The Mind, Explained (2019) s01e02 Episode Script
Dreams
This is a video of a dream.
One created by a computer.
It recorded the brain patterns of people when they were awake and looking at hundreds of different pictures.
When those people were asleep, the program tried to reverse-engineer their brain patterns back into images.
When the subjects awoke, many of their descriptions matched.
One said they saw a hall with female figures in it.
Another reported seeing a page covered in writing.
This experiment was just the latest attempt to catch a glimpse of the dream world.
For thousands of years, humans have seen dreams as mystical, or as some kind of window into our deeper selves.
They've reportedly inspired great literature, like Dr.
Jekyll and Mr.
Hyde.
Scientific breakthroughs, like the arrangement of the periodic table of elements and hits like the Rolling Stones' "Satisfaction.
" I actually dreamt the damn thing.
But hearing about other people's dreams can be really boring.
If I go to a party and tell someone I study dreams, almost without exception the next eight words out of their mouth are "Oh, I had the most amazing dream.
" And then they tell me this really stupid, uninteresting dream.
Do our dreams have any meaning or serve any purpose? Why do we dream? Oh, I've never had a dream like that before.
Our dreams are constructed entirely from our memories.
And you, and you, and you were there.
It's a dream they dreamed of sailing that beautiful sea.
Sometimes when I eat a lot of cheese, I dream a lot.
That was a dream, I think, but at the same time, it seemed so real.
And when she awoke, she realized it was all a dream.
In this Salvador Dalà masterpiece, a woman is woken by a passing bee, and her brain makes up an elaborate dream to explain the buzz and the sting: roaring tigers and the stab of a bayonet.
Dalà loved dreams.
He said his best ideas came from them.
And this particular painting, Dream Caused by the Flight of a Bee Around a Pomegranate a Second Before Waking, reflected a common view of dreams in 1944.
But they didn't actually happen during sleep.
When you woke up, the entire dream happened in that moment of awakening.
And we now know that that's not the case.
Before we fall asleep, our brains are a mess of chattering neurons.
And all that electrical activity creates chaotic electromagnetic waves.
Kind of like there's wind on the surface of the water, a lot of little white caps.
As we fall asleep, um, and as we lose consciousness, it's like the wind has quieted down and you see the undulating waves beneath it.
Activity all across the brain decreases dramatically.
If you wake people up out of this state and ask them what they were thinking, they'll say, "Nothing, let me go back to sleep.
" But then, an hour and a half later, something odd happens.
The brain roars back to life.
Our brain waves look exactly like we're awake.
Neurons are talking to each other, sending out signals to move and speak and jump.
But a tiny area of our brain stem called the pons stops us from moving around.
Our bodies are temporarily paralyzed, except for our eyes.
That's called rapid eye movement sleep.
In rare cases, that spot in the brain stem malfunctions with pretty scary results.
But the comedian Mike Birbiglia has turned it into a regular joke.
This is a real sleep disorder that you suffer from where you physically act out your dreams.
Yeah, it's called REM behavior disorder, which means I sleep in a sleeping bag up to my neck and I wear mittens so I can't open the sleeping bag.
But for most people, only the eyes act out their dreams.
If they were dreaming that they were watching a tennis game, their eyes will go back and forth and back and forth, and if they were dreaming that they were climbing stairs, your eyes will go up, up, up, up.
We don't make up our dreams in the moment of awakening, we experience them as we sleep.
The brain in REM sleep looks uniquely different from any other time in our day or night.
One area of the brain that's off is the logical judgment filter.
So that's probably why our dreams are so bizarre and don't make any sense.
And the entire emotional part of the brain lights up like a fire even now more active than during waking.
So it looks when we're in REM sleep, the emotional brain is cranked up and the reasoning brain is cranked down, and that's certainly how our dreams tend to feel.
It looks like we spend about a fifth of the time we sleep dreaming.
But most of those dreams are forgotten.
When people ask me, "How can I remember my dreams?" I say drink three large glasses of water before you go to bed.
If they do, they're going to wake up multiple times during the night and they'll discover that they do remember dreams.
But it's still hard because during sleep, we have much lower levels of norepinephrine.
That's a chemical messenger that causes us to feel awake and alert.
And in the brain, it helps us form memories.
Our levels of another chemical, serotonin, plummet too.
And it looks like that when serotonin release is shut off, it biases the brain to think that whatever it's observing, whatever it's connecting, uh, is important.
When we wake, we're left with a hazy impression of something profound.
And we see this across thousands of years of history.
We see this across hundreds of cultures.
These clay cylinders are the oldest surviving record of a dream, one from a Mesopotamian ruler.
The ruler exclaims, "Profound things came suddenly to me, but the meaning I do not understand.
Well, I have to tell her about this.
" His dream interpreter explains that a god is telling him to build this temple.
Go back a couple thousand years.
There was sort of unanimous agreement that dreams were messages from the gods.
They were portents, they were warnings, they were instructions.
Many ancient civilizations created huge manuals to decipher them, like this one, written in Egypt 3,000 years ago.
It proclaimed, "If a man sees himself in a dream baring his own bottom, it means that he will be poor in the end.
" In ancient Egyptian, the word for "bottom" and "end" sounds the same.
Puns were a big part of dream interpretation in Egypt.
In the 2nd Century A.
D.
, a man named Artemidorus became the first real dream researcher.
His dream guide was based on scores of interviews from all over the Roman Empire.
The belly button portends the death of your parents.
If a widow dreams she has a beard, she'll get a second husband.
Cakes without cheese are good.
Cakes with cheese signify deceit.
The specific meanings changed over time, but the belief that there was meaning held for hundreds of years.
Then, in the late 1600s, European scholars started to look down their noses at dream interpretation.
The British philosopher John Locke called dreams "incoherent," "frivolous," and "irrational.
" By the reign of Queen Victoria, it was a popular belief that eating certain foods and the resulting indigestion caused the wildest dreams.
In A Christmas Carol, when Scrooge sees an apparition of his former business partner, he says, "You may be an undigested bit of beef, a fragment of underdone potato.
" In 1899, two books were published that would change the study of dreams.
One was by Santiago Ramòn y Cajal, the father of modern neuroscience.
His book spelled out the idea that neurons were the basic units of the nervous system.
Experiments by other scientists showed that these neurons communicate using electrical signals.
In the 1930s, one surgeon zapped the exposed brains of patients with electricity, and they experienced sudden visions.
You are about to hear the actual words of patients in response to this stimulus.
Now I see them, they're laughing.
I hear children's voices.
I see the whole thing.
A guy coming through the fence at a baseball game.
Some scientists still believe dreams are like this, random electrical storms in our sleeping brains that created equally random and essentially meaningless visions.
But the other book, The Interpretation of Dreams by Sigmund Freud, claimed that dreams were so much more.
Dream images were "disguised representations" of our innermost desires.
A lot of these symbols were sexual: climbing stairs, swords, suitcases, sticks, tearing branches off trees, chapels, balloons, a woman's hat, fish, fountains, reptiles, airplanes, any complicated machine, and the number 3.
One of Freud's earliest supporters, Carl Jung, also believed dreams were messages from the subconscious, but they weren't all about sex.
Instead, they contained characters that represented aspects of our inner lives: Anxiety, purity, wisdom.
In getting away from the concept that dreams were from the gods or that dreams reflected stomach ailments, that was all progress.
But the theory that symbols and dreams have universal meanings is rejected by most scientists today.
Still, Freud and Jung had started a movement.
Dreams were once again interesting.
In 1933, copies of The Interpretation of Dreams lay burning in Nazi bonfires, like hundreds of other books by Jewish authors.
That same year, German journalist Charlotte Beradt began to secretly collect the dreams of her fellow citizens.
They were full of corpses and torture.
Household items like ovens and lamps betrayed their owners to the Nazis.
The protective walls of houses vanished into thin air.
Dreams that now seem tragically prophetic.
In the decades since, researchers have meticulously compiled thousands and thousands of dreams in dozens of countries, and they noticed some patterns.
Dreams of being chased, of having sex, and of falling are some of the most popular.
About one in five people have dreams of their teeth falling out.
Men are more likely to dream about other men while women dream about both sexes pretty equally.
Children are more likely to dream about animals.
And only about 5% of dreams are set in locations the dreamer doesn't recognize.
In fact, most things people dream come from memories of their waking lives, like at the end of The Wizard of Oz, when Dorothy is told it was all a dream.
She realizes that the characters from that dream were all from her real life.
And you, and you, and you and you were there.
Oh.
Although everybody knows that our dreams relate strongly to the events that happened during the day, there were actually no good studies that had shown the incorporation of our waking life into our dreams.
So Dr.
Stickgold recruited a bunch of students to play Tetris for three to four hours a day.
And lo and behold, they started dreaming about Tetris-like images.
He also studied people with memory disorders who couldn't even remember what Tetris was after playing it.
But the game still found its way into their dreams.
They reported things like seeing shapes on a screen or seeing things that looked like rectangles turned on their sides.
And take that dream of losing teeth.
A lot of ancient dream manuals mention this dream.
And most say it portends the death of a family member or employee.
Freud thought it represented castration as a punishment for masturbating.
And in one 1984 study of dreams, people who dreamed about their teeth falling out tended to be more anxious, but they also just thought about their teeth more than the average person.
Kids probably dream more about animals because their days are filled with them.
Men might dream more about men because that's who they worry about most when they're awake.
The dreams of Germans as Hitler came to power weren't prophecies, but they also weren't completely random.
They were reflections of the dreamers' waking fears.
I don't think the dreaming brain is trying to give our conscious mind some sort of a message.
But there is a story there, and it's created from our own memories and our own emotions.
One could think of dreams as being sort of an idiosyncratic, personal Rorschach test.
The things that I really enjoy doing quite a bit are talking to dream characters.
It feels like a reflection of what I don't know I'm thinking.
Allison McCarthy is a lucid dreamer, which means she can consciously influence her dreams.
She says anyone can lucid-dream, but Lucid dreaming is a skill like any other skill.
It's like basketball.
You're not just going to be, um, the best at that skill overnight.
First, you have to practice remembering your dreams.
Allison keeps detailed records.
Dream recall, the most important thing.
Each square represents one dream.
I fly with giraffes quite a bit.
This is the Terry Crews dream.
This is when, um Terry Crews is my my dream guide, and he told me that I have to face my fears, the monsters that turned into horses.
This is an aquarium in which I was a fish wearing a fish costume.
You also have to learn how to recognize when you're in a dream, and it helps to practice questioning reality.
Looking for dreamlike qualities in the day and then asking yourself, "Wait a minute, is this a dream?" She says the more you ask the question in waking life, the more likely you are to ask it while dreaming.
And once you've realized you're in a dream, you can influence it.
If you look at the activity of the brain when someone is in lucid dreaming, the frontal cortex, the part right up in the very front, the prefrontal cortex, that seems to almost wake up while the rest of the brain remains asleep.
So the frontal cortex can say, "Oh, boy, it would be fun to fly.
" And then, in the dream, they can actually fly.
But dreams may be about more than nocturnal joyrides.
Some scientists think they might play a critical role in creativity and learning.
In one experiment, researchers asked people to study a maze and then take a nap.
What we found is that it was the people who reported when we woke them up early in their nap that they had been dreaming about the maze, that those were the people who showed the largest improvement after the nap was finished.
Lab rats seem to dream about the mazes they explore during the day.
As they move through the maze, you can see one pattern of brain activity.
And when the rat goes over here and curls up to take a nap, those same exact patterns replay.
So it looks like that dreaming about the task is part of that process of enhancing and improving the memory while we sleep.
It looks like REM sleep doesn't just help us remember, it helps us forget.
Forgetting is really an important part of learning and it seems like REM sleep is really important for erasing things that our brain needs to erase, that it doesn't need to store, so you can incorporate new pieces of information.
This selective forgetfulness might help people work through emotional memories.
If you've been through a traumatic experience you're fighting in Afghanistan and you hear the sound of a helicopter and you need to get out of its way or you'll be in trouble when you come back home after a tour of duty, and you see and hear a helicopter approaching, you don't want all of the same fear signals to be going off in your body.
Instead, you want to incorporate the context of safety.
That was then, that was there.
In order to incorporate that new piece of information, like "I'm home now," into that old memory, you need REM sleep.
Scientists have found something like REM sleep in mammals, lizards, cuttlefish, and birds.
One really interesting line of research is in bird songs.
Male zebra finches must learn their own unique song to try and impress a mate.
Young males listen to the songs of their fathers and then try their hardest to sing their own version.
During these practice sessions, their neurons fire and their vocal muscles twitch in specific patterns.
And then those same patterns replay at night, just a little looser.
These feathered Casanovas appear to be dreaming about variations of their love songs.
In this state, the bird is actually free of actually having to produce the song but they're able to test out different patterns, prune out the things that are wrong.
Each night, the songs get looser, and each day, they're tightened back up until a unique, clear melody emerges from the chatter.
Something similar may happen in humans.
When we're in that hazy dream-state, unbound by reason or consequences, it might be the perfect time to lay the groundwork for insights and breakthroughs.
I think in REM sleep, the brain is creating dreams that are not designed to settle on a single answer, but to help us realize all the possible answers that are out there.
If you're not focused on one particular route through the maze, you might discover paths you never knew were possible.
We can test out new ideas, put things together without the constraints of logic.
It might be that part of the function of REM sleep dreaming is to identify sort of wacky associations, connections, that we would never discover while we're awake.
Salvador Dalà believed in this creative power of dreams.
My work consists in the meticulous execution of my dreams.
Creativity is nothing more than taking information we already have and seeing how it fits together in a new and exciting way.
You dream your paintings? DalÃdream in glorious Technicolor.
One created by a computer.
It recorded the brain patterns of people when they were awake and looking at hundreds of different pictures.
When those people were asleep, the program tried to reverse-engineer their brain patterns back into images.
When the subjects awoke, many of their descriptions matched.
One said they saw a hall with female figures in it.
Another reported seeing a page covered in writing.
This experiment was just the latest attempt to catch a glimpse of the dream world.
For thousands of years, humans have seen dreams as mystical, or as some kind of window into our deeper selves.
They've reportedly inspired great literature, like Dr.
Jekyll and Mr.
Hyde.
Scientific breakthroughs, like the arrangement of the periodic table of elements and hits like the Rolling Stones' "Satisfaction.
" I actually dreamt the damn thing.
But hearing about other people's dreams can be really boring.
If I go to a party and tell someone I study dreams, almost without exception the next eight words out of their mouth are "Oh, I had the most amazing dream.
" And then they tell me this really stupid, uninteresting dream.
Do our dreams have any meaning or serve any purpose? Why do we dream? Oh, I've never had a dream like that before.
Our dreams are constructed entirely from our memories.
And you, and you, and you were there.
It's a dream they dreamed of sailing that beautiful sea.
Sometimes when I eat a lot of cheese, I dream a lot.
That was a dream, I think, but at the same time, it seemed so real.
And when she awoke, she realized it was all a dream.
In this Salvador Dalà masterpiece, a woman is woken by a passing bee, and her brain makes up an elaborate dream to explain the buzz and the sting: roaring tigers and the stab of a bayonet.
Dalà loved dreams.
He said his best ideas came from them.
And this particular painting, Dream Caused by the Flight of a Bee Around a Pomegranate a Second Before Waking, reflected a common view of dreams in 1944.
But they didn't actually happen during sleep.
When you woke up, the entire dream happened in that moment of awakening.
And we now know that that's not the case.
Before we fall asleep, our brains are a mess of chattering neurons.
And all that electrical activity creates chaotic electromagnetic waves.
Kind of like there's wind on the surface of the water, a lot of little white caps.
As we fall asleep, um, and as we lose consciousness, it's like the wind has quieted down and you see the undulating waves beneath it.
Activity all across the brain decreases dramatically.
If you wake people up out of this state and ask them what they were thinking, they'll say, "Nothing, let me go back to sleep.
" But then, an hour and a half later, something odd happens.
The brain roars back to life.
Our brain waves look exactly like we're awake.
Neurons are talking to each other, sending out signals to move and speak and jump.
But a tiny area of our brain stem called the pons stops us from moving around.
Our bodies are temporarily paralyzed, except for our eyes.
That's called rapid eye movement sleep.
In rare cases, that spot in the brain stem malfunctions with pretty scary results.
But the comedian Mike Birbiglia has turned it into a regular joke.
This is a real sleep disorder that you suffer from where you physically act out your dreams.
Yeah, it's called REM behavior disorder, which means I sleep in a sleeping bag up to my neck and I wear mittens so I can't open the sleeping bag.
But for most people, only the eyes act out their dreams.
If they were dreaming that they were watching a tennis game, their eyes will go back and forth and back and forth, and if they were dreaming that they were climbing stairs, your eyes will go up, up, up, up.
We don't make up our dreams in the moment of awakening, we experience them as we sleep.
The brain in REM sleep looks uniquely different from any other time in our day or night.
One area of the brain that's off is the logical judgment filter.
So that's probably why our dreams are so bizarre and don't make any sense.
And the entire emotional part of the brain lights up like a fire even now more active than during waking.
So it looks when we're in REM sleep, the emotional brain is cranked up and the reasoning brain is cranked down, and that's certainly how our dreams tend to feel.
It looks like we spend about a fifth of the time we sleep dreaming.
But most of those dreams are forgotten.
When people ask me, "How can I remember my dreams?" I say drink three large glasses of water before you go to bed.
If they do, they're going to wake up multiple times during the night and they'll discover that they do remember dreams.
But it's still hard because during sleep, we have much lower levels of norepinephrine.
That's a chemical messenger that causes us to feel awake and alert.
And in the brain, it helps us form memories.
Our levels of another chemical, serotonin, plummet too.
And it looks like that when serotonin release is shut off, it biases the brain to think that whatever it's observing, whatever it's connecting, uh, is important.
When we wake, we're left with a hazy impression of something profound.
And we see this across thousands of years of history.
We see this across hundreds of cultures.
These clay cylinders are the oldest surviving record of a dream, one from a Mesopotamian ruler.
The ruler exclaims, "Profound things came suddenly to me, but the meaning I do not understand.
Well, I have to tell her about this.
" His dream interpreter explains that a god is telling him to build this temple.
Go back a couple thousand years.
There was sort of unanimous agreement that dreams were messages from the gods.
They were portents, they were warnings, they were instructions.
Many ancient civilizations created huge manuals to decipher them, like this one, written in Egypt 3,000 years ago.
It proclaimed, "If a man sees himself in a dream baring his own bottom, it means that he will be poor in the end.
" In ancient Egyptian, the word for "bottom" and "end" sounds the same.
Puns were a big part of dream interpretation in Egypt.
In the 2nd Century A.
D.
, a man named Artemidorus became the first real dream researcher.
His dream guide was based on scores of interviews from all over the Roman Empire.
The belly button portends the death of your parents.
If a widow dreams she has a beard, she'll get a second husband.
Cakes without cheese are good.
Cakes with cheese signify deceit.
The specific meanings changed over time, but the belief that there was meaning held for hundreds of years.
Then, in the late 1600s, European scholars started to look down their noses at dream interpretation.
The British philosopher John Locke called dreams "incoherent," "frivolous," and "irrational.
" By the reign of Queen Victoria, it was a popular belief that eating certain foods and the resulting indigestion caused the wildest dreams.
In A Christmas Carol, when Scrooge sees an apparition of his former business partner, he says, "You may be an undigested bit of beef, a fragment of underdone potato.
" In 1899, two books were published that would change the study of dreams.
One was by Santiago Ramòn y Cajal, the father of modern neuroscience.
His book spelled out the idea that neurons were the basic units of the nervous system.
Experiments by other scientists showed that these neurons communicate using electrical signals.
In the 1930s, one surgeon zapped the exposed brains of patients with electricity, and they experienced sudden visions.
You are about to hear the actual words of patients in response to this stimulus.
Now I see them, they're laughing.
I hear children's voices.
I see the whole thing.
A guy coming through the fence at a baseball game.
Some scientists still believe dreams are like this, random electrical storms in our sleeping brains that created equally random and essentially meaningless visions.
But the other book, The Interpretation of Dreams by Sigmund Freud, claimed that dreams were so much more.
Dream images were "disguised representations" of our innermost desires.
A lot of these symbols were sexual: climbing stairs, swords, suitcases, sticks, tearing branches off trees, chapels, balloons, a woman's hat, fish, fountains, reptiles, airplanes, any complicated machine, and the number 3.
One of Freud's earliest supporters, Carl Jung, also believed dreams were messages from the subconscious, but they weren't all about sex.
Instead, they contained characters that represented aspects of our inner lives: Anxiety, purity, wisdom.
In getting away from the concept that dreams were from the gods or that dreams reflected stomach ailments, that was all progress.
But the theory that symbols and dreams have universal meanings is rejected by most scientists today.
Still, Freud and Jung had started a movement.
Dreams were once again interesting.
In 1933, copies of The Interpretation of Dreams lay burning in Nazi bonfires, like hundreds of other books by Jewish authors.
That same year, German journalist Charlotte Beradt began to secretly collect the dreams of her fellow citizens.
They were full of corpses and torture.
Household items like ovens and lamps betrayed their owners to the Nazis.
The protective walls of houses vanished into thin air.
Dreams that now seem tragically prophetic.
In the decades since, researchers have meticulously compiled thousands and thousands of dreams in dozens of countries, and they noticed some patterns.
Dreams of being chased, of having sex, and of falling are some of the most popular.
About one in five people have dreams of their teeth falling out.
Men are more likely to dream about other men while women dream about both sexes pretty equally.
Children are more likely to dream about animals.
And only about 5% of dreams are set in locations the dreamer doesn't recognize.
In fact, most things people dream come from memories of their waking lives, like at the end of The Wizard of Oz, when Dorothy is told it was all a dream.
She realizes that the characters from that dream were all from her real life.
And you, and you, and you and you were there.
Oh.
Although everybody knows that our dreams relate strongly to the events that happened during the day, there were actually no good studies that had shown the incorporation of our waking life into our dreams.
So Dr.
Stickgold recruited a bunch of students to play Tetris for three to four hours a day.
And lo and behold, they started dreaming about Tetris-like images.
He also studied people with memory disorders who couldn't even remember what Tetris was after playing it.
But the game still found its way into their dreams.
They reported things like seeing shapes on a screen or seeing things that looked like rectangles turned on their sides.
And take that dream of losing teeth.
A lot of ancient dream manuals mention this dream.
And most say it portends the death of a family member or employee.
Freud thought it represented castration as a punishment for masturbating.
And in one 1984 study of dreams, people who dreamed about their teeth falling out tended to be more anxious, but they also just thought about their teeth more than the average person.
Kids probably dream more about animals because their days are filled with them.
Men might dream more about men because that's who they worry about most when they're awake.
The dreams of Germans as Hitler came to power weren't prophecies, but they also weren't completely random.
They were reflections of the dreamers' waking fears.
I don't think the dreaming brain is trying to give our conscious mind some sort of a message.
But there is a story there, and it's created from our own memories and our own emotions.
One could think of dreams as being sort of an idiosyncratic, personal Rorschach test.
The things that I really enjoy doing quite a bit are talking to dream characters.
It feels like a reflection of what I don't know I'm thinking.
Allison McCarthy is a lucid dreamer, which means she can consciously influence her dreams.
She says anyone can lucid-dream, but Lucid dreaming is a skill like any other skill.
It's like basketball.
You're not just going to be, um, the best at that skill overnight.
First, you have to practice remembering your dreams.
Allison keeps detailed records.
Dream recall, the most important thing.
Each square represents one dream.
I fly with giraffes quite a bit.
This is the Terry Crews dream.
This is when, um Terry Crews is my my dream guide, and he told me that I have to face my fears, the monsters that turned into horses.
This is an aquarium in which I was a fish wearing a fish costume.
You also have to learn how to recognize when you're in a dream, and it helps to practice questioning reality.
Looking for dreamlike qualities in the day and then asking yourself, "Wait a minute, is this a dream?" She says the more you ask the question in waking life, the more likely you are to ask it while dreaming.
And once you've realized you're in a dream, you can influence it.
If you look at the activity of the brain when someone is in lucid dreaming, the frontal cortex, the part right up in the very front, the prefrontal cortex, that seems to almost wake up while the rest of the brain remains asleep.
So the frontal cortex can say, "Oh, boy, it would be fun to fly.
" And then, in the dream, they can actually fly.
But dreams may be about more than nocturnal joyrides.
Some scientists think they might play a critical role in creativity and learning.
In one experiment, researchers asked people to study a maze and then take a nap.
What we found is that it was the people who reported when we woke them up early in their nap that they had been dreaming about the maze, that those were the people who showed the largest improvement after the nap was finished.
Lab rats seem to dream about the mazes they explore during the day.
As they move through the maze, you can see one pattern of brain activity.
And when the rat goes over here and curls up to take a nap, those same exact patterns replay.
So it looks like that dreaming about the task is part of that process of enhancing and improving the memory while we sleep.
It looks like REM sleep doesn't just help us remember, it helps us forget.
Forgetting is really an important part of learning and it seems like REM sleep is really important for erasing things that our brain needs to erase, that it doesn't need to store, so you can incorporate new pieces of information.
This selective forgetfulness might help people work through emotional memories.
If you've been through a traumatic experience you're fighting in Afghanistan and you hear the sound of a helicopter and you need to get out of its way or you'll be in trouble when you come back home after a tour of duty, and you see and hear a helicopter approaching, you don't want all of the same fear signals to be going off in your body.
Instead, you want to incorporate the context of safety.
That was then, that was there.
In order to incorporate that new piece of information, like "I'm home now," into that old memory, you need REM sleep.
Scientists have found something like REM sleep in mammals, lizards, cuttlefish, and birds.
One really interesting line of research is in bird songs.
Male zebra finches must learn their own unique song to try and impress a mate.
Young males listen to the songs of their fathers and then try their hardest to sing their own version.
During these practice sessions, their neurons fire and their vocal muscles twitch in specific patterns.
And then those same patterns replay at night, just a little looser.
These feathered Casanovas appear to be dreaming about variations of their love songs.
In this state, the bird is actually free of actually having to produce the song but they're able to test out different patterns, prune out the things that are wrong.
Each night, the songs get looser, and each day, they're tightened back up until a unique, clear melody emerges from the chatter.
Something similar may happen in humans.
When we're in that hazy dream-state, unbound by reason or consequences, it might be the perfect time to lay the groundwork for insights and breakthroughs.
I think in REM sleep, the brain is creating dreams that are not designed to settle on a single answer, but to help us realize all the possible answers that are out there.
If you're not focused on one particular route through the maze, you might discover paths you never knew were possible.
We can test out new ideas, put things together without the constraints of logic.
It might be that part of the function of REM sleep dreaming is to identify sort of wacky associations, connections, that we would never discover while we're awake.
Salvador Dalà believed in this creative power of dreams.
My work consists in the meticulous execution of my dreams.
Creativity is nothing more than taking information we already have and seeing how it fits together in a new and exciting way.
You dream your paintings? DalÃdream in glorious Technicolor.