Anatomy of a Sneeze

A simple sneeze can travel up to 100 miles an hour and spray a cloud of 100,000 germs.

Sounds gross, but sneezing is actually a protective reflex that's designed to keep you healthy.

It begins when tiny nerve endings detect something irritating in your nose.

It could be bacteria, dirt, dust, or other particles that get trapped in the mucus.

The nerves transmit a signal to your brain's sneeze center, which in turn sends messages to other body parts.

The abdominal and chest muscles activate, compressing your lungs and producing a blast of air.

Then the back of your tongue elevates, partially closing the passage to your mouth and forcing the air out through both your nose and mouth.

[SNEEZE] And for that split second, your eyelid muscles are locked shut, making it impossible to keep your eyes open when you sneeze.

Not all sneezes are related to your body's defenses.

Some people sneeze in bright sunlight, during exercise, or after eating a large meal.

But the one time you'll never sneeze?

It's when you're sleeping.

That's because your sneeze nerves are snoozing, too.