Lower rates of suicide are associated with more daily sunshine in the 14 to 60 days prior to the suicide event, researchers said.
Light interacts with brain serotonin systems and possibly influences serotonin-related behaviours, such as mood and impulsiveness, which can play a role in suicide, according to research author Benjamin Vyssoki, of the Medical University of Vienna, Austria, and colleagues.
The authors examined the relationship between suicide and the duration of sunshine after mathematically removing seasonal variations in sunshine and suicide numbers.
There was a positive correlation between the number of suicides and hours of daily sunshine on the day of the suicide and up to 10 days before that seemed to facilitate suicide, while sunshine 14 to 60 days prior appeared to have a negative correlation and was associated with reduced suicides.
The correlation between daily sunshine hours and suicide rates was seen largely among women, while negative correlations between the two were mainly found among men.