Scientists have found a link between sunlight and suicide rates — but not in the way you’d expect.
As summer winds down, concern turns to seasonal affective disorder, in which too little sun can bring on depression. But the data shows that it’s in springtime, as days get longer again and sunshine returns, that the suicide rate peaks.
Studies on seasonal variations among suicides have been done for centuries, but the actual effect of sunshine has been unclear because, along with changes in sunlight, new seasons bring temperature changes and other factors that may influence suicide risk, such as holidays.
Three decades of data
The team of scientists led by Dr. Matthaeus Willeit from the University of Vienna took a closer look at the role of sunshine by using information on 69,462 suicides that occurred in Austria between January 1970 and May 2010. That information was then matched to data collected from 86 weather stations that recorded the hours of sunshine per day.
What happenson sunny days
Willeit’s team discovered a correlation: Suicide risk went up with the amount of sunshine over the previous 10 days. However, it also decreased with increasing sun exposure between 14 to 60 days earlier. Sunlight, they suggest, may increase the risk of suicide over a short period but actually protect against it over a longer period of time.
Lower impulse control
“Light has an influence on serotonin, and serotonin has an influence on mood and suicidality,” Willeit says. Antidepressants that boost the body’s levels of serotonin have been known to affect impulsivity first, then mood later on. That early effect on impulsivity may explain the increased suicide risk over a short period of time, and the delayed effect on mood may explain the lower risk over a longer time span.
Don’t avoid the sun
People shouldn’t keep out of the sun based on the study’s findings, says Willeit. Instead, doctors should consider adding sunshine to the list of factors that may influence the risk of suicide. “Suicide is complicated and has many risk factors. People always tend to think of it in either biological or social terms, but there is no single cause. It’s a bunch of risk factors that you have.”