Objective. To assess the effectiveness of light therapy in two groups of patients with bipolar or unipolar affective disorder.
Method. 51 consecutive patients with affective disorder referred to light treatment were qualified - 37 diagnosed with bipolar, and 14 with unipolar affective disorder (by ICD-10 criteria). Assessments were made at baseline and at treatment completion at 14 days. The Hamilton Depression Rating Scale - 21-item version (HAMD-21), Clinical Global Impression (CGI), and the self-report Beck Depression Inventory (BDI) were used, along with the measurement of simple and choice reaction time.
Results. After the 14-day light treatment a significant improvement was found in both groups. However, the range of improvement was statistically larger in bipolar patients, which may be due to a higher incidence of seasonal mood disorders in this group.
Conclusions. Light treatment, in monotherapy or as an augmentation, is an effective method of therapy for both bipolar and unipolar affective disorder. In the treatment of bipolar patients light therapy is significantly more effective than in those with unipolar disorder. To address the cause of this difference further research is needed.