Bright light therapy in the treatment of patients with bipolar disorder: A systematic review and meta-analysis.
Study Goal
The researchers aimed to evaluate the role of bright light therapy (BLT) in treating depressive symptoms in patients with bipolar disorder (BD) through a meta-analysis of randomized controlled trials and cohort studies.
Results Summary
The meta-analysis found significant reductions in depression severity with BLT compared to placebo, particularly with light intensity ≥5000 lux, and noted efficacy varied by duration/timing and color/color temperature of light therapy. Patients not using psychotropic drugs showed greater improvement.
Population
Patients with bipolar disorder experiencing depressive symptoms (847 participants across 12 studies).
Effective Dosage
Light intensity ≥5000 lux (specific frequency not detailed).
Duration
Not specified (study notes limitations regarding short-term effects).
Interactions
Patients without psychotropic drugs showed significantly decreased disease severity.
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
bright light therapy (BLT) | decrease | depression severity before and after BLT | patients with BD depression | SMD = -0.43, 95% CI (-0.73,-0.13), P<0.05 in RCT | significant differences between BLT and placebo | #1 |
bright light therapy (BLT) | decrease | depression severity before and after BLT | patients with BD depression | SMD = -2.12, 95% CI (-2.3,-1.94), P<0.05 in cohort studies | significant differences between BLT and placebo | #2 |
bright light therapy (BLT) | decrease | depressive symptoms in BD | patients with BD depression | SMD = -1.88, 95% CI (-2.04, -1.71), P<0.05 | efficacy of duration/timing of light therapy | #3 |
bright light therapy (BLT) | decrease | depressive symptoms in BD | patients with BD depression | SMD = -2.1, 95% CI(-2.24, -1.96), P<0.05 | efficacy of duration/timing of light therapy | #4 |
bright light therapy (BLT) | decrease | depressive symptoms in BD | patients with BD depression | SMD = -0.56, 95% CI (-0.92, -0.19), P<0.05 | efficacy of different color/color temperatures | #5 |
bright light therapy (BLT) | decrease | depressive symptoms in BD | patients with BD depression | SMD = -1.74, 95% CI (-1.99, -1.49), P<0.05 | efficacy of different color/color temperatures | #6 |
light intensity≥5000 lux | decrease | severity of depression | patients with BD depression | - | significantly reduced | #7 |
bright light therapy (BLT) | decrease | disease severity | patients without psychotropic drugs | SMD = -0.6, 95% CI (-1.06,-0.13), P<0.05 | significantly decreased disease severity | #8 |
bright light therapy (BLT) | decrease | bipolar depression | patients with BD depression | - | significant efficiency | #9 |
The treatment of depressive symptoms of bipolar disorder (BD) has received increasing attention. Recently, some studies have shown that bright light therapy (BLT) seems to be useful for BD depression. This meta-analysis is intended to further elucidate the role of BLT in depressive symptoms in patients with BD. Register of Systematic Reviews PROSPERO: CRD 420191 33642.Randomized controlled trials and cohort studies were retrieved in PubMed, Cochrane Library, EMbase, Web of Science, CINHAL, CBM, CNKI, VIP, and Wanfang from their foundation to March 2020, and other sources as supplement was also retrieved. Data were extracted after strict evaluation of literature quality by two researchers, and Meta-analysis was conducted on literatures that met the inclusion criteria. Meta-analysis was performed using Revman 5.3 software. In total, 12 studies including 847 patients with BD depression were included in our meta-analysis. A meta-analysis found significant differences between BLT and placebo for the following outcomes: (1) depression severity before and after BLT [SMD = -0.43, 95% CI (-0.73,-0.13), P<0.05] in RCT and [SMD = -2.12, 95% CI (-2.3,-1.94), P<0.05] in cohort studies.; (2) the efficacy of duration/timing of light therapy for depressive symptoms in BD [I2 = 85%, SMD = -1.88, 95% CI (-2.04, -1.71),P<0.05] and [I2 = 71%, SMD = -2.1,95% CI(-2.24, -1.96), P<0.05]; (3) the efficacy of different color/color temperatures for depressive symptoms in BD [I2 = 0%, SMD = -0.56, 95% CI (-0.92, -0.19), P<0.05] and [I2 = 97%, SMD = -1.74, 95% CI (-1.99, -1.49), P<0.05].We performed a subgroup meta-analysis of studies that used different light intensities. The results showed that light intensity≥5000 lux significantly reduced the severity of depression. And patients without psychotropic drugs revealed significantly decreased disease severity [I2 = 0%, SMD = -0.6, 95% CI (-1.06,-0.13), P<0.05]. Limitations of the study include studies only assessed short-term effects, and insufficient duration may underestimate adverse reactions and efficacy. Our results highlight the significant efficiency of BLT in the treatment of bipolar depression. Prospective studies with more rigorous design and consistent follow-up.