Does the sun make you sneeze?

This phenomenon doesn't affect everyone, but it certainly affects me -- and about a third of the world's population, as Scientific American reports. In fact, some of the world's great natural philosophers have pondered the cause of sun-sneezes:

Aristotle mused about why one sneezes more after looking at the sun in The Book of Problems: "Why does the heat of the sun provoke sneezing?" He surmised that the heat of the sun on the nose was probably responsible.

Some 2 ,000 years later, in the early 17th century, English philosopher Francis Bacon  neatly refuted that idea by stepping into the sun with his eyes closed—the heat was still there, but the sneeze was not (a compact demonstration of the fledgling scientific method). Bacon's best guess was that the sun's light made the eyes water, and then that moisture ("braine humour," literally) seeped into and irritated the nose.

But Bacon was wrong:

Humours aside, Bacon's moisture hypothesis seemed quite reasonable until our modern understanding of physiology made it clear that the sneeze happens too quickly after light exposure to be the result of the comparatively sluggish tear ducts. So neurology steps in: Most experts now agree that crossed wires in the brain are probably responsible for the photic sneeze reflex.

A sneeze is usually triggered by an irritation in the nose, which is sensed by the trigeminal nerve, a cranial nerve responsible for facial sensation and motor control. This nerve is in close proximity to the optic nerve, which senses, for example, a sudden flood of light entering the retina. As the optic nerve fires to signal the brain to constrict the pupils, the theory goes, some of the electrical signal is sensed by the trigeminal nerve and mistaken by the brain as an irritant in the nose. Hence, a sneeze.

How about you? Are your wires crossed too?

Comments

[prairie biker]

I think they're both wrong. It's a reaction to the previous presence of an irritant (finger) that was extricated from the nose immediately prior to stepping out in public.

[Julie]

Yes. My wires are crossed. This always baffled me. Now I know what causes it.

[Rob B]

Ditto, Julie.

Now if we can just correlate that data with some sucessful or desired trait like "of these 1/3 of people, 98% have reported having an exciting and vivacious sex life" then we can start a new trend in Hollywood. This would allow us to laugh at the emo poptarts as they fake sneeze in thier red carpet enterences.

Further proof, that I enjoy taunting entirely too much.