Why do bright lights make me sneeze

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.

To find out, Morris shined some bright lights into her eyes in a variety of different ways. Because its prevalence is higher in individuals with a family history of the disorder, the handful of scientists who have studied the phenomena suspect a genetic, autosomal dominant — a person needs only one parent with the condition to inherit it. Photic sneeze reflex is a relatively harmless disorder that causes people to sneeze in bright light after being in a dark space.

A regular sneeze is a violent preemptive strike. It is a reflex meant to protect the nasal passages and lungs from infectious agents or irritants. An estimated 40, microscopic particles can spew out of the human body — at a rate 85 percent the speed of sound — each time we sneeze.

How delightful. But why did evolution decide for some of us to sneeze when accosted by bright light? Answer: Likely, no. But large, in-depth studies on this or other theories are lacking, with most photic sneeze reflex research based on small case studies of single families or small groups of photic sneezers. Subscribe to our Science Newsletter to explore the wide worlds of science, health and technology.

For example, in , a Swiss study found greater stimulation of the primary and secondary visual cortex — regions of the brain that processes visual information — of 10 photic sneezers when exposed to various wavelengths of light compared to those who do not have the reflex.

The optic nerve feeds information to the visual cortex. Those nerves exit the eye via the trigeminal nerve. In that study, however, the 13 individuals analyzed were all from the same family. Taking a closer look at photic sneeze reflex could reveal important insights on other diseases. His lab has collected surveys on photic sneeze reflex for years but has lacked funding to analyze the information in depth.

Cross the sneeze reflex with the pupillary light reflex and you might get both responses to the singe stimulus of a bright light. Scientists don't yet fully understand this phenomenon.

But it's fairly certain that its alternative name is sure to produce an uncontrollable groan reflex: autosomal dominant compelling helio-opthalmic outburst, or ACHOO, syndrome. Seriously, it's in the literature.