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Sunshine and Suicide

Sunshine affects suicide risk in unexpected ways.

There’s a bit of a saying amongst psychiatrists that any modestly effective antidepressant can make some vulnerable people manic. That’s true for prescription antidepressants (and a well-known risk of taking them) but also for certain effective supplements such as SAM-E (1). It’s also true for nature’s own antidepressants, including sunshine (2) and acute sleep deprivation (3). 

Mania, a symptom of bipolar disorder where someone is extremely euphoric or agitated, impulsive, often reckless, and doesn’t need sleep, is an unusual and dramatic risk of antidepressants (meds, supplements, sunshine). However, even in folks who don’t have bipolar disorder, antidepressants (again, both the prescription variety and the natural ones) can make someone acutely agitated, irritable, and anxious. Psychiatrists are trained to watch very carefully over people in the first few days of antidepressant treatment, and this effect was known in the old-fashioned tricyclic antidepressants and became famously “black-boxed” into a warning on use of SSRIs in young people. The main worry here is that someone who is deeply depressed and suicidal will get a bit of energy along with irritability from treatment, yet the suicidal thoughts haven’t left, increasing risk of suicide attempts in the early days of treatment.

So if that risk of suicide is a worry known to psychiatrists who use medications, what about the effect of sunshine on suicide? Will a bright sunny day make it more or less likely for someone to end his or her life? A recent study in JAMA Psychiatry tries to shed some light on that exact question. 

First off, some of you may be shaking your heads at the idea of sunshine as an antidepressant. However, sunshine has direct effects on mood via the optic nerve and hypothalamus of the brain. Light therapy, for example, uses very bright white light as a substitute for sunshine and is also an effective antidepressant (that can also cause mania). Most of us would take that information and come to the conclusion that bright sunny days will therefore decrease the risk of suicide.

However, it’s not so simple. While many people think that mood problems likely peak midwinter, most psychiatrists and therapists will tell you their phones ring off the hook during the springtime, and the second hardest time for people seems to be during the fall. It’s the rapid change in amount of light, especially at more extreme latitudes, that seems to affect agitation and irritability more so than the absolute amount of light.

In the JAMA Psychiatry study, the researchers compared number of completed suicides on any given day in Austria with amount of sunlight for a 40 year period from 1970-2010 (71.8% of those suicides were male!).  What they found was a slight increase in suicides on a bright sunny day and for ten days after, however, a long period of sunny days (14-60 days) was protective against suicides. They managed to statistically remove the effect of seasonal variance on suicide (which tend to, not surprisingly, peak in the spring) and found the absolute, direct effect of sunlight on risk of suicide was preserved.

Biologically, low serotonin levels in the cerebrospinal fluid are known to correlate with suicide, irritability, and violence (though not, as it is commonly assumed, with depression). Sunshine has direct and immediate effect on serotonin transporter binding (4) which in turn directly effects the concentration of serotonin in the synapse. These changing levels with the first few sunny days (or the first few darker ones, in the fall) may be the most difficult for the brain to manage, leading to perturbations in behavior and irritability. 

What is the takeaway? It’s not to keep suicidal people in the dark. We should recognize that sunshine is an antidepressant with the associated risks and benefits. Most folks are (fortunately) not suicidal, but this finding might explain why you are agitated rather than gloriously happy those first few sunny days. For those deeply depressed, suicidal folks, intensive treatment and close observation is a must. Multiple factors play into suicide risk, and suicides can be prevented if interventions are done at the right time and place. Any antidepressant (including sunshine and light therapy) can cause a short-term irritability prior to a longer-term stabilization and improvement in those who respond.

Please see Climate and Suicide for a follow up to this post.

Image credit (flickr creative commons)

Image credit (flickr creative commons)

Copyright Emily Deans, MD