Summer light can increase risk of suicide

A study from Karolinska Institutet shows that the number of suicides on Greenland increases sharply during the bright summer months. Too little sleep and chemical imbalance could explain the phenomenon.

The study, which was led by Karin Sparring Björkstén at the Department of Neurobiology, Care Sciences and Society, was conducted on Greenland, where variations in sunlight are extreme over the year. What they found was that 82 per cent of the suicides committed in northern Greenland between 1968 and 2002 were during the constantly light part of the year, reaching a peak in June. Almost all the suicides were unplanned and carried out with violent means, such as shooting or hanging.

According to the researchers, the results suggest that surplus light can increase the risk of suicide, probably by disrupting sleep patterns and brain chemistry. They also examined the possible effects of depression and alcohol consumption, but found no observable correlation with the suicides committed during the summer.