Bless You and Gesundheit - Why Do We Say This When People Sneeze?

Your body tends to tense up when you sneeze (the power has to come from somewhere right?)  and if you sneeze in "serial" (over and over again in succession) then you can find yourself in perpetual "tension" where "catching" a breath is hard just by the redundancies and close proximity of each sneeze.

The heart may stop only if the sneeze stops your oxygen flow too much but that would require something like sneezing over and over for 30 minutes or something crazy like that.
You'd likely pass out first then return to a "relaxed" state and breathing normally.

Some believe saying “God Bless You” comes from an ancient story told that states that man once thought the soul of a person was actually in the form of “air” and resided in a persons body, primarily the head itself.

The sneeze was thought to expel the soul from the body accidentally, unless God blessed you, preventing this from happening.

There is often a pause and a moment of awareness that your about to sneeze which gave you time to stop it.

This blessing was for the person about to sneeze and anyone around them. This is, however, just a superstition, a myth but an interesting idea/story!

The scientific explanation makes the most sense to me and explains what the body does.
The immune system is constantly trying to break down  things that somehow got in there and shouldn’t be (white cells break down toxins in the body and “invaders”).

When possible, the body also has other defense mechanisms in place to protect you.
The most efficient for something entering the olfactory (nose) is to get rid of it before the body has to use up resources to break it down or worse, something that may not be so easy to rid the body of!

A sneeze is often taken for granted but every time you sneeze keep in mind- your body just had your back!

Marisawright  (copied from comments section)

I've heard it said that if you try to suppress a sneeze it can be dangerous. True or old wives' tale? But since you say a sneeze is very powerful, maybe it is true.

If you hold your nose but the sneeze prevails (this has happened to me) then it could damage a membrane or cause a nose bleed (rare).

Many actually experience a moment of light-headed-ness or a painful sensation in the nasal cavity- this is because your actually containing a "Grenade" made of saliva and dropplets forced out of your nose, lungs, and anything between the two.

It could also cause something worse depending on the strength your body puts forth to expel it.
Another thing it could cause is carbon dioxide to enter the brain much like holding your breath and pushing on your chest.

The pressure caused can cause Co (your body creates when you breath out) instead of oxygen to enter the blood stream and although this isn't necessarily dangerous it's what causes that light-headed-ness (also note being high in any way is the result (the feeling) of the brain suffocating.

To answer this question, based on the aforementioned, I'd say it's not necessarily dangerous, but potentially.

Based on your health, the state of your nose and internal structures, lung capacity and so forth it could be or it likely isn't- but I don't recommend it either way- it can lead to a very painful (all be it temporary) condition where your nasal cavity and lungs hurt.

I doubt this would truly be dangerous- maybe not comfortable and could cause you to become light headed. I wouldn't recommend you let a sneeze pursue course if your eating or drinking something, however, as this will cause a bullet or grenade effect, and holding it in armed with grape-nuts cereal could blow your teeth out (I'm kidding but it will feel that way!).

One situation this may actually be dangerous in is when working with machinery, driving, swimming, or anything that requires your wits- as holding a sneeze before putting your hand near a sharp blade or while cutting something, you could get light headed, lose attention enough to cause an accident.

This is also true of continuing to work during a sneeze- luckily most sneezes come with a warning (the breathing in fast and pressurizing it period last about a second before the violent sneeze happens). Sometimes you don't get a warning like when a lot of dust is collecting around you and the body freaks out.

In driving it's likely you could become light headed which isn't good but it's the tearing up eyes that may be the most dangerous there.

It's circumstantial and dependent on the person but there is enough potential for it to be yes.
How's that for an answer :)
 
Jerrico