Prevalence of the photic sneeze reflex: A systematic review and meta-analysis

The photic sneeze reflex (PSR), in which exposure to bright light triggers sneezing, is widely recognised but inconsistently defined and measured. We conducted the first systematic review and meta-analysis of PSR prevalence to synthesise the epidemiological evidence, assess methodological quality, and identify priorities for future research. We included 18 articles comprising 31 study groups and extracted prevalence estimates, study characteristics, ascertainment methods, and epidemiological information. Fifteen eligible study groups classified as healthy were included in the primary meta-analysis. The pooled prevalence was 22% (95% CI, 15%-29%), with extreme between-study heterogeneity (I² = 99.3%). Reported prevalence estimates and associations with participant characteristics varied widely, and nearly all studies were judged to be at high risk of bias. The pooled estimate should therefore be interpreted as a descriptive summary of the available evidence rather than a precise estimate of population prevalence. Future studies require a standardised operational definition, representative sampling, transparent reporting, and reproducible methods for assessing light-triggered sneezing.