May 4, 2017

Here’s Why Some People Sneeze When They Look at the Sun


For those living in spring to summer climates, it’s the season for sneezing. Flowers are blooming, lawns are getting mowed, and the allergen and pollen counts are on the rise. Pollen and allergies lead to all sorts of annoying physical ailments, but one of the most frustrating is the constant sneezing. Some people, however, find their sneezes triggered by light. In the latest YouTube video from Veritasium, Derek details the Sun Sneeze Gene.

People have known about this for a few thousand years. Derek references a notation in Aristotle’s writing; apparently, the great thinker was a sun sneezer himself. Francis Bacon put it to the test, finding that he was not a sun sneezer. However, sneezing cannot be controlled. It’s a bodily reflex sent through the nervous system. Once it reaches your brain, your body reacts with a powerful release of air through your mouth and nasal cavities. It both clears your system of mucus and other irritants, it contracts muscles throughout your body — most notably the eyelids. (For many drivers, sneezing while driving can be a potential nightmare.)

It wasn’t until recently that scientists understood photic sneeze reflex (or having a sun sneeze). First, it’s more common than one would assume given its rather clinical name. It occurs anywhere between 17 percent to 35 percent of the world’s population depending on which study you use. Now that percent of the world knows why. The reflex is called the ACHOO. No, seriously. It stands for the Autosomal-dominant Compelling Helio-Opthalmic Outburst. ACHOO is caused by a gene located in a non-sex related chromosome. It’s dominant because you only need to get it from one parent to express ACHOO as a trait.

Via Veritasium

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