Why does bright light cause people to sneeze

But by the time that physician H C Everett, who seems to have coined the phrase "photic sneeze reflex", wrote about it in the journal Neurology in , it seems as if quite a bit more was known about the condition. For one thing, it was known to be somewhat more common than Sedan had assumed.

The tendency of some people to sneeze in response to bright light wasn't only just noticed in the last century; the Greek philosopher and scientist Aristotle observed the phenomenon as well. In his Book of Problems, he or possibly his students asked, "why does the heat of the Sun provoke sneezing, and not the heat of the fire?

The heat of a fire, on the other hand, not only vaporises those fluids, but also consumes them, thus drying out the nose, which actually inhibits a sneeze. Never mind that he wasn't exactly spot on either in the cause for the sunny sneeze — it's light, not heat — nor in the explanation, but it means that the reflex was known to some perhaps as early as the third century BC. We now know quite a bit more about the biology that underlies the photic sneeze reflex. For example, the reflex is now also known by the hilariously apt acronym Achoo, which stands for Autosomal Dominant Compelling Helio-opthalmic Outburst.

In , a group of geneticists led by Nicholas Eriksson of the genetic testing company 23andMe identified two single nucleotide polymorphisms, or SNPs, that were associated with the sunny sneeze by assessing the genotypes of nearly 10, 23andMe customers.

These SNPs are alterations to single letters within a person's genetic library. One is called rs and the other, about which there is somewhat less statistical certainty, is called rs One of them is located nearby a gene known to be involved in light-induced epileptic seizures, which raises the possibility that there might be some kind of biological link between the two syndromes. Driving from dark tunnels into the light can be dangerous if you're a photic sneezer Credit: Getty Images.

A year-old woman referred to him had a history of suffering from seizures, both spontaneous and in response to light. She described herself as an "easy sneezer", but never really noticed if her sneezes could be a response to light as well. However, it may be some time before these questions are answered. She is a lawyer by education, a poet by accident, and a painter by shaukh. You can find her on Instagram devruparakshit. Follow us. Newsletter Exclusive news delivered to your inbox. Mar 30, Share.

Image Credit: Masterfile. See all articles by Devrupa. Latest Science articles. Early To Rise. Pagon, a professor of pediatrics at the University of Washington, explains. 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.