A new study published this week in JAMA Psychiatry and quickly picked up by both Time and Newsweek delivers a simple message in its title: “Direct Effect of Sunshine on Suicide.” It’s an important study revealing, once again, the powerful role that light plays in our lives.

Sunshine does indeed appear to have a direct effect on suicide. Days with more sunshine increase suicidal behavior in the short run and protect against suicide in the long run. How can that be?

Psychiatrists have known for a very long time that spring is the season with the highest rate of suicide. It’s a fact that may come as a surprise to many SAD sufferers. So many things change with the seasons, not only in nature but in our social lives too. The spring rise in suicide rates might have nothing at all to do with increased sunlight.

That’s the question a group of researchers at the Medical University of Vienna set out to answer. Looking at 40 years of data, they first subtracted out the seasonal variations in light (their math is too complicated for our blog) and then examined the relationship between suicide and the amount of daily sunshine – independent of seasonal changes. What they found was a small but significant increase in the number of suicides on days that had more hours of sunshine. And a day that had increased sunshine during the prior 10 days also carried an increased risk of suicide. Conversely, they found that more hours of sunshine during the prior 14 to 60 days actually decreased the number of suicides. Getting more light regularly seems protective. It’s the shift to more light that seems risky.

That makes sense. It’s something we already know about all antidepressant medications. When a severely depressed person begins to get better from medication, energy and motivation can sometimes increase before mood improves. That means he or she may shift from thinking about suicide to taking action on those thoughts. In fact, the study found the increase was entirely in violent not “nonviolent” suicides (for example, overdoses.)

Sunshine, like antidepressant medication, is “activating.” Sunshine, like most antidepressant medications, has powerful effects on the serotonergic systems in our brain. Those effects on serotonin, the study’s authors suggest, are most likely the cause of the connection between sunshine and suicide. Serotonergic medications like Prozac carry “Black Box Warnings” about suicide risk and the need for close observation and communication. Light is also powerful medicine and, in severe depression, should carry the same warnings.

Bottom line: if you are seriously depressed or thinking about suicide, treatment with bright light, medication, or psychotherapy can help. It can even be life-saving. But it is not a do-it-yourself treatment. Psychotherapy always requires another person and you can’t get antidepressant medication without a prescription from a doctor or nurse practitioner. Bright light and sunshine is there to use on your own. But if you’re seriously depressed, you shouldn’t be on your own.