Predicting Effectiveness of Light Treatment for Winter Seasonal Affective Disorder

Inclusion Criteria: * Current major depressive disorder, by structured diagnostic interview (SCID), or current bipolar II disorder, if no prior history of rapid cycling, by SCID * Prior history of major depressive disorder or bipolar II disorder with seasonal specifier, by SCID * Score of 21 or greater on Hamilton Rating Scale for Depression - Seasonal Affective Disorder Version (SIGH-SAD), met at three time points (informed consent session, 24 hours prior to first light therapy session, and at first light therapy session) Exclusion Criteria: * Current bipolar I disorder, psychotic disorder, or cognitive disorder, by SCID * Illicit drug use in the past year, by self-report, or alcohol abuse by SCID * History of systemic lupus erythematosus * History of heart attack or stroke * No antidepressant, mood stabilizer, or antipsychotic medication treatment 30 days before treatment * Current occupation involves shift work * Current sensitivity to bright light or vision problems not correctable by glasses, by self-report * Inability to distinguish colors or see stars at night because of increased light sensitivity, by self-report * Current suicidal ideation, by self-report during SCID interview * Women of childbearing potential who are pregnant, nursing, or trying to become pregnant. Female participants of childbearing potential must agree to one of the following types of birth control: oral, transdermal, or implantable hormonal contraceptives; intrauterine device; diaphragm plus s…