Light therapy is the use of a high-intensity fluorescent lamp (usually 10,000 lux) to treat certain types of depression that occur during the fall and winter months (seasonal affective disorder). These lamps are usually available in health food or lighting fixture stores.
Lamps used for light therapy are about 10 to 20 times as bright as ordinary indoor lighting. A person sits in front of the light for at least 30 minutes a day. Some people sit in the light for as long as 2 hours. A person can usually read, use a computer, or do other types of desk work while sitting in front of the light.
WebMD Medical Reference from Healthwise