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

Background Studies of light therapy have not been conducted previously in primary care.

Aims To evaluate light therapy in primary care.

Method 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.

Results 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.

Conclusions Primary care patients with seasonal affective disorder improve after light therapy, but bright white light is not associated with greater improvements.

Declaration of interest The study was funded by the Chief Scientist Off ice of the Scottish Executive Department of Health.