Some people call them the winter blues. Others might think they're depressed simply because of holiday stress. In fact, what all of them may be suffering from is seasonal affective disorder, or SAD, a very real malady with symptoms that occur from October through March and go into remission during spring and summer.

"Typical patients with SAD come in to see me during the winter months. They're doing more eating, more sleeping, more staying in bed. They're depressed," said Dr. Syed Anwar, a psychiatrist at St. Joseph Hospital in Elgin. "If somebody's a little down for a day or two, that's not a major problem. But it's a problem when it's more severe, when you can't concentrate, when you can't function. That's when you need to seek help."

According to researchers at the National Institute of Mental Health in Bethesda, Md., millions of Americans experience this disorder. They estimate that 6 percent of people in the United States suffer from SAD and that another 14 percent have a milder form of the disorder called winter blues.