Some people feel sad or depressed during the winter months in northern areas of the world. They may have trouble eating or sleeping. They suffer (1) a condition known as Seasonal Affective Disorder, or SAD. (2) of SAD (3) its effects during the short, dark days of (4) . The problems are most (5) in the months when there are fewer hours of daylight. When spring arrives, these signs (6) and SAD victims feel (7) again. The National Mental Health Association reports that SAD can (8) anyone. The group says young people and women are (9) the highest risk for the disorder. It says that an estimated twenty-five percent of the American population suffers from some form of SAD. About five percent suffer from a severe form of the (10) . (11) , many people in other parts of the world also have the condition. To treat the disorder, victims of SAD do not need to wait until (12) . Experts know that (13) affected individuals (14) bright light each day (15) the condition. (16) , there are other things people can do to ease the problem. They can (17) the sunlight in their homes and workplaces. They can spend (18) time outdoors in the fresh air during the day. One study found that walking for an hour in winter sunlight was as (19) as spending two-and-one-half hours in (20) light indoors.