Here's Why You Sneeze When You Look At The Sun

We've all had that friend who would look up at the sun and immediately sneeze. It used to be an old running joke. Funny if you're not the person and frustrating if you are that person who can't catch seem to catch a gaze without collapsing into a fierce "achoo." Still, certain things happen to your body when you hold in a sneeze, so it's always good to let them out.

Often, people may not connect sneezing with looking at the sun. Sometimes it can be difficult to distinguish from seasonal allergies. You can go outside and look up at the sky and suddenly sneeze simply due to pollen flying around. If you're allergic to dust, mold, or trees, you can find yourself randomly sneezing with irritants in the air.

Though some consider sneezing at the sight of the sun on demand to be a great party trick, there is actual science behind why this happens. A sneeze is triggered by a cranial nerve known as the trigeminal nerve (via Scientific American). Once triggered by an irritant, a sneeze is produced. Since the trigeminal nerve is close to the optic nerve, this is likely how light can produce a sneeze.

A sneeze is one of the gross things that you body does that's actually good because it typically helps expel particles out of your nose that shouldn't be there. The reason why some sneeze at the sun is purely physical. Oddly enough, yet quite aptly named, what makes people sneeze when observing bright light is known as ACHOO, autosomal dominant compelling helio-ophthalmic outburst (via Healthline). It's also known as photic sneeze reflex since light triggers the sneeze instead of what usually does, like an allergen or irritant, or when you have a cold or virus.

In addition, it's not usually one sneeze but a cascade of back-to-back sneezes. The number can range from 2-40 sneezes at a time. The condition has a genetic component so if it runs in your family, you're more likely to have it.

Though there isn't one defined cause of why some people have it, there are theories. Some researchers think having a deviated septum plays a role (via PubMed). Others think it may be due to eye tears occurring and dripping down into the nose or the optic nerve being triggered.

The unfortunate answer is there isn't anything you can do to fully stop yourself from sneezing when you look at the sun if this happens to you regularly. The fortunate news is that this strange phenomenon in and of itself is not at all harmful.

However, what happens as a result of the sneeze can be dangerous in certain situations (via BBC). For example, when driving on a sunny day, if you're going through a tunnel and emerge into bright sunlight, you may start sneezing which can hinder your view. It can also be troublesome for those that play sports.

That being said, there are some preventative measures you can take. The first is to keep your allergies at bay to cut down on sneezes from allergens which may heighten the photic sneeze reflex (via Healthline). You'll also want to create a barrier between your eyes and the sun. A large sunhat can work, but wearing dark sunglasses every time you go out is your best bet.