Lighten Up; October 2005; Scientific American Mind; by Ulrich Kraft; 8 Page(s)

Autumn. Mornings are dark. Dusk comes dishearteningly early. You are feeling more tired, melancholy. The rapidly disappearing daylight seems almost to drag away part of your spirit with it. Should this dip in humor worry you? Not really--you'll adjust. Unless you are prone to seasonal affective disorder. For the several million Americans who succumb, the darker half of the year brings a heavy veil of sadness. They become depressed, listless, chronically fatigued, and their mood does not rebound until March, when the daylight extends to early evening.

In general, the farther north one lives on the globe the more common seasonal depression becomes. Below the 30th parallel, which links Jacksonville, Fla., to Houston and the Baja Peninsula south of San Diego, the winter blues are virtually unknown. In sunny Florida, just 1 percent of the population suffers from seasonal affective disorder, appropriately known as SAD, but in New York State the rate is 5 percent. In Alaska, one out of every 10 residents experiences winter mood problems.