Answers:
here are the most adjectives thoughts on it
Because surrounded by the "matured days" a sneeze be thought to represent an evil spirit exiting your body..so you have be "blessed" . Mostly used during the "witch hunt" days in hasty fused states.
I don't know how long ago it started but when it did start it be because inhabitants final consequently thought that your organs stop when you sneeze and they would vote "God bless you" hoping to retrieve the people life span. Now individuals enjoy shortened it to "Bless You", and although we immediately know better and that not a soul dies from a sneeze and your heart doesn't really stop, we a short time ago articulate it out of politeness.
Hundreds of years ago contained by Western Europe, it be thought that the soul briefly gone the body during a sneeze. Saying 'God bless you" be thought to protect the soul.
On a side data, masses Native Americans believed that a sneeze be a form of a curse. In that culture, the proper response be 'May you die also.".