I'm Allergic to the Sun (or Why I Sneeze in the Sun)
The Sun Makes Me Sneeze
Do you ever find that you sneeze when you are exposed to sunlight? I used to think this was a common experience for everyone, and I spent many years of my life oblivious to the fact that most people do not sneeze as a result of being in sunlight. For as long as I can remember, I have experienced this, and one day several years ago, my boyfriend jokingly made fun of me for having a "sun allergy". He was certain I was sneezing because of allergens in the air, since I was obviously not a super tough vampire who found sunlight to be only an annoyance. So, I looked online and I found there is an established scientific term called "photic sneeze reflex" which describes a genetic anamoly of a minority of the human population. To understand photic sneeze reflex, we should also understand what causes a sneeze in the first place.
What Causes Sneezing
Usually, a sneeze is triggered by an irritation in the nose. This irritation is sensed by the trigeminal nerve, which has the function of facilitating facial sensation and motor control. The trigeminal nerve is close to the optic nerve, which connects the eyes to the brain. As the optic nerve tells the brain to constrict the pupils, the signals are also sensed by the trigeminal nerve, which incorrectly senses there is an irritant in the nose. So, if I'm outside on a particularly bright and sunny day, I will sneeze.
Complications with Photic Sneeze Reflex
Photic sneeze reflex could possibly be dangerous for people if they're driving or flying a plane, but I've never experienced long bouts of sneezing from it. Scientists suspect there is a genetic link, but experiments are still being conducted. Meanwhile, we can only speculate. If anyone ever tells you they sneeze in the sun, don't think they're wacky. I can assure you there are definitely more of us who exist.