The people that sneeze when they go from a dark room into sunlight aren’t allergic to the Sun’s rays, but there is something happening to them physiologically, a process known as photic sneezing.
How photic sneezing works is very poorly understood, but the prevailing theory relates to a specific complex nerve in our heads, called the trigeminal nerve. Parts of this nerve sit next to your optic nerve, which is responsible for transmitting information from your eyes to the brain, including how much light they are being exposed to. When our eyes are exposed to a particularly bright light, the nerve impulse that shoots down the optic nerve may also affect the trigeminal nerve that connects to the nose and mouth, mimicking a nasal tickle, and resulting in a sneeze.
Find out the science behind photic sneezing in our video below…
Generally a sneeze happens when some form of irritant enters the nose, causing a reflex reaction that fires air, and other unmentionables, from your nose at an impressive 93 miles per hour. This weird phenomenon isn’t harmful to us in any way, but for brain surgeons, airline pilots or even trick drivers, a badly timed photic sneeze could be extremely dangerous.
If you’d like an alternative term for photic sneezing, there is a pun-tastic acronym that’s used in the associated literature – autosomal dominant compelling helio-opthalmic outburst, or ACHOO syndrome. Worryingly, that’s a real scientific term.
Bright sunlight isn’t the only thing that can cause sneezing. Some people will sneeze when they have a full stomach, which is known as snatiation, a particularly useful condition if your eyes are bigger than your belly!
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