Biological Cause for Winter Blues

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Biological Cause for Winter Blues

Jan. 2, 2002 (Ivanhoe Newswire) - There may be a biological explanation for

people who suffer from depression during the winter, according to a recent

study.

Seasonal Affective Disorder is a common ailment resulting in depression during

the winter. Symptoms often include weight gain, increased sleep and decreased

activity. People with SAD often respond to treatment with bright light

Researchers with the National Institute of Mental Health have found individuals

with SAD produced more melatonin during the winter than during the summer.

Healthy patients had no seasonal change in melatonin levels, leading researchers

to believe melatonin production is a biological signal of seasonal change in SAD

patients. Melatonin is a hormone secreted in the brain that regulates the body's

internal clock.

The study measured 110 participants, 55 with SAD and 55 volunteers without the

condition, for melatonin levels during both the summer and winter. Patients with

SAD produced melatonin for an average of 9 hours during the winter but only 8.4

hours during the summer. The control group had no seasonal change in melatonin

levels.

This is the first study to demonstrate that humans, much like other mammals,

generate a biological signal of changing seasons.

SOURCE: Archives of General Psychiatry, 2001;58:1108-1114