Why do we yawn?

why is it we need to yawn every presently and thenWhy do we yawn?
we yawn as it is the bodies means of access of getting more oxygen to the brain,to make us get the impression more livey.
When we yawn we take surrounded by air slowly and severely and then breathe out.
shortage of oxygen x
Because you're not taking in satisfactory oxygen. You usually yawn when you are tired because you don't breathe as deeply as it take more effort, so you yawn to draw from more oxygen.
There is not enough oxygen getting to the brian
To embezzle in more oxygen
We yawn because our brain desires more oxygen.
beause we just ate a big antiquated double cheese burger and a chocolate milkshake
because the brain needs more oxygen.
to thieve in more oxygen, plus your body unfolding you to go to bed.
Boredom.
Why does seeing someone else yawn craft us yawn?
B O R E yawn D
CAUSE IT PUTS AIR TO HOUR BRAIN IF YOU HAVE 1