Unless you were raised without any manners, you likely say "bless you" when someone sneezes (or some variation, like "gesundheit," which literally means "health").
Why tho? According to The Library of Congress, there are quite a few origins of this response, but they all center around the same idea: that by saying "bless you," you're protecting the sneezer from possible death after their heart stops (yes, really).
It sounds super far-fetched...but also, maybe a little possible? So what's the deal with sneezing, and what kind of impact does it have on your heart?
What *exactly* happens when you sneeze?
Think of a sneeze as a defense mechanism. "It’s an instinctual behavior designed to clear the nose of dust and debris," says Christopher Kelly, MD, a cardiologist and author of Am I Dying?!: A Complete Guide to Your Symptoms—and What to Do Next.
Basically, when the inside of your nose gets irritated, you close your eyes, take a super deep breath, and your chest muscles force air out of your lungs at high speeds, blowing through your nose and clearing out anything your body thinks shouldn’t be there, he says.
So what’s with all the heart-stopping talk?
This is one of those myths that does have a kernel of truth to it, says Benjamin S. Bleier, MD, an otolaryngologist at Mass Eye and Ear in Boston, MA.
Think about the heart’s position in the body—it’s pretty darn close to the lungs and in the chest. And taking a deep breath (which you do right before you sneeze) can activate a long nerve called the vagus nerve (it literally runs from the brain to part of the colon), says Dr. Bleier.
Among its many other responsibilities (like causing involuntary contractions in the digestive tract), the vagus nerve sends a signal to your heart to slow down, says Dr. Kelly. (Hence why a few deep breaths can help slow down your heart rate and calm you the heck down when you’re stressed.)
"In some people, the deep breath that occurs at the onset of a sneeze can activate the vagus nerve so much that the heart briefly slows down or even skips a beat," says Dr. Kelly. But for most people? "The heart will keep ticking away at its normal rate during a sneeze, with no noticeable effect."
But even if your heart skips a beat or slows down for a second, it's not really anything to worry about. "The heart beats, on average, about 70 to 90 times per minute," says Dr. Kelly. The real issue, however, is when the heart actually stops (duh):"If it stops for more than four or five seconds, you'll pass out. Longer than that, and someone better start performing CPR." But again, that won't happen from a sneeze.
The bottom line: No, your heart doesn't actually stop when you sneeze. It may slow down or skip a beat, but that's nothing to worry about. (You can keep saying "bless you" to be polite, though.)