Effectiveness of bright light therapy in patients suffering from unipolar or bipolar depression: a naturalistic study

Abstract

Background and objectives

Depressive disorders, both unipolar (MDD) and bipolar (BD), greatly impact patients and society. In bipolar depression and seasonal affective disorder, the episodic nature and periodicity relate to changes in circadian rhythms. Bright light therapy (BLT) is thought to ameliorate symptoms of depression through its influence on these rhythms. However, the effectiveness of BLT has not been thoroughly established in real-world clinical samples.

Methods For seventy-four patients, Inventory of Depressive Symptoms – Self Rated (IDS-SR) scores were available through Routine Outcome Monitoring (ROM) used in BLT at an outpatient clinic for mood disorders. Patients received one or two weeks of add-on BLT as part of usual care. Individuals suffering from MDD (n = 33, 60.6% female, mean age 36.1 ± 11.5 years) were compared to those with BD (n = 41, 70.7% female, mean age 45.0 ± 14.5 years). Changes in individual symptoms were analyzed for both groups and for the whole cohort. Results IDS-SR scores decreased significantly in both patient groups, with no difference in effect size between MDD and BD. Exploratory analyses of individual IDS-SR items indicated that core depressive symptoms—such as mood, concentration, and energy level—showed the greatest improvements. Conclusion Self-reported depressive symptoms in patients with either MDD or BD decreased in this naturalistic clinical cohort after receiving BLT.