What is sleep?

Have you ever wondered what your brain actually does when you close your eyes at night? You might be resting, but your brain is actually throwing a massive, high-speed cleaning party! Join Mira and Finn on Science is Not Boring as they uncover the wild and wacky secrets of sleep. Did you know you will spend about 25 years of your life completely asleep? It sounds like a lot of time, but sleep is a matter of life and death! Discover the shocking true story of a teenager who stayed awake for 11 straight days (and started hallucinating!), and learn about the amazing Great Frigatebird that takes 10-second micro-naps while flying high over the ocean. But the absolute coolest part? Your brain cells literally shrink at night so a special fluid can power-wash away toxic waste! That’s right, you have a built-in brain dishwasher called the Glymphatic System. Plus, find out how sleep saves your coolest memories, why your body paralyzes itself during dreams, and how clever dolphins sleep with only half their brain at a time!

Transcript

SPEAKER_00 0:48

Welcome to Science is Not Boring by Kidopoly.com. I'm Mira. And I'm Finn! Hey Finn, have you ever thought about what your body actually does when you close your eyes every single night?

SPEAKER_01 1:02

Mostly I just dream about eating infinite pizza. And I guess my body is just resting, right?

SPEAKER_00 1:09

You are definitely resting. But inside your head, your brain is actually throwing a massive high-speed cleaning party. Today, we are exploring why every animal on Earth needs sleep and the completely wild things happening in your brain when you do.

SPEAKER_01 1:26

Wait, a cleaning party in my head? That sounds so weird. It is!

SPEAKER_00 1:32

And here is a shocking number to start us off. You will spend about one-third of your entire life completely asleep. One third? No way! That is a huge amount of time! Yes, way. Imagine this! If you live to be 75 years old, you will have spent 25 straight years just lying there, completely unconscious, staring at the back of your eyelids. 25 years?

SPEAKER_01 2:02

That is longer than I've even been alive. That means I will sleep through a third of my birthdays. That seems like a giant waste of time. I could be building a million Lego sets.

SPEAKER_00 2:15

That is exactly what scientists used to think. But it turns out sleep is a matter of life and death. If you don't do it, things go very, very wrong.

SPEAKER_01 2:26

Okay, so if I am basically paralysed in bed for 25 years of my life, why do we have to do it? Why can't we just stay awake forever and get more stuff done?

SPEAKER_00 2:38

Well, we actually know exactly what happens when you do not sleep. Thanks to one of the wildest science fair projects ever, back in 1964.

SPEAKER_01 2:48

Ooh, I love a crazy experiment. What happened? Did someone drink a swimming pool full of coffee?

SPEAKER_00 2:55

No coffee allowed. A 17-year-old high school student named Randy Gardner decided to see how long he could stay awake. He was in San Diego, California, and a famous sleep researcher from Stanford University, named Dr. William Dement actually came down to monitor him. Did he make it a whole day?

SPEAKER_01 3:17

Two days?

SPEAKER_00 3:18

Thin! He stayed completely awake for 11 days and 25 minutes! That is 264 hours of zero sleep.

SPEAKER_01 3:30

11 days? That is like staying up from Monday all the way through the next week and into Friday. Did his brain melt?

SPEAKER_00 3:39

Almost. By day four, his brain was so confused that he started having extreme hallucinations. He looked at a wooden street sign and actually thought it was a real human person standing there.

SPEAKER_01 3:53

Whoa, that is so freaky. I would be terrified.

SPEAKER_00 3:57

And later, he got super paranoid and even thought he was a famous football player. His brain was literally glitching out like a broken computer.

SPEAKER_01 4:07

So your brain just stops working right if you don't shut it down.

SPEAKER_00 4:11

Exactly, because when you are awake, your brain is burning energy and creating toxic waste. Just like a car engine makes exhaust fumes. If you don't sleep, that toxic waste builds up and poisons your brain cells.

SPEAKER_01 4:26

So every animal on earth has to sleep to clear out the toxic waste. Even birds and fish.

SPEAKER_00 4:32

Yes, but they do it in some completely mind-blowing ways, because sleeping in the wild is dangerous. Let's look at the great frigate bird. It is a massive seabird with a seven-foot wingspan. Seven feet? That is taller than my dad. And taller than a door. Yep, and they have a huge problem. Unlike ducks or seagulls, their feathers are not waterproof. If they land in the ocean, they will get waterlogged and drown. So they fly over the ocean hunting for flying fish. And they can stay in the air for up to two whole months.

SPEAKER_01 5:12

Two months of non-stop flying. But wait, how do they sleep? If they fall asleep, wouldn't they just drop out of the sky and crash into the ocean?

SPEAKER_00 5:21

That is exactly what a scientist named Niels Rattenberg from the Max Planck Institute wanted to know. He literally built tiny, feather-weight brain monitors and attached them to the birds' heads to record their brain waves in the wild. And what did he find? Did they just stay awake for two months? No! He discovered they actually sleep while flying. But only for about 10 seconds at a time. They literally take micro naps high up in the sky. No way. Ten seconds? That is barely a long blink. It gets crazier. When they catch a warm updraft of wind and circle higher into the clouds, they sometimes put both halves of their brain to sleep at the exact same time while soaring.

SPEAKER_01 6:10

They sleep with their whole brain while flying. How much do they sleep in a whole day doing that?

SPEAKER_00 6:16

Only 42 minutes a day while they are in the air. That is compared to over 12 hours a day when they are safely resting on land. They just powernap their way across the ocean.

SPEAKER_01 6:28

Okay, so seabirds take crazy 10-second sky naps to survive. But what happens in my brain when I am sleeping safely in a normal bed?

SPEAKER_00 6:38

You enter a stage called slow wave deep sleep, and that is when the night shift clocks in. In 2012, a scientist named Dr. Mikein Niedergaard made a massive discovery.

SPEAKER_01 6:51

What did she find? Did she find the dream factory?

SPEAKER_00 6:54

She found the brain's secret dishwasher. It is called the gymphatic system, and what it does is absolutely wild. Haha, a dishwasher? Does it use soap and hot water? Not quite. But during deep sleep, specific helper cells in your brain, called glial cells, do something incredible. They physically shrink and contract. My brain cells shrink! Does my head get smaller? No, your skull stays exactly the same. But because the microscopic cells shrink, the empty space between your brain cells expands by an amazing 60%. It is like opening up the floodgates in a dam. Whoa, 60% is a huge gap. What happens next? Then, a clear liquid called cerebrospinal fluid rushes into your brain. Scientists use special brain scanners to see it. Large waves of this fluid wash in every 20 seconds, driven by slow brainwave rhythms.

SPEAKER_01 7:58

So my brain is literally getting power washed like a dirty driveway.

SPEAKER_00 8:03

Yes, that fluid washes away toxic waste proteins, including a bad one called amyloid beta that builds up during the day. It scrubs the deep tissues of your brain clean, carrying the trash out through your veins.

SPEAKER_01 8:17

So if the dishwasher doesn't run, that is why Randy Gardner was hallucinating street signs.

SPEAKER_00 8:23

Exactly. When you don't get enough sleep, that toxic junk stays trapped in your head. It causes serious brain fog, makes you grumpy, and scientists think it can even lead to serious memory diseases when you get much older.

SPEAKER_01 8:37

Note to self: do not skip the brain power wash. I need my brain clean.

SPEAKER_00 8:44

Good idea. Plus, sleep is when your brain hits the save button on your memories. It moves what you learn today from short-term storage into long-term storage.

SPEAKER_01 8:54

So if I learn a cool skateboard trick, I have to sleep to actually remember how to do it tomorrow.

SPEAKER_00 9:00

Precisely! Your brain actually replays the day's events while you sleep, firing the exact same neurons to lock the memory in. And during REM sleep, your brain temperature actually goes up and you dream. Oh, I love dreaming. But why don't I act out my dreams and run into walls? Because your brain literally paralyses your body. It sends a chemical signal down your spine that locks your muscles in place so you stay safe in bed. My brain paralyzes me.

SPEAKER_01 9:30

That is slightly terrifying, but also kind of awesome.

SPEAKER_00 9:34

Science is full of awesome tricks. Did you know dolphins take it a step further? They sleep with only half their brain at a time. It is called unihemispheric sleep. They keep one eye open to watch out for sharks and keep swimming to the surface to breathe, all while the other half of their brain is fast asleep. Alright, Finn, it's quiz time! Let's see how much you remember about sleep.

SPEAKER_01 9:58

Okay, I'm ready. My brain is fully washed and focused.

SPEAKER_00 10:03

First question. How much of our lives do we spend sleeping? Next one. In 1964, how many days did 17-year-old Randy Gardner stay awake? Question 3. What is the name of the seabird that can sleep for 10 seconds at a time while flying? Here's number four. In 2012, Dr. Mike and Nedegaard discovered the brain's dishwasher. What is it officially called? Last question. During deep sleep, how much does the space between your brain cells expand to let fluid wash through? Great job! Let's see how you did. The first answer is, we spend about one-third of our lives sleeping, which is roughly 25 years. For question two, Randy Gardner stayed awake for 11 straight days, or 264 hours. The answer for number three is the great frigate bird. For question four, the brain's dishwasher is called the gymphatic system. And the final answer is the space between brain cells expands by 60%.

SPEAKER_01 11:25

I am never going to look at sleeping the same way again. My brain is basically a high-tech car wash running every single night.

SPEAKER_00 11:33

It really is. And it is working hard every single night to keep you healthy, smart, and ready for the next day's adventures.

SPEAKER_01 11:42

Well, if you love learning about the brain's dishwasher as much as I did, please leave us a five-star review. Just scroll down on your podcast app and tap the stars. That's right!

SPEAKER_00 11:52

And don't forget to check out our site, kidopoly.com. We've got tons of fun learning games and activities there.

SPEAKER_01 12:00

And if you want a shout out on the show, or just want to say hi, email us at hello at kidopoly.com.

SPEAKER_00 12:07

We love hearing from you guys. Thanks for exploring the amazing science of sleep with us today.

SPEAKER_01 12:13

See you next time on Science Is Not Boring. Bye everyone!