Question

Why we yawn when we are sleepy or drowsy?

Answer 1

A yawn is a reflex when the oxygen level in the blood drops.By yawing more oxygen enters in our system ans it is a huge breath.When we are tired we overload our body as it needs rest and thus it needs extra oxygen to keep going so yawning provide that oxygen needed.So we would keep yawning until we get some rest.

Answer 2

Answer: yawning allows us to take extra deep breath, which reduces the formation of carbon dioxide and enhances more oxygen for our body to use.