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It's a bright and beautiful day outside, but you start to sneeze as soon as you walk into the sunshine. If this has ever happened to you, then you may have photic sneeze reflex. It's also called sun sneezing. AncestryDNA® can tell you if your DNA suggests you might sneeze when exposed to bright light.

More About the Photic Sneeze Reflex

Another name for photic sneeze reflex is ACHOO syndrome, which is short for “autosomal compelling helio-ophthalmic outbursts of sneezing.” That long name means uncontrollable sneezing in sunlight.

It usually starts with a prickling sensation in your nose followed by one or more sneezes in the sun.

Interestingly it wasn't until the 1950s that this phenomenon was investigated formally. J. Sedan, a French researcher, noticed that his patients would sometimes sneeze because of the light coming from his ophthalmoscope (device to see the eyes). He figured out that many types of bright light made them sneeze.

Genetics of the Photic Sneeze Reflex

Whether or not bright light makes you sneeze is at least partially determined by genetics

Scientists know there are multiple markers, or locations, in your DNA that can help predict if you'll be a sun sneezer. For example, one marker is on chromosome 2, near the ZEB2 gene. Another is located on chromosome 15, near the NR2F2 gene.

Researchers have also discovered that photic sneeze reflex is more common among females and Caucasians. In one study, 94.3% of the photic sneezers were white, and 67% were female. Scientists aren't sure why this is true, but it's possible that genetics are responsible for these trends.

What Science Says About the Photic Sneeze

Scientists aren't totally sure why some people are sun sneezers and others aren't. But one theory suggests sun sneezing may have something to do with crossed wires in the cranial nerves. The bright light causes your pupils to contract, which the nervous system misreads as nasal irritation, so you sneeze. 

Since photic sneeze reflex isn't a life-threatening condition, it hasn't been studied extensively in the past. But some researchers are now starting to take more interest in photic sneezing, since it may shed light on other conditions that can be triggered by light, such as epileptic seizures.

Interesting Facts About the Photic Sneeze 

A photic sneeze doesn't mean you're allergic to the sun or being outside. And there are other triggers for this kind of sneezing in addition to sunshine and bright lights; some people also start sneezing uncontrollably from eating mints, taking a sudden, deep breath of cold air, or from plucking their eyebrows.

As far back as 350 B.C., the Greek philosopher Aristotle wrote about sun sneezing. In his Book of Problems, Aristotle believed that the heat of the sun caused a tickle in the nose, which led to sneezing. But he couldn't figure out why the sun affected the nose, yet the heat of fire didn't. 

 

References

Eriksson N, Macpherson JM, Hon LS, Naughton B, Saxonov S, Avey L, Wojcicki A, Pe’er I, Mountain J. Web-based, participant-driven studies yield novel genetic associations for common traits. PLoS Genetics. 2010 Jun 24;6(6):e1000993. doi: 10.1371/journal.pgen.1000993.

Looking at the Sun Can Trigger a Sneeze. Scientific American. January 10, 2008. https://www.scientificamerican.com/article/looking-at-the-sun-can-trigger-a-sneeze/

Pickrell J, Berisa T, Segurel L, Tung JY, Hinds D. Detection and interpretation of shared genetic influences on 40 human traits. Nature Genetics. 2016;48(7):709–717. doi:10.1101/019885.

Why Does Bright Light Cause Some People to Sneeze? Scientific American. November 18, 2002. https://www.scientificamerican.com/article/why-does-bright-light-cau/