For as long as I can remember, when I’ve walked outside and its sunny out, I’ve sneezed. I can usually count on a good two or three sneezes. In the past few years, I finally was curious enough to do some research and found out that I have the condition called photic sneeze reflex.
Photic sneeze reflex (also whimsically called ACHOO, a backronym for Autosomal dominant Compelling Helio-Ophthalmic Outburst) is a medical condition by which people exposed to bright light involuntarily sneeze. It has been suggested that the photic sneeze reflex occurs only after someone has been adapted to the dark for at least five minutes, although this is not certain, and is not uniform amongst people with the photic sneeze reflex. The condition occurs in one-sixth to one-quarter of humans, with more common occurrence in Caucasians than other human races. The trait is passed along genetically, with a 50 percent chance of inheritance.
The probable cause is a congenital malfunction in nerve signals in the trigeminal nerve nucleus. The fifth cranial nerve, called the trigeminal nerve, is apparently responsible for sneezes. Research suggests that some people have an association between this nerve and the nerve that transmits visual impulses to the brain. Overstimulation of the optic nerve triggers the trigeminal nerve, and this causes the photic sneeze reflex.
Lately, I’ve noticed that Dinah has been sneezing when exposed to bright light. Looks like she inherited it from me.