I think I may have seasonal affective disorder. What is SAD and what can I do about it?

E.K.,Winchester

Seasonal affective disorder, or SAD, also known as winter depression, is a problem all too familiar to New Englanders and others who live in northern latitudes. SAD is "not just feeling bummed out because it's winter," said Janis Anderson, director of the seasonal affective disorder service at Brigham and Women's Hospital. It includes physical changes such as trouble getting up in the morning, lack of energy, gaining weight and problems concentrating for weeks or months at a time. Symptoms typically start in the fall and lift in the spring.

SAD is actually a bad name for this common disorder, which to a mild or moderate degree affects 25 percent of people living at latitudes like that of New England and strikes 5 percent so badly they meet the criteria for major depression. A better name would be "light deprivation disorder," said Dr. Dan Oren, a SAD specialist and psychiatrist at Yale University.

The most effective treatment is to restore this bright light, either by getting outside or by sitting in front of a light box for 30 to 90 minutes a day, preferably in the morning. Antidepressants like Prozac also have been shown to be effective against SAD.

But consumer, beware: Not all light boxes sold on the Internet are safe or effective because some wave lengths, especially those used for tanning, can damage eyes, said Anderson said.

For information on SAD and light boxes, visit www.sunboxco.com, www.cet.org/cet2000 (the Center for Environmental Therapeutics) or www.sltbr.org (the Society for Light Treatment and Biological Rhythms).

Be sure to get a light box with fluorescent bulbs that provide 10,000 lux (a measure of intensity). The boxes can cost around $400, but most insurers now pick up the tab.

JUDY FOREMAN