Suicide linked to... too much summer sunlight?

In a curious twist on the old axiom that the prolonged dark periods of northern hemisphere winters lead to depression, a new study indicates that suicide rates in Greenland are exacerbated by too much sunlight in the summer.

Karin Sparring Björkstén from the Karolinska Institutet, Sweden, led a team of researchers who studied the seasonal variation of suicides in all of Greenland from 1968-2002. They found that there was a concentration of suicides in the summer months, and that this seasonal effect was especially pronounced in the North of the country – an area where the sun doesn't set between the end of April and the end of August.

Björkstén said, "In terms of seasonal light variation, Greenland is the most extreme human habitat. Greenland also has one of the highest suicide rates in the world. We found that suicides were almost exclusively violent and increased during periods of constant day. In the north of the country, 82% of the suicides occurred during the daylight months (including astronomical twilight)"...

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