Why Do People Yawn When They Are Tired?

Yawns happen when we are tired because our brains need more oxygen. When you're sleepy, your brain gets less energy and needs a little boost. Yawning helps by letting in fresh air and sending out the old, tired air, it's like giving your brain a quick refresher.

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Examples

A kid yawns after sitting through a long storytime.
A person yawns while waiting for the bus, feeling really sleepy.
You see your friend yawn and start yawning too.

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Categories: Psychology · yawning· sleepiness· brain activity· contagious behavior· neuroscience