Why do we yawn when we are tired or see others yawn?

We yawn when we are tired or see others yawn because our bodies and brains like to copy each other, just like playing tag with friends.

When you’re tired, your brain is like a sleepy cat, it needs a little help to wake up. A yawn is like stretching your mouth wide open, letting in more air and giving your brain a fresh boost of oxygen. It's as if you're saying, "Hey, brain! Time to get going again!"

Sometimes, just seeing someone else yawn is enough to make you yawn too. Your brain is like a group of friends who all start laughing at the same joke, once one person starts, it's hard to stop! This copying is called contagion, and it helps people feel more connected, like they're part of a team.

So next time you see someone yawn, you might just be joining in on a little brain-teamwork!