[ INTRO ].

Oh hey Squeaks! I just woke up from the weirdest dream.

You were there, Squeaks, and so was our friend Dino, except he was a full-grown dinosaur! I think he was a T. rex … whew. Strange.

I wonder why I dreamed that! Dreams can seem confusing, but scientists think we have them for a reason. When we go to sleep at night, it can look like our bodies and our brains are turning off.

But while the rest of your body is resting and recharging, your brain is actually working pretty hard – and showing you dreams, like a movie going on inside your head! When you’re dreaming, some parts of your brain are switched on and working hard – like the ones that think about what you see, and some of the parts that focus on your feelings. Meanwhile, the part that does some of your more complicated thinking, like by asking great questions – like why you’re suddenly able to fly, for example – is turned off.

So if dream-you is flying, you can just enjoy the ride! While you sleep, your brain is going through a bunch of different steps, then starting over from the beginning. That happens a few times every night.

At first, you sleep very lightly. You might feel like you’re still awake, even while you’re dozing off. Then, your brain starts to slow down a little more.

Your sleep gets a little deeper. You might have a few dreams, but they’re more likely to be about what you were doing the day — nothing too nutty. But then comes the weirdest part of the night.

During this step, your breathing and your heart beat slow down a little. Your body is completely still, but behind your eyelids, your eyes are moving around a lot, in what we call rapid eye movement, or REM sleep for short. REM sleep is really important for your body, and it’s when you’ll have the most epic, story-like dreams, and the ones that you’ll remember best in the morning.

Some people remember lots of crazy details from their dreams, and some people don’t. But even if you don’t remember your dreams very well, you still have them. Everybody does, and some other animals do too!

All mammals – animals like dogs and cats and humans and rats – experience REM sleep, and so do some birds. During sleep, our brains sort out all the information we’ve been taking in while we’re awake. Some of your dreams might be about things that happened during the day, like playing with your friends at school.

But then your dreams can start to jump into all kinds of wacky stories. Maybe you’re bouncing around on the moon, or having a conversation with a giant talking lemon! So why do our brains put on this big production for us every night?

We may never know for sure, but scientists have a few ideas. Over the course of a day, you’re hearing and seeing and smelling millions of little details about the world around you. And while you sleep, your brain needs to find the most important things you’ve just learned, so that it can store it away in your memory for good.

That way, you’ll be able to remember it for years. Some scientists think that’s what dreams are for — they help you figure out the most important things you learned during the day. That helps you remember them, and connect them with things you’ve learned before, so that you’re ready to learn more new things tomorrow!

We might also need dreams to help us sort out the feelings we’ve had during the day. If you’ve been scared or worried about something, you might have a dream about being scared or worried about a different thing at night, to help you work out how you feel. That might help you be more prepared to tackle the scary thing the next morning!

Other scientists don’t think that dreams are related to memories or feelings at all! Even though your brain still needs sleep to sort out your feelings and memories, it could be that the movies you see in your dreams just come from your brain calming down after a long day. Some people try to use dreams to help them figure out what’s bothering them, or to help them solve problems.

A lot of creative people, like people who write songs or make movies, and even scientists, get ideas in their dreams! They connect what they’ve been thinking about during the day to what they already know, and in their dreams, they’ll suddenly have an awesome idea! No matter what our brains use dreams for, we know that we need sleep to help us learn, and to help us feel great when we wake up!

And on that note …. I’m ready to enjoy whatever adventure my brain has waiting for me when I fall asleep! How about you, Squeaks?

What’s the weirdest dream you’ve ever had? Do you have any questions for us about sleeping, or anything at all? Ask a grownup to help you leave a comment below, or send us an email at kids@scishow.com.

We’ll see you next time, here at the Fort! [ OUTRO ].