Why do people sneeze when they look towards the sun?

Question

Why do people sneeze when they look towards the sun?

Answer 1

it causes your eyes to squint, which in turn causes the blood vessels in your sinuses to contract.

Answer 2

All the info , right here !

http://en.wikipedia.org/wiki/Photic_snee...

Answer 3

I don't know,but I'd like to find out.

i just looked at the link yas left,i've got that.

Answer 4

Wow Ace, you are a douche bag.

Answer 5

I just looked toward the sun and I didn't sneeze. So that must mean that not all people sneeze when they look toward the sun.

Ey Mr T. I didn't know ok. So I assumed this was a load of c**p.

Answer 6

i dont sneeze.  sneezeing is when ppl take in somthing their lungs dont like

Answer 7

I sneeze wen i look at any light (if i feel a sneeze coming on!)

Sneezing as the result of being exposed to a bright light—known as the photic sneeze reflex—is a genetic quirk that is still unexplained by science, even though it has intrigued some of history's greatest minds.

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.

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.

But because this harmless (albeit potentially embarrassing) phenomenon doesn't seem to be linked with any other medical condition, scientific study of the subject has been scarce. Research has done little more than document its existence and attempt to gauge its prevalence. No rigorous studies exist, but informal surveys peg 10 to 35 percent of the population as photic sneezers. A study in the 1960s showed that the trait is autosomal-dominant—the gene is neither on the X nor Y chromosome and only one copy of the gene has to be present for the trait to be expressed—so if one parent sneezes when they look at a bright light, about half of his or her children will, too.

The genetic culprit remains unidentified, but scientists are starting to take an interest in trying to find out. "I think it's worth doing," says Louis Ptácek, a neurologist at the University of California, San Francisco, and an investigator at the Howard Hughes Medical Institute. Ptácek studies episodic disorders such as epilepsy and migraine headaches, and he believes that investigating the photic sneeze reflex could shed light on their related neurology.

Epileptic seizures are sometimes triggered by flashing lights and migraine headaches are often accompanied by photophobia. "If we could find a gene that causes photic sneezing, we could study that gene and we might learn something about the visual pathway and some of these other reflex phenomena," Ptácek says.

Answer 8

no direct correlation, this is the 1st time,  I have ever heard this question.

sneezing is a part defense mechanism to reduce the micro organism's concentration and rid of potential pathogens.

Answer 9

The commonly believed cause of sun-sneezing is a malfunction in a nerve signal.  A nerve called the trigeminal nerve is responsible for sneezes, and when the eyes adjust to bright light, the overstimulation of the optic nerve triggers the trigeminal nerve, and causes a sneeze, or many sneezes.