Question

what is the reason behind our yawning

Answer 1

One is that when we are bored or tired, we just don't breathe as deeply as we usually do. As this theory goes, ourbodies take in less oxygen becauseour breathing has slowed. Therefore,yawning helps us bring more oxygen into the blood and move more carbon dioxide out of the blood.

Answer 2

The lack of oxygen in our body is the main reason for our yawning. Our brain receives less oxygen which makes it unable to do any work. So we yawn making us understand that we are tired.