Leo Sher, M.D.

Our research paper, “Early response to light therapy partially predicts long-term antidepressant effects in patients with seasonal affective disorder” was published 20 years ago in the September 2001 issue of the Journal of Psychiatry and Neuroscience (1). The aim of the study was to determine if the antidepressant effect of 1 hour of light therapy is predictive of the response after 1 and 2 weeks of treatment in patients with seasonal affective disorder (SAD).

Study participants were required to meet the criteria for SAD; score at least 14 points on the 21-item Hamilton Depression Rating Scale (HDRS) or score at least 12 points on the HDRS, with a total of 20 on the Structured Interview Guide for the HDRS-SAD Version (SIGH-SAD), a revised version that merges the HDRS with a supplementary 8 item scale for atypical symptoms; and be physically healthy. Baseline HDRS SIGH-SAD ratings were obtained for each subject by an experienced clinician immediately before the first hour of light therapy (8,200 lux) and at the end of this hour. SIGH-SAD ratings were also obtained after patients underwent 1 and 2 weeks of light therapy (10,000 lux for 45 min twice a day). Twelve patients with SAD participated in the study.

We found a significant correlation between the effect of 1 hour of light therapy on the atypical depressive symptoms and the effect of 2 weeks of light therapy on the same symptoms, suggesting a relation between the early and long-term response to light exposure in patients with SAD. Our study suggests that in patients with SAD, the early response to light therapy may predict some aspects of long-term response to light therapy.

Reference

1. Sher L, Matthews JR, Turner EH, Postolache TT, Katz KS, Rosenthal NE. Early response to light therapy partially predicts long-term antidepressant effects in patients with seasonal affective disorder. J Psychiatry Neurosci. 2001 Sep;26(4):336-8.