5 Facts About Sneezing That Will Blow You Away

Sneezing Reboots Your Nose

Sneezing is essentially an emergency cleaning system for the body. When irritants such as dust, smoke, strong scents, excess mucus, or viruses enter your nasal passage, sensory nerves in the nasal lining send signals to the brain and trigger the sneeze reflex. The brain then initiates a coordinated reflex involving the chest, diaphragm, throat, eyes, and facial muscles. Air is sharply drawn into the lungs and blasted out through the nose and mouth, taking those irritants with it.

Scientists sometimes compare the process to a reboot for the body, since sneezing helps reset an overwhelmed environment inside the nasal cavity. Sneezing may also help restore normal function to the tiny hairlike structures called cilia that line the nasal passages and help filter debris. Research suggests that the sudden rush of air during a sneeze temporarily stimulates the cilia, the tiny hairlike structures that line your nasal passages and beat in coordinated, wave-like motions to move mucus and trapped particles from the nasal passages.

A Sneeze Can Start Far From Your Nose

If plucking your eyebrows has ever triggered a sneeze (or at least the feeling that you’re about to), you’re not imagining it. That unexpected connection can be traced to the trigeminal nerve, the largest nerve in your head. 

This nerve is responsible for carrying sensory information from the face to the brain (and vice versa), including sensations from the nose, parts of your eyes, forehead, and eyebrows. Because those pathways are closely connected, stimulating one area can sometimes accidentally activate another. When you pluck an eyebrow hair, the sudden pain signal may be interpreted as one from nearby nasal nerve pathways, triggering the brain’s sneeze reflex. 

A similar mechanism may explain the ACHOO syndrome (Autosomal-dominant Compelling Helio Ophthalmic Outburst), also known as photic sneezing, the name given to some people’s tendency to sneeze when they’re exposed to bright sunlight. Scientists believe sudden intense light may overstimulate nerve pathways connected to the eyes and nose, causing the brain to misinterpret the signal as nasal irritation. This condition often runs in families, so while it suggests a genetic component, the exact mechanisms still aren’t yet fully understood.

Each Sneeze Contains About 40,000 Droplets

There’s a good reason coughs and sneezes spread diseases. A sneeze doesn’t just send air flying out of your body; it also shoots out around 40,000 droplets of mucus and saliva into the environment around you — roughly the same number of people that would fill a standard sports stadium. 

Those droplets span a wide range of sizes, from large visible particles to ultra-fine aerosols smaller than 5 micrometers. The smaller ones can remain suspended in the air for hours at a time, though they do, of course, also move around depending on humidity and ventilation. 

Larger droplets, meanwhile, fall out of the air much more quickly, sometimes in fewer than 10 seconds, landing within a few feet of the source. Coughs, by comparison, release roughly 3,000 droplets, so while they do both spread germs, an uncovered sneeze seems to be the one you really don’t want to be caught standing near.

You Can’t Sneeze in Your Sleep

You probably know a few people who snore in their sleep, but chances are you don’t know anyone who sneezes while they snooze, and there’s a reason for that. Despite the fact that your nasal passages can actually swell when you lie down, there tends to be less airflow and movement during sleep, meaning fewer particles are getting stirred up in the first place. 

More importantly, the same temporary muscle paralysis that occurs during REM sleep, suppressing most muscle activity, also applies to the systems behind the sneeze reflex. People can, however, still wake up because they feel the need to sneeze. If nasal irritation becomes bad enough, the brain may briefly shift the body into wakefulness so the reflex can do its thing.

There’s No Universal Way To Spell a Sneeze

Even though sneezing itself is a universal human reflex, the way people vocalize it can be influenced by language and culture. The explosive burst of air is the same basic biological process everywhere, but the sounds people make during a sneeze can vary from person to person and from culture to culture.

As a result, some different languages have developed their own sneeze sounds. English speakers commonly say “ah-choo” when they sneeze, while in France it may sound more like “at-choum.” In Japan, you might hear a sneeze sound as “hakushon,” while in Portugal it’s closer to “atchim.” Those differences reflect both slight variations in how the sneezes are actually vocalizes as well as how the sounds are interpreted and spelled.

The reactions to sneezing also vary widely across cultures. In many English-speaking countries, people say “bless you,” a custom often linked to ancient beliefs about illness or spirits, but other cultures respond differently. In Italy, for example, it’s customary to say “salute” (meaning “health”), while in others, such as Taiwan, it’s customary not to acknowledge a sneeze at all.