Is there a difference in clinical efficacy of bright light therapy for different types of depression? A pilot study.

Background: There is growing interest in the possible applications of Bright Light Therapy (BLT). BLT might be a valid alternative or add-on treatment for many other psychiatric disorders beyond seasonal affective disorder. This pilot study aims to examine whether the efficacy of Bright Light Therapy (BLT) is similar for different subtypes of mood disorders.

Methods: Participants were 48 newly admitted outpatients with major depressive disorder with either melancholic features (n=20) or atypical features (n=28). Morning BLT was administered daily for 30 min at 5.000-10.000 lx on working days for up to 3 consecutive weeks.

Results: Participants' depressive symptoms improved significantly after BLT (p<.05, d=-.53). The effects of BLT remained stable across a 4 week follow-up. There were no significant differences in efficacy of BLT between groups (p>.05). No effect of seasonality on the improvement in depressive symptoms after BLT was found, (p=.781).

Limitations: The study had a small sample size and lacked a control condition.

Conclusions: This pilot study provides preliminary evidence that BLT could be a promising treatment for depression, regardless of the melancholic or atypical character of the depressive symptoms.