Light room therapy effective in mild forms of seasonal affective disorder - A randomised controlled study

Background: The most common way to provide bright light therapy to Swedish patients with Seasonal Affective Disorder (SAD), is treatment in a light therapy room. Since few studies have evaluated treatment provided in this setting and few have evaluated the effect of bright light in sub-clinical SAD (S-SAD), such a study including a one-month follow-up was designed. Methods: Fifty adults recruited from a previous prevalence study and clinically assessed as having SAD or S-SAD, were randomised to treatment in a light room or to a three-week waiting-list control group. The Hamilton Depression Rating Scale-Seasonal Affective Disorders Self-rating 29-items Version (SIGH-SAD/SR) was used to measure depressive mood at baseline, directly following treatment and at the one-month follow-up. Results: ANCOVA with adjustment for baseline depression score, showed a significant main effect for the light room therapy group Q, < 0.001). Fifty-four percent (n=13/24) improved >= 50% while no such improvement was seen in the control condition(n=0/24). After merging the two groups, repeated measures ANOVA confirmed the experimental analysis (p < 0.001). At the one-month follow-up, 83.0% (n=39/47) had improved >= 50% and 63.8% (n=30/47) had normal depression scores, i.e. <= 58. Conclusions: Light room therapy was effective in reducing depressive symptoms in subjects with winter depressive mood. Results were maintained over a period of one month. (c) 2007 Elsevier B.V. All rights reserved.