To test the hypothesis that the antidepressant effects of bright light
in seasonal affective disorder are mediated by the suppression of
melatonin, 19 patients with this disorder were given atenolol, which
suppresses melatonin secretion, and placebo in a double-blind crossover
study. No difference in antidepressant efficacy was found between drug and
placebo in the sample as a whole, which argues against the melatonin
hypothesis of phototherapy. However, in three of the patients atenolol
provided repeated, marked, and sustained relief of symptoms, suggesting
that it may be useful in treating the winter depressive symptoms of some
patients with seasonal affective disorder.Abstract Teaser