OBJECTIVE: Winter worsening of mood and eating symptoms, similar to that of seasonal affective disorder, has recently been reported in patients with bulimia nervosa. To assess the effectiveness of light therapy for treatment of bulimia nervosa, the authors conducted a study of light therapy during winter comparing an active (bright white light) condition to a control (dim red light) condition in bulimic patients who were not selected for a seasonal pattern of bulimia. METHOD: After a 2-week baseline assessment, 17 female patients with a DSM-III-R diagnosis of bulimia nervosa underwent early morning light treatment with 2 weeks of bright white light exposure (10,000 lux for 30 min/day) and 2 weeks of dim red light exposure (500 lux for 30 min/day) in a counterbalanced, crossover design. Outcome measures included daily binge/purge diaries, objective and subjective measures of mood, and the Eating Attitudes Test. Expectation of response for each condition was also assessed before treatment. RESULTS: Although pretreatment expectation ratings were similar for each condition, the bright white light condition was superior to the dim red light condition for all mood and eating outcome measures. Patients with "seasonal" bulimia (N = 7) had significantly greater improvement after the bright white light treatment than patients with nonseasonal bulimia (N = 10). No significant order effects were noted, nor differential effects for patients taking concurrent antidepressant medications (N = 4). CONCLUSIONS: These data suggest that bright white light therapy is an effective short-term treatment for both mood and eating disturbances associated with bulimia nervosa, although the therapeutic effect may be greater in those patients with a seasonal pattern.Abstract Teaser