why do I tend to sneeze when I look directly add a bright light or at the sun ?

Answer 1

I dont kno but i do the same thing! Like if i look up at the sun for a few seconds i'll sneeze. It is wierd

Answer 2

"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 photic sneeze reflex. The reflex also is called Autosomal Dominant Compelling Helioophthalmic Outburst Syndrome, known by the acronym ACHOO. (Not making this up. Really.)"

http://vision.about.com/od/opticsvisiontheory/f/sneezereflex.htm

"This sneeze reflex is inherited and thought to be prevalent in approximately 24 percent of the population. The cause of it is still unknown but there are a few theories. The speculations as to the cause are somewhat technical but they all involve direct stimulation by light to nerves found in the face. This reflex does not involve mechanisms similar to allergies, and there are no known problems associated with this syndrome."

http://parenting.ivillage.com/baby/bhealth/0,,435d,00.html

Answer 3

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.

There are actually three questions here:

1) Do people really sneeze when they look at the sun? This is an important question! There a lot of things that people say they do that they donbt really do. I personally do not sneeze when I look at the sun, and for a long time I thought this was a myth. But I am guessing that you are a sun-sneezer from your question. It seems that some people really do sneeze when they look at the sun, or actually at any bright light (there is nothing special about the sun). This has been recognized in medical journals for at least 40 years, and is called different things, including the "photic sneeze reflex" and even the "ACHOO syndrome". In a few instances the reflex has been documented by shining bright lights at people to make them sneeze, so it probably really does happen.

The thing is, the sun does not make most people sneeze. The best estimates are that only about 25% of people (i.e. 1 in 4) are sun-sneezers, and even sun-sneezers donbt do it most of the time. Other studies suggest that sun-sneezers might have inherited the trait in a dominant fashion from their parents (which means that if only one parent was a sneezer, they would pass the trait on to half of their kids). The problem with these estimates is that they generally rely on asking people if they sun-sneeze, and if their parents do. This is VERY unreliable. People who sun-sneeze tend to assume everyone does, and people who donbt sun-sneeze have often never even considered the possibility!!

2) What is the mechanism by which sun-sneezing occurs? What actually makes it happen? The simplest answer is that we donbt really know. There are many theories that I wonbt get into specifically, since most require a detailed understanding of brain anatomy to even describe. What I will try to do instead is to briefly explain the nature of the sneeze reflex and offer a simple understanding of how light might act as a trigger.

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 canbt 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.

3) What is the benefit or value of sun-sneezing? Is it a good thing? Again, not an easy question! Some people argue that it must be a good thing since the trait has been maintained in our population. Ibm not so sure.

What is the benefit of sneezing in general? The easy answer is that the thing tickling your nose might be a bad thing (like a virus, bacteria or pollen), and sneezing forces it out. The problem is that most adults sneeze mostly through their mouth, and so sneezing wonbt force anything out of the nose. This is in contrast to most animals, who sneeze largely through their nose (watch your dog or cat next time). So I think that sneezing really serves little purpose to humans (little kids might be an exception to this). I think that sneezing is important to animals that rely heavily on the sense of smell, but that in us it is just an annoying "holdover" of evolution. But that is just my opinion.

But even if a normal sneeze does function in ridding the nose of foreign materials, I can think of no reason why shining a light in the eye would create a need to force things from the nose! And in the several papers I have read on this subject, no one else gave a reason why sun-sneezing would be beneficial. Sun-sneezing must truly either be an accident of brain anatomy, or an evolutionary holdover from our animal friends, that serves no purpose in humans.

Answer 4

I've wondered that for a long time. I do the same thing. Maybe it's dust or something. Whenever I feel like I need to sneeze, I purposely look at a bright light or go outside to look up at the sun. It works every time.

Answer 5

Really? You do that? The rumor is, that when you feel like you are going to sneeze and you don't want to, you should look directly at a bright light or the sun. lol. Weird.

Answer 6

Do you know anyone who sneezes when they step outside into the sunshine? About one out of every three people sneezes when exposed to bright light. They are called photic sneezers (photic means light). If you are a photic sneezer, you got it from one of your parents because it is an inherited trait. You could say that it runs in your family. Most people have some sensitivity to light that can trigger a sneeze.

Answer 7

I notice that looking at a bright light strains my eyes in a way that I can feel. Becaus our eyes are so close to our sinuses, that feeling almost seems to tickle the sinuses, which could be a cause for sneezing. Just an observation.

Answer 8

looking at a bright light or the sun is supposed to prevent you from sneezing.

Answer 9

The nose mistakes strong odors, sudden chills, BRIGHT LIGHTS (see photic sneeze reflex), and even orgasms in some people for nasal irritants, and it tries to defend itself with a sneeze.

Answer 10

I know of no absolute medical reason for this. It may be that bright light triggers a reflex. Interesting, I've never come across this.