Why do we yawn? When you yawn, you inhale air and stretch your eardrums. That's why your ears pop when you yawn. If you yawn and at the same time stretch your whole body, that is called pandiculation. A common misconception about yawn is that people yawn when they need more oxygen. But studies have shown that no matter how much oxygen is around a person they won't yawn more or less frequently. And when people exercise and their bodies in fact do need more oxygen, they don't yawn more often. Instead, researcher say that our first answer likely lies in being "cool". When you are tired, deep brain temperatures decrease. But your brain is like a computer, it operates best at a very specific temperature. So yawning, bringing all this outside air through your ears and your mouth, cools your facial blood and actually helps cool down your brain.
