Adjunctive bright light therapy improves remission and response in nonseasonal depression and may accelerate early benefit.

Background

While bright light therapy (BLT) is established for seasonal affective disorder, its role as an adjunctive treatment for nonseasonal depressive disorders has been uncertain. This systematic review and meta-analysis evaluates whether adding BLT to standard care improves outcomes in nonseasonal unipolar and bipolar depression.

Patients

• Total: 858 participants across 11 randomized clinical trials (RCTs)
• Sex: 649 female (75.6%), 209 male (24.4%)
• Diagnoses: Nonseasonal major depressive disorder (unipolar) and bipolar depressive disorder
• Settings: Predominantly outpatient adults; one inpatient adolescent study

Intervention

• Bright light therapy (BLT): Primarily 10,000 lux white light via light box for 30–60 minutes daily (morning timing typical); some trials used 7,000 or 5,000 lux
• Duration of BLT courses: 1–6 weeks
• Adjunctive use: Added to usual care/antidepressant therapy

Control

• Dim red/low-intensity light (typically 50–100 lux) or sham (e.g., negative ion generator)
• Antidepressant monotherapy in some trials

Outcome

• Primary outcomes: Remission of depressive symptoms; response to treatment
• Secondary outcomes: Change in depression severity scales (HAM-D, MADRS, CGI)

Study Design

• Systematic review and meta-analysis of RCTs (January 2000–March 25, 2024)
• Mantel-Haenszel random-effects models; heterogeneity via I²
• Overall risk of bias: low across included RCTs

Level of Evidence

Level I (systematic review and meta-analysis of randomized clinical trials)

Follow up period

• Range: 1 to 6 weeks
• Subgroups: Less than 4 weeks vs greater than 4 weeks

Results

Primary outcomes

• Remission: 40.7% with BLT vs 23.5% control; OR 2.42 (95% CI, 1.50–3.91)
  • Absolute risk difference (ARD): 17.2%
  • NNT: 6
• Response: 60.4% with BLT vs 38.6% control; OR 2.34 (95% CI, 1.46–3.75)
  • ARD: 21.8%
  • NNT: 5

Primary outcomes by follow-up duration

• Remission <4 weeks: 27.4% vs 9.2%; OR 3.59 (95% CI, 1.45–8.88)
  • ARD: 18.2%; NNT: 6
• Remission >4 weeks: 46.6% vs 29.1%; OR 2.18 (95% CI, 1.19–4.00)
  • ARD: 17.5%; NNT: 6
• Response <4 weeks: 55.6% vs 27.4%; OR 3.65 (95% CI, 1.81–7.33)
  • ARD: 28.2%; NNT: 4
• Response >4 weeks: 63.0% vs 44.9%; OR 1.79 (95% CI, 1.01–3.17)
  • ARD: 18.1%; NNT: 6

Secondary outcomes

• HAM-D: Mean difference −1.44 (95% CI, −2.40 to −0.48) favoring BLT
• CGI: Mean difference −0.06 (95% CI, −0.29 to 0.16); no meaningful difference
• MADRS: Mean difference 0.36 (95% CI, −2.60 to 3.31); no meaningful difference

Limitations

• Follow-up durations varied across trials.
• One inpatient adolescent study had high discontinuation and setting differences vs adult outpatient trials.
• Heterogeneous definitions of remission/response and varying depression severities and diagnoses (unipolar and bipolar) limited subgroup analyses by subtype.
• Moderate number of trials; some variability in BLT parameters (lux, timing).

Funding

Not reported in the article text provided.

Citation

de Almeida AM, de Moraes FCA, Souza MEC, Cardoso JHCO, Tamashiro F, Miranda C, Fernandes L, Kreuz M, Alves Kelly F. Bright Light Therapy for Nonseasonal Depressive Disorders: A Systematic Review and Meta-Analysis. JAMA Psychiatry. 2025;82(1):38–46. Published online October 2, 2024. doi:10.1001/jamapsychiatry.2024.2871.