Why Your Body Yawns When You're Sleepy
Right before bedtime, your mouth opens wide, your eyes squeeze shut, and you suck in a big gulp of air. That's a yawn! Did you know you started yawning even before you were born? Babies yawn inside their mommy's tummy, months before their first birthday.
What You'll Learn
- Why your body yawns when it gets tired - What happens inside your brain during a yawn - Why yawns spread from person to person like a wave - One stretch that helps your body get ready for sleep
Your Brain Needs a Cool Breeze
Scientists think one big reason we yawn is to cool down our brain. When you get tired, your brain warms up just a little bit, like a phone that gets warm after you use it a long time. A big yawn pulls in a rush of cool air and speeds up blood flow to your head, helping cool your brain back down so it can keep working.
Stretching Wakes Up Your Muscles
Have you noticed you often stretch your arms right when you yawn? That combo even has a name: pandiculation. When you've been sitting still for a long time (like during a long car ride or right after waking up), your muscles get stiff. Stretching them tells your brain and body, 'Let's get moving again' or 'It's time to power down for sleep.'
Catching a Yawn
Have you ever yawned just because you saw someone else yawn? That's called contagious yawning, and it happens to almost everyone, even dogs can catch a yawn from their favorite human! Scientists believe this happens because our brains are wired to copy the people (and pets) we care about most.
Lions, snakes, and even fish yawn. Scientists have watched lions yawn together right before the whole pride gets up to go hunt, almost like a signal that says, 'Everybody get ready!'
Match each word to what it means.
Terms
Definitions
Drag terms onto their definitions, or click a term then click a definition to match.
Why do scientists think we yawn?
What is it called when yawning and stretching happen together?
Before bed, try a slow yawn-and-stretch combo: reach your arms up high, yawn if one comes, then relax. It can help signal to your body that sleep time is near.
Yawn Detective
For one full day, keep a small tally sheet. Every time you yawn, write down the time and what you were doing right before (waking up, watching TV, doing homework, etc). At the end of the day, look at your list: did most of your yawns happen when you were tired, bored, or about to change activities? Share your findings with a family member and ask them to try the same tally tomorrow.
Flashcards — click each card to reveal the answer
Want to keep learning?
Sign up for free to access the full curriculum — all subjects, all ages.
Start Learning Free