Science explains why random things like looking at bright lights can make you sneeze

Aside from allergies, you can sneeze at seemingly random things. I sneeze every time I start chewing a piece of gum.

It happens to other people whenever they look at a bright light or toward the sun, or even when they pluck their eyebrows or have sex.

So why does this happen?

It turns out that sneezes start in your nerves. They are one of your body's ways of keeping out irritants in your nose and throat, according to a post on the blog Penn Medicine News, which is maintained by the University of Pennsylvania.

"It's a nerve transmission that tells your brain something is in your nose that needs to come out," Dr Neil Kao, an allergy and asthma specialist at the Allergic Disease and Asthma Center in Greenville, South Carolina told WebMD.

When something enters your nose, it sets off the "sneeze sensor" in your brain, which then sends signals for you to to close your throat, eyes. and mouth. Next, your chest muscles contract and your throat muscles relax. This forces air (along with anything else) out of your mouth and nose. That's a sneeze.

However, our noses don't always get it right, and sometimes our body mistakes harmless things as an attack.

Strange sneeze triggers:

• Plucking your eyebrows is a common culprit. Dr. Melanie Grossman, an assistant clinical professor of dermatology at Columbia University, told New York Magazine's The Cut that tweezing may set off the trigeminal nerve, which passes sensations between the brain and the face.
• Exercise can set some people off on a sneeze spree. You hyperventilate when you're over-exerted, which means your nose and mouth start to dry up. Your nose compensates for this by drippings, which triggers a sneeze.
• Bright sunlight causes sneezing for a third of people. This light sensitivity is an inherited trait and is known as the "photic sneeze reflex." There's no hard evidence for why it happens, but some research suggests that the reflex that makes your pupils dilate and the reflex that makes you sneeze are connected in light-sensitive people.
• Sex may make some people sneeze too. A 2008 review in the Journal of the Royal Society of Medicine called it an "underreported phenomenon." Researchers think that the stimulation of the parasympathetic nervous system - part of the nervous system responsible for the stimulation of "rest-and-digest" or "feed and breed" activities - fires off signals that makes people sneeze either when they're thinking about or orgasming from sex.
• Alcohol. Some people sneeze after drinking alcohol, as well as other nasal symptoms. Doctors think this is probably because blood vessels in the nose dilate, resulting in mucus production, known as a form of non-allergic rhinitis.
• Chewing gum. I can't find a definitive answer for this one, but it seems to affect a fair few people. One answer I've got is that the vapour given off by minty flavours is very powerful, and this tickles the inside of your nose, triggering a sneeze.