How Does the Sun Shine on Risk for Suicide?

Suicidal behavior is influenced by both seasonal variations in available daylight and other factors. To differentiate between these effects, investigators examined data on all 69,462 confirmed suicides that took place in Austria during a 40-year period and calculated the amount (i.e., hours) of sunshine per day from meteorological data. The researchers used a complex statistical technique to control for seasonal effects.

Duration of sunshine up to 10 days prior to death correlated positively with suicide risk, whereas duration of sunshine in the 14 to 60 days preceding death correlated negatively with risk. These correlations held for all forms of suicide. Positive correlations between daily sunshine duration and suicide risk shortly before …