Sunshine can act as 'driver' for suicide

These are the findings of a recent study led by Matthäus Willeit and Nestor Kapusta from the University Department of Psychiatry and Psychotherapy and the University Department of Psychotherapy and Psychoanalysis at the MedUni Vienna which, to mark World Suicide Prevention Day on 10th September, has now been published in the journal JAMA.

By analysing suicide data in Austria between January 1970 and May 2010, the scientists were able to use mathematical models to determine that the daily amount of sunshine had a link to the likelihood of suicide, and in fact sunshine acts as a "driver," especially in the days immediately before the actual suicide. The study correlated data on almost 70,000 suicides and meteorological data gathered from 86 measuring stations in Austria between 1970 and 2010. To exclude the influence of other seasonal rhythms on the results -- such as seasonal changes in employment levels -- the seasonality factor was removed mathematically from the data so that only the influence of sunlight was measured on the frequency of suicides.

"Between the 14th and 60th day of a fine weather phase, the effect of the sun was clearly positive, there were fewer suicides and the sun almost provides protection against it," explains Willeit. "Our figures, however, highlight the theory that sunshine should be regarded as a driver on the day of the suicide itself and also in the 10 to 14 days before it."

The more immediately after a period of little light the sunshine affects the human mind, the more at-risk vulnerable people are. Says Willeit: "During the first few days, a lot of sunshine leads to increased levels of activity in general. For people with depression, this can produce an increase in drive, inner unrest and increased impulsiveness and subsequently lead to suicidal thoughts being put into action." This is also highlighted by the fact that in Austria, but also in most other countries, most suicides are committed in spring. "Research into the relationship with the seasons provides insight into the biological control mechanisms that we research in great detail in our department," says Head of the University Department of Psychiatry and Psychotherapy at the MedUni Vienna, Siegfried Kasper. Says Willeit: "And the further north you go, the most marked this effect is."

Overall, suicide is reassuringly a relatively rare event among the general population. People who have several known risk factors for suicide -- such as psychiatric illness, substance abuse, life crises or attempted suicides in the past -- will need increased psychiatric and psychotherapeutic support in times of rapidly-increasing daylight, i.e. generally in the spring and early summer.