Biology
What's the science behind closing our eyes when we sneeze?
Quick fact
Sneezing is a protective reflex that expels irritants from the nasal passages, triggered by nerve endings in the nose responding to dust, allergens, or pathogens.
Why this is interesting
A sneeze rockets out of your nose at speeds up to 100 mph, but your eyes close automatically not to protect them—it's a vestigial reflex from when our ancestors sneezed while chewing leaves, but no one knows why.
Read the full explanation
Understanding What's the science behind closing our eyes when we sneeze?
The sneeze center in the brainstem coordinates a deep inhalation, followed by a forceful exhalation that clears the nasal cavity, while simultaneously closing the eyes and relaxing the throat to prevent damage.
A deeper explanation
Closing your eyes during a sneeze is an involuntary autonomic reflex—but contrary to myth, your eyes won't pop out if you keep them open (though it's difficult). The eye closure may be a protective response to prevent airborne particles from hitting the eyes during the forceful spray. The sneeze itself can expel up to 40,000 droplets at speeds of 100 mph, making it a highly effective but also highly contagious process. Some people sneeze when exposed to bright light (the photic sneeze reflex), a genetic trait affecting about 18-35% of people. So every achoo is a billion-year-old respiratory defense, honed to keep your airways clean—and your closed eyes are just along for the ride.