Shining a light on cognitive performance: A systematic review and meta-analysis on light therapy on simulated night shifts

We aimed to assess the effect of light therapy on cognitive performance in simulated night-shift conditions. PubMed, Cochrane, PsycInfo, Web of Science, and Embase were searched until March 2026. The multilevel meta-analyses compared the changes in cognitive performance in light therapy group compared to control group, during light therapy (t1) and after (t2) vs. baseline (t0). We also computed meta-analyses at each measurement time between groups, and on changes within groups, as well as several sensitivity analyses. 16 articles were included, with 311 participants (24.1 yo; 78% male): 162 in the light therapy group and 156 in the control group. Improvements in executive functions were greater in the light therapy group at t1 vs. t0 (0.29, 0.01 to 0.58) and in alertness and attention / reaction time between t2 and t0 (1.20, 0.77 to 1.62 and 0.70, 0.23 to 1.18), compared with the control group. Several sensitivity analyses were also significant at these times (i.e. using only RCTs, following the exclusion of outliers, assessing only PVT and in conventional metanalysis). In conclusion, despite heterogeneity and methodological limitations, light therapy in simulated night-shift settings, progressively ameliorated cognitive performance over time for alertness and attention/reaction time, with largest effects after the intervention.