Have you ever had to sneeze when you were exposed to light from the sun, or after switching a light on in your house?
About a quarter of people have what is called photic sneeze reflex, which is what causes people to sneeze when they see a bright light after being in the dark. The effect was first documented by the Greek scientist Aristotle around 350 B.C.
It is caused by a genetically dominant trait, which means that one parent has the reflex then the child has a 50% chance of also inheriting it. Researchers have even come up with a suitable acronym, calling it the Autosomal dominant Compelling Helio-Ophthalmic Outburst or, ACHOO syndrome.
Further studies from University of Zurich professor Nicholas Langer have offered two theories why light causes some people to sneeze. One theory claims that the visual system of the brain is more sensitive in people who have the syndrome.
Langer’s other theory suggests that light triggers the optic nerve to send a signal to the brain to restrict the people’s eyes. Due to its nearby location, the Trigeminal nerve may sense this. The brain then mistakes this for an irritating stimulation on the nose, causing some people to sneeze.
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