Bright light therapy (BLT) does not provide significant antidepressant effects in patients with bipolar disorder, according to a systematic review and meta-analysis published in Psychiatry and Clinical Neurosciences. Solid evidence for BLT is lacking, with few well-controlled studies clearly establishing proof that this therapeutic approach can prevent the recurrence of mood episodes, improve manic symptoms, and effectively manage depression in patients with bipolar disorder.

This systematic review and meta-analysis of randomized controlled trials assessed the efficacy of BLT for managing the manic or depressive states of type 1 or type 2 bipolar disorder. In the studies included in this analysis, control groups consisted of a sham treatment, such as low-intensity light, negative iron, dim red light, or no light (treatment as usual). For the purposes of this meta-analysis, investigators examined rates of remission from depressive or manic episodes, rates of relapse from euthymic states, and changes in scores for depression or mania.

A total of 6 trials were included in the meta-analysis. The investigators found no difference between BLT and sham/usual treatment in terms of the rates of remission from depressive episodes (risk ratio [RR], 1.81; 95% CI, 0.43-7.64; P =.42), changes in depressive symptom scores (standardized mean difference, −0.25; 95% CI, −0.74-0.23; P =.30), and rates of manic switching (RR, 1.00; 95% CI, 0.28-3.59; P =.26).

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In the sensitivity analysis, there was a significant difference in remission rates from depressive episodes between the BLT approach vs control (RR, 3.09; 95% CI, 1.62-5.90; P =.006). There were no differences between light intensities or colors in terms of remission rates from depressive episodes. Conversely, a significant difference in remission rates from depressive episodes was found between ≤2 weeks (RR, 3.12; 95% CI, 1.25-7.78; P =.01) vs >2 weeks (RR, 1.18; 95% CI, 0.31-4.50; P =.81).

Limitations of the meta-analysis included the reliance on 6 randomized controlled trials with only 280 patients, as well as the relatively short treatment duration of some studies. The investigators suggest that “it would be appropriate to judge the usefulness of BLT for the treatment of bipolar depression by considering not only randomized controlled trials but also case series and expert opinions based on existing evidence.”

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.


Takeshima M, Utsumi T, Aoki Y, et al. Efficacy and safety of bright light therapy for manic and depressive symptoms in patients with bipolar disorder: a systematic review and meta-analysis [published online January 9, 2020]. Psychiatry Clin Neurosci. doi:10.1111/pcn.12976