Too much sunlight may trigger suicide risk

Details of the study
The novel study led by researchers at the Karolinska Institute in Sweden has linked the exposure to constant daylight to a hike in suicides.

The Swedish researchers say this summer-suicide hike in places like Greenland could be due to insomnia caused by the incessant sunlight of long summer days.

To reach their findings, Karin Sparring Bjorksten of the Karolinska Institute in Sweden and colleagues looked at the suicide rates of people living in Greenland, where the sun shines 24 hours in the summer, and barely shines at all in the winter. The team also examined the seasonal variation of suicides in this entire region from 1968 to 2002.

“In terms of seasonal light variation, Greenland is the most extreme human habitat,” Bjorksten said. "We found that suicides were almost exclusively violent and increased during periods of constant day."

Bjorksten and team noted that the number of suicides increased between the end of April and the end of August, mostly occurring in Northern Greenland and involving mostly young men.

She said, "In the north of the country, 82% of the suicides occurred during the daylight months."

After studying the records of 1,351 deaths due to suicide, the team found that most of the suicides were committed by young men and were notably violent in nature. To be precise, 80 percent of the suicide victims were men and about 95 percent of the suicides could be termed as violent, where the victims took their lives by shooting themselves, hanging themselves, or jumping.

Cause behind the summer-suicide trend
Researchers speculate that prolonged daylight triggers insomnia and imbalances in serotonin, a brain chemical that plays crucial role in the central nervous system.

"People live their lives differently during the Arctic summer. Farmers plough their fields in the middle of the night, and children are out playing after midnight. They lose their daily rhythm," Bjorksten said.

This imbalance of serotonin may lead to impulsive behavior that, when combined with sleep deprivation, can stimulate people to commit suicide.

"People living at high latitudes need extreme flexibility in light adaptation. During the long periods of constant light, it is crucial to keep some circadian rhythm to get enough sleep and sustain mental health. A weak serotonin system may cause difficulties in adaptation," Bjorksten said.

"Light is just one of the many factors in the complex tragedy of suicide, but this study shows that there is a possible relationship between the two,” she concluded.

Bjorksten and colleagues reported their study in the BioMed Central journal BMC Psychiatry.

Suicide, attempted suicide, and thoughts of committing suicide are the growing problems among the adolescents worldwide. The World Health Organization estimates that 877,000 people worldwide end their lives each year.