Human Body Pushing The Limits (2008) s01e04 Episode Script
Brain Power
NARRATOR: Too often, we take our bodies for granted, but under pressure, our bodies can show us how extraordinary they truly are.
This complex machine grew out of millions of years of evolution.
So intricate, we're still mystified by many of the things going on inside us.
A hidden world, but one we can now explore in 3-D as never before.
At the top of our spines rides 3 pounds of tissue controlling everything we do.
Our brain works faster than any computer' processing an astounding every second.
But to save our lives, it can slow down time tell us what to eat even when to consume ourselves, and, as we sleep, unleash im mense power.
Our brain drives our muscles and steers our lives when we're pushed to the limits.
When firefighters face one of nature's deadliest forces, it seems impossible that they should survive.
Yet six men walk away from a devastating fire storm unharmed.
What saved them was their brains by making time run slower.
A lightning strike ignites a fire in Little venus, Wyoming.
Ryan Jordan leads a team on a routine mission to make sure the blaze burns itself out.
We're gonna be there in a couple of hours.
Over.
NARRATOR: But the fire isn't fading.
The wind shifts, giving the flames new life, and they're bearing down on Ryan and his team.
JORDAN: As we're hiking in on the trail, about two miles in, we had some scratchy radio com munication that the wind was picking up.
The fire had changed some of its behavior and started burning downcanyon.
NARRATOR: Any firefighter would know a nightmare was approaching.
MAN: Repeat.
This is a warning.
Winds are changing direction.
F ar as we can tell, it's headed southwest.
lt could be headed your way, and it's moving fast.
NARRATOR: As Ryan hears the warning, his brain takes control.
Deep in the brain, two parts, each an inch across, make up the control center.
lt manages our fight-or-flight response hardwired by evolution.
Okay, let's go! NARRATOR: lt drives us to act without thinking.
Come on, guys! NARRATOR: The control center collects information from the outside.
Normally, the data goes to the brain's thought center for study and reflection.
But in emergencies, the controller works differently, signaling nearby areas that make up the disaster center.
Without a thought' the firefighters' brains com mand them to flee.
l n a blink' the men take off.
JORDAN: You could feel the heat starting to get closer on you.
l n your mind, you're wanting to run.
That's your instinct.
To get away from this heat source.
NARRATOR: Stoked by gusts, the flames close in.
l n the firefighter's brain, the disaster center engages automatically.
lt orders release of a natural, turbocharged stimulant.
Adrenaline.
Keep going, guys! Come on! Let's go! Let's go! NARRATOR: Their hearts beat faster.
Blood is redirected from nonessential tasks like digestion to parts of the body that can mean the difference between life and death.
Blood floods their muscles with fuel and oxygen.
l n a burst of strength, the firefighters race to survive, but the fire storm explodes faster.
Their bodies are near collapse.
But their brains are working furiously.
When time seems about to run out' the human brain can pull an amazing trick.
lt appears to slow time itself' creating precious moments that might help us escape.
We've puzzled over this for years.
To help understand the effect' volunteers were tested as they made their first' stressful jump from a platform 1 50 feet high.
They were given a display which, under normal conditions, moved too fast to read.
But perhaps a brain under stress could slow the numbers enough to register them.
[ Screams .]
NARRATOR: For all the jumpers, their descent seemed to last almost twice as long as it really did.
l ncredibly, some were able to make out the speeding digits.
One explanation is that our brain sees in a series of snapshots.
About 30 frames a second.
l n an emergency, that rate increases, letting the brain take in more information in less time.
The effect slows time.
As the flames near' the firefighters' brains are observing at maximum speed.
Seconds feel like hours, giving them a chance to work out what to do.
JORDAN: Feels like things are happening really slow.
You have time to think about it' but it's actually seconds that you ran through, "Should l run? Should we go upcanyon? Should we deploy our shelter here?" NARRATOR: With time stretched, the team can assess their critical situation.
They agree to stop and take cover.
MAN: Come on! Let's go! NARRATOR: And just in time.
JORDAN: You heard that fire, and you felt that fire coming, and you knew you weren't going any further' and you're relying on this fire shelter to save your life.
You just -- lt was disbelief.
You couldn't believe it was happening.
MAN: Come in! Talk to me! You hang in there! After that fire passed, some people were really pumped up and excited from the situation, and some people were very quiet and kind of in shock and disbelief' wondering, "How did this just happen? Now l'm crawling out of a situation that l maybe shouldn't have survived.
" NARRATOR: An aerial image shows where the team made its last stand.
Each dot marks a firefighter's shelter.
All around, desolation.
This extraordinary survival story has its roots in the brainpower that we all have.
Our brain controls every decision we make, even our taste in food.
Our urge to eat resides deep in the brain.
A walnut-sized lump of tissue is the brain's want center.
We are only just starting to understand its many functions.
Above all, it wants to feed.
No organ is hungrier than the brain.
lt consumes nearly 1 /5 of the energy we take in.
But the want center responds to the needs of the whole body for nutrients, including vitamins and other minerals.
When the body runs short of anything, the brain drives us to mind-boggling lengths to fill the gap, as yachtsman Steve Callahan learned.
Steve's boat sank' leaving him adrift alone.
He needed a miracle.
CALLAHAN: l was basically in the middle of the Atlantic Ocean.
l knew l was a long way away from any kind of possibility of rescue.
l put my chances of survival as very, very slim.
[ Grunts .]
NARRATOR: When his rations ran out' Steve turned predator.
Fish were plentiful.
He wouldn't go hungry.
But he had a big problem.
lt's rich in protein, but fish flesh lacks vitamins and minerals that the human body needs.
On a flesh-only diet' Steve's body couldn't work properly.
lt would shut down and die.
What he doesn't realize is that the fish he catches does contain the nutrients he needs.
They're just in parts that he usually discards.
As his body is about to shut down, Steve finds his tastes taking a bizarre turn.
CALLAHAN: l was less and less interested in the fish flesh and more and more interested in things like fish eyes and the little plates between the vertebrae and fresh fish liver and fish roe.
Basically ate almost all of the interior of the fish with the exception of the stomach itself.
NARRATOR: Unconsciously, with death looming, Steve consumes the nutrients that can keep him alive.
Only now are we working out why a man could eat and even enjoy what he'd normally find repulsive.
Realizing something's missing in Steve's diet' his want center generates intensive cravings driving him to eat anything to satisfy them.
This survival instinct forced our ancestors to try anything to keep their diets in balance to the point of overriding taste.
Chili peppers, to avoid being eaten, evolved a flavor animals can't tolerate.
That flavor comes from a chemical that burns our mouths.
Even so, we eat them.
That's because our brain knows survival can depend on pushing the limits.
A red chili contains four times the vitamin "C" that's in an orange.
So that we can absorb that essential chemical, our brain has learned to overcome discomfort.
Eating chilies bombards the brain with pain signals.
l n response, the brain releases endorphins, natural painkillers that induce sensations of pleasure.
The chilies' heat activates the brain's learning center.
lt stores the memory that' despite a fierce flavor' chilies are rich in nutrients and a peculiar pleasure.
DR.
H EBER: So, if you can get used to the initial pain of the chili, the endorphins then become a pleasant response.
So, people actually get used to eating things they're not supposed to eat' like chili peppers, like onions and garlic.
NARRATOR: To keep Steve Callahan eating what he needs, his brain uses a similar tactic.
Triggering a sensation of pleasure whenever he digests needed nutrients, his brain transformed fish parts that once disgusted him into delicious treats.
CALLAHAN: lt's like my body was constantly telling me, "You need this physically "' and was changing my psychology.
l wasn't eating fresh fish liver because l had to, but because my mind was telling me, "Hey, that's great stuff.
That's dessert.
" NARRATOR: Steve Callahan is rescued after 76 days.
Steered by his brain, not only has he saved his own life, he's eaten his way to very good health.
The brain's power over diet is core to our survival.
So powerful that scientists have tested it against one of the strongest human urges.
They fitted volunteers with electrodes to record brain activity.
Then they compared how our pleasure centers respond when we eat chocolate and when we kiss.
Not surprisingly, when couples kissed, their pleasure centers reacted.
But kissing couldn't touch the effect achieved when chocolate hit the tongue.
That pleasure was more intense and lasted longer.
Our obsession with eating makes perfect evolutionary sense.
During most of human history, food has been scarce.
That experience drives us to gorge when we can and store nutrients for survival.
But even when food runs out completely, our brain has a response.
The want center' buried at the brain's base, has instructions for beating starvation.
This cell bundle saved a French cave explorer's life.
He expected a one-day adventure underground.
lt became the greatest challenge he ever endured.
[ Snap .]
[ Screams .]
NARRATOR: Just above the spine is the human brain's most ancient part.
The want center kept our ancestors alive when food ran out.
Now it's Jean-Luc Josuat's only hope of escaping death.
l n animals, this part of the brain evolved around the time of the dinosaurs, before mam mals existed.
lt's hardwired to beat starvation.
For three days, Jean-Luc has been trapped underground.
He hasn't had a morsel to eat.
He doesn't know it' but his brain is changing how his body functions and how he behaves.
DR.
H EBER: There are a couple different brain centers that regulate feeding behavior as well as hunger.
They're in different parts of the central part of the brain called the hypothalamus.
And in that part of the brain, you're driven to seek out food, to eat almost anything to try to stop yourself from starving to death.
NARRATOR: To drive Jean-Luc's search for food, his brain first releases a hormone.
Orexin.
Orexin comes in tiny doses, but it has a profound effect.
This hormone makes us more alert' improves our muscle efficiency, making us better hunters.
lt even sharpens our problem-solving skills.
For days, Jean-Luc scours the caves.
He finds water but nothing to eat.
He starts to fear the worst.
[ Speaking French .]
l NTERPRETER: Even if when l had a little hope, l thought obsessively what would happen over the last few days or the last hours before dying.
lt was a big question, how l would die.
Was it going to be cold or hunger? lt was a question that l always had in my head.
NARRATOR: Sure that he's doomed, he records a message.
But as hope fades, Jean-Luc's brain switches strategy to help him survive with no food.
With his fuel stores depleted, his body becomes even more efficient.
lt makes him slow down.
Now his muscles use less energy.
So do all his internal organs.
New cells grow more slowly.
Nonessentials -- fingernails, toenails, hair -- hardly grow at all.
Jean-Luc is entering a survival state that evolved to keep starving animals alive until they could get to food.
This enforced efficiency, which kicks in when we're at our limit' may have bigger implications.
Some say it could help us all live longer.
l n a recent trial, researchers compared semi-starved rats to those fed a normal diet.
Surprisingly, the less the rats ate, the longer they lived.
Some animals' life-spans doubled.
Based on these findings, some people drastically cut their food intake, hoping to live longer.
The average American adult consumes almost 4,000 calories a day.
Brian Delaney eats half that.
He's trying to fool his brain into staying in superefficient starvation mode.
Right now, l take in about 1,950 calories per day.
At the most strict' l was eating about 1,650 calories per day.
NARRATOR: lf the theory holds, this could slow the aging process.
lt seems to work.
When people who slash their caloric intake were compared with normal eaters, the dieters' hearts resembled those of much younger people.
DELAN EY: The heart is actually rejuvenated by 1 0 or 1 5 years.
We know that calorie restriction does slow aging and, in some respects, even reverse it in humans.
NARRATOR: Reducing food intake may help people like Brian live longer.
Right now, a starved brain is keeping Jean-Luc Josuat alive.
But he's gone three weeks without food, more than even his slowed metabolism can stand.
Jean-Luc's brain adopts a final, desperate plan.
His brain orders Jean-Luc's body to eat itself.
A hormone from his brain signals his liver' triggering the release of chemicals.
These chemicals have already broken down body fat.
Now they start ripping apart protein, Jean-Luc's muscles, a last-ditch source of energy.
DR.
H EBER: So, a typical non-obese individual would have 1 30,000 to only about 54,000 calories stored in muscle, and only half of that 54,000 calories is available for energy, because once you've lost half of the protein in your body, it's no longer compatible with life.
NARRATOR: Simply speaking, when your body consumes half your muscle cells, the game is up.
But a brain desperate for fuel holds nothing sacred.
lt will even sanction burning heart muscle to keep itself going.
DR.
H EBER: So you have to start eating the protein in your body -- literally eating it up -- to produce the sugar that's needed by the brain and the red blood cell.
NARRATOR: Miraculously for Jean-Luc' his brain's high-risk strategy pays off.
searchers find him only His ordeal cost him over but his brain is just fine.
[ Speaking French .]
l NTERPRETER: Now that l look back at it' l think that everyone has a survival instinct' but it's just when one faces a situation like this that one really discovers it.
AN NOU NCER: Boogity, boogity, boogity! Happy Memorial Day, everybody! NARRATOR: The brain works flat-out at all times, digesting reams of information, and never more than during a NASCAR race.
MAN: Back it down! Back it down! l can't see! Go high! NARRATOR: The brain manages thousands of systems that keep us alive.
And it has to do that faster than any computer could, processing an astonishing every second.
As any central processing unit does, the brain produces heat.
Without cooling, our brain would overheat.
lts internal temperature is rising one degree every five minutes.
causes disorientation.
can do permanent damage.
And after 50 minutes, if the brain is 1 0 degrees too hot' you're dead.
Because our brain manages everything else, its main duty is to protect itself.
Few settings test the brain's cooling system more than the blast-furnace world of a stock-car race.
A split-second hesitation can cost you the race.
BOWYER: So staying cool is key, to keep your brain cool and your blood cool.
You know, it's no different than the engines in our race cars.
lf we don't keep them cool, they overheat' and they'll blow up eventually, and you'll be out of the race.
We won't blow up, but we don't run good when we're hot.
NARRATOR: The drivers are ready for 400 laps of white-knuckle, all-out speed.
On the track' the temperature already runs past 1 00 degrees.
l nside those 850-horsepower beasts, it's even hotter.
PETERSON: Driver is working in a strenuous environment.
He's generating heat himself just through the exercise of steering and braking and all that.
But then you have the added thing of the exhaust pipes generating heat into the forward panel.
So, typically, we see cockpit temperatures 1 25 to 1 40 degrees.
NARRATOR: l n such extremes, our brain needs sophisticated ways to stay cool.
Our body's cooling system works like a car's.
We've got a radiator system which basically cools the water that's circulated through the engine.
You got airflow, which comes in the front of the car.
lt circulates through the core of the radiator.
And you have airflow that goes over the top of the castings and the rest of the engine to help cool it by air.
NARRATOR: A car cools itself with water.
The brain uses blood, which carries heat to the skin's surface.
As sweat evaporates, it cools the blood.
The forehead and face are the best sites for cooling.
They have many sweat glands, and air can get at them.
NASCAR drivers have fresh air piped through their helmets to enhance the cooling effect.
The rest of the body is harder to cool.
Tl PTON: So, if you're in a situation, say, driving a racing car' you have to wear protective clothing that's gonna protect you in a crash or if you're in a fire.
Sweating in that situation is not really gonna help you, 'cause it's absorbed into the clothing.
Eventually, the surface of the clothing will be wet' and that will evaporate.
NARRATOR: As the laps roar by, sweat saturates the drivers' suits.
This keeps perspiration from evaporating.
But even after 2 1 0 laps, when the cars' interiors are baking hot' the drivers must still perform at their peak.
BOWYER: Out on the racetrack' you're looking, literally, hitting your mark within every time you go off in a corner at 200 miles an hour.
So, you really have to be focused on hitting your marks on the racetrack' and you can't do that if you're focusing on how hot you are.
NARRATOR: We still don't know exactly how our brain maintains the correct temperature under such conditions.
One controversial theory says it has an extra cooling method.
The brain is such an important organ that there are various capabilities and facilities there to try and maintain its normal internal environment.
There are those that would argue that we have a special system that allows us to have selective brain cooling.
NARRATOR: On the way to the heart' blood cooled by a sweating face and forehead runs close to arteries feeding the head.
That lowers the temperature of blood bound for the brain.
Considering the brain's of blood vessels, this may be how the core stays at optimum temperature.
After 5 hours and 600 miles, the drivers cross the line still 1 00% focused.
Yeah! l like driving the National Guard! AN NOU NCER: He's out of gas, but that's all right! MAN: Unbelievable! NARRATOR: They can do that thanks to the brain's astonishing ability to stay cool even in the swelter of a NASCAR race.
Of all that goes on in the human brain, the biggest mystery surrounds the time when we sleep.
One surprise is that at night' your brain is as busy as during the day.
The brain's first job is to put us to sleep.
As night falls, a dot-sized gland in the brain triggers release of our natural sleeping pill.
Melatonin.
Acting on our central nervous system, melatonin makes us drowsy.
But as the body slows, the brain goes to work.
Every night' it performs a tune-up.
Brain cells that have worked all day shut down for repair.
Chemicals clean up the by-products of brain-cell activity, and, in some parts, new brain cells grow.
Without this internal diagnostic and repair service, the brain couldn't maintain peak performance.
lf we stay awake too long, our brain knocks us out' no matter what the consequences.
That's what happened to explorer David Hempleman-Adams when he attempted a record-breaking solo balloon trip to the North Pole.
David planned to sleep briefly at times during the 1,500-mile journey.
But he didn't stick to his schedule.
The first couple days, l was on top of the game and, you know, the adrenaline was up.
You know, l'm not too bad for the first couple days, anyway.
NARRATOR: After 48 hours without sleep, the balloonist's thought center was the first to go.
H EMPLEMAN-ADAMS: Going into the second, into the third day, l was making silly mistakes.
[ l ndistinct radio chatter .]
Okay, what's the new track? [ Chatter continues .]
You're going too fast.
Can you repeat that? Over.
When l would call up the control room, they would give me a track' and l'd repeat it three or four times just to make sure.
And they'd go, "No, no, no.
What are you, stupid? lt's this.
" And so, you realize your performance is going.
[ Chatter continues .]
NARRATOR: David has now gone 72 hours without letting sleep perform its critical repair.
Sensing a crisis, the brain begins damage control.
lt shuts down areas not key to vital body function, including the thought center' the seat of logic.
David soon starts imagining things.
When you get very, very tired, you tend to talk to yourself.
The worst thing about tiredness is disorientation.
Disorientation.
l had a little rubber duck' and you start talking to the duck.
[ Chuckles .]
You just do start talking to anything.
Say "hi.
" "Hi.
" NARRATOR: 88 hours in, and still David remains awake.
To avoid permanent harm, his brain pulls the plug, and David is out.
Now, in the extreme when you haven't had enough sleep, your brain will shut you down, whatever the circumstance.
Even in a life-threatening circumstance, if your brain needs sleep so much, it'll shut you down.
NARRATOR: The balloon starts losing altitude.
Even though he's asleep, David is not without defenses.
As we sleep, the part of the brain that hears remains alert' which is why alarm clocks and other noises wake us.
ROSEKl N D: When we fall asleep, we're actually still vigilant and alert to the outside world.
So, your brain is still on, and you know what's going on outside.
[ Alarm ringing .]
NARRATOR: When the balloon dips below 9,000 feet' the autopilot screams out a warning.
David's emergency response center jolts him.
His groggy impulse is to try to flee the scary noise by climbing from the basket.
[ Wind howling .]
l n the wild, this survival instinct could save your life.
But thousands of feet up, it almost brings disaster.
H EMPLEMAN-ADAMS: After that split second that you realize where you were seeing the clouds down below, getting back into the basket' l remember just shaking, and my knees were just knocking.
That was the closest l've ever come to killing myself.
NARRATOR: David's brief but deep sleep was enough to get him back on track.
He was able to complete his record flight.
H EMPLEMAN-ADAMS: You realize now you just need your sleep, and if you don't sleep, you're gonna die.
And not die because you haven't slept' but die because you've made a mistake which will cause an accident' and that's what l learned from that trip.
NARRATOR: Sleep means more than vital brain-cell maintenance.
lt also lets the brain treat us to spellbindingly original shows.
Our minds are screens for dreams.
No one can know for sure why we have these mystifying nightly visions.
Some say dreams let us unlock the brain's awesome potential.
Our brains may buzz while we're awake, but there's a time while we sleep when they get even busier.
lt's when our body is perfectly still when practically every area of our brain comes alive.
That's when we dream.
But there's only one part that virtually shuts down.
Our logic center.
Unrestricted by reason, our dreaming brain can wander infinite and fantastic worlds that it creates.
lt's a human potential to have dreams which are like a virtual world in which we can simulate any imaginable experience.
NARRATOR: Behind closed lids, our eyes flicker wildly in time to our dreams, hence the term "rapid eye movement"' or "REM" sleep.
During REM sleep, our brain grows so busy that blood flow to it nearly doubles.
So that we can't act out our dreams, our brain sends signals to the spinal cord, temporarily paralyzing our limbs.
lt may feel as if we dream all night' but we dream in bursts, a few minutes at a time.
Yet in a lifetime, we'll spend six years dreaming.
Dreams do more than entertain our brain.
They are part of the job of storing memories.
Only at rest can the brain sift the day's experiences, discarding useless details.
SALEM l: Some people believe REM sleep, it's almost like a filing system, that your brain is going through these random bits of information, filing away the things that are important and discarding the things that are not important.
NARRATOR: Events occurring while we're awake are only stored in temporary memory.
l n dreams, we throw away irrelevant material and file useful information into permanent storage.
ROSEKl N D: When you go to sleep at night' especially during REM or dreaming sleep, that's when your memories are consolidated.
That's when you learn more things.
lt's very clear that if you study and then sleep, you're gonna do better on the test.
As opposed to what most people do.
"Let's stay awake cram ming and take the test.
" That sleep is critical for memory and learning.
NARRATOR: But the sorting process can be strange.
With no logic to impose order' thoughts can collide, unleashing creativity, generating fresh ideas.
This may explain how some great minds work.
Einstein's dream of traveling on a sled at the speed of light influenced his theory of relativity.
Nobel Prize winner Niels Bohr revolutionized physics when a dream of horses offered a clue to atomic structure.
And artist Salvador Dali described his surreal work as handpainted dream photographs.
Dreaming pays off' even for space technologists.
While dreaming, NASA designer Bruce Damer cracked a problem that had bugged him for months.
How to build a permanent moon base.
DAMER: There were all these elements.
How do you shield astronauts from radiation? How do you have them use local resources, maybe get oxygen out of the lunar surface material? And so l basically absorbed all this stuff for months.
And then one night' l consciously said, "Okay, everything's in there.
Go for it.
Boot up the dream processor and give me something.
" NARRATOR: That night' brain unbound, Bruce found his answer.
Robots, sent in a space vehicle, could land on the moon and build a base even before astronauts left Earth.
When he woke, he began sketching, and the people at NASA like the idea.
DAMER: The NASA civil servants who have written reports about how innovative the work is and how forward-thinking it is, and l credit this to sort of the unfettered world of dreams.
NARRATOR: The challenge is not to leave dreams to chance.
We may be able to harness the sleeping brain's power by using a technique called lucid dreaming.
LABERGE: Typically, lucid dreams happen when you're in a dream and some oddity occurs, and you start to wonder' "What's going on? Why are you floating up in the air? How do you do that? Oh! Because it's a dream.
" NARRATOR: The key is to learn how to know that you're dreaming without waking.
The next step is to take the dream where you want it to go.
To help, Stephen Laberge made an ingenious mask.
l nside, sensors detect rapid eye movement.
The mask flashes a light bright enough to pass through your eyelids but not bright enough to wake you up.
lt's a gentle signal that you're dreaming.
With practice, you can steer your dreaming brain, guiding your mind into uncharted territory.
LABERGE: There are many different kinds of applications of this dream.
For example, if you're an artist' want a new painting idea' you walk into the next room with the thought that there will be a new painting on the wall there.
And what do you know? There is the painting.
NARRATOR: Managing dreams may be the only chance we get to influence what's normally out of our control.
Our brain.
There's no more complex or mysterious organ than the human brain.
lt runs our lives, conscious and unconscious, often pushing us in directions of its own choosing.
A 3-pound universe whose mysteries we are only starting to reveal.
lt's a journey of scientific exploration that could unlock potential we can't yet see, pushing our bodies to new limits.
This complex machine grew out of millions of years of evolution.
So intricate, we're still mystified by many of the things going on inside us.
A hidden world, but one we can now explore in 3-D as never before.
At the top of our spines rides 3 pounds of tissue controlling everything we do.
Our brain works faster than any computer' processing an astounding every second.
But to save our lives, it can slow down time tell us what to eat even when to consume ourselves, and, as we sleep, unleash im mense power.
Our brain drives our muscles and steers our lives when we're pushed to the limits.
When firefighters face one of nature's deadliest forces, it seems impossible that they should survive.
Yet six men walk away from a devastating fire storm unharmed.
What saved them was their brains by making time run slower.
A lightning strike ignites a fire in Little venus, Wyoming.
Ryan Jordan leads a team on a routine mission to make sure the blaze burns itself out.
We're gonna be there in a couple of hours.
Over.
NARRATOR: But the fire isn't fading.
The wind shifts, giving the flames new life, and they're bearing down on Ryan and his team.
JORDAN: As we're hiking in on the trail, about two miles in, we had some scratchy radio com munication that the wind was picking up.
The fire had changed some of its behavior and started burning downcanyon.
NARRATOR: Any firefighter would know a nightmare was approaching.
MAN: Repeat.
This is a warning.
Winds are changing direction.
F ar as we can tell, it's headed southwest.
lt could be headed your way, and it's moving fast.
NARRATOR: As Ryan hears the warning, his brain takes control.
Deep in the brain, two parts, each an inch across, make up the control center.
lt manages our fight-or-flight response hardwired by evolution.
Okay, let's go! NARRATOR: lt drives us to act without thinking.
Come on, guys! NARRATOR: The control center collects information from the outside.
Normally, the data goes to the brain's thought center for study and reflection.
But in emergencies, the controller works differently, signaling nearby areas that make up the disaster center.
Without a thought' the firefighters' brains com mand them to flee.
l n a blink' the men take off.
JORDAN: You could feel the heat starting to get closer on you.
l n your mind, you're wanting to run.
That's your instinct.
To get away from this heat source.
NARRATOR: Stoked by gusts, the flames close in.
l n the firefighter's brain, the disaster center engages automatically.
lt orders release of a natural, turbocharged stimulant.
Adrenaline.
Keep going, guys! Come on! Let's go! Let's go! NARRATOR: Their hearts beat faster.
Blood is redirected from nonessential tasks like digestion to parts of the body that can mean the difference between life and death.
Blood floods their muscles with fuel and oxygen.
l n a burst of strength, the firefighters race to survive, but the fire storm explodes faster.
Their bodies are near collapse.
But their brains are working furiously.
When time seems about to run out' the human brain can pull an amazing trick.
lt appears to slow time itself' creating precious moments that might help us escape.
We've puzzled over this for years.
To help understand the effect' volunteers were tested as they made their first' stressful jump from a platform 1 50 feet high.
They were given a display which, under normal conditions, moved too fast to read.
But perhaps a brain under stress could slow the numbers enough to register them.
[ Screams .]
NARRATOR: For all the jumpers, their descent seemed to last almost twice as long as it really did.
l ncredibly, some were able to make out the speeding digits.
One explanation is that our brain sees in a series of snapshots.
About 30 frames a second.
l n an emergency, that rate increases, letting the brain take in more information in less time.
The effect slows time.
As the flames near' the firefighters' brains are observing at maximum speed.
Seconds feel like hours, giving them a chance to work out what to do.
JORDAN: Feels like things are happening really slow.
You have time to think about it' but it's actually seconds that you ran through, "Should l run? Should we go upcanyon? Should we deploy our shelter here?" NARRATOR: With time stretched, the team can assess their critical situation.
They agree to stop and take cover.
MAN: Come on! Let's go! NARRATOR: And just in time.
JORDAN: You heard that fire, and you felt that fire coming, and you knew you weren't going any further' and you're relying on this fire shelter to save your life.
You just -- lt was disbelief.
You couldn't believe it was happening.
MAN: Come in! Talk to me! You hang in there! After that fire passed, some people were really pumped up and excited from the situation, and some people were very quiet and kind of in shock and disbelief' wondering, "How did this just happen? Now l'm crawling out of a situation that l maybe shouldn't have survived.
" NARRATOR: An aerial image shows where the team made its last stand.
Each dot marks a firefighter's shelter.
All around, desolation.
This extraordinary survival story has its roots in the brainpower that we all have.
Our brain controls every decision we make, even our taste in food.
Our urge to eat resides deep in the brain.
A walnut-sized lump of tissue is the brain's want center.
We are only just starting to understand its many functions.
Above all, it wants to feed.
No organ is hungrier than the brain.
lt consumes nearly 1 /5 of the energy we take in.
But the want center responds to the needs of the whole body for nutrients, including vitamins and other minerals.
When the body runs short of anything, the brain drives us to mind-boggling lengths to fill the gap, as yachtsman Steve Callahan learned.
Steve's boat sank' leaving him adrift alone.
He needed a miracle.
CALLAHAN: l was basically in the middle of the Atlantic Ocean.
l knew l was a long way away from any kind of possibility of rescue.
l put my chances of survival as very, very slim.
[ Grunts .]
NARRATOR: When his rations ran out' Steve turned predator.
Fish were plentiful.
He wouldn't go hungry.
But he had a big problem.
lt's rich in protein, but fish flesh lacks vitamins and minerals that the human body needs.
On a flesh-only diet' Steve's body couldn't work properly.
lt would shut down and die.
What he doesn't realize is that the fish he catches does contain the nutrients he needs.
They're just in parts that he usually discards.
As his body is about to shut down, Steve finds his tastes taking a bizarre turn.
CALLAHAN: l was less and less interested in the fish flesh and more and more interested in things like fish eyes and the little plates between the vertebrae and fresh fish liver and fish roe.
Basically ate almost all of the interior of the fish with the exception of the stomach itself.
NARRATOR: Unconsciously, with death looming, Steve consumes the nutrients that can keep him alive.
Only now are we working out why a man could eat and even enjoy what he'd normally find repulsive.
Realizing something's missing in Steve's diet' his want center generates intensive cravings driving him to eat anything to satisfy them.
This survival instinct forced our ancestors to try anything to keep their diets in balance to the point of overriding taste.
Chili peppers, to avoid being eaten, evolved a flavor animals can't tolerate.
That flavor comes from a chemical that burns our mouths.
Even so, we eat them.
That's because our brain knows survival can depend on pushing the limits.
A red chili contains four times the vitamin "C" that's in an orange.
So that we can absorb that essential chemical, our brain has learned to overcome discomfort.
Eating chilies bombards the brain with pain signals.
l n response, the brain releases endorphins, natural painkillers that induce sensations of pleasure.
The chilies' heat activates the brain's learning center.
lt stores the memory that' despite a fierce flavor' chilies are rich in nutrients and a peculiar pleasure.
DR.
H EBER: So, if you can get used to the initial pain of the chili, the endorphins then become a pleasant response.
So, people actually get used to eating things they're not supposed to eat' like chili peppers, like onions and garlic.
NARRATOR: To keep Steve Callahan eating what he needs, his brain uses a similar tactic.
Triggering a sensation of pleasure whenever he digests needed nutrients, his brain transformed fish parts that once disgusted him into delicious treats.
CALLAHAN: lt's like my body was constantly telling me, "You need this physically "' and was changing my psychology.
l wasn't eating fresh fish liver because l had to, but because my mind was telling me, "Hey, that's great stuff.
That's dessert.
" NARRATOR: Steve Callahan is rescued after 76 days.
Steered by his brain, not only has he saved his own life, he's eaten his way to very good health.
The brain's power over diet is core to our survival.
So powerful that scientists have tested it against one of the strongest human urges.
They fitted volunteers with electrodes to record brain activity.
Then they compared how our pleasure centers respond when we eat chocolate and when we kiss.
Not surprisingly, when couples kissed, their pleasure centers reacted.
But kissing couldn't touch the effect achieved when chocolate hit the tongue.
That pleasure was more intense and lasted longer.
Our obsession with eating makes perfect evolutionary sense.
During most of human history, food has been scarce.
That experience drives us to gorge when we can and store nutrients for survival.
But even when food runs out completely, our brain has a response.
The want center' buried at the brain's base, has instructions for beating starvation.
This cell bundle saved a French cave explorer's life.
He expected a one-day adventure underground.
lt became the greatest challenge he ever endured.
[ Snap .]
[ Screams .]
NARRATOR: Just above the spine is the human brain's most ancient part.
The want center kept our ancestors alive when food ran out.
Now it's Jean-Luc Josuat's only hope of escaping death.
l n animals, this part of the brain evolved around the time of the dinosaurs, before mam mals existed.
lt's hardwired to beat starvation.
For three days, Jean-Luc has been trapped underground.
He hasn't had a morsel to eat.
He doesn't know it' but his brain is changing how his body functions and how he behaves.
DR.
H EBER: There are a couple different brain centers that regulate feeding behavior as well as hunger.
They're in different parts of the central part of the brain called the hypothalamus.
And in that part of the brain, you're driven to seek out food, to eat almost anything to try to stop yourself from starving to death.
NARRATOR: To drive Jean-Luc's search for food, his brain first releases a hormone.
Orexin.
Orexin comes in tiny doses, but it has a profound effect.
This hormone makes us more alert' improves our muscle efficiency, making us better hunters.
lt even sharpens our problem-solving skills.
For days, Jean-Luc scours the caves.
He finds water but nothing to eat.
He starts to fear the worst.
[ Speaking French .]
l NTERPRETER: Even if when l had a little hope, l thought obsessively what would happen over the last few days or the last hours before dying.
lt was a big question, how l would die.
Was it going to be cold or hunger? lt was a question that l always had in my head.
NARRATOR: Sure that he's doomed, he records a message.
But as hope fades, Jean-Luc's brain switches strategy to help him survive with no food.
With his fuel stores depleted, his body becomes even more efficient.
lt makes him slow down.
Now his muscles use less energy.
So do all his internal organs.
New cells grow more slowly.
Nonessentials -- fingernails, toenails, hair -- hardly grow at all.
Jean-Luc is entering a survival state that evolved to keep starving animals alive until they could get to food.
This enforced efficiency, which kicks in when we're at our limit' may have bigger implications.
Some say it could help us all live longer.
l n a recent trial, researchers compared semi-starved rats to those fed a normal diet.
Surprisingly, the less the rats ate, the longer they lived.
Some animals' life-spans doubled.
Based on these findings, some people drastically cut their food intake, hoping to live longer.
The average American adult consumes almost 4,000 calories a day.
Brian Delaney eats half that.
He's trying to fool his brain into staying in superefficient starvation mode.
Right now, l take in about 1,950 calories per day.
At the most strict' l was eating about 1,650 calories per day.
NARRATOR: lf the theory holds, this could slow the aging process.
lt seems to work.
When people who slash their caloric intake were compared with normal eaters, the dieters' hearts resembled those of much younger people.
DELAN EY: The heart is actually rejuvenated by 1 0 or 1 5 years.
We know that calorie restriction does slow aging and, in some respects, even reverse it in humans.
NARRATOR: Reducing food intake may help people like Brian live longer.
Right now, a starved brain is keeping Jean-Luc Josuat alive.
But he's gone three weeks without food, more than even his slowed metabolism can stand.
Jean-Luc's brain adopts a final, desperate plan.
His brain orders Jean-Luc's body to eat itself.
A hormone from his brain signals his liver' triggering the release of chemicals.
These chemicals have already broken down body fat.
Now they start ripping apart protein, Jean-Luc's muscles, a last-ditch source of energy.
DR.
H EBER: So, a typical non-obese individual would have 1 30,000 to only about 54,000 calories stored in muscle, and only half of that 54,000 calories is available for energy, because once you've lost half of the protein in your body, it's no longer compatible with life.
NARRATOR: Simply speaking, when your body consumes half your muscle cells, the game is up.
But a brain desperate for fuel holds nothing sacred.
lt will even sanction burning heart muscle to keep itself going.
DR.
H EBER: So you have to start eating the protein in your body -- literally eating it up -- to produce the sugar that's needed by the brain and the red blood cell.
NARRATOR: Miraculously for Jean-Luc' his brain's high-risk strategy pays off.
searchers find him only His ordeal cost him over but his brain is just fine.
[ Speaking French .]
l NTERPRETER: Now that l look back at it' l think that everyone has a survival instinct' but it's just when one faces a situation like this that one really discovers it.
AN NOU NCER: Boogity, boogity, boogity! Happy Memorial Day, everybody! NARRATOR: The brain works flat-out at all times, digesting reams of information, and never more than during a NASCAR race.
MAN: Back it down! Back it down! l can't see! Go high! NARRATOR: The brain manages thousands of systems that keep us alive.
And it has to do that faster than any computer could, processing an astonishing every second.
As any central processing unit does, the brain produces heat.
Without cooling, our brain would overheat.
lts internal temperature is rising one degree every five minutes.
causes disorientation.
can do permanent damage.
And after 50 minutes, if the brain is 1 0 degrees too hot' you're dead.
Because our brain manages everything else, its main duty is to protect itself.
Few settings test the brain's cooling system more than the blast-furnace world of a stock-car race.
A split-second hesitation can cost you the race.
BOWYER: So staying cool is key, to keep your brain cool and your blood cool.
You know, it's no different than the engines in our race cars.
lf we don't keep them cool, they overheat' and they'll blow up eventually, and you'll be out of the race.
We won't blow up, but we don't run good when we're hot.
NARRATOR: The drivers are ready for 400 laps of white-knuckle, all-out speed.
On the track' the temperature already runs past 1 00 degrees.
l nside those 850-horsepower beasts, it's even hotter.
PETERSON: Driver is working in a strenuous environment.
He's generating heat himself just through the exercise of steering and braking and all that.
But then you have the added thing of the exhaust pipes generating heat into the forward panel.
So, typically, we see cockpit temperatures 1 25 to 1 40 degrees.
NARRATOR: l n such extremes, our brain needs sophisticated ways to stay cool.
Our body's cooling system works like a car's.
We've got a radiator system which basically cools the water that's circulated through the engine.
You got airflow, which comes in the front of the car.
lt circulates through the core of the radiator.
And you have airflow that goes over the top of the castings and the rest of the engine to help cool it by air.
NARRATOR: A car cools itself with water.
The brain uses blood, which carries heat to the skin's surface.
As sweat evaporates, it cools the blood.
The forehead and face are the best sites for cooling.
They have many sweat glands, and air can get at them.
NASCAR drivers have fresh air piped through their helmets to enhance the cooling effect.
The rest of the body is harder to cool.
Tl PTON: So, if you're in a situation, say, driving a racing car' you have to wear protective clothing that's gonna protect you in a crash or if you're in a fire.
Sweating in that situation is not really gonna help you, 'cause it's absorbed into the clothing.
Eventually, the surface of the clothing will be wet' and that will evaporate.
NARRATOR: As the laps roar by, sweat saturates the drivers' suits.
This keeps perspiration from evaporating.
But even after 2 1 0 laps, when the cars' interiors are baking hot' the drivers must still perform at their peak.
BOWYER: Out on the racetrack' you're looking, literally, hitting your mark within every time you go off in a corner at 200 miles an hour.
So, you really have to be focused on hitting your marks on the racetrack' and you can't do that if you're focusing on how hot you are.
NARRATOR: We still don't know exactly how our brain maintains the correct temperature under such conditions.
One controversial theory says it has an extra cooling method.
The brain is such an important organ that there are various capabilities and facilities there to try and maintain its normal internal environment.
There are those that would argue that we have a special system that allows us to have selective brain cooling.
NARRATOR: On the way to the heart' blood cooled by a sweating face and forehead runs close to arteries feeding the head.
That lowers the temperature of blood bound for the brain.
Considering the brain's of blood vessels, this may be how the core stays at optimum temperature.
After 5 hours and 600 miles, the drivers cross the line still 1 00% focused.
Yeah! l like driving the National Guard! AN NOU NCER: He's out of gas, but that's all right! MAN: Unbelievable! NARRATOR: They can do that thanks to the brain's astonishing ability to stay cool even in the swelter of a NASCAR race.
Of all that goes on in the human brain, the biggest mystery surrounds the time when we sleep.
One surprise is that at night' your brain is as busy as during the day.
The brain's first job is to put us to sleep.
As night falls, a dot-sized gland in the brain triggers release of our natural sleeping pill.
Melatonin.
Acting on our central nervous system, melatonin makes us drowsy.
But as the body slows, the brain goes to work.
Every night' it performs a tune-up.
Brain cells that have worked all day shut down for repair.
Chemicals clean up the by-products of brain-cell activity, and, in some parts, new brain cells grow.
Without this internal diagnostic and repair service, the brain couldn't maintain peak performance.
lf we stay awake too long, our brain knocks us out' no matter what the consequences.
That's what happened to explorer David Hempleman-Adams when he attempted a record-breaking solo balloon trip to the North Pole.
David planned to sleep briefly at times during the 1,500-mile journey.
But he didn't stick to his schedule.
The first couple days, l was on top of the game and, you know, the adrenaline was up.
You know, l'm not too bad for the first couple days, anyway.
NARRATOR: After 48 hours without sleep, the balloonist's thought center was the first to go.
H EMPLEMAN-ADAMS: Going into the second, into the third day, l was making silly mistakes.
[ l ndistinct radio chatter .]
Okay, what's the new track? [ Chatter continues .]
You're going too fast.
Can you repeat that? Over.
When l would call up the control room, they would give me a track' and l'd repeat it three or four times just to make sure.
And they'd go, "No, no, no.
What are you, stupid? lt's this.
" And so, you realize your performance is going.
[ Chatter continues .]
NARRATOR: David has now gone 72 hours without letting sleep perform its critical repair.
Sensing a crisis, the brain begins damage control.
lt shuts down areas not key to vital body function, including the thought center' the seat of logic.
David soon starts imagining things.
When you get very, very tired, you tend to talk to yourself.
The worst thing about tiredness is disorientation.
Disorientation.
l had a little rubber duck' and you start talking to the duck.
[ Chuckles .]
You just do start talking to anything.
Say "hi.
" "Hi.
" NARRATOR: 88 hours in, and still David remains awake.
To avoid permanent harm, his brain pulls the plug, and David is out.
Now, in the extreme when you haven't had enough sleep, your brain will shut you down, whatever the circumstance.
Even in a life-threatening circumstance, if your brain needs sleep so much, it'll shut you down.
NARRATOR: The balloon starts losing altitude.
Even though he's asleep, David is not without defenses.
As we sleep, the part of the brain that hears remains alert' which is why alarm clocks and other noises wake us.
ROSEKl N D: When we fall asleep, we're actually still vigilant and alert to the outside world.
So, your brain is still on, and you know what's going on outside.
[ Alarm ringing .]
NARRATOR: When the balloon dips below 9,000 feet' the autopilot screams out a warning.
David's emergency response center jolts him.
His groggy impulse is to try to flee the scary noise by climbing from the basket.
[ Wind howling .]
l n the wild, this survival instinct could save your life.
But thousands of feet up, it almost brings disaster.
H EMPLEMAN-ADAMS: After that split second that you realize where you were seeing the clouds down below, getting back into the basket' l remember just shaking, and my knees were just knocking.
That was the closest l've ever come to killing myself.
NARRATOR: David's brief but deep sleep was enough to get him back on track.
He was able to complete his record flight.
H EMPLEMAN-ADAMS: You realize now you just need your sleep, and if you don't sleep, you're gonna die.
And not die because you haven't slept' but die because you've made a mistake which will cause an accident' and that's what l learned from that trip.
NARRATOR: Sleep means more than vital brain-cell maintenance.
lt also lets the brain treat us to spellbindingly original shows.
Our minds are screens for dreams.
No one can know for sure why we have these mystifying nightly visions.
Some say dreams let us unlock the brain's awesome potential.
Our brains may buzz while we're awake, but there's a time while we sleep when they get even busier.
lt's when our body is perfectly still when practically every area of our brain comes alive.
That's when we dream.
But there's only one part that virtually shuts down.
Our logic center.
Unrestricted by reason, our dreaming brain can wander infinite and fantastic worlds that it creates.
lt's a human potential to have dreams which are like a virtual world in which we can simulate any imaginable experience.
NARRATOR: Behind closed lids, our eyes flicker wildly in time to our dreams, hence the term "rapid eye movement"' or "REM" sleep.
During REM sleep, our brain grows so busy that blood flow to it nearly doubles.
So that we can't act out our dreams, our brain sends signals to the spinal cord, temporarily paralyzing our limbs.
lt may feel as if we dream all night' but we dream in bursts, a few minutes at a time.
Yet in a lifetime, we'll spend six years dreaming.
Dreams do more than entertain our brain.
They are part of the job of storing memories.
Only at rest can the brain sift the day's experiences, discarding useless details.
SALEM l: Some people believe REM sleep, it's almost like a filing system, that your brain is going through these random bits of information, filing away the things that are important and discarding the things that are not important.
NARRATOR: Events occurring while we're awake are only stored in temporary memory.
l n dreams, we throw away irrelevant material and file useful information into permanent storage.
ROSEKl N D: When you go to sleep at night' especially during REM or dreaming sleep, that's when your memories are consolidated.
That's when you learn more things.
lt's very clear that if you study and then sleep, you're gonna do better on the test.
As opposed to what most people do.
"Let's stay awake cram ming and take the test.
" That sleep is critical for memory and learning.
NARRATOR: But the sorting process can be strange.
With no logic to impose order' thoughts can collide, unleashing creativity, generating fresh ideas.
This may explain how some great minds work.
Einstein's dream of traveling on a sled at the speed of light influenced his theory of relativity.
Nobel Prize winner Niels Bohr revolutionized physics when a dream of horses offered a clue to atomic structure.
And artist Salvador Dali described his surreal work as handpainted dream photographs.
Dreaming pays off' even for space technologists.
While dreaming, NASA designer Bruce Damer cracked a problem that had bugged him for months.
How to build a permanent moon base.
DAMER: There were all these elements.
How do you shield astronauts from radiation? How do you have them use local resources, maybe get oxygen out of the lunar surface material? And so l basically absorbed all this stuff for months.
And then one night' l consciously said, "Okay, everything's in there.
Go for it.
Boot up the dream processor and give me something.
" NARRATOR: That night' brain unbound, Bruce found his answer.
Robots, sent in a space vehicle, could land on the moon and build a base even before astronauts left Earth.
When he woke, he began sketching, and the people at NASA like the idea.
DAMER: The NASA civil servants who have written reports about how innovative the work is and how forward-thinking it is, and l credit this to sort of the unfettered world of dreams.
NARRATOR: The challenge is not to leave dreams to chance.
We may be able to harness the sleeping brain's power by using a technique called lucid dreaming.
LABERGE: Typically, lucid dreams happen when you're in a dream and some oddity occurs, and you start to wonder' "What's going on? Why are you floating up in the air? How do you do that? Oh! Because it's a dream.
" NARRATOR: The key is to learn how to know that you're dreaming without waking.
The next step is to take the dream where you want it to go.
To help, Stephen Laberge made an ingenious mask.
l nside, sensors detect rapid eye movement.
The mask flashes a light bright enough to pass through your eyelids but not bright enough to wake you up.
lt's a gentle signal that you're dreaming.
With practice, you can steer your dreaming brain, guiding your mind into uncharted territory.
LABERGE: There are many different kinds of applications of this dream.
For example, if you're an artist' want a new painting idea' you walk into the next room with the thought that there will be a new painting on the wall there.
And what do you know? There is the painting.
NARRATOR: Managing dreams may be the only chance we get to influence what's normally out of our control.
Our brain.
There's no more complex or mysterious organ than the human brain.
lt runs our lives, conscious and unconscious, often pushing us in directions of its own choosing.
A 3-pound universe whose mysteries we are only starting to reveal.
lt's a journey of scientific exploration that could unlock potential we can't yet see, pushing our bodies to new limits.