Seasonal affective disorder (SAD) is a form of severe depression that occurs in autumn and winter. Two of the most popular forms of therapy for it are cognitive behaviour therapy (CBT) and light therapy in which sufferers sit in front of a light box that produces an artificial version of sunlight. Kelly Rohan from the University of Vermont looked into the long-term effectiveness of these treatments comparing those treated with light therapy, those treated with CBT, those treated with a combination of the two techniques and people on a waiting list for treatment. Rohan's study looked into how people were doing a year after their treatment. She found that the combination group did best with only 5.5% having a recurrence of their depression. 7% of those treated with CBT suffered a recurrence compared to 36.7% of those treated with light therapy. The recurrence of depression was also less severe in those with CBT than in the other groups. Previous studies have shown that light therapy is very effective so it is not so much that it does not work, rather that, left to their own devices, people find it hard to make time for a daily, half-hour session in front of a light box.
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