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  • Comedian Mike Birbiglia was having trouble with sleep.

  • Though not with the actual sleeping part -- one night, while staying in a hotel, he dreamed

  • that a guided missile was on its way to his bed, and in his dream, he jumped out the window

  • to escape it.

  • Unfortunately, he also did this not in his dream.

  • From the second floor. And the window was not open.

  • This little episode cost him 33 stitches and a trip to a sleep specialist.

  • Mike now sleeps in zipped-up mummy bags for his own safety.

  • The lesson here? Sleep is not some break time when your brain, or your body, just goes dormant.

  • Far from it. In truth, sleep is just another state of consciousness. And only in the past

  • few decades have we begun to really plumb its depths -- from why we sleep in the first

  • place, to what goes on in our brains when we do, to what happens when we can’t sleep.

  • And there is a lot that science has to say about your dreams!

  • Talk about weird! It’s like Sigmund Freud meets Neil Gaiman.

  • So, even though it may seem like youre dead to the world, when you sleep, your perceptual

  • window remains slightly open.

  • And kinda like Mike Birbiglia’s hotel room window, a trip through it can make for a pretty

  • wild ride.

  • But for your safety and enjoyment, I’m here to guide you through this state of consciousness,

  • where youll learn more than a few things about human mind, including your own.

  • And here’s hoping you won’t need any stitches when were through.

  • [INTRO]

  • Technically speaking, sleep is a periodic, natural, reversible and near total loss of

  • consciousness, meaning it’s different than hibernation, being in a coma, or in say, an

  • anesthetic oblivion.

  • Although we spend about a third of our lives sleeping, and we know that it’s essential

  • to our health and survival, there still isn’t a scientific consensus for why we do it.

  • Part of it probably has to do with simple recuperation, allowing our neurons and other

  • cells to rest and repair themselves. Sleep also supports growth, because that’s when

  • our pituitary glands release growth hormones, which is why babies sleep all the time. Plus,

  • sleep has all kinds of benefits for mental function, like improving memory, giving our

  • brains time to process the events of the day, and boosting our creativity.

  • But even if were not quite sure of all the reasons why we sleep, technology has given

  • us great insight into how we sleep.

  • And for that we can thank little Armond Aserinsky. One night in early 1950s Chicago, eight-year-old

  • Armond was tucked into his bed by his father. But this night, instead of getting a kiss

  • on the forehead, little Armond got some electrodes taped to his face.

  • Armond’s dad was Eugene Aserinsky, a grad student looking to test out a new electroencephalograph,

  • or EEG machine, that measures the brain’s electrical activity.

  • That night, as his son slept peacefully, he watched the machine go bonkers with brain

  • wave patterns, and -- after making sure that his machine wasn’t somehow broken -- discovered

  • that the brain doesn’t just "power down" during sleep, as most scientists thought.

  • Instead, he had discovered the sleep stage we now call REM or rapid eye movement, a perplexing

  • period when the sleeping brain is buzzing with activity, even though the body is in

  • a deep slumber.

  • Aserinsky and his colleague Nathaniel Kleitman went on to become pioneers of sleep research.

  • Since then, sleep specialists armed with similar technology have shown that we experience four

  • distinct stages of sleep, each defined by unique brainwave patterns.

  • Say youre just going to bed. All day your endocrine system has been releasingawake

  • hormones like cortisol. But with nightfall comes the release of sleepy melatonin hormones

  • from the pineal gland. Your brain is relaxed, but still awake, a level of activity that

  • EEGs measure as alpha waves.

  • Youre feeling sleepy, your breath slows, and suddenly youre asleep. This exact moment

  • is clearly evident on an EEG reading, as those alpha waves immediately transition to the

  • irregular non-Rapid Eye Movement stage one (NREM-1) waves. It’s in this first stage

  • of sleep you might experience hypnagogic sensations -- those brief moments when you feel like

  • youre falling, and your body jerks, startling you.

  • As you relax more deeply, you move into NREM-2 stage sleep, as your brain starts exhibiting

  • bursts of rapid brain wave activity called sleep spindles. Youre now definitely asleep,

  • but you could still be easily awakened.

  • NREM-3 comes with slow rolling delta waves. We now know that you can have brief and fragmentary

  • dreams in the first three stages of sleep, but eventually youll get to the most important

  • stage: full REM sleep, that famous stage of sugarplum slumber that makes eyeballs go nuts,

  • grants vivid visual dreams, and provided the namesake for a certain famous rock band.

  • REM sleep is kinda paradoxical. Your motor cortex is jumping all over the place, but

  • your brainstem is blocking those messages, leaving your muscles so relaxed that youre

  • basically paralyzed. Except for your eyes. That whole sleep cycle repeats itself every

  • 90 minutes or so, transitioning back and forth between the stages of sleep.

  • Obviously sleep is super important, and lack of sleep is terrible for your health, mental

  • ability, and mood. In fact it’s a predictor for depression, and has been linked to things

  • like weight gain, as your hunger-arousing and -suppressing hormones get out of whack.

  • Sleep deprivation also causes immune system suppression, and slowed reaction time which

  • is why you should not drive sleepy.

  • Of course, a bad night’s sleep here and there is part of life, but there are a host

  • of bona fide sleep disorders out there that can really make life pretty terrible, or in

  • Mike Birbiglia’s case, land you in the emergency room.

  • Weve got insomnia, which is persistent problems of falling or staying asleep. And

  • kind of its opposite, narcolepsy, whose sufferers sometimes experience brief, uncontrollable

  • attacks of overwhelming sleepiness, calledsleep attacks.” This, as you can imagine,

  • can get in the way of all sorts of things that you might enjoy doing, like driving,

  • eating, pole-vaulting.

  • Narcolepsy may have several different causes, including a deficiency in the neurotransmitter

  • hypocretin, which helps keep you awake. But in more rare cases, brain trauma, infection,

  • and disease may contribute to it as well.

  • So, that’s rare, but you probably know someone with sleep apnea, the disorder that causes

  • sleepers to temporarily stop breathing, until their decreased oxygen levels wake them up.

  • Birbiglia, meanwhile, turned out to have a REM sleep behavior disorder, which we don’t

  • fully understand yet, but appears to be associated with a dopamine deficiency.

  • Then weve got night terrors, which are as terrible as they sound... spurring increased

  • heart and breathing rates, screaming, and thrashing that’s seldom remembered upon

  • waking. Night terrors are most common in children under seven, and may be spurred by stress,

  • fatigue, sleep deprivation, and sleeping in unfamiliar surroundings. Much like sleepwalking

  • and sleeptalking, night terrors occur during the NREM-3 stage of sleep, and are NOT the

  • same as nightmares, which occur, like most dreaming, during REM sleep.

  • But oh, in REM sleep, what dreams may come... There you are, running naked as your teeth

  • fall out, being chased down the beach by a Matt Damon centaur. You wake up, feel around

  • your mouth thinking what? What? What?! WHAT?!

  • Welcome to your dreams, those vivid, emotional images racing through your sleeping brain,

  • often providing a backdrop so bizarre that it may seem like David Lynch, Terry Gilliam,

  • and Tim Burton are trying to out-weird each other in a film festival. A really, really

  • long festival, considering the average person spends about six years of their lives dreaming.

  • So yeah, sometimes you have really crazy dreams. But mostly, your average dream usually just

  • sort of unpacks and reshuffles what you did that day. For example last night I dreamt

  • about Tumblr, cause I spent a lot of time on Tumblr yesterday.

  • If you played Tetris all afternoon, you might dream of blocks falling from the sky. If something

  • traumatic happened to you, your brain might provide you with a nightmare to help extinguish

  • your daytime fears - Thanks, brain!

  • Then again...you might be unable to stop dreaming about the trauma, which well look at in

  • the future when we discuss post-traumatic stress disorder.

  • Our two-track minds of course allow us to register more stimuli than we outwardly acknowledge

  • during the day, and in that way, the sounds of car alarms or stinky dog farts that you

  • might not even have noticed may get incorporated into your dream, too.

  • And that’s all interesting and weird and sometimes a little gross, but what’s the

  • real purpose of dreaming? Whyyy do we do this? Well, as you might have guessed, there’s

  • more than one idea out thereThe study of dreams is is a mix of neuroscience

  • and psychology known as oneirology. Oneiros is the Greek for dream, and if youre a

  • Neil Gaiman fan you may recognize it as one of the Sandman’s many names. The one that

  • comes with a toga and Orpheus’s head.

  • But Sandman aside, if you want to talk dreams, we might want to start with our old friend

  • Freud. In his landmark 1900 book The Interpretation

  • of Dreams, Freud proposed that our dreams offer us wish-fulfillment.

  • He thought a dream’s manifest content, the stuff you remember in the morning, was a sort

  • of censored and symbolic version of whatever inner conflict was really going on in that

  • dream’s unconscious, or latent, content.

  • Not surprisingly, the wish-fulfillment theory lacks scientific chops and has for the most

  • part fallen out of favor -- because, really, you can interpret a dream any way you want.

  • Like, sometimes a cigar is just a cigar.

  • Luckily we have some other theories to consider. The information processing theory proposes

  • that our dreams help us sort out and process the day’s events and fix them into our memories.

  • This may be particularly important when it comes to learning and remembering new information,

  • and some studies show that people recall new tasks better after a good REM sleep full of

  • dreams. But if brainwave readings show us anything,

  • it’s that there’s a lot going on in your brain when you dream, and the physiological

  • function theory suggests that dreaming may promote neural development and preserve neural

  • pathways by providing the brain with stimulation. When our brains are stimulated, they expand

  • their connections more. So, babies, for example, spend much of their sleep time dreaming, perhaps

  • in part to help their brain circuitry develop more quickly.

  • This is similar to the idea that dreams are part of our cognitive development. By this

  • model, dreams draw on our knowledge and understanding of the world, mimicking reality, and engaging

  • those same brain networks that light up when we daydream.

  • And finally, there are theories that focus on the way REM sleep triggers neural activity,

  • and the idea that dreams are just sort of accidental side-effects, the brain’s attempt

  • to weave a story out of a bunch of random sights, emotions, and memories -- which is

  • how in dreamland you might actually marry that Matt Damon centaur and give birth to

  • a baby with banana fingers and a raccoon tail.

  • For now scientists continue to debate the function of dreams, but one thing we know

  • for sure is that REM sleep is vital, both biologically and psychologically.

  • But, hey, you think your dreams are nut-bar? Next week, were looking at other altered

  • states of consciousness, where youll learn what your brain really looks like on drugs,

  • and whether you can actually hypnotize someone to do your evil biddingor just act like

  • a chicken.

  • For now, if youve stayed awake during this episode, you learned about the four stages

  • of sleep -- NREM 1, 2, 3 and REM itself -- as well as some major theories for the psychological

  • purpose of dreaming, including information processing, physiological function, cognitive

  • development, and neural activity models. Thanks for watching, especially to all of

  • our Subbable subscribers, who make this whole channel possible. If you’d like to sponsor

  • an episode of Crash Course, get a special Laptop Decal, or even be animated into an

  • upcoming episode, just go to Subbable.com/crashcourse. This episode was written by Kathleen Yale,

  • edited by Blake de Pastino, and our consultant is Dr. Ranjit Bhagwat. Our director and editor

  • is Nicholas Jenkins, the script supervisor is Michael Aranda, who’s also our sound

  • designer, and the graphics team is Thought Café.

Comedian Mike Birbiglia was having trouble with sleep.

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眠るために、ひょっとして夢を見るために - クラッシュコース心理学 #9 (To Sleep, Perchance to Dream - Crash Course Psychology #9)

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    Johnny Tsai に公開 2021 年 01 月 14 日
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