Household light bulbs are not bright enough to effectively combat Seasonal Affective Disorder (SAD). The intensity of a bright day in the summer can be as much as 100,000 lux and the minimum dose needed to treat SAD is 2500 lux, whereas the average lighting in your home or office only emits an intensity of 200~500 lux. During the winter light therapy should be used daily, beginning at the onset of autumn when the first symptoms appear.
Light therapy consists of sitting close to a specially designed lamp or lightbox allowing the bright light to shine directly through the eyes. While using the light box you do not need to stare directly at the light and can carry out normal activities including reading, working, eating and watching TV while stationary in front of the box. Treatment is usually effective within three or four days and while it is used every day the positive effect continues. While the minimum dose needed to treat SAD is 2500 lux, some light boxes emit up to 10,000 lux which can cut treatment time down to half an hour a day.