14. Light can make some people sneeze – In about a quarter of people, sudden exposure to bright light can bring on a sneezing fit known as the photic sneeze reflex. Normal sneezes happen when something irritates the nose lining. This stimulates the trigeminal nerve and the body expels the irritant with a sneeze. The nearby optic nerve, meanwhile, alerts the brain to changes in light levels, to which it responds by constricting or enlarging the pupils. In photic sneezers, a flood of light creates electric signals in the optic nerve sensed by the trigeminal nerve, triggering a sneeze.
