Asked by: Anonymous
The technical wording for this is the photic sneeze reflex. Its exact cause is not known but it’s been found to run in families. One theory is that photic sneezers are unusually sensitive to light. The irritation caused by emerging out of the dark into the light or staring towards the Sun causes a similar reaction to that from pollen, leading to the sneezing reflex.
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.
