Photic sneeze reflex - Wikipedia, the free encyclopedia

Photic sneeze reflex - Wikipedia, the free encyclopedia:

"Photic sneeze reflex (also referred to as sun sneezing, photogenic sneezing, or whimsically called ACHOO, a backronym for Autosomal dominant Compelling Helio-Ophthalmic Outburst) is a medical condition by which people exposed to bright light sneeze. The photic sneeze reflex can also cause one to sneeze many times consecutively. The condition occurs in 17% to 25% of humans with more common occurrence in Caucasians than other human races. The condition is passed along genetically as an autosomal dominant trait.

The first mention of the phenomenon is probably in the later work attributed to Aristotle (Problems, book XXXIII).

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."

I have it, my father has it, my wife and children have it -- now I know why.