A unique monthly distribution of suicide and parasuicide through firearms among Israeli soldiers.

The monthly distribution of completed suicide and parasuicide by Israeli soldiers was analyzed during the 7-year period of 1984-1990. Although parasuicide in general showed a constant incidence throughout the year, the monthly rate of suicide as well as parasuicide through firearms varied during the year in a similar way. The seasonal pattern of completed suicides, the vast majority of which occur with firearms, was correlated with the seasonal pattern of parasuicides through firearms. The combined variability of the two seasonal patterns was found to be significantly different from a pattern of a constant monthly incidence with a peak in December and a nadir in October. The monthly incidence of suicide and parasuicide through firearms was found to be negatively correlated with the duration of the daily photoperiod, when the latter was phase-advanced by 1-2 months. This unique pattern of seasonal incidence of suicide and parasuicide through firearms is different from most of the patterns reported in the Northern Hemisphere.