Bright Light Therapy Boosts Therapeutic Response in Bipolar Depression
March 16, 2023   

Bright Light Therapy

In 1984, Rosenthal et al. proposed that the use of Bright-Light Therapy (BLT) could be utilized as an effective treatment for seasonal affective disorder. For over three decades BLT has been used to treat seasonal affective disorder (SAD), unipolar depression, and bipolar depression, with a growing body of literature to support its efficacy. BLT has physiological effects by resynchronizing the biological clock (circadian system), enhancing alertness, increasing sleep pressure (homeostatic system), and acting on serotonin and other monoaminergic pathways. The neural mechanism behind this idea is that light has the ability to modulate the activation of serotonergic pathways associated with the biological clock. Subsequent studies extended the positive effects of BLT to other symptoms of depression not specifically associated with SAD. Now, BLT is considered an effective non-pharmacological monotherapy and adjunctive therapy for unipolar and bipolar depression.

In a recent study, Cuomo and colleagues sought to determine if BLT accelerated and increased the therapeutic response to antidepressants after 4 and 8 weeks of treatment. A total of 41 patients ages 49.1 ± 15 years were enrolled (23 females) and randomly divided into either the treatment group (20 patients) or the control group (21 patients). It is important to note that all patients were being treated with antidepressants, 29 patients were also being treated with antipsychotics (primarily aripiprazole or quetiapine), 37 patients were also treated with mood stabilizers, mainly valproic acid or lithium, and only 8 patients were on benzodiazepines.

The BLT exposure procedure was relatively easy to complete and required the patient to be 30-80 cm away from a 10,000 lux light and keep their eyes open throughout the course of treatment for 30 minutes. Patients were able to perform other activities during the exposure such as reading or watching TV and was repeated daily. Participants’ MADRS and HAMD-17 scores were assessed at the 4- and 8-week mark. After 4 weeks of treatment, although not statistically significant, the BLT-exposed group reported decreases in both MADRS and HAMD-17 scores along with improvements in their quality of life assessed by the IQR. Following the full 8 weeks of treatment, the BLT-exposed group showed statistically significant reductions in their MADRS and HAMD-17 scores along with more participants reporting improvements in their quality of life. It is important to note that none of the participants in the control group showed significant improvements in their quality of life. These positive findings support previous research showing that BLT exposure can help those with unipolar and bipolar depression.


Cuomo, A. (2023). J Affect Disord, 321, 102-107. doi:10.1016/j.jad.2022.10.009 Abstract.

Rosenthal, N.E. et al. (2023) Gen. Psychiatry 41 (1), 72–80.

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