, or SAD, is a common problem of people living in northern United States. People who are affected by this disorder commonly suffer from depression, lethargy, inability to concentrate, overeating and weight gain. People from the north tend to suffer more from this disorder because of the shortened days. It appears, that due to the deficiency of sunlight some people suffer from these symptoms. The shortened days have a hormonal effect on the body that causes these symptoms, and the use of artificial sunlight is the best way to relieve the d ....