"Bless you"

Why are these words spoken? People say these words because when a person sneezes, their heart stops, and they're wishing them good health and long life.

When did this saying originate? 

How did it originate?It began during the Roman age when they would say "Jupiter preserve you." but the term "bless you" began circulating after Pope Gregory told that to victims of the bubonic plague since sneezing was a regular symptom.

Where did this originate? This saying originated in the 6th century throughout Europe, during the bubonic plague, But now every country in the world has its own way of saying live healthy and strong after a sneeze.