Bright light treatment is effective in the treatment of seasonal affective disorder. It also responds to SSRIs. Seasonal affective disorder is a depressive disorder in which patients experience depressive episodes, which begin in fall or winter and remit in spring. It is more common in higher latitudes and among younger people, paicularly in females. It is characterized clinically by hypersomnia, anergia, and a craving for sweets. Ref: Current Diagnosis & Treatment: Psychiatry, 2e chapter 18; Kaplan & Sadock's Comprehensive Textbook of Psychiatry, 9th edition, page 3671 - 6.