Background Moderate-to-severe cancer related fatigue occurs in 45% of patients with cancer and interferes with many aspects of quality of life. Although physical exercise has level 1 evidence for improvement of cancer related fatigue, it has a relatively high behavioural demand compared with other non-pharmacological interventions. The aim of this updated meta-analysis was to address the efficacy of light therapy in improving cancer related fatigue in patients with cancer.

Methods We included randomised controlled trials investigating the efficacy of bright white light (BWL) therapy in ameliorating cancer related fatigue in patients with cancer. This meta-analysis was conducted using a random-effects model. The target outcomes were changes in cancer related fatigue associated with BWL or dim red light (DRL).

Results There were 9 articles with 231 participants included. The main results revealed that daily morning BWL for 30 min was associated with significantly better improvement in fatigue severity compared with DRL (k=5, Hedges’ g=−0.414, 95% CI −0.740 to −0.087, p=0.013). The subgroup without psychiatric comorbidities (k=4, Hedges’ g=−0.479, 95% CI −0.801 to −0.156, p=0.004) was associated with significantly better improvement in fatigue severity with BWL than with DRL. In contrary, BWL was not associated with significantly different changes in depression severity or quality of life compared with DRL. Finally, BWL was associated with similar acceptability (ie, dropout rate) and safety profile (ie, any discomfort) as those of DRL.

Conclusions This meta-analysis provides an updated evidence on the rationale for application of BWL in ameliorating cancer related fatigue in patients with different types of cancer.

Trial registration number INPLASY202140090.