Light makes you sneeze? Don’t worry, there are more people like you

Have you noticed that some people tend to start sneezing when exposed to the sun's rays?

It happens almost every week: I leave the doorway of my house and, just when my face crosses the border where the shadow of the porch gives way to direct sunlight, a tingling appears that starts near the eyes and advances to the nose to end up becoming one or more sneezes.

It has happened to me for as long as I can remember, usually when I have been in the shade for a long time and suddenly I am exposed to intense sunlight. It took me many years to learn that this phenomenon is nothing like the "sun allergy" I thought I had, which is called "sun allergy". I thought I had, which is called bright light sneeze reflex, o photic sneezingIt is fixed in the DNA of many people: 18% to 35% of the population experiences it.

The false Allergy to the sun

The idea that foreign stimuli produce the uncontrollable urge to sneeze is often directly associated with types of allergies. Perhaps because of this, some people believe that their propensity to sneeze right after coming into direct contact with a strong light source is due to some sort of foreign allergy, something that does little to explain why they need to sneeze at the moment of being illuminated and not during the entire time they are under that light source.

Other people don't even stop to think about whether sneezing because of light is strange or not; they assume it happens to everyone and, when they first notice that others notice their sneezing because of light, they wonder if they are playing a joke on them.

Both possibilities are very reasonable, since the propensity for photic sneezing is a characteristic that is sufficiently rare to be considered rare, but not so problematic as to be considered a disease-like condition. but, at the same time, it does not give so many problems to be considered something like a disease. The bright light sneeze reflex may be somewhat annoying on the rare occasions when it is expressed, but it is not a form of sunlight allergy.

What is photic sneezing?

The photic sneezing reflex is a genetically inherited characteristic which is expressed in the appearance of the impulse (automatic and involuntary) to sneeze when the area of the face is suddenly exposed to a source of intense light.

It is necessary to keep in mind that what produces this sneezing is not so much the intense light itself as the contrast experienced between the shaded area in which one has been before and the area exposed to direct light in which one is afterwards. That is why this false "sun allergy" is only expressed during the first seconds or minutes after moving to a well-lit place.

Causes of photic sneezing

The phenomenon of the photic sneeze reflex is relatively common, as it could affect a third of the population, but despite this, more research is still needed to find out what triggers these sneezes.

There are, however, several possible causes of the photic sneeze reflex. The most widely accepted is one that has to do with the trigeminal nerve, one of the cerebral nerves that come directly from the brain without passing through the spinal cord that runs along the spinal column.

This group of neurons fulfills the function of both informing the brain of things happening in other parts of the body and acting as a channel through which the brain transmits orders to other organs. Specifically, one of the tasks of the trigeminal nerve is to detect signs of irritation in the nose to initiate the necessary steps to start sneezing right afterward.

In people who have inherited the photic sneeze reflex, the trigeminal nerve may be closer than normal to the ocular nerve in each half of the face, so that it "intercepts" information from the latter and confuses it with data coming from the nose. Thus, when you go into sudden exposure to intense light, the trigeminal nerve would be taking this surge of sensory data as a cue that something is going on in the nose; hence the sneezing.

Is it dangerous to have this reflex?

Currently, the only context in which photic sneezing is considered to be potentially dangerous is in the piloting of combat aircraft.. 

For the rest of us, we can just use extra caution when driving.We can celebrate the small eccentricities of our organism by wearing sunglasses, for example.