# What is a dream?

An episode of [Science for Kids / Science's Not Boring: The Kids Science Podcast](https://invisiblenetwork.ai/podcast/1896928296), 4 Jul 2026, 12 min.

Audio: https://www.buzzsprout.com/2624612/episodes/19417588-what-is-a-dream.mp3

Have you ever wondered what your brain is up to when you fall asleep? Even though your body is resting, your brain is busy putting on a wild, technicolor show! We spend about six whole years of our lives dreaming, and the science behind it is absolutely unbelievable! Join Mira and Finn as they uncover the secrets of sleep and discover why our brains act like a giant filing cabinet at night. Did you know that your brain literally washes itself with a built-in dishwasher while you snooze? Or that your brain temporarily freezes your muscles so you don't jump out of bed to act out your superhero dreams? We'll dive deep into the amazing world of REM (Rapid Eye Movement) sleep and learn how nightmares are actually just helpful "fire drills" to make us braver! Plus, we will find out if animals dream, too. From rats practicing mazes in their sleep to a real-life octopus named Heidi who changes stunning colors while dreaming of catching crabs, this episode is packed with mind-blowing secrets! Get ready to explore exactly what happens in the dark.

## Transcript

[0:46] SPEAKER_00: Welcome to Science Is Not Boring by Kidopoly.com.
[0:49] SPEAKER_00: I'm Mira.
[0:50] SPEAKER_00: And I'm Finn.
[0:51] SPEAKER_00: Hey Finn, did you know your brain is a massive energy hog?
[0:55] SPEAKER_00: Even though it only weighs about three pounds, it uses 20% of your body's total energy while you are awake.
[1:02] SPEAKER_00: Wait, 20%?
[1:04] SPEAKER_00: That is a huge amount for something that just sits inside my skull all day.
[1:09] SPEAKER_00: It works hard.
[1:11] SPEAKER_00: But what is even crazier is what happens when you go to sleep.
[1:14] SPEAKER_00: Over your lifetime, you will spend about six whole years doing something completely wild.
[1:21] SPEAKER_00: Six years?
[1:22] SPEAKER_00: What is it?
[1:23] SPEAKER_00: Eating?
[1:24] SPEAKER_00: Playing video games?
[1:26] SPEAKER_00: Nope.
[1:26] SPEAKER_00: You will spend six entire years dreaming.
[1:30] SPEAKER_00: Every night, your brain puts on a strange and wonderful Technicolor show.
[1:35] SPEAKER_00: Whoa! Six years just dreaming?
[1:38] SPEAKER_00: That is almost my entire life so far.
[1:40] SPEAKER_00: Today we are diving into the incredible science of why we dream, what our brains are actually doing while our bodies rest, and how our minds literally wash themselves in the dark.
[1:51] SPEAKER_00: Brainwashing?
[1:52] SPEAKER_00: That sounds like something out of a science fiction movie.
[1:56] SPEAKER_00: It really does.
[1:57] SPEAKER_00: But the science of sleep is packed with unbelievable secrets, colour-changing octopuses, and maze-running rats.
[2:04] SPEAKER_00: Let's go! So if my body is resting, why is my brain making up all these crazy stories?
[2:10] SPEAKER_00: Why doesn't it just turn off?
[2:12] SPEAKER_00: Well, your brain cannot turn off.
[2:14] SPEAKER_00: While you sleep, it acts like a giant filing cabinet.
[2:18] SPEAKER_00: It sorts through everything you learned and experienced that day.
[2:22] SPEAKER_00: Oh, so it is like cleaning up my messy bedroom, putting all my toys back in the right bins.
[2:27] SPEAKER_00: Exactly like that.
[2:28] SPEAKER_00: It takes temporary memories from an area called the hippocampus and moves them to the neocortex for long-term storage.
[2:36] SPEAKER_00: Ha, hippocampus?
[2:38] SPEAKER_00: That sounds like a university for hippos.
[2:41] SPEAKER_00: It actually comes from the Greek word for seahorse because it is shaped exactly like one.
[2:47] SPEAKER_00: But for a long time, scientists had no clue this was happening during sleep.
[2:52] SPEAKER_00: When did they finally figure it out?
[2:54] SPEAKER_00: It happened in 1953 at the University of Chicago.
[2:58] SPEAKER_00: A scientist named Eugene Azarinsky and his professor Nathaniel Kleitman made a huge breakthrough.
[3:05] SPEAKER_00: What did they find?
[3:06] SPEAKER_00: Eugene was studying his eight-year-old son Armand while he slept.
[3:11] SPEAKER_00: He noticed that at certain times in the night, Armand's eyes darted back and forth super fast behind his closed eyelids.
[3:19] SPEAKER_00: Wait, his eyes were moving while they were closed?
[3:22] SPEAKER_00: That is a little freaky.
[3:24] SPEAKER_00: It surprised Eugene too.
[3:26] SPEAKER_00: He hooked up a machine that drew brain waves on a continuous roll of paper and found the brain was incredibly active.
[3:33] SPEAKER_00: No way! What did they call this darting eye sleep?
[3:37] SPEAKER_00: They called it rapid eye movement or rem sleep, and they realised this REM stage is when our most vivid dreams happen.
[3:45] SPEAKER_00: How much REM sleep do we get?
[3:47] SPEAKER_00: Did we just dream once a night?
[3:50] SPEAKER_00: Actually, you cycle into REM sleep multiple times, having about three to six dreams every single night.
[3:58] SPEAKER_00: Six times?
[3:59] SPEAKER_00: I only ever remember one, if I'm really lucky.
[4:02] SPEAKER_00: That is totally normal.
[4:05] SPEAKER_00: We spend about two hours dreaming in total, but we forget 90% of our dreams within ten minutes of waking up.
[4:12] SPEAKER_00: That is so much forgotten adventure.
[4:15] SPEAKER_00: What else happens to our bodies during REM sleep?
[4:18] SPEAKER_00: Something brilliant.
[4:20] SPEAKER_00: Your brain sends a signal down your spine to temporarily freeze your muscles, keeping you completely still.
[4:27] SPEAKER_00: Freeze them?
[4:29] SPEAKER_00: Why would it do that?
[4:31] SPEAKER_00: So you do not actually get up and run around trying to act out your dreams.
[4:37] SPEAKER_00: Oh, that makes sense.
[4:38] SPEAKER_00: It would be really bad if I tried to fly off my bed while dreaming about being a superhero.
[4:44] SPEAKER_00: Definitely.
[4:45] SPEAKER_00: But while your muscles are frozen, your brain is doing something even wilder.
[4:50] SPEAKER_00: It is giving itself a literal bath.
[4:53] SPEAKER_00: Wait, you mentioned brainwashing earlier.
[4:56] SPEAKER_00: Is that actually real?
[4:57] SPEAKER_00: Yes.
[4:58] SPEAKER_00: In 2012, a scientist named Micah Nedegaard discovered the gymphatic system.
[5:05] SPEAKER_00: It works just like a dishwasher for your brain.
[5:08] SPEAKER_00: A dishwasher inside my head?
[5:10] SPEAKER_00: How does it even work?
[5:12] SPEAKER_00: While you sleep, your brain cells shrink slightly, expanding the space between them by up to 60%.
[5:19] SPEAKER_00: The space expands.
[5:21] SPEAKER_00: What happens with all that extra room?
[5:24] SPEAKER_00: It creates wide channels for cerebrospinal fluid to rush in and wash away toxic waste proteins, like one called beta-amyloid, that build up during the day.
[5:34] SPEAKER_00: So if humans dream and wash their brains, do animals dream too?
[5:40] SPEAKER_00: They absolutely do! In 2001, a scientist named Matthew Wilson at MIT wanted to know what rats dream about.
[5:48] SPEAKER_00: How do you ask a rat about its dreams?
[5:51] SPEAKER_00: You look at their brain waves.
[5:53] SPEAKER_00: He had rats run through a physical maze while measuring the tiny electrical sparks in their brains.
[5:59] SPEAKER_00: Okay, and then what happened?
[6:01] SPEAKER_00: When the rats fell asleep, their brains produced the exact same electrical sequence.
[6:06] SPEAKER_00: They were literally replaying the maze in their dreams.
[6:10] SPEAKER_00: That is amazing! They were practicing their maze skills while taking a nap.
[6:14] SPEAKER_00: Exactly.
[6:15] SPEAKER_00: But it is not just mammals.
[6:17] SPEAKER_00: A marine biologist named David Sheel filmed something incredible with an octopus named Heidi.
[6:23] SPEAKER_00: Octopuses sleep?
[6:25] SPEAKER_00: What do they dream about?
[6:26] SPEAKER_00: Catching giant crabs?
[6:28] SPEAKER_00: Probably.
[6:29] SPEAKER_00: Octopuses have special cells called chromatophores that let them change colour.
[6:34] SPEAKER_00: While Heidi was fast asleep clinging to her tank, she started flashing different colours.
[6:39] SPEAKER_00: No way.
[6:40] SPEAKER_00: She changed colour in her sleep.
[6:42] SPEAKER_00: Yes.
[6:43] SPEAKER_00: She went from pale white to a dark, rippling magenta, and even made her skin look bumpy and geometric.
[6:50] SPEAKER_00: Dr.
[6:50] SPEAKER_00: Sheel said it looked just like she was dreaming of hunting a crab.
[6:54] SPEAKER_00: That is like watching her dreams play out on her skin like a movie screen.
[6:58] SPEAKER_00: It really is.
[6:59] SPEAKER_00: From rats to octopuses, it seems like many amazing brains use dreams to practice and sort through their day.
[7:05] SPEAKER_00: So if dreams are just for practising and saving memories, why do we sometimes have scary dreams?
[7:12] SPEAKER_00: I don't want to practice being chased by a monster.
[7:14] SPEAKER_00: That is a really great question.
[7:17] SPEAKER_00: Scientists think dreams are also a safe space for our brains to process big, heavy emotions.
[7:23] SPEAKER_00: So if I am nervous about a big math test, my brain makes up a story about it.
[7:28] SPEAKER_00: Yes.
[7:29] SPEAKER_00: An area of your brain called the amygdala is super active during REM sleep.
[7:34] SPEAKER_00: Sometimes a nightmare is just your brain running a test simulation, like a fire drill.
[7:40] SPEAKER_00: A fire drill in my brain.
[7:42] SPEAKER_00: Exactly.
[7:43] SPEAKER_00: Even if a dream feels scary, it is just your brain practicing how to handle tough situations.
[7:50] SPEAKER_00: It is not real.
[7:51] SPEAKER_00: And it is actually helping you grow braver for the real world.
[7:55] SPEAKER_00: That makes me feel a lot better about bad dreams.
[7:58] SPEAKER_00: They are just practice mode.
[7:59] SPEAKER_00: You got it.
[8:01] SPEAKER_00: And here is a wild fun fact about all that nighttime work.
[8:05] SPEAKER_00: Remember how we said your brain uses 20% of your energy?
[8:09] SPEAKER_00: Wait, really?
[8:10] SPEAKER_00: Does it still use that much energy even when we are fast asleep?
[8:14] SPEAKER_00: It sure does.
[8:15] SPEAKER_00: Because it is doing so much memory filing and cleaning, it uses almost as much energy asleep as it does when you are fully awake.
[8:23] SPEAKER_00: That is incredible! My brain is acting like a busy power plant just to put on all these dream movies.
[8:30] SPEAKER_00: It totally is.
[8:31] SPEAKER_00: Sleep is when your brain does its most important filing, cleaning and repairing.
[8:36] SPEAKER_00: A good night's sleep literally makes you smarter, happier, and healthier.
[8:41] SPEAKER_00: I am definitely never complaining about bedtime again.
[8:44] SPEAKER_00: Alright, Finn, time for the quiz.
[8:46] SPEAKER_00: Are you ready?
[8:48] SPEAKER_00: Okay, I'm ready.
[8:49] SPEAKER_00: Let's see how much I remembered.
[8:51] SPEAKER_00: First question.
[8:53] SPEAKER_00: What year did Eugene Azarinsky and Nathaniel Kleitman discover REM sleep?
[9:01] SPEAKER_00: Next one.
[9:02] SPEAKER_00: What do the letters R E M stand for?
[9:06] SPEAKER_00: Question 3.
[9:07] SPEAKER_00: What kind of animal dreamed about running a maze in the MIT study?
[9:15] SPEAKER_00: Here's number four.
[9:16] SPEAKER_00: What was the name of the octopus that changed colour while she was sleeping?
[9:24] SPEAKER_00: Last question.
[9:26] SPEAKER_00: How much does the space between brain cells expand to let washing fluid in during sleep?
[9:35] SPEAKER_00: Great job.
[9:36] SPEAKER_00: Let's see how you did.
[9:38] SPEAKER_00: The first answer is they discovered REM sleep in 1953.
[9:43] SPEAKER_00: For question two, REM stands for rapid eye movement.
[9:51] SPEAKER_00: Number three, the answer is rats.
[9:55] SPEAKER_00: They replayed the maze in their dreams.
[9:57] SPEAKER_00: Question four.
[9:58] SPEAKER_00: The colour changing octopus was named Heidi.
[10:02] SPEAKER_00: And the final answer is the space between them expands by up to 60% to wash away toxins.
[10:09] SPEAKER_00: I really cannot believe how much heavy lifting my brain does when I am supposedly just resting.
[10:15] SPEAKER_00: Right?
[10:16] SPEAKER_00: Between filing away memories, washing out toxins, and putting on a Technicolor dream show, your brain is the ultimate multitasker.
[10:25] SPEAKER_00: I just love the idea of Heidi the Octopus playing out her underwater dreams right on her skin.
[10:31] SPEAKER_00: If you loved learning about Heidi and the brain's secret washing machine, we would love it if you could leave us a five-star review.
[10:39] SPEAKER_00: Just scroll down on your podcast app and tap the five stars.
[10:43] SPEAKER_00: Yeah, it helps other kids find the show so we can all learn about cool science stuff together.
[10:49] SPEAKER_00: Oh, and don't forget to check out our site, kidopoly.com.
[10:53] SPEAKER_00: We have tons of fun learning games and amazing activities waiting for you there.
[10:58] SPEAKER_00: Kidopoly.com is awesome, and if you want a shout out on the show, or just want to say hi, email us at hello at kidopoly.com.
[11:07] SPEAKER_00: We love hearing what strange and wonderful topics you are curious about.
[11:11] SPEAKER_00: Thanks for exploring the science of sleep with us today.
[11:14] SPEAKER_00: See you next time on Science is Not Boring.
[11:17] SPEAKER_00: Bye everyone.

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