What's going on inside our brains?

我們的大腦做了些什麼？

The scientific study of dreaming is called oneirology.

研究夢境的科學稱為「夢學」，

And for most of history, it didn't really exist,

但大部分歷史上，並非真的有這項科學，

because you can't hold a dream.

因為夢境是捉摸不到的。

It's difficult to measure a dream, you can't taste it.

測量夢境很難，因為你沒辦法實際體驗它，

You can't see other people's dreams,

你無法看到別人的夢境，

and if you ask them to tell you what they dreamt,

如果你問別人夢了什麼，

the results are almost always unreliable.

他們的回答通常都是不太可信的。

In fact, it's estimated that we forget 95 percent of the dreams we have,

事實上，我們估計會忘掉 95% 我們做的夢，

especially within the first ten minutes of having them.

尤其是夢的前 10 分鐘。

But then, in 1952, something amazing happened.

不過 1952 年的時候，驚人的事情發生了，

Researchers at the University of Chicago found this.

芝加哥大學的研究人員有了新發現，

It's a unique type of electrical activity that occurs

人類睡眠到某個階段，

during a certain stage of a person sleeping.

大腦會產生一種獨特的腦電活動，

When researchers awoke people during this stage,

當研究人員在這個階段叫醒受試者的時候，

they almost always reported that they had been dreaming.

發現受試者幾乎都正在做夢。

Also, at the same time, during this stage, people's eyeballs are going crazy,

同時，在這個階段，受試者的眼球會瘋狂轉動，

rapidly darting all over the place underneath their eyelids.

快速地在眼皮下轉來轉去，

You can actually see this happening if you watch people sleep like I usually do.

如果你像我一樣，常常觀察別人睡覺，你也會發現這件事。

During REM sleep, some pretty bizarre stuff happens.

在睡眠的快速動眼期，會發生一些非常奇特的事情，

If you look at the electrical activity of a brain that is in REM sleep,

如果你觀察大腦在快速動眼期的腦電活動，

it almost exactly mimics the way the brain acts when it's awake.

你會發現，它和大腦清醒時的腦電活動幾乎一模一樣，

The biggest difference being that the production of chemicals inside the brain

最大的不同，就是大腦裡面的化學物質，

like norepinephrine, serotonin, and histamine,

像正腎上腺素、血清素、和組織胺，

is almost completely blocked,

都幾乎停止製造，

and that causes the muscles to stop moving,

而使肌肉停止活動，

which is why you can dream about flying or running around

這就是為什麼，你能夢到你在飛、你在跑、

or fighting ninjas, but your body doesn't move.

或跟忍者打架，你的身體卻不會動。

People who have a disorder achieving complete REM atopia (atonia)

有些人，因為快速動眼期時，肌肉無法完全麻痺，

move around in their sleep and act out their dreams.

所以睡覺、做夢的時候，就會拳打腳踢，

They can even get out of bed and sleep walk.

有些甚至會下床、夢遊。

Oh, before we move forward, I should say two things.

繼續往下之前，我應該要說明兩件事，

One is that it's possible to wake up and not be able to move your body

一是你有可能醒過來，卻發現身體無法動彈，

because you're still in REM atopia (atonia).

那是因為你還在快速動眼期的肌肉麻痺中，

You're completely conscious and you know that you're awake,

你的意識完全清楚，也知道自己醒著，

but your body is not ready to move.

但你的身體還沒有醒來。

On the flip side, you can also be inside a dream

另一件是，你也能在做夢的同時，

and know that you're dreaming.

知道自己正在做夢，

This phenomenon is known as lucid dreaming,

這現象叫做「清醒夢」，

and it's particularly attractive, because while in a lucid dream,

這非常吸引人，因為在清醒夢裡面，

I can make conscious decisions about what I do.

我可以決定我要做什麼，

I can go fly to wherever I want, or I can have a tea party with Abraham Lincoln.

我可以飛去任何我想去的地方，或是跟林肯總統喝下午茶，

I'm in control, but achieving a lucid dream is quite illusive.

一切由我掌控，不過要做清醒夢並不簡單，

Howcast has a great video, which I've put in the description

Howcast 有部很棒的影片，我把連結放在下方介紹，

that gives some tips and tricks on how to achieve one.

影片會教你做清醒夢的一些技巧。

Researchers were able to deprive mice of REM sleep by using this

研究人員都用這個剝奪老鼠的快速動眼期睡眠，

inverted inside a tub of water way up to the tippy top,

把這個倒放在有水的桶子裡，

meaning that the mouse was only able to sit right on top of this little tiny surface.

代表老鼠能待的地方，只有這小小一塊表面，

When that happens, the mouse can still fall into non-REM sleep,

如此一來，老鼠雖然能進入非快速動眼期睡眠，

but as soon as they reach REM sleep and their muscles relax,

可是一旦牠們進入快速動眼期，肌肉就會鬆懈，

they fall off the platform into the water waking up.

牠們就會掉進水裡醒來，

What they found was that when mice are not allowed to achieve REM sleep,

研究人員發現，當老鼠無法進入快速動眼期睡眠，

they have incredible amount of trouble remembering things.

牠們的記憶力會大幅減退，

This happens in humans too.

人類也是如此，

If you have people remember word pairs and then you don't allow them to sleep,

如果在睡眠被剝奪的情況下，要求受試者背一些詞對，

the next day, their memory for that stuff is incredibly terrible.

隔天，他們幾乎記不起來，

But memory and REM does not stop there.

記憶力和快速動眼期的關係不只這些，

If a person learns a difficult new task during the day,

如果受試者在白天學習困難的新事物，

say a new instrument or a new type of difficult puzzle,

像是新的樂器、新的難題，

you can measure the electrical activity in their brain while they do that,

當他們在學習時，你可以測到他們大腦的腦電活動，

and then while they sleep that night, whether they know it or not,

而當他們晚上睡覺時，無論他們知不知道，

their brain replays those electronic impulses.

他們的大腦會再次釋放一樣的腦電脈衝。

Many popular theories about why we dream

關於做夢的原因，有很多著名的理論，

are variations on the idea that while we sleep,

都從這個想法變化而來，就是當我們睡覺時，

the unconscious part of our brain is busy organizing memories,

我們大腦的潛意識區塊，正忙著整理我們的記憶，

and strengthening connections from the day before that we need in the future

加強白天記憶的連結，以待來日所需，

while getting rid of the junk that would otherwise clog the brain.

同時清除大腦不要的記憶，騰出空間。

Now, so the theory goes,

理論是這樣的，

these electrical impulses are detected by our conscious brain,

我們有意識的大腦偵測到這些腦電脈衝，

and our cortex freaks out. It doesn't know what it means,

大腦的皮層嚇壞了，因為它不知道這是什麼意思，

and so it tries its best to create a cohesive story,

所以它竭盡全力創造一個連貫的故事，

creating a dream.

也就是你的夢。

This would explain why dreams are often so fantastic and seemingly random.

這大概可以解釋，為什麼夢的內容是隨機的，而且往往很奇怪，

They're not supposed to make sense, they're not an actual message from our brain.

因為夢沒有道理可言，它不是我們大腦實際發出的訊息，

It's just the results of our cortexes trying to synthesize the noise

只是我們大腦的皮層，試圖與潛意識

coming from all the work being done back in the unconsciousness.

作業時所傳來的訊息同步而已，

Under this way of thinking, dreams are an epiphenomenon.

這樣想的話，夢其實是一種附帶現象，

They're not a primary process that has a purpose.

它並不是大腦有目的的主要程序，

Instead, they're the accidental result of a more important process

相反地，它是有意識的大腦中某個更重要的程序，

going on behind the conscious brain.

意外造成的結果。

But some researchers don't believe that.

不過有些研究人員不這麼認為，

They believe the dreams serve a primary purpose,

他們覺得夢有主要目的，

and that purpose is to prepare us for threats.

就是為我們做好應付威脅的準備，

They think this because the most prevalent emotions felt during dreams are negative.

他們這樣想是因為，普遍在夢裡感受到的情緒，都是負面的，

Abandonment, anger, and the most common of all, anxiety.

遺棄、憤怒、和最常見的焦慮，

Theory goes like this: back when we were early humans especially,

理論這樣解釋：回溯到早期人類的生活，

we had no idea what kind of threats we might encounter during the day.

我們不知道白天會遇到什麼威脅，

And so, to prepare us, our brain would simulate anxieties while we slept

因此，為了讓我們做好準備，我們的大腦會在睡眠的時候，模擬焦慮的感覺，

to make us better prepared for that feeling in the real world.

以便我們在真實世界，對這樣的感覺做好準備，

So people who had terrifying dreams

所以常做惡夢的人，

were better at dealing with anxiety in the real world,

比較能應付現實生活中的焦慮感，

and had stronger genes.

也擁有較強大的基因。

All right, so the theories we discussed today are quite popular,

雖然今天討論的理論都非常有名，

but they don't really enjoy a consensus.

但是它們沒有獲得一致的認同，

Not everyone agrees on them,

並非每個人都對它們持一致意見，

and they barely scratch the surface of scientific thought about dreams.

且關於「夢學」，這些還只是九牛一毛。

But that's kind of the cool thing about dreams.

不過夢真的蠻神奇的，

Think of it like this.

想像一下，

Here is the eagle nebula,

這是鷹狀星雲，

a giant structure in outer space 6,500 light years away.

6500 光年之外太空中的巨大結構體，

But despite its distance, we pretty much know what it's made out of.

儘管距離很遠，我們仍清楚知道它是什麼組成的，

We know that it's 100 trillion kilometers tall,

知道它的高度有 100 兆公里，

we know what caused it, and we know where it's going to be in 750 million years.

知道它的起源，也知道 750 年後它會在哪裡。

But last night, I had dreams,

但我昨晚做的夢，

and no one really knows why or for what reason.

卻沒有人真正知道原因、來由，

And that's pretty cool, and that's why. Thanks for watching.

這件事非常神奇，也是夢很神奇的原因，謝謝你的收看。

If you want to learn more about the world, I highly recommend Smarter Every Day,

如果你想知道更多世界上的大小事，我強力推薦 Smarter Every Day，

it's a show here on YouTube by a guy named Destin

是名叫 Destin 的 YouTuber 開的頻道，

who I've met, he's awesome, I've learned a lot from him.

我見過他，他非常棒，我從他身上學到很多東西，

He's the guy who did the chicken thing from the Leanback.

他就是那個測試雞頭穩定性的人，

He's also studied what causes poop splash,

他也研究過，大便落入馬桶為什麼會濺水，

slow motion water balloons,

水球的慢動作畫面，

and has a lot of guns and explosions. What more could you ask for?

還有很多射擊、爆炸的實驗，應有盡有。

So do me a favor and go check it out and subscribe if you like it.

所以幫我個忙，到他的頻道看看，如果你喜歡可以訂閱他，

And if you haven't seen it yet, go check out "Whatswhat reviews my beard."

如果你沒看過他的頻道，可以看《Whatswhat reviews my beard》，

I've got that in the description, and as always, thanks for watching.

連結放在下方介紹，謝謝你的收看。