Health Discovery: Wintertime Blues

Do you feel low in the cold, dark days of winter? New research explains why. Many healthy people have seasonal affective disorder (SAD); they feel depressed and fatigued only in wintertime. Now, Canadian scientists have concluded that SAD is a physiological problem, not a psychological one.

Researchers at the University of Toronto Centre for Addiction and Mental Health analyzed brain scans done on 88 healthy volunteers from 1999 to 2003. They found that levels of serotonin, a mood-adjusting chemical in the brain, were lower in autumn and winter than in spring and summer. Because sunlight regulates a protein controlling serotonin levels, a lack of sunshine means less of the feel-good substance.

Jeffrey Meyer, M.D., coauthor of the study, which was reported in September’s Archives of General Psychiatry, said in a statement that identifying the cause may ultimately help “prevent the illness itself.”

Roberta Yared is senior editorial researcher at the AARP Bulletin.