that we can do each and every day

我們可以每天做，

to reset the health of our brain and our body.

來讓我們頭腦和身體恢復健康。

And by understanding a little bit more about what sleep is,

透過多了解睡眠一點，

perhaps we can get the chance to improve both the quantity and the quality

也許我們可以有機會

of our sleep.

同時增加睡眠的時數和品質。

[Sleeping with Science]

【睡眠科學】

(Music)

（音樂）

So, exactly what is sleep?

準確來說，什麼是睡眠？

Well, sleep, at least in human beings,

睡眠──至少對人類來說──

is subdivided into two main types.

分為兩大類型。

On the one hand, we have non-rapid eye movement sleep,

一方面我們有非快速動眼期睡眠，

or non-REM sleep for short.

或簡稱為「非 REM 睡眠」。

But on the other hand,

另一方面，

we have rapid eye movement sleep, or REM sleep.

我們有快速動眼期睡眠， 簡稱為「REM 睡眠」。

And non-REM sleep has been further subdivided

非 REM 睡眠又進一步分為

into four separate stages,

四個不同的階段，

unimaginatively called stages one through four,

名字沒什麼創意， 就叫做第一到第四階段，

increasing in their depth of sleep.

隨著睡眠深入程度遞增。

And as we go into those light stages of non-REM sleep,

一旦進入非 REM 睡眠期 那些比較淺層的階段，

your heart rate starts to decrease,

你的心跳速度就會開始變慢，

your body temperature starts to drop

體溫開始下降，

and your electrical brain wave activity starts to slow down.

你的腦波活動也會開始變慢。

But as we move into deeper non-rapid eye movement sleep,

但當我們進入深層的非 REM 睡眠期，

stages three and four,

也就是第三和第四階段，

now all of a sudden the brain erupts

突然間大腦會出現

with these huge, big, powerful brain waves.

這樣強大的腦波。

The body is actually recharged in terms of its immune system.

身體其實是在為免疫系統充電。

We also get this beautiful overhaul of our cardiovascular system.

我們還徹底整修了心血管系統。

And, in fact, upstairs in the brain,

其實在上層大腦中，

deep non-REM sleep will help consolidate memories

深層非 REM 睡眠期 還能幫忙鞏固記憶，

and fixate them into the neural architecture of the brain.

將記憶深植入大腦的神經結構。

So that's non-REM sleep.

這就是非 REM 睡眠期。

But let's come on to REM sleep,

接下來我們來談 REM 睡眠期，

which is the other main type of sleep.

這是睡眠另一個主要類型。

And it's during REM sleep when we principally have the most vivid,

我們在 REM 睡眠期 原則上會有最生動、

the most hallucinogenic types of dreams.

最奇幻的夢。

The brain wave activity actually starts to speed up again.

腦波活動開始再次加速。

It's during REM sleep that we receive almost a form of emotional first aid.

也是在 REM 睡眠期 我們的情緒會得到某種急救。

And it's also during REM sleep where we get a boost for creativity,

在這個階段我們的創造力也會大增，

that it stitches information together

並將資訊結合起來，

so that we wake up with solutions

這樣我們一覺醒來

to previously difficult problems that we were facing.

就會得到之前面臨難題的解方。

Coming back to these two types of sleep,

回來談這兩個睡眠型態，

it turns out that non-REM and REM will play out

非 REM 睡眠期和 REM 睡眠期

in a battle for brain domination throughout the night,

在夜裡會爭著支配大腦，

and that cerebral war is going to be won and lost

兩者在這場腦內戰爭

every 90 minutes,

每九十分鐘會贏一次、輸一次，

and then it's going to be replayed every 90 minutes.

九十分鐘後再重演一次。

And what this produces is a standard cycling architecture of human sleep,

這就形成了人類睡眠的 標準週期架構，

a standard 90-minute cycle.

標準的九十分鐘週期。

But what's different, however,

然而不同的地方在於，

is that the ratio of non-REM to REM within those 90-minute cycles

非 REM 睡眠期和 REM 睡眠期 在九十分鐘週期的比例

changes as we move across the night,

會在夜裡改變，

such that in the first half the night,

因此在上半夜，

the majority of those 90-minute cycles

九十分鐘裡的絕大多數時間

are comprised of lots of deep non-REM sleep,

是由深層的非 REM 睡眠期構成，

particularly stages three and four of non-REM sleep.

特別是第三和四階段的 非 REM 睡眠期。

But as we push through to the second half of the night,

但當我們進入下半夜，

now that seesaw balance actually shifts over,

蹺蹺板向另一邊傾，

and instead, most of those 90-minute cycles

九十分鐘週期之中的大部分時間

are comprised of a lot more rapid eye movement sleep, or dream sleep,

是 REM 睡眠期，也就是做夢期，

as well as stage-two non-REM sleep,

和第二階段的非 REM 睡眠期，

that lighter form of non-REM sleep.

那個比較淺層的非 REM 睡眠期。

And it turns out that there are implications

這也說明了

for understanding how sleep is structured in this way.

睡眠是怎麼透過這個方式形成。

Let's take someone who typically goes to bed at 10pm,

舉例來說，有人 每天都十點上床睡覺，

and they wake up at 6am,

六點起床，

so they have an eight-hour sleep window.

所以他們就有八小時的睡眠時間。

But this morning, they have to wake up early

但某天早上他們要早點起床，

for an early morning meeting,

因為隔天一早要開會，

or they want to get a jump start on the day

或是他們想早起上健身房。

to get to the gym.

結果他們早上四點就起床，

And as a consequence, they have to wake up at 4am in the morning,

而不是平常的早上六點。

rather than 6am in the morning.

他們實際上失去多少睡眠？

How much sleep have they actually lost?

八小時的睡眠少了兩小時

Two hours out of an eight-hour night of sleep

等於他們少了 25% 的睡眠。

means that they've lost 25 percent of their sleep.

這樣的說法對也不對。

Well, yes and no.

他們失去 25% 的睡眠，

They have lost 25 percent of all of their sleep,

但 REM 睡眠期 大多是在後半夜出現，

but because REM sleep comes mostly in the second half of the night

特別是在最後的幾個小時，

and particularly in those last few hours,

他們可能失去了 50、60%，甚至 70%

they may have lost perhaps 50, 60, maybe even 70 percent

REM 睡眠期。

of all of their REM sleep.

所以了解睡眠是什麼

So there are real consequences to understanding what sleep is

以及睡眠的架構非常重要。

and how sleep is structured.

我們在後續單元會談到 這兩個不同階段的所有好處，

And we'll learn all about the benefits of these different stages of sleep

以及睡眠不足帶來的危害。

and the detriments that happen when we don't get enough of them

in subsequent episodes.