Your heart does not actually stop when you sneeze. What happens is that the rhythm of your heartbeat may be briefly thrown off or interrupted, but the heart continues beating. This brief change in heart rhythm is caused by sudden changes in pressure in your chest and alterations in blood flow to the heart during a sneeze. The vagus nerve, which can slow the heart rate when stimulated, also plays a role in this temporary change. Specifically, just before you sneeze, you inhale deeply, building up pressure that affects blood flow and heart rate. When you sneeze, the pressure suddenly releases, causing a rapid change in blood flow and heart rate, which can lead to what feels like a skipped or delayed heartbeat. However, these changes are very brief, and your heart quickly returns to its normal rhythm. There is an extremely rare condition called "sneeze syncope" where the heart rate and blood pressure drop enough during a sneeze to cause dizziness or fainting, but this is not common and not the same as the heart stopping. In summary, although it might feel like your heart stops or skips a beat when you sneeze, medically your heart does not stop beating at any point during a sneeze.