ACHOO! The science behind the solar sneeze
Does looking at the sun make you go ACHOO? Researchers are still trying to solve the mystery behind the solar sneeze.
Imagine walking out of a movie theatre into the bright afternoon sun when suddenly you start uncontrollably sneezing! For many people this is a regular occurrence, and there is a reason behind the sneezin’.
Autosomal dominant compelling helio-ophthalmic outburst (ACHOO) syndrome is a phenomenon that causes some people to sneeze when suddenly exposed to bright light, such as the sun. You may also hear it called a photic sneeze or solar sneeze.
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Why exactly this happens is still being researched, but the leading theory is that it involves your trigeminal nerve, which is a complex nerve that connects between your eyes, nose, and mouth.
Exposure to bright light makes your pupils contract, while dark spaces make your pupils expand in size. A sudden transition from a dark space to a bright space will cause your pupils to rapidly contract, which can stimulate the trigeminal nerve and trigger a sneeze reflex—similar to hitting just below your kneecap to trigger a muscle reflex in your legs.
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Scientists also believe ACHOO syndrome is a dominant genetic trait. So if one of your parents tends to suddenly sneeze in the sun, there’s at least a 50 per cent chance you do too.
Like any sneeze, though, the only danger it may present is if you start sneezing while driving or operating machinery.
Sneezing fits can be annoying, especially when you’re just trying to enjoy a nice day in the sunny outdoors. Wearing sunglasses and a hat can help reduce the amount of incoming light to your eyes, not only protecting your eyes from the sun but also lowering the chance for any sneezing to occur.
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