How come looking into the sun makes you want to sneeze?

Question

ive always wondered...

Answer 1

An excellent question. This is far more complicated than you might imagine. Since the detailed answer below got kind of long, I will summarize the main points up front. About 25% of people do actually sneeze when exposed to bright lights like the sun. We do not know exactly why this happens, but it might reflect a "crossing" of pathways in the brain, between the normal reflex of the eye in response to light and the sneezing reflex. There is no apparent benefit from "sun-sneezing", and it probably is nothing more than an unimportant (but annoying) holdover of evolution.

Your body has many reflexes - the other one important to us here is called the "pupillary light reflex". If you shine a light in your eyes, your pupils get smaller, or constrict. You should be able to see this easily in a friend using a flashlight (or in the mirror).

In the pupillary light reflex, shining a light in the eye causes nerve signals to go from the eye to the brain and then back the eye again, telling the pupil to constrict. In the usual sneeze reflex, tickling the nose causes nerve signals to go from the nose to the brain and then back out to the nose, mouth, chest muscles and everything else involved in the actual sneeze. The key point is that the nerve signals take complicated routes through the brain, but usually the pupillary light reflex and sneeze reflex take different routes. Apparently what happens in sun-sneezers is that shining a bright enough light in the eye ALSO sends nerves signals from the eye to the brain and then back out to the nose, mouth and chest! In short, the wires are crossed a little bit in some people, and so shining a light in the eye "accidentally" activates two different outgoing pathways.

Answer 2

It actually STOPS me from sneezing! If i get the feeling im goin to sneeze i will look at the sun and it will make the feeling go away!

Answer 3

I don't have any nice scientific terms to back this up but I think it may be caused by the fact that our eyes tear when we look at the sun and this excess fluid flows into the nose and makes us want to sneeze

Answer 4

Sneezing in response to bright light is a parasympathetic reflex (triggered by contraction of the pupil) that about 10% of the population has.

Aloha

Answer 5

looking into the sun makes you sneeze?? ive never heard that before..it doesn't make me sneeze

Answer 6

Its your bodies organic reaction the get you to look away. mom is often precise, It ruins your eyes. whether I nonetheless do it by way of fact its demanding when I definitely have a trapped sneeze.

Answer 7

light can sometimes irritate the eye just enough to cause mucous to form and cause that 'itch' in the nasal passages..

it's like with dust, pepper... some spices... foods and incandescent lighting.

some react to it some don't.

i get more of a sneeze out of bright xmas lights.

Answer 8

" Strobe Lighting, Stimulates The Brain. "

http://www.patient.co.uk/showdoc/27000326/

Answer 9

its not the sun, its the pollen in the air from cross pollination caused by wind, birds, bees

Answer 10

Check this site http://www.madsci.org/posts/archives/aug97/865380242.Me.r.html