Subject:
Suicide

Short Description:

Sunshine Linked to Suicide Rates

Background:

Sunshine and other forms of bright light are considered to be helpful for depressed patients. Patients with seasonal affective disorder (SAD) feel better as the days lengthen, and bright light therapy is effective for the depression in patients with and without SAD. However, seasonal studies of suicide have found that the prevalence is highest in the spring, which is counterintuitive if we consider light to be an antidepressant. A new study out of Austria clarifies this seasonal finding by separating out the effects of sunshine per se versus seasonality. The results are a bit perplexing.

Researchers analyzed retrospective data on all officially confirmed suicides in Austria for a 40-year period (nearly 70,000 deaths from 1970 to 2010). They then looked at data derived from meteorological stations on the average duration of sunshine per day in hours. Finally, they used mathematical techniques to separate the effect of sunshine exposure from the season.

On each day studied, independent of season, researchers found that the hours of sunshine and the number of suicides were highly correlated. They found a positive correlation between sunshine and suicide that held not only on the day of the suicide but also 10 days prior to the event. Conversely, they found a negative correlation between the number of suicides and the daily hours of sunshine for the 14 to 60 days prior to the suicide, suggesting more daily sunshine over a prolonged period may protect against suicide. This protective effect was more pronounced in men than women.

The implications are that brief exposure to sunshine may increase the risk of suicide, especially in female patients. Why this might happen is unclear. The authors hypothesize that brief sunlight might energize depressed patients before significantly improving mood, and that this could increase their motivation to do something about their condition, no matter how drastic.

Researchers said more study is needed to determine which patients with depression are most susceptible to the effects of sunshine (Vyssoki B et al, JAMA Psychiatry 2014; Epub ahead of print).

TCPR’s Take: There were some limitations to this study—for example, it did not account for other climatic factors (such as temperature, humidity, and air pressure) that vary along with the amount of sunshine to a certain degree. While the findings may represent a statistical anomaly and need to be replicated, you might consider more closely monitoring your suicidal patients, especially women, when the weather takes a sudden turn toward sunny days.