35 Percent of People Sneeze Because of This Weird Reflex

The next time you sneeze and it's not because you're sick, maybe invest in a good pair of sunglasses to slow down your use of tissues.

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It's called the photic sneeze reflex (PSR) or the ACHOO (autosomal dominant compulsive helio-ophthalmic outbursts of sneezing) syndrome. That's right, the syndrome that describes why you're sneezing is called ACHOO.

According to Scientific American, the genetic nature of the condition has been known for at least the last 25 years.

"Observations that emerging from dim light into sunlight or turning to face directly into the sun commonly triggers the reflex prompted early inquiries into the trait. The number of induced sneezes--which seems to be genetically mediated and can be predicted within a family--is constant from episode to episode and typically numbers two or three."

And this can be dangerous in some situations, such as if an affected person suddenly turns into bright sunlight while driving for example.

However, it's not as simple as putting on some sunglasses after all.

In recent military studies, PSR appears to be triggered by specific wavelengths of lights, which aren't affected by filters like sunglasses.

"Investigators concluded that the PSR is induced by changes in light intensity. Others have not found flickering light to precipitate the PSR. Exactly how sunlight causes some people to sneeze remains unknown."