Phototherapy with broad spectrum white fluorescent light: a comparative study.

The principles of photobiology suggest that the antidepressant effect of phototherapy depends on the dose and spectrum of light. We investigated the effect of spectrum by comparing two broad spectrum fluorescent light sources with different spectral distributions. In a crossover design, 11 patients with seasonal affective disorder (SAD) were treated with broad spectrum fluorescent and cool white light for 7 days. Scores on the Hamilton Rating Scale for Depression were reduced from 22.5 to 8.1 with broad spectrum fluorescent light and from 23.5 to 8.8 with cool white light. The results suggest that both light sources are effective treatments.