Original subtitles

Terrifying nightmares

linked to inexplicable deaths.

Unconscious visions

that foretell of unspeakable tragedies.

And emerging technologies

that can engineer our wildest dreams.

Just like breathing, everyone dreams.

We might not always remember it,

but it happens every night of our lives.

Some believe our sleeping thoughts are nothing more

than nonsensical concoctions of the mind,

while others claim our dreams and nightmares

could be messages from beyond,

premonitions of the future,

or even secret signals

that have the power to transform mankind.

Could there be more to our subconscious stories

than we realize?

Well, that is what we'll try and find out.

It is said that the average person dreams

between one to two hours per night,

which adds up to about six years over a lifetime.

And while it might be easy

to dismiss these involuntary images,

thoughts and sensations that are conjured during sleep,

it's clear that dreaming is as hard-wired

into the human experience as breathing.

Yet, the meaning and purpose

of these enigmatic mental expressions

remains one of the longest-standing mysteries

of the mind.

Throughout history

and cultures all around the world,

people have turned to their dreams for reassurance,

wisdom, guidance and warnings of dangers to come.

People generally agreed

that dreams are valuable and important.

There's something about the intense visual qualities

of dreaming.

We are asleep.

And yet, our imaginations can create

these marvelous visual experiences.

Dreams hold so much influence over humans

because they're just inherently

a dramatic, attention-grabbing experience.

And in some cases, are very fantastic

and surreal and adventurous.

They just inherently grab us from childhood onward.

You've had experiences that didn't really happen,

but it's a piece of your life.

It appears we've been trying to make sense

of what happens when we slumber since the dawn of civilization.

The first documented dream was recorded

in 2500 BC in Mesopotamia.

The Egyptian Dream Book--

written on ancient papyrus over 3,000 years ago--

compiled 108 different dreams and their proposed meanings.

And in all this time,

we've yet to answer one very basic question.

What is the purpose of dreams?

There's a lot of disagreement among dream researchers

about why we dream, whether dreams have any meaning.

People will speak of God.

They'll speak of evolutionary wisdom.

Sigmund Freud was a medical doctor

and psychiatrist in Vienna, Austria,

who, in 1900, published The Interpretation of Dreams.

And in this book, Freud taught

that dreams are the royal road

to a knowledge of the unconscious mind.

By studying our dreams,

we learn about the deepest wishes and desires

and fears and instinctual drives within each of us.

Some of the theories about what happens

while we're dreaming

is, we're consolidating our memories.

Being able to take all of these different things

that have happened to us

throughout our lifetimes

and create a coherent self-identity.

That that's where our sense of self comes from.

Is that true? We don't know.

Inside this century-old hospital

lies the Dream and Nightmare Laboratory,

one of the few facilities in the world

trying to reveal

what is really happening while we sleep.

The Dream and Nightmare Laboratory

was founded in 1991.

And we're really trying to form links between

what's happening during sleep and during dreams.

In the sleep lab, we measure these through brain activity

and eye movement activity and muscle activity.

You go through four different stages of sleep.

And when we first fall asleep,

that's called stage-one sleep.

This stage is very short.

Even in stage one, people will have dreams.

Then someone descends a bit further into a stage-two sleep.

They also will have dreams

that can sometimes be mundane or thought-like.

And then they descend even further

into a deeper stage:

stage-three sleep.

Dreams are very vague

and very hard to recall when people wake up.

And then, stage-four sleep, the deepest state of sleep,

where finally you enter REM sleep,

rapid eye movement sleep,

which is really the main stage of interest

for a dream scientist.

The brain practically wakes up.

We have more activation of emotional areas of the brain.

The eyes are moving, the muscles are twitching,

and people are usually in very vivid and elaborate

and wake-like dreams in this stage.

Let's say dream science has uncovered, like,

25, 30% of what's going on,

but there's still a lot to learn.

Like, 70% is completely unknown.

It's actually very, very difficult to study dreams

because we do not have direct access to them.

Oh, here we got some eye movements. -Yeah, there.

So, in all of our scientific studies,

we wake people up, sometimes repeatedly during the night,

so that they can report some of their dreams.

- Sit up when you're ready. - Okay.

But probably 95% of dream activity

is still completely forgotten.

Apart from scientific curiosity,

you might wonder,

why should we even care about dream research?

Well, many of mankind's greatest ideas and innovations

are said to have been inspired by brain activity during sleep.

There are many great minds

whose dreams have helped them

to formulate some of their greatest work.

So, for example, Russian scientist Dmitri Mendeleev,

actually dreamt the periodic table.

That's the table of all the elements.

Einstein claimed that dreams

helped him to realize the theory of relativity,

and how the observer perceives time and space

according to where they are.

The Google search engine, uh, was invented in a dream.

Larry Page describes that he woke up from a dream

and immediately started scribbling out a plan

that was to list and rank all Internet sites.

But there are breakthroughs in every field of endeavor.

Another example

would be Paul McCartney's song "Yesterday."

He dreamed that he was listening

to this just beautiful piece of music,

and he persuaded the Beatles to perform it,

and it became their all-time hit.

Famous people like Edison and Tesla

really wanted to access the creative sleep state

as you're falling asleep.

They thought that was the kind of key

to creativity and invention.

And so, they developed this steel ball trick

where they would hold a steel ball in their hands,

and then, as they fell asleep, as their muscles relaxed,

the steel ball would drop, and it would wake them up.

And then they would record whatever that creative,

imaginative idea and dream was that had happened.

What these stories of creative insights

and inventions through dreaming tells us is that

if we devote ourselves

to a task, to a challenge, to a problem,

and we throw ourselves at it, our dreams will help us.

And I think that that if you can tap into that resource,

nothing will stop you.

Could a better understanding of dreams

help us unlock our greatest innovations and achievements?

Perhaps.

And as scientists continue

to probe our sleeping subconscious,

what might be revealed?

Dream science is still seen as peripheral and weird.

But your dreams 15 years out

can predict the onset of Parkinson's.

But nobody knows that.

Your nightmares are a huge part

of post-traumatic stress disorder.

Nobody's asking questions about that.

We are dreaming in every stage of sleep.

This is a lot of your lived experience.

You wouldn't walk around all day just ignoring your thoughts

and saying, "Oh,

those don't have any influence on my behavior

or my emotional well-being."

But that's what we're doing at night.

But dreams are in touch with more than the science can see,

and that is fine with me as a scientist,

and makes it so much more interesting

to work on as a challenge.

In a working-class section of the city,

a quiet yet unsettling epidemic starts to unfold.

A group of young Southeast Asian immigrants

belonging to an ethnic group known as the Hmong

succumb to a truly nightmarish fate.

They are dying

in their sleep.

In January of 1987,

the L.A. Times published an article about

over 140 Hmong men dying in their sleep

with no real explanation.

The CDC did autopsies on the individuals,

they couldn't find any reason

on why these individuals passed away.

There was no sign of a heart attack or a stroke.

They were young, they were healthy,

they didn't have prior existing health conditions.

Looking at the surface of the story,

there's no reason for these men to have died.

There's still a lot that we don't understand

about why this happened.

But one thing that's really interesting about these cases

is that a lot of these men reported

that in the days preceding their death,

they were having terrifying nightmares.

It was really a mystery.

Public health officials coined the term

"Sudden unexplained nocturnal death syndrome"

to at least categorize these bizarre deaths,

but it doesn't explain the cause.

And it certainly begs a truly haunting question.

Could bad dreams actually cause healthy men

to suddenly die in their sleep?

According to Hmong culture and belief, nightmares can kill.

In the Hmong tradition, dream is how the spirit world

and deceased communicate with the living.

And so, they come to us in our dreams,

and they communicate their needs and how they're doing.

There are many spirits.

There are good spirits and evil spirits.

The poj dab pob, for example, are evil spirits.

So, dreams are a place to receive communication.

Uh, however, if you don't listen to the spirit,

it can come to your nightmares and kill you.

This is something which is not unique

to this particular population.

Um, in East Asia,

for instance, there was a strong belief

in a creature that could invade dreams

known as the Leyak.

The term "nightmare" has its own origin,

and it comes from this supernatural creature

in East European tradition called the mara,

that could shape-shift

and enter into the dreams,

and could even bring about death.

Demonic entities and evil spirits

that prey upon their victims in the dream world

can be found in folkloric traditions around the world.

But what is so confounding about the nightmare deaths

that ravaged the American Hmong community in the 1980s

is that, inexplicably,

these men all seemed to experience

the same horrific dream.

There are some men who survived,

and they shared with us

that they had nightmares for many nights in a row.

They would see these evil, dark figures

come and sit on their chest, that would suffocate them

and kept constricting their body so they couldn't breathe.

They could not scream, they could not move.

Spouses of-of the men who passed away

shared similar stories.

So, we believe that in these dreams,

evil spirits called the poj dab pob

was visiting the person,

causing the sudden, unexplained death.

Was the same supernatural entity

really squeezing the life

from these men in their nightmares?

The Hmong community certainly believes it's true,

but how might the scientific community

try to interpret this phenomenon?

This reminds me a lot of other phenomena

that we've studied, such as,

in sleep paralysis, a specific type

of usually very terrifying dream experience

that happens right at the onset or the offset of sleep,

and most of our body is paralyzed.

And often, people will hallucinate

some kind of threat or menacing figure

suffocating them or sitting on them.

There's some thought that these could be related

to some extreme form of, um,

sleep paralysis or night terror that occurred to these people.

I'm not sure that's the case.

Not all of the men died, necessarily,

of the same exact physiological process

with the heart or some other part of the body,

so it makes it all the more likely

that whatever triggered their actual dying

was something, as strange as it might sound,

psychological or even spiritual.

And it sure sounds like some kind of dream phenomenon.

But how could something kill you in your dreams?

Could psychological distress

have been the cause of the nightmare-induced deaths

of around 140 healthy men?

Some believe it's a distinct possibility,

based on the shared experience the Hmong had

in their war-torn homeland.

In 1954, the United States CIA

recruited them to fight against communism

during the Vietnam War.

Ten percent of the Hmong population

passed away during this war.

And after the United States left the war,

the Hmong became enemies of the state

and they were persecuted.

To escape genocide from the communist government,

they then fled to other countries,

like the United States.

These men had just survived a devastating war,

so they were going through a traumatic,

traumatic time in their life.

Was psychological trauma

from the Vietnam War

connected to these inexplicable nightmare deaths?

All we can do is speculate.

But strangely, by the late 1980s,

these unexplained deaths all but stopped.

And the Hmong believe it proves this phenomenon

was a matter of spirituality.

As these men were dying,

it was a crisis in the community.

They didn't know what was going on,

and so, it took elders and shamans coming together

and talking to the spirits to have a better understanding.

And the spirits shared that these men

were not honoring the spirits like they had done in the past.

When they came to America,

they were no longer building an altar to pray to them,

offering animals as sacrifices to honor and feed the spirits.

So, the spirits were then angry and causing harm to the living.

Since then, we recognize that we have to continue

making sure that, um, the spirits are being honored

as well as, um, supported.

And so, that helped reduce the number of these deaths.

But we believe that nightmares still kill even today.

The mere suggestion that a nightmare can kill

is profoundly disturbing.

It really makes the thought of dying in your sleep

a bit more unsettling, doesn't it?

Perhaps less alarming

is the notion that while we slumber,

our brains may be able to open a window

and allow us to predict the future.

Nestled in the hills of the Peloponnese

lies one of the ancient world's

most remarkable medical sanctuaries

that has been preserved for over 2,000 years.

Today, it's a UNESCO World Heritage Site,

but in the time of Classical Greece,

it was something more.

A sacred destination for pilgrims to be healed

in their sleep.

Thousands of years ago,

people were dreaming in temples,

and these were specifically for healing.

One of the most famous ones

is the Epidaurus,

where people would try to have dreams

of the Asclepieion, the serpent god

who would come down and heal you in your sleep.

And so, people would sleep surrounded by these serpents,

and they would ask for a dream visit

from the healing serpent god.

Asclepius is the Greek and Roman god

of healing through dreams.

You go to his temple, really, not for diagnosis.

You go in hopes of a sacred experience of healing.

And we have testimonies, I mean, written reports,

of what happened in the Temple of Asclepius,

and they're quite fascinating.

We see people who believe

that they've been healed of specific physical symptoms

after interaction with a sacred being.

In the ancient world, many believed that dreams

offered more than spiritual guidance.

One of the most influential voices of the time

argued that dreams could diagnose illness

from deep within the body.

One explanation comes from

the most renowned physician of the ancient Greek world.

Galen was the personal physician

of Marcus Aurelius, the Stoic emperor.

He wrote a number of treatises on diagnosis through dreams.

And he said that the reason why dreams

can give you an accurate diagnosis

of what's going on through the body

is that there's some function of consciousness during sleep

that may travel through the body

and bring back a really exact report

of what's going on inside the body.

Today, nightmares or visions

that seem to foreshadow disease before physical symptoms appear

are known as prodromal dreams.

But is this phenomenon real or imagined?

As night begins to fall over her suburban home,

43-year-old Kathleen O'Keefe-Kanavos

heads upstairs to go to bed.

And as she drifts off to sleep,

she is visited by a strange messenger.

I had gone in for my yearly mammogram,

and I had gotten a clean bill of health.

And that night, I had the strangest dream.

And all of a sudden, my dream froze

like, like the page on your computer freezes.

And in the middle of that frozen page

was a door.

And through that door

walked a Franciscan monk-- in the brown robe--

and this monk took my hand,

put it right on my breast, and said, "Do you feel that?"

and I said, "Yeah."

And he said, "That's breast cancer."

You go back to your doctor tomorrow

and you tell him you need exploratory surgery

to find this cancer.

Was the arrival of this strange visitor

simply a figment of Kathleen's imagination?

Or did she experience a real prodromal dream?

An accurate assessment of her health

delivered during sleep?

Whatever the case, Kathleen was convinced

it was all too haunting to ignore.

I said to the doctor,

"I need exploratory surgery to find this breast cancer.

I know I have it.

I need you to do this.

I'm not leaving without a yes."

And so, long story short,

I had the surgery,

and when I first woke up,

I was told that, yes, it was breast cancer.

My first reaction was, I just started crying.

"Well, thank goodness

they found that cancer early enough."

And so, the monk was right.

Was Kathleen's dream a miraculous coincidence,

or proof that the ancients were right,

that dreams really do have the power

to diagnose and even heal?

This doesn't make sense of the typical,

traditional, modern, Western medicine.

And yet, it does make more sense if we think of dreaming

in its traditional healing capacity,

as giving us insights into these kinds of

illnesses and problems.

The mysteries of dreaming

involve our rediscovering things that earlier people knew,

things like the healing power of dreams.

I think there's something in the idea that

amongst all the things going on in dreams,

dreams can be body talk,

and the message may come veiled as a messenger

who has our best interests at heart.

We've been taught that a dream is just a dream.

You don't really need to pay any attention to it.

It's just the mind firing off neurons

when you're asleep.

But I've always said it has to mean something.

I'm not really sure why I listened to that monk

other than it was such an odd dream.

But if I had not believed him,

I believe I'd be dead today,

and you wouldn't be speaking to me.

If dreams do, in fact, have the power to heal,

then telling someone they'll feel better

after a good night's sleep

may have a deeper meaning than we think.

And there's growing evidence that dreams

can influence our waking lives in other ways as well.

Because researchers have developed a technology

that allows people to unlock new potential

as they sleep.

This esteemed university has produced remarkable innovations

in computer technology,

pioneering work in medical imaging

and advanced robotics.

But recently,

MIT researchers have been developing technology

to quite literally engineer our dreams.

Dream engineering

is a pretty new field,

under a decade.

And what it means is if we took all these technological advances

in sensors, devices, in A.I.,

and we aimed them at dream science,

how can we help people shift what they dream about

to better themselves the next day?

Historically, the way that people tried to determine

whether they could control a dream is

they'd show you a stimulus, maybe a scary film,

and then you would fall asleep.

And then they'd wake you up, maybe four hours later,

eight hours later, and they'd say, "What'd you dream about?"

Well, you'd say, "I have no idea."

And the really simple shift that we made was,

we said, "Let's focus on the whole sleep onset period."

It's where your imagination starts turning into pictures.

Where you're dreaming, but you can still hear

the outside world around you.

That's when we try to slip something into dreams.

If we can control a small piece of a dream,

then we can run a controlled experiment on a dream.

Can technology really control

the content of our dreams?

Well, in 2017, that's exactly what Adam Haar Horowitz

and other researchers at MIT tried to find out.

And they would create a groundbreaking

glove-like device known as Dormio.

This is the Dormio device that we built at MIT.

This device is a research prototype.

It works really well in the lab.

This is not built for consumers at home.

The way this will work is we put this on

before someone goes to bed.

You have these sensors.

This person's sleep will be tracked,

and then Dormio looks for a special moment in sleep

where dreams are beginning

but you can still hear the world around you.

In that special moment, that device will talk to you.

"Remember to think of a tree,

remember to think of a fork,

a volcano, Beyoncé," your pick.

And we found that 92% of people who came in

would have a dream where directly they would report

the thing that we suggested.

We're hitting this 92% number, which feels pretty exciting,

and feels like it opens up a lot of ground for new experiments.

Will dream technology such as Dormio

one day allow us to live out our wildest fantasies

while we sleep?

Climb to the summit of Mount Everest?

Win the World Series with a towering home run?

Or fly to a galaxy far, far away?

It's certainly an enticing prospect,

but how can shaping our dreams when we first fall asleep

actually help us while we're awake?

Right when you fall asleep,

the brain is, uh, what we call "hyperassociative."

And it's kind of like creative thinking,

that you are making links between concepts

that you don't normally link.

Recently, there was a study where they had people

try to do these hard-to-solve math problems.

They found if people fell asleep for just one minute,

they were almost three times more likely to suddenly come up

with the hidden solution to these problems.

Dormio is designed to help people

access that state as you're falling asleep

to try to extend that period of creativity.

So, imagine that you are dreaming

about flying, uh, above the clouds.

And the researchers say, "What were you dreaming about?"

and you say, "I was in the clouds and I was flying,

but I had this incredible contraption, this new way

of being able to paraglide through the clouds."

And the researchers play audio about paragliding

and clouds and flying.

And then you fall asleep again,

and extend the dream

so that you start to develop more of it.

And now you're able to describe that invention.

We can boost creativity, we can improve

somebody's learning

just by playing the right bedtime story,

maybe in a foreign language,

which helps them learn French faster.

That's a study.

How well you learn something

with a 10X difference is dependent on your sleep

and your dreams.

Devices like Dormio

could have a profound effect on creativity and learning,

but studies have also revealed

an even more astonishing application

for dream-shaping technology.

It may have the power

to save millions of lives.

We know that 80% of people with PTSD

will have recurring nightmares of the same topic every night.

These are really high stakes

because we know that if you have nightmares,

it increases your likelihood of attempting suicide by 4X.

So, if you're working with folks who are,

for instance, post-combat veterans,

and they struggle with suicidal ideation,

one of the most surprising results that we've gotten

is that just by having people choose a dream,

instead of whatever difficult dream comes naturally,

when we follow up a week later,

they significantly reduce their suicidal ideation.

That just a shift in the dream landscape

can shift their waking thoughts so much

has been a big surprise and, also, uh, really moving.

What happens if at scale, the three million people

who are struggling with those specific kinds of nightmares

suddenly aren't scared to go to bed at night?

The exciting thing about dream research

in the next ten years is it being applied,

and the implications for mental health and for learning.

How would that change the world?

Psychologist Dr. Keith Hearne

monitors a test subject who has achieved

rapid eye movement sleep, or R.E.M.,

a mental state when dreams are at their most vivid.

Suddenly, his test subject performs a series

of predetermined eye movements similar to Morse code

and successfully communicates, "I'm dreaming."

This experiment provides the first verified

scientific evidence of a phenomenon called

lucid dreams.

Lucid dreaming is the kind of rare brain state

when you know you're dreaming and can steer that dream.

It's kind of this magical space where

it seems like anything is possible

and that heightened state of awareness

is a really extraordinary one.

But lucid dreaming is a more rare occurrence.

There's probably a reason

that we don't enter into lucid dreaming every night

and that not everybody enters into lucid dreaming

and that it's a rare occurrence.

Usually, lucid dreamers can control

the dream content to some extent.

And so, we really want to better understand,

how are lucid dreamers able to do this?

We found that lucid dreams are very useful

in the treatment of nightmares.

Lucid dreaming can also be used

to practice real-world skills.

Athletes and musicians can use the dream world to practice,

say, snowboarding or playing their musical instrument.

Or someone who's writing a novel,

they could enter into a lucid dream and actually

engage with one of their characters.

So, there's a lot of different uses to lucid dreaming,

and-and that's why we study them.

Could lucid dreams provide the next stage

of personal awareness and growth?

Perhaps.

Yet, the problem is, as little as one percent

of the population experience lucid dreams on a weekly basis.

But what if we all had access

to a device that could trigger this powerful state?

There's a new tech start-up called Prophetic,

and they're working on

an idea of a head-worn device called the Halo.

And the idea is to blast

focused ultrasound into your brain

and to activate it while you're asleep.

And their hope is that that would make you

more likely to have lucid dreams,

because in lucid dreams,

that part of your brain is more active.

But so are other parts of your brain.

So, they have a really hard job ahead of them,

but I am totally excited to see more people

entering into the dream tech space.

If we could all gain access to lucid dreams,

when the conscious and subconscious mind seem to merge,

will we be able to not only push

our understanding of dreams farther

but also, finally answer the most elusive mystery:

why do we dream?

We tend to depreciate dreams

and treat them as irrational nonsense,

but dreams reflect a profound source of wisdom

that is very closely correlated

with people's most important, uh, emotional concerns,

uh, and interests in waking life.

But it's something that we just haven't quite figured out yet.

We should stay open to the possibility

that the state of dreaming may give us access to ourselves

and an understanding of ourselves in ways

that have never before been thought possible.

There's been a lot learned over the past couple of decades,

but it's still, in many ways, a science in its infancy.

Whether it's glimpsing future events before they occur,

healing the body

or learning entirely new skills,

dreams seem to be far more powerful than we may think.

But as science continues

to delve deeper into the mystery of dreaming...

...what else might we discover?

Could we unlock hidden powers?

Or open a new door to a world of nightmares?

Pondering these questions

will no doubt keep many of us awake at night

for a long time to come, because for now,

they continue to remain...

...unexplained.

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