It’s that time of year again — cold and flu season. Being sick is no fun at all, and oddly enough, some activities can encourage the reflex to sneeze.

It’s common knowledge that sneezing, also known as sternutation in the medical field, is a cleaning and clearing of the nose of bacteria and irritants.

However, it isn’t quite clear to the general public why certain things make us sneeze, like light or plucking your eyebrows, and why other factors inhibit sneezing, like thinking about not sneezing or saying something weird, like “purple elephant.”

The act of sneezing is relatively self-explanatory. There are nerve endings in the nasal linings of the nose, and when these nerve endings are tickled or irritated in some way, they send signals to the lower portion of the brain stem, explains Adam Hadhazy, an online health writer for Scienceline.org.

At this point, the brain signals the lungs to increase oxygen intake and hold it. While these muscles tighten, there is a point of eventual release through the nose that cleanses the nasal pathways.

But why is it that when you pluck your eyebrows or look at a bright light, it can cause you to sneeze?

When you pull hair out of the eyebrow, the pain receptors send signals to the trigeminal nerve, a nerve that is responsible for sensations in the face. Sometimes, the trigeminal nerve will send “impulses that reach the nerve endings inside the nose … sparking the sneezing reflex,” Neeta Ogden, a health writer for Bottom Line Health, wrote.

The same is true for bright light. This kind of sneezing is called photic sneeze reflex and occurs when a rush of light hits the pupil. The pupil will then send a signal to the optic nerve and the optic nerve sends a signal to the pupil to constrict (protecting it from harmful damage). Sometimes, when the optic nerve sends a signal to the pupil to constrict, the trigeminal nerve is exposed to the signal and interprets it as a sneeze reflex.

Sydney Thompson, a graduate student studying journalism and media communication, recommended drinking liquids to help relieve sneezing.

“I drink a lot of tea with honey to help clear out my sinuses,” Thompson said.

While you may not be able to control your sneezing, at least you know how it works.

Collegian Science Columnist Madeline Bombardi can be reached at news@collegian.com or via Twitter @madelinebombard.