Why does looking at the sun make you sneeze?

An excellent, 4 star answer.

Frank - Thanks from me too!

I've always heard they didn't know why bright light made some people sneeze - guess they still don't exactly. But it's cool to know such a scientific name for it!

Ah-Ah-Ah-

The reason for sneezing at the sun when you look at it is intriguing. Because the sun uses the gravitational pull of the moon's largest 7-11 store to rotate on its axis (after 7 PM and until 6 AM it uses the moon's only Circle K store), it shoots out hundreds of super-radioactive gamma hydrocarbon energy bursts, or as I like to call them, Death Rays. Most of these Death Rays are deflected by the Gigametabitochloride in the earth's atmosphere, shot off to hit Pluto, which nobody likes anyway. However, some of them do manage to penetrate the Gigametabitochloride and consequently speed at anyone looking at the sun. Your sneeze gives off enough force (measured by a Universal Sneeze Index Monitor, or USIM) to prevent the Death Ray from hitting and consequently dissintegrating you and reducing you to a pile of ash.

well, isn't that interesting!!! (the real answer - - not the one just prior!!)

The sun and/or bright light doesn't MAKE me sneeze, but if I feel one stifeled and it won't come out - I look at the sun (or a light) and voila!! Sneeze accomplished!!

1 in 4??? Let's find our own result. Go to "Science Related Polls" and take the Sun Sneezer poll.

Since the link Frank provided is now dead, I'll add this:

* What is photic sneezing ?

Photic sneezing is a response to sudden exposure to strong light, resulting in an urge to sneeze, usually followed by one or more sneezes.

* How is it caused ?

Several theories have been advanced to explain the phenomenon, but the generally accepted explanation is the " crossed wires " theory.

The sudden exposure to bright light sends a signal through the optic nerve fibers. These fibers run close to and into the same hub as the trigeminal nerve. The second division of the trigeminal nerve supplies sensory fibers to the nasal mucosa. The assumption is that nerve impulses in the optic nerve cause a sympathetic discharge in the trigeminal nerve fibers. which produces the sneezing.

A second theory involves the simultaneous activation of neighboring parasympathetic branches. In this case, the stimulus to the retina also causes tears to be formed, leading to congestion in the nose and a " trickling sensation ". A third scenario posits a more generalized parasympathetic system hypersensitivity, and could be linked to the subject's emotional state. The fourth theory links intraorbital trigeminal nerve stimulation and increased ocular sensitivity to light ; this would account for photic sneezing in cases of nephropathic cystinosis.

These theories are discussed at length in Everett (1964) and Whitman and Packer (1993) in the bibliography.

* Who has the photic sneezing reaction ?

Photic sneezing has been claimed to affect children more than adults, people of European descent more than Africans or Asians ; early studies suggested that men were more prone to it than women, but this has not been borne out by more recent research.

Prevalence of photic sneezing in American and European populations has been variously estimated at between 18 and 35%. The large discrepancy can be explained in several ways : firstly, most studies are based on reported occurrence, which is an unreliable method ; secondly, the phenomenon is probably not discrete, i.e. some people may experience the reaction only in exceptional circumstances, as when suffering from inflammatory conditions of the eyes or nasal passages.

* How is photic sneezing transmitted ?

The generally accepted theory has been that photic sneezing is an inherited condition. Most early researchers were struck by reports of photic sneezing running in families. It was therefore supposed that this was a dominant trait, meaning that if one parent had the trait, on average half the children would inherit it. However, one study (Whitman 1993) suggests that it can be acquired in life, casting doubt on the original hypothesis. - http://www.photic-sneezing.fr.st/

I have this happen all the time. One time in the middle of summer I walked out of my office onto the street and started sneezing like crazy. An African American was standing there and said "Cold?" and I said "No, Sun." He looked at me with the most confused look... "The sun makes you sneeze?" "Oh yeah... all the time!"

He then laughed at me for a good 5 minutes. Then he proceeded to follow me out of the building whenever possible to witness my sneezing reaction.

My theory is that it's a reaction to sudden bright light that causes an impulse for the eyes to close which is crossed with an impulse to sneeze because you have to close your eyes when you sneeze. It is funny. I do laugh at myself as well.

But I honestly think it's a white girl/boy problem from being poorly adapted to bright sun. I can tell that my skin doesn't like bright sun either. It certainly hasn't become better or worse as I've matured so I question that aspect of the study.