A sneeze happens when something like mucus, a tiny object, or an allergen interacts with skin or the tiny hairs that line your nose.

Sneezing is a mechanism your body uses to clear the nose. When foreign matter such as dirt, pollen, smoke, or dust enters the nostrils, the nose may become irritated or tickled. When this happens, your body does what it needs to do to clear the nose — it causes a sneeze. A sneeze is one of your body’s first defenses against invading bacteria and bugs.

When a foreign particle enters your nose, it may interact with the tiny hairs and delicate skin that line your nasal passage. These particles and contaminants range from smoke, pollution, and perfume to bacteria, mold, and dander.

When the delicate lining of your nose experiences the first tinge of a foreign substance, it sends an electric signal to your brain. This signal tells your brain that the nose needs to clear itself. The brain signals your body that it’s time for a sneeze, and your body responds by preparing itself for the impending contraction. In most cases, the eyes are forced shut, the tongue moves to the roof of the mouth, and the muscles brace for the sneeze. All of this happens in just a few seconds.

Sneezing, also known as sternutation, forces water, mucus, and air from your nose with an incredible force. The sneeze can carry with it many microbes, which can spread diseases like the flu.

Sneezes also perform another vital role in the body. In 2012, researchers from the University of Pennsylvania discovered that sneezing is the nose’s natural way to “reset.” The study found that cilia, the cells that line the tissue inside the nose, are rebooted with a sneeze. In other words, a sneeze resets the entire nasal environment. What’s more, the researchers found that sneezing didn’t have the same “reset” effect on people who have chronic nasal issues like sinusitis. Figuring out how to reactive those cells may help treat these ongoing issues.

Not all sneezes happen when foreign substances enter our nostrils. Sometimes, we find ourselves bracing for a sneeze’s impact at unusual moments.

Why do we close our eyes when we sneeze?

Closing your eyes is a natural reflex your body has each time you sneeze. Despite common lore, leaving your eyes open while you sneeze will not cause your eyes to pop out of your head.

Why do we sneeze when we’re sick?

Just like our body tries to clear house when a foreign substance enters the body, it also tries to eliminate things when we’re sick. Allergies, the flu, a common cold — they can all cause a runny nose or sinus drainage. When these are present, you may experience more frequent sneezing as the body works to remove the fluids.

Why do we sneeze when we have allergies?

Dust stirred up while cleaning may make anyone sneeze. But if you are allergic to dust, you may find yourself sneezing more often when you clean because of how frequently you come into contact with dust.

The same is true for pollen, pollution, dander, mold, and other allergens. When these substances enter the body, the body responds by releasing histamine to attack the invading allergens. Histamine triggers an allergic reaction, and symptoms include sneezing, runny eyes, coughing, and runny nose.

Why do we sneeze when looking at the sun?

If you walk out into the day’s bright sun and find yourself close to a sneeze, you’re not alone. According to the National Institutes of Health, the tendency to sneeze when looking at a bright light affects up to one third of the population. This phenomenon is known as photic sneeze reflex or solar sneeze reflex.

Why do some people sneeze multiple times?

Researchers aren’t sure why some people sneeze multiple times. It may be a sign that your sneezes aren’t quite as strong as a person who only sneezes once. It could also be a sign that you have ongoing or chronic nasal stimulation or inflammation, possibly as a result of allergies.

Can orgasms cause sneezes?

Indeed, it’s possible. Researchers have discovered that some people sneeze when they have sexual thoughts or when they orgasm. It’s not clear how the two things are connected.

Sneezing can be bothersome, especially if you find yourself running through a box of tissues every allergy season. However, sneezing is rarely a sign of a serious problem.

Some people with specific conditions may experience additional symptoms or complications if they sneeze too much. For example, people with frequent nosebleeds might experience more bleeding episodes with sneezing. People with migraines may experience additional discomfort if a sneeze occurs while a headache is present.

Not every person will respond to external stimuli or allergens the same as people around them. If you don’t sneeze after walking in a hay field or taking a deep breath from a bouquet of daisies, don’t worry. Some people’s nasal passages aren’t as sensitive.

If you begin frequently sneezing and cannot pinpoint any obvious cause, make an appointment to see your doctor. While a few sneezes may not be an indication of anything worrisome, it’s always better to talk about your new symptoms and look for an underlying issue than suffer frequent sneezing.

Whether you rarely sneeze or you’re frequently reaching for tissues, it’s important that you practice proper sneeze hygiene. The water and mucus you expel with each sneeze can carry microbes and bacteria that spread illnesses.

If you have to sneeze, cover your nose and mouth with a tissue. If you can’t grab a tissue quickly, sneeze into your upper sleeve, not your hands. Then, wash your hands with soap and water before touching another surface. This will help stop the spread of germs and disease.