Photic Sneeze Reflex
The sneeze reflex to a bright light is known as photic sneeze reflex. The persons exposed to a bright light (looking at the sun, coming out of a tunnel while driving, etc.) respond involuntarily by sneezing. Once the eyes become used to the light, the sneezing stops.
This reflex can be found in one of every four persons and occasionally is hereditary. The exact cause of this reflex is not known but it is thought to be an electric process in which the light stimulates the various nerves which are linked to the sneeze reflex.
The only way for persons who suffer from this reflex to prevent photic sneezing is to avoid looking directly at the sun or direct exposure to the sun by wearing sunglasses or to avoid sudden exposure to bright light.
Gene or region studied