Photobiomodulation and sleep quality: systematic review and meta-analysis

Sleep disturbances are increasingly prevalent and associated with altered brain metabolism and neuroinflammation. Photobiomodulation, a non-invasive technique using red or near-infrared light, can modulate mitochondrial activity, cerebral perfusion, and glial function, suggesting potential benefits for sleep regulation. This systematic review and meta-analysis evaluated the effects of photobiomodulation on sleep quality in clinical and experimental populations. A comprehensive search was performed in PubMed, Embase, and Cochrane databases through September 2025 using the terms (photobiomodulation OR "low level laser therapy") AND sleep. Five randomized controlled trials involving 240 participants met inclusion criteria. The pooled analysis suggested that photobiomodulation improved the Pittsburgh Sleep Quality Index (PSQI) scores compared with sham-control (MD = - 1.25; 95% CI - 2.38 to - 0.11; p = 0.03, I2 = 36.2%), although the wide confidence intervals indicate limited precision of the estimate. Mechanistic and neuroimaging evidence supports that PBM enhances mitochondrial metabolism, modulates astrocytic activity, and reorganizes prefrontal networks involved in sleep regulation. Despite methodological heterogeneity among studies, these findings suggest that photobiomodulation may have potential as a non-pharmacological approach for improving sleep quality; however, the current evidence remains limited and should be interpreted with caution. Further large-scale, standardized, and multimodal trials are required to establish optimal stimulation parameters and confirm long-term efficacy and safety.