If you think you sneeze because it is your body's way of getting rid of mucus you'd be right... but only partially.

Achoo! What you just heard was a sneeze. Sneezing can happen at any time, for a variety of reasons. Whether you’re sick, or allergic to something, or for some people; just staring at the sun.

If you think you sneeze because it is your body’s way of getting rid of mucus you’d be right… but only partially. So why exactly do we sneeze? How do sneezes happen from things other than particles? And why can’t we keep our eyes open when do it?

First, let’s start with the basics. Sneezing is your body’s way of clearing your nose. Whenever dust, germs, pollen or any other particles your nose doesn’t agree with invade your nostrils it triggers reaction. Achoo! And it sounds like that. It happens because your nose gets irritated. Sneezing is your body’s way of protecting you from things that may cause harm. But how exactly is it doing that?

When your nose becomes irritated your brain sends a signal down to your chest. From there your chest expands and contracts blasting air up to your nose and mouth. Voila! You just sneezed. Or should I say bless you? When this happens, about 5,000 particles comprised of, mucus, germs, bodily fluids and other bacteria shoot out of your
body at up to 160 km/h (100 mph)!

Sometimes our nose might take one, two or even ten tries to get all that bacteria out. Now, let’s go back into your nose. In here, there are tiny nerve endings intended to detect any unwanted particles within it.

Further up your nose are the cilia. Cilia are tiny microscopic hairs that move the mucus around your inner nasal passages. They’re triggered after you sneeze and continue to work overtime even after you say excuse me.

For several minutes your cilia will continue to move rapidly inside your nose. This provides you with a full reset of your entire nasal cavity. Not just the areas where particles might have entered.

It’s also possible for a sneeze to happen without any dust particles entering our system. Like when we’re sick. This is our body simply trying to rid of unwanted germs and fluids. Also, when we have a cold, our noses are much more sensitive to things like dust and other particles, which causes us to sneeze more often.

As for why we close our eyes during sneezing, well, it could be for any number of reasons. Scientists believe our eyes close to prevent the germs coming out of our nose from getting into our eyes. It might also have something to do with one of the many muscles that contract when we sneeze. Even then, some of us, sneeze with our eyes open.

Do you feel the urge to sneeze whenever you look directly at the sun? Well, you’re not alone. Up to one-third of the world’s population feels the same way. Science isn’t sure exactly why this is, but one scientific theory attributes it to the optical nerve being crossed with a nerve that triggers sneezing in your brain.

So seeing a super bright light produces the urge to sneeze. Weird huh?