Light therapy for seasonal affective disorder in primary care: Randomised controlled trial

Studies of light therapy have not been conducted previously in primary care. To evaluate light therapy in primary care. Fifty-seven participants with seasonal affective disorder were randomly allocated to 4 weeks of bright white or dim red light. Baseline expectations for treatment were assessed. Outcome was assessed with the Structured Interview Guide for the Hamilton Depression Scale, Seasonal Affective Disorder Version. Both groups showed decreases in symptom scores of more than 40%. There were no differences in proportions of responders in either group, regardless of the remission criteria applied, with around 60% (74% white light, 57% red light) meeting broad criteria for response and 31% (30% white light, 33% red light) meeting strict criteria. There were no differences in treatment expectations. Primary care patients with seasonal affective disorder improve after light therapy, but bright white light is not associated with greater improvements.