A 21-year-old man wore a light sensor on a necklace for a month and logged every sneeze. Over 30 days, he recorded 82 sneezing episodes, about 2.7 a day. In most of them, the light around him had just jumped sharply.
The man is Lucien Bickerstaff, first author of the study in F1000Research and its only participant. He has the photic sneeze reflex, and he and colleagues at the Technical University of Munich and the Max Planck Institute for Biological Cybernetics in Tübingen, Germany, set out to measure it in daily life instead of relying on what people remember. The paper first appeared in October 2025, and a revised, peer-reviewed version followed in March 2026. The data were collected in the summer of 2022.
