
authors.lastname: Hakko
authors.forename: Jari
authors.initials: J
authors.lastname: Jokelainen
authors.forename: Jari
authors.initials: J
authors.lastname: Tiihonen
mesh_terms: D002423:Cause of Death; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008297:Male; D012042:Registries; D012307:Risk Factors; D012621:Seasons; D012737:Sex Factors; D013405:Suicide / Q000706:statistics & numerical data*; D014754:Violence / Q000523:psychology*