title: Light therapy for non-seasonal depression: systematic review and meta-analysis.
abstract: BACKGROUND
  Light therapy is a known treatment for patients with seasonal affective disorder. However, the efficacy of light therapy in treating patients with non-seasonal depression remains inconclusive.
  
  
  OBJECTIVE
  To provide the current state of evidence for efficacy of light therapy in non-seasonal depressive disorders.
  
  
  METHODS
  Systematic review of randomised controlled trials (RCTs) was conducted by searching MEDLINE, EMBASE, PsycINFO, CINAHL, and CENTRAL from their inception to September 2015. Study selection, data abstraction and risk of bias assessment were independently conducted in duplicate. Meta-analyses were performed to provide a summary statistic for the included RCTs. The reporting of this systematic review follows the PRISMA guidelines.
  
  
  RESULTS
  A meta-analysis including 881 participants from 20 RCTs demonstrated a beneficial effect of light therapy in non-seasonal depression (standardised mean difference in depression score -0.41 (95% CI -0.64 to -0.18)). This estimate was associated with significant heterogeneity (I2=60%,P=0.0003) that was not sufficiently explained by subgroup analyses. There was also high risk of bias in the included trials limiting the study interpretation.
  
  
  CONCLUSIONS
  The overall quality of evidence is poor due to high risk of bias and inconsistency. However, considering that light therapy has minimal side-effects and our meta-analysis demonstrated that a significant proportion of patients achieved a clinically significant response, light therapy may be effective for patients with non-seasonal depression and can be a helpful additional therapeutic intervention for depression.
  
  
  BACKGROUND
  None.
  © The Royal College of Psychiatrists 2016. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) licence.
authors.affiliation: , BSc, Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Canada.
authors.forename: Stefan
authors.initials: S
authors.lastname: Perera
authors.affiliation: , BHSc, MiNDS Neuroscience Graduate Program, McMaster University, Hamilton, Canada.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Eisen
authors.affiliation: , BSc, Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Canada.
authors.forename: Meha
authors.initials: M
authors.lastname: Bhatt
authors.affiliation: , MLIS, Health Sciences Library, McMaster University, Hamilton, Canada.
authors.forename: Neera
authors.initials: N
authors.lastname: Bhatnagar
authors.affiliation: , ScD, RD, Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Canada; Population Genomics Program, Chanchlani Research Centre, McMaster University, Hamilton, Canada.
authors.forename: Russell
authors.initials: R
authors.lastname: de Souza
authors.affiliation: , PhD, McMaster University, Hamilton, Canada; Biostatistics Unit, Centre for Evaluation of Medicine, Hamilton, Canada.
authors.forename: Lehana
authors.initials: L
authors.lastname: Thabane
authors.affiliation: , MBChB, MRCPsych, PhD, Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Canada; Biostatistics Unit, Centre for Evaluation of Medicine, Hamilton, Canada; Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, Canada.
authors.forename: Zainab
authors.initials: Z
authors.lastname: Samaan