October 19, 2021

I, Science

The science magazine of Imperial College

Although I am a massive fan of all this warm weather and cloudless sky, the inevitable rise in the pollen count does tend to put a downer on this time of year. However, this year I seem to be escaping the usually debilitating side effects of hay fever. I am, however, not quite as smug about this fact as I would like to be. Despite having managed to avoid the watery eyes, itchy throat and clogged sinuses I am still sneezing my head off at regular intervals.

These sneezing fits are not limited to the spring and summer months. I am a silent sufferer of an annoying and unexplained genetic condition known as the photic sneeze reflex. It really isn’t as dramatic as I make it sound but whenever I walk out into the sun, I sneeze and sneeze and sneeze. Many people ‘stare into the light’ to try and induce a sneeze they can feel brewing. However, I belong to a third of the population who posses the photic sneeze reflex and can’t help but sneeze repeatedly whenever the sun comes out to play. It is one of my parent’s faults. The trait is autosomal-dominant, and if one of my parents posses the trait (which they hopefully do or my worries about sneezing will seem rather insignificant) then half of their children will also be photic sneezers.

As many of life’s great conundrums are, this reflex remains unexplained by scientists, which has led me to lose just a little bit of faith in the power of science. Normally, the trigeminal nerve in the nose senses an irritation and makes you sneeze but the cause of sneezing fits in the absence of any irritation remains a mystery. Aristotle thought the heat of the sun was responsible, Francis Bacon (one of the many famous members of ‘photic sneezers anonymous’) cleverly closed his eyes when stepping into the sun and noted the absence of a sneezing fit. He decided that the sun’s light made your eyes water and this irritation somehow induced a sneezing fit.

Not bad guesses! But we now know that the tear duct cannot secrete tears quickly enough after exposure to bright light to cause the sneezes. The most probable answer for why some people suffer from this condition is that the cranial nerves of those with this genetic condition are a little bit muddled. The optic nerve lies in close proximity to the trigeminal nerve and functions to transmit visual information from the retina to the brain. The optic nerve senses the bright light sends signals to the brain causing the eyes to close. It is thought that this signal is sensed by the trigeminal nerve and misinterpreted by the brain as an irritation in the nose.

I have used the word ‘suffer’ quite a lot, and this is definitely an over exaggeration. I tend to be quite dramatic about these things. Thinking about it, I actually quite like sneezing so am not really sure of the reasoning behind my rant. The worst thing that happens after a bout of sun-sneezes is that people think you have the lurgy and as they happen all year round its not a great look to have. Because of the relative lack of negative side effects, no one has really spent much time or energy investigating exactly why these fits of uncontrollable sneezing happen.

But if anyone has any more ideas then let me know. Perhaps you haven’t got a dissertation topic yet? I would be glad to be a case study

By Nathan Wren