The Danger of Long Days

Researchers puzzle over increase of suicides in spring and summer. A new study examined suicide rates over a 10-year period and found a link between the length of the day and the number of suicides.

By Colin Allen, published on April 01, 2003

Even though the "winter blues" may disappear with warmer weather, suicide rates peak during the spring and summer months. A new study examined suicide rates over a 10-year period in Victoria, Australia and found a link between the length of the day and the number of suicides.

Other weather conditions, such as temperature and rainfall, were not linked to a change in the rate of suicides, according to Gavin Lambert, Ph.D., author of the study and colleagues at the Baker Heart Research Institute in Melbourne, Australia. But the reason for the season-suicide connection remains unclear. The study was published in this April's American Journal of Psychiatry.

Lambert suggests a chemical component in the relationship. Other studies have shown that sunlight increases levels of the neurotransmitter serotonin, a chemical implicated in many processes of the body, including sleep, pain and mood disorders. And a lack of serotonin has been linked to increased suicide rates.

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The results of the study are at odds with earlier findings. Lambert surmises that the serotonin-suicide relationship may be more complex than once thought. As a suggestion, he offers that a change in season--thus serotonin levels-- could put a suicidal person at risk until their mind adjusts to the new chemical balance.

Social factors are also important. Rhoda Olkin, Ph.D., a professor of clinical psychology at the California School of Professional Psychology, says the increased social activities of summer may make non-active people feel more isolated--and at greater risk of hurting themselves.