For some people, the bright sun can mean big sneezes! Why does the sun make some people sneeze? We turn to PBS for the answer!
PHOTIC SNEEZE REFLEX
The sensation of sneezing when you see the sun is called the photic sneeze reflex. Photic means “light,” so it literally means the reflex that makes light cause a sneeze. Some scientists have given it another name - the Autosomal Dominant Compelling Helio-Ophthalmic Outburst Syndrome, or ACHOO for short!
Between 10 and 35% of people experience sun sneezing, but the truth is that even scientists aren’t 100% sure what causes this experience. There haven’t been any in-depth studies because sneezing from the sun isn’t a serious medical condition. Since nobody is at danger from these sneezes, nobody wants to spend money to research it!
People have been wondering about the reason behind sun sneezes for thousands of years. The ancient Greek philosopher Aristotle wrote a collection of Problems that asked the answer to many of life’s small mysteries, and one of them was about sun sneezing! He theorized that the sun’s heat irritated your nose and caused the sneeze.
English philosopher Francis Bacon wasn’t entirely convinced by Aristotle’s explanation. Instead, he suggested that the sun’s light made your eyes water, and that water tickled the nose to provoke a sneeze.
THE CURRENT THEORY
Sneezes are usually caused by something irritating your nose. Whether it’s a tickle from a feather or pollen causing allergies, most sneezes happen when something physically touches your nose or nostrils.
The nerve that controls the senses in your face is called the trigeminal nerve, and it’s located right next to the nerve that’s attached to your eyes. Scientists think that because they’re so close together, bright flashes of light that trigger your optical nerve can accidentally stimulate the trigeminal nerve.
Your body reads that sensation as though something is irritating your nose, so that’s how bright light can make you sneeze!
Looking for more Never Stop Asking "Why?" questions? Catch up on all of the past "Whys" on the blog!