Some reports show that the use of light therapy in advance of the development of winter symptoms is effective. The duration of light therapy sessions depends on the intensity of the light reaching the eyes. In the early 1980' s, treatment consisted of two to three hours of exposure to two thousand five hundred lux. More recently it was found that thirty minutes exposure to ten thousand lux was equally effective, and less disruptive for many patients. Light therapy has now become an accepted form of therapy, and a new ingredient of daily routine for those who find relief from the symptoms.
Treatment is safe.
There have been a few reports of patients temporarily developing a mild form of manic behaviour as a result of light therapy, and some incidence of headaches, but these have disappeared after readjustment of the therapy schedule. No deleterious effects on the eyes have been reported. Some do not find relief, and in their case, SAD may be superimposed on other psychological problems, or the diagnosis of SAD may not be appropriate. Attention should be given to the quality of the light used in light therapy. The illuminated area should be large so as to avoid uncomfortable glare, and the presence of ultraviolet rays should be minimised by careful choice of the light source and by the use of filters.