When you go to sleep each night, your mind goes on a sort of sleep roller coaster. As you sleep, your brain passes through different sleep stages again and again.

Over the course of a typical night, your brain cycles back and forth through the various stages of sleep four to five times!

Most dreaming occurs during the stage of deepest sleep, called “Rapid Eye Movement” or “REM.” During REM, our eyes begin to move around quickly under our eyelids.

If you have ever watched people sleeping (even family pets!), then you may have noticed their twitching eyelids. This is a perfectly normal part of REM sleep.

Researchers used to believe that people dreamed only during REM, but most experts now agree that dreams can occur at any time during the sleep cycle.

So why do we dream? For centuries, humans have wondered about the meaning and purpose of dreams.

Despite improvements in medical technology and sleep research, experts today still have not reached a conclusion about why people dream. They have, however, developed some interesting theories.

Some experts believe dreams are a way to process all the events and emotions we experience throughout the day. They believe dreams play an important role in our physical, mental and emotional health.

Similarly, other experts claim dreams are a form of problem-solving. They believe our dreams provide us with a safe place to work through problems, questions and dilemmas in our lives.

Other researchers claim dreams are simply a bodily function, much like blinking or burping. Researchers may not be able to agree on why we dream, but they can all agree on one thing: We all do it.

It’s probably a good thing that we dream since we spend a lot of time asleep. Though we may not call it a hobby, we sleep about one-third of our lives. On average, most people sleep about eight hours per night.

When you do the math, you find that most humans sleep approximately 122 days out of every year. By the time you’re 75 years old, you will have spent about 25 years asleep!


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    • Your comment just made our day, EmmaleeTEAM! Thanks for letting us know that you learned a lot from this Wonder and that you’re excited to explore even more Wonders of the Day! :-)

    • Hi there Angelina, what a great observation! Dreams are SUPER interesting and we all have different reactions to how we fall asleep and what we dream about! We hope you have a WONDERful day– we are so glad you joined us today! :)

    • Isn’t that fascinating to Wonder about, Ellie? We think dreams are very cool, but very curious, too! Thanks for sharing your comment about dreaming– we hope you have a WONDERful day! :)

  1. Why do people loose their memory when they hit your head really hard? I need to know. I’m reading this book in my class room named “Three times Lucky ” and in the book a character loses his memory in a car crash. Please tell me Wonderopolis!!!!!!

    • Hey there, Kennedy, that sounds like a very interesting book! We Wonder if you can Wonder with the help of an adult, or even ask your doctor the next time you’re in for a check up! We bet you’ll learn something new! :)

    • Many of us have bad dreams from time to time, Kaite, and it would be really cool if we could figure out why that happens! Sometimes it helps to talk about those dreams with a grown up, or perhaps reading instead of watching TV before bed will help, too! Thanks for sharing your comment, Wonder Friend! Keep dreaming! :)

  2. Hello Wonderopolis,
    Our second grade class really liked learning why we dream. We were just wondering why do people talk and walk in their sleep? We also wonder do all animals dream like the dog in the video?

    • Thanks for visiting us today, Mrs. Barboza’s Class! We’re glad you’ve been using your WONDERful imaginations to think about what happens when we close our eyes and our heads hit the pillow at night! We dream, we snore, we (sometimes) drool, and we even talk! How crazy!

      We are glad you’ve been exploring our Wonder and you have created some awesome questions of your own! Keep up the great work! We hope you’ll do some more research and WONDERing to find the answers to those questions! :)

  3. Wow I wonder if the reason we talk in our sleep is because we are talking in our dream and so it’s happening outside our dreams too. =)

    • What a great idea, AndriaRose! We think it’s funny to imagine talking in our sleep– but many of us here at Wonderopolis do it! We must be very chatty in our dreams! :)

      Do you dream, Wonder Friend? Sometimes we daydream, while we are awake, or dream while we’re asleep. Do you remember your dreams, AndriaRose? :)

    • You are so very welcome, Wonder Friend Rachel! Thanks for joining us to learn cool new things and Wonder! We hope you have a super duper weekend! :)

  4. When I read the part that said “dreams are a way to process all the events and emotions we experience throughout the day,” I wondered if nightmares happen when something bad happens during the day?

  5. I read the part that says that researchers had developed some interesting theories. I wonder what some of those other theories are. My teacher wonders if, since Wonder #71 was published, researchers have found any new theories?

    • Hey Mohamad! You can read more about those theories right under that paragraph! Some experts believe dreams help us process events and emotions from the day, some believe dreams are a form of problem solving, and some believe is just a normal body function! Which one of those ideas do YOU think is right? We like your idea of WONDERing about NEW dream theories! Where do you think you could look something like that up? Maybe at the library? or online with your teacher or family member? Let us know what you find out! :)

  6. I noticed that you mention researchers a LOT. I wonder why our eyes move rapidly in our sleep, and how researchers know all that they know about dreams. I also wonder why people forget their dreams.

    • Hey Alexis! Thanks for WONDERing with us today! Researchers can provide a lot of good information to answer the things we WONDER about! Where could you learn more about how they study dreams? Can you ask you librarian about any books about rapid eye movement? We WONDER what you would find out! :)

    • This reminds me of when someone told me that, if you think you didn’t have any dreams, it’s because you forget 99% of your dreams every night.

      My class wonders why that is.

      • Hey Libbey! That is a great question! We’ve wondered about dreams before – check out #71 Why Do We Dream? You’ll learn about how we sleep in different cycles. Maybe when our dream happens can impact if we remember them? Can you look up dreams with your class or your librarian? We WONDER what you would find! :)

    • He did indeed, Donavin! He looked like he was having quite a vivid dream! We WONDER what was happening in his dream! :)

  7. What causes sleep walking then? I’ve slept walked a few times and have done strange things. Once I grabbed a hairbrush, put it in the kitchen, then went back to bed while I was sleeping! i don’t remember it but my dad told me what happen.
    Why do we do it?

    • That’s a great question, Samantha! Why not enter it in the “What Are You Wondering?” section? It could end up as a new Wonder of the Day!

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Have you ever wondered…

  • Why do we dream?
  • What is Rapid Eye Movement?
  • How many days per year do most humans spend asleep?

Wonder Gallery

Wonder #71- Sleep Static ImageVimeo Video

Try It Out

Need a place to write down your dreams so you don’t forget them? Try making your own dream journal.

A dream journal is a special place where you can keep a record of dreams when you wake up. You can even add illustrations by drawing pictures, too!


Still Wondering

Are you a poet and don’t even know it? Try your hand at “found poetry” with the Word Mover for “I Have a Dream” student interactive from ReadWriteThink.org.

Use the words from Martin Luther King, Jr.’s famous speech as your inspiration to create a new poem entirely your own! What dreams do you have?


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