Why do you sneeze when walking into the sun?

Answer 1

Reflexive sneezing induced by light, and sunlight in particular, is estimated to occur in 18 to 35 percent of the population and is known as the photic sneeze reflex (PSR) or the ACHOO (autosomal dominant compulsive helio-ophthalmic outbursts of sneezing) syndrome. Its genetic nature has been known for at least the last 25 years; it is periodically discussed in the medical literature and lay press. Observations that emerging from dim light into sunlight or turning to face directly into the sun commonly triggers the reflex prompted early inquiries into the trait. The number of induced sneezes--which seems to be genetically mediated and can be predicted within a family--is constant from episode to episode and typically numbers two or three.

Some consequences of the PSR include danger to automobile drivers when emerging from dim light, such as a tunnel, into full sunlight, and disruption of outdoor group photos. More recently, reports in publications oriented to military medicine have noted the potential danger to pilots experiencing the PSR. In fact, studies conducted by the military revealed that the PSR is not mediated by specific wavelengths of light and thus cannot be mitigated by the use of filtering lenses; rather the investigators concluded that the PSR is induced by changes in light intensity. Others have not found flickering light to precipitate the PSR. Exactly how sunlight causes some people to sneeze remains unknown.

Answer 2

i have no idea. I think it's

genetic because my grandfather and I both sneeze when we look at bright lights. Its not jus the sunlight, it's any bright light.

One theory I heard was that the bright light sneeze was a hang-over from our caveman days: emerging from a dirty cave into sunlight, a cave dweller would sneeze to clear his sinus passages, ensuring he could better sense game and/or danger.

Answer 3

When you walk into sunlight, the bright light can trigger a photic sneeze reflex in some people. This reflex causes the nerve signals from the eyes to cross paths with the nerves that control sneezing, resulting in a sneeze. It is known as the Autosomal Dominant Compelling Helio-Ophthalmic Outburst (ACHOO) syndrome.

Answer 4

There are many reasons why sunlight makes you sneeze. You squint your eyes causing tension in your sinus cavity causing the sneeze.

Answer 5

It is the dust which gets activated by the sun's energy which makes us sneeze.

Answer 6

The photic sneeze reflex causes you to sneeze in response to various stimuli, including bright light. No one really knows why.

Answer 7

it's called photic sneeze reflex. it happens to 1/4 of people, mostly in caucasions. you wont be able to fly a combat plane if you have it.

Answer 8

They sneeze into the sun because they just do.