For people suffering from Seasonal Affective Disorder, the shortest day of the year may offer hope that the worst is over.

Seasonal Affective Disorder, or SAD, is a mood disorder generally associated with the decrease of daylight in late fall and winter. (There's a rare variant in which people become depressed in the summer.) Symptoms include common features of depression, such as lethargy, lack of interest in normal activities and social withdrawal. Other signs are oversleeping, a craving for sugary and/ or starchy foods and weight gain.

An estimated 10 million Americans, mostly women, suffer from SAD; another 25 million or so have a less-intense form commonly called "winter blues."

The cause of SAD is not clear, says Dr. Marshall Thomas, a psychiatrist at the University of Colorado Hospital in Denver. But it appears to be linked to melatonin, a hormone secreted by the pineal gland in the brain; melatonin, which helps regulate the body's internal clock and may cause symptoms of depression, is produced at increased levels in the dark.

The cure for these dark days is simple: light. Bright fluorescent light, most commonly provided by a device called a light box, can ease SAD. In some cases, antidepressants also are used to treat the condition.

Some basic measures can help people chase away the milder winter blues, Marshall says - "paying attention to getting exercise and activity, trying to get outside when the sun is shining, trying to make sure they're getting enough light in their home or their office."

Don't self-diagnose. If you think your depression is severe enough that you might benefit from a light box, first see your doctor or a mental-health professional, Marshall advises.

For more information: the Depressive and Manic-Depressive Association Consumer Resource Center at St. Francis Health Center, 477-1515; www.nosad.org, Web site of the National Organization for Seasonal Affective Disorder; and the National Alliance for the

　　From Nami.org