Why do you sneeze when you walk into sunlight?

Answer 1

Not everyone does. You have a condition that makes you photosensitve (I forgot what its called). I'm the same. I also used to sneeze at bright lights, but as I've got older, this hasn't affected me. You're in a minority, so feel special!!!

Answer 2

Here's Why:


Close association between the eye’s optic nerve and nerves causing the sneeze reflex may explain why an estimated 5-25% of people sneeze with sudden exposure to bright sunlight or other light sources.


Sudden bright stimulation of the eye that occurs after a person has become adapted to darker surroundings is thought to bring on the condition, known as the "photic sneeze reflex". The reflex also is called Autosomal Dominant Compelling Helioophthalmic Outburst Syndrome, known by the acronym ACHOO. (Not making this up. Really.)

Ophthalmologists conducting eye examinations long have known about the sneeze reflex because it occurs so often under bright light used for viewing the eye’s interior structures.


Because the condition is considered mostly harmless and certainly not life threatening (unless you happen to be landing a plane), there aren’t many scientific studies regarding photic sneeze reflex.
The common photic sneeze reflex, which often creates multiple sneezes, is considered an inherited condition found more often in Caucasians.



A study reported by the British Journal of Ophthalmology noted that one form of the sneeze reflex appears related to another condition (nephropathic cystinosis) that causes abnormal crystal deposits on the clear front covering of the eye ( cornea). Nephropathic cystinosis, an inherited disease found mostly in Caucasians, is a metabolic condition affecting various parts of the body.



Injections to numb the eye for eye surgeries or procedures also have been associated with a sneeze response, although at least one study notes the condition does not appear the same as the more common photic sneeze reflex.



Speculation continues that more in-depth studies of photic sneeze reflex might enhance understanding of a central nervous system disorder (epilepsy), triggered by stimulus such as strobe lights.

That's It, have a sunny-sneezy day :)

Answer 3

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

What is a sneeze? Well, everybody knows what a sneeze is, but try and describe it sometime! The fact is, a sneeze is a very complicated thing, involving many areas of the brain. A sneeze is a reflex triggered by sensory stimulation of the membranes in the nose, resulting in a coordinated and forceful expulsion of air through the mouth and nose. A "reflex" means that some type of stimulation of your body causes you to react in a way that is NOT under your control, in other words you do it automatically without thinking and you can’t even stop it. 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 4

There is a name for this i think it is rhinitis. It is common about 1 in 3 people have it. I do! when i need to see i look towards sunlight and it works everytime, i love a good sneeze!

Answer 5

Your sinuses sit right under your eyes and behind your nose when the light hits your eyes it stimulates the sinus passages thus causing them to sneeze. Sneezes are cause by stimulation to the sinusesthey do not know it was a phony stimulant. A bright light will do the same thing.

Answer 6

OK I have no references to back this up but,
I thought it was to do with the sunlight warming the hairs in the nose and, making them move. The same feeling as when you (dont try this at home kids) might gently put a knitting needle up your nose. - dont tell me you havent done it as well.

On the same tack, when smokers quit, they get a cough that lasts for a couple of months. That is due to the cigarette tar, that lines the hairs in the throat, slowly draining away. That causes the tickly cough.

Answer 7

It's called photosynthetic reflex. Only 10 percent of the population has it. I have it. Sneeze every time I glance at the sun.

Answer 8

my friend does too ..even when we get out at the same time to the sunlight she always does but I don't ..so she said she has it coz of the difference in the temperture from cold room to sunlight ,,so don't worry ..

Answer 9

I don't- maybe it's hay fever? I sneeze when I eat mints or have some gum, it's quite embarrassing really!

Answer 10

dust gets lighter and floats well in the path of the sunlight.