シャドーイング練習: Why Do We Actually Need Sleep?? - 動画で英語スピーキングを学ぶ

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Sleeping.

Every day you go to your bed, lie down and do nothing.

For like eight hours.

This is stupid.

The time you spend doing literally nothing could be spent on so many other things.

Like eating, drinking, exercise, getting a job, spending time remembering that time you accidentally called your teacher mum.

But instead you're doing this.

Why?

Why haven't we figured out a way to not need to do this?

What does sleep even do?

And why do you feel sleepy?

What is sleepy?

Two things.

First is the suprachiasmatic nucleus, which is just your body clock.

It relies on light to get an idea of what time it is.

When it's day, it's chillin'.

But when it becomes night though, your retinas in your eyes see this

and then send messages to your body clock and it goes.. bed and then allows the release of melatonin,

which pretty much tells the brain it's nighttime.

And second is adenosine.

The heck is that?

Well all of your cells use this thing called ATP as energy, but as your body uses it, adenosine accumulates.

This accumulation increases sleep pressure, which makes you more tired.

So you finally climb into your bed and then you just lie there?

Don't worry, even

Even though you might feel like you're just lying there like a useless blob,

your part of the brain called the hypothalamus is getting ready to send

you into your dreamy state where you ride unicorns and eat fluffy clouds.

During the day, your brain is constantly sending messages using all these different chemicals in your brain called neurotransmitters,

but it's being extra sure to use these special neurotransmitters to stay awake.

But as your sleepiness builds,

it gets to a point where it lets this thing out of the cage the ventrolateral preoptic area inside the hypothalamus,

or VELPO for short.

What this does is blocks all the systems in the brain

that are making sure that it's using these neurotransmitters to stay awake, and thus gets you to fall asleep.

So now you're sleeping like a baby.

But again, why have we even evolved to need this absolute waste of time?

We'll get to that.

But first, what's happening while you're asleep?

It's called the sleep cycle, which you've probably heard of before.

And there's four parts to it.

First is stage one.

This is when you're barely asleep.

Your awareness goes down and muscle activity relaxes.

This is also the stage where this happens.

That was what the pros call a hypnic jerk.

So why does your own body give you a jump scare?

Well, researchers think that it could be your brain reacting to a sudden relaxation in the muscles and because it's stupid,

it interprets that as we're falling and jolts your muscles to double check.

But they aren't actually certain, so it could be something else.

Anyway, next is stage two, which is a light sleep.

This is where your heart rate slows, your body temperature decreases, and muscles relax even more.

But two other really interesting things happen here.

Sleep spindles, which are short bursts of brain activity, and K -complexes, which are big distinctive brainwaves.

Why?

Well, they seem to both have roles in protecting sleep and memory processing, but again, meh.

Then you get to stage three, deep sleep.

This is where activity is at its lowest, and your body takes advantage of that, increasing growth hormone secretion, tissue repair,

immune function support, and metabolic regulation.

It also takes that opportunity to use the glymphatic systems, which is a nerdy way of saying a waste clearing system for the brain as well.

And this is the stage where you're the most dead to the world.

You're just there, in your bed, catching your Z's, sleeping like a baby.

BOOM!

REM sleep.

All of a sudden your heart rate starts going up and down, brain activity jumps, and irregular breathing increases as well.

REM, or rapid eye movement, is where the most vivid of your dreams happen.

And yes, it's called rapid eye movement because your eyes are literally darting around while you sleep.

But, if you're having a dream that you're running away from the scariest thing you can imagine,

a job application, why don't you move in real life?

It's called REM -a -tonia.

Pretty much, your brainstem literally stops messages going from your brain to your skeletal muscles, while other messages for vital muscles such as your heart,

lungs and yes your eyes are allowed through.

But on the odd occasion it goes over time and is still stopping you from moving even when you wake up.

That's what causes sleep paralysis.

The thing where you're awake but you can't move.

And yes, because of this mix -up, dreamlike processes can still intrude your awakeness.

Hence why you sometimes can start hallucinating really scary things.

Like that job application.

Then you finish the cycle.

So, you do it again.

This whole cycle takes roughly 90 minutes.

But that can vary depending on the person.

And they're not even lengths either.

Usually, earlier in the night you actually get more deep sleep, whereas later in the night you get more REM sleep.

But then you wake up in the morning and think to yourself, why?

Think about it though, every night you're putting yourself in a state where you are extremely vulnerable to enemies, you can't eat, you can't drink,

you can't care for your children, you can't look for a girlfriend, you can't even fill out that job application.

And yet evolution has gone to extreme lengths in order to preserve this strange routine.

And when I say extreme, I mean extreme.

Think about dolphins for instance.

They need air to survive, but if they slept they would drown.

So they evolved to not need sleep right?

Nope.

They evolved so that to sleep they shut down half of their brain

and let that side sleep and just use the awake side and then just swap it over.

And not just dolphins, but many birds also do this too.

So why hasn't evolution just gotten rid of it altogether?

Why is it so persistent on keeping sleeping?

Well, we do know the important stuff that sleep does do.

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First, the brain needs maintenance, and it can't do it as effectively while it's awake.

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It's like trying to do maintenance in a warehouse.

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It's much easier to do it while it's empty rather than when it's full of customers.

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Second, the brain also needs to manage and sort what it learnt that day.

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Organise memories, new skills and get rid of old ones.

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Again, it seems that it can't do it as effectively while it's awake.

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And third is body repair.

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Yet again, it does it better when it's asleep.

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But I still have a problem with that.

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Why do we need to actually be asleep?

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As in unconscious?

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We could have just evolved to be able to repair, sort and maintain ourselves while awake.

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And yet evolution has been determined to keep it,

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and has clearly decided that it's worth the risk of not being conscious for 8 hours every day, than not to sleep at all.

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And that's the real mystery of sleep that no one has been able to really answer.

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Why do we really need sleep?

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And if you want to get a good night's sleep,

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a little birdie told me that hitting the subscribe button and show it two cold sides to your pillow for a week.

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このレッスンの語彙とスピーキングのポイント

このスピーキングレッスンは、動画「Why Do We Actually Need Sleep??」を教材にしています。繰り返し出てくる語は次のとおりです：sleep, brain, awake, muscle, asleep。この動画には、シャドーイング用の文が118文、単語が1262語あります。音声の長さは7:47です。話す速さは1分あたり約162語で、日常会話に近い自然なペースです。単語の84%は英語の頻出3,000語に含まれます。残りは練習の前に確認しておきましょう。全118文のうち19文が疑問文なので、疑問文のイントネーションや短い受け答えの練習に向いています。

この動画の重要語彙

動画に出てくる覚えておきたい単語15語を、発音と意味つきで紹介します。

単語	発音	意味
awake 動詞	/əˈweɪk/	目覚める, 目を覚ます
muscle 名詞	/ˈmʌs.əl/	筋肉, 筋
asleep 形容詞	/əˈsliːp/	寝ている, 眠っている
repair 動詞	/ˈɹiːpɛɚ/	修理する
clock 名詞	/klɑk/	走行距離計
sudden 形容詞	/ˈsʌd.ən/	突然の
rapid 形容詞	/ˈɹæp.ɪd/	速い, 急な
scary 形容詞	/ˈskɛə.ɹi/	怖い
relax 動詞	/ɹɪˈlæks/	くつろがせる
sleepy 形容詞	/ˈsliːpi/	眠い, 眠たい
dolphin 名詞	/ˈdɑlf.ɪn/	海豚, イルカ
cloud 名詞	/ˈklaʊ̯d/	雲, 雲霞
mystery 名詞	/ˈmɪs.t(ə.)ɹi/	ミステリー, 不思議
awareness 名詞	/əˈwɛɹ.nəs/	意識
skill 名詞	/skɪl/	腕, 技

動画に出てくる句動詞

単語	発音	意味
fill out 動詞	/fɪl ˈaʊt/	書き込む, 記入する
go down 動詞		降りる, 降下する
go up 動詞		上がる, 登る
lie down 動詞		横になる, 臥す
shut down 動詞		シャットダウン
wake up 動詞	/ˌweɪk ˈʌp/	目覚める, 目を覚ます

繰り返し練習したい文

動画に出てくる短く完結した文です。日常会話でそのまま使えます。

But first, what's happening while you're asleep?
This is when you're barely asleep.
The thing where you're awake but you can't move.
Why do we need to actually be asleep?
Why do we really need sleep?

この動画の文法

話し手がよく使っている文型を、動画の実際の表現とともに紹介します。

文型	動画での表現
現在完了形 have/has + 過去分詞 — 過去の出来事が今も関係している	haven't we figured · have we even evolved · you've probably heard
関係詞節 who / which + 節 — 人や物について情報を加える	nucleus, which is · pressure, which makes · two, which is
受動態 be + 過去分詞 — 誰がするかより、何が起きるかに焦点を当てる	could be spent · are allowed

注意したい発音

話し手はyou're, can't, don'tなど、短縮形や弱形を28回使っています。聞こえたとおりの短い形で発音しましょう。

「th」の音: breathe /bɹiːð/, altogether /ɔl.tuˈɡɛð.ɚ/
「sh」と「zh」の音: evolution /ˌiːvəˈluːʃ(ə)n/, occasion /əˈkeɪ̯ʒən/, regulation /ˌɹɛɡjʊˈleɪʃən/, tissue /ˈtɪʃ.(j)u/, conscious /ˈkɑn.ʃəs/
長い単語（アクセントの位置に注意）: evolution /ˌiːvəˈluːʃ(ə)n/, regulation /ˌɹɛɡjʊˈleɪʃən/, accidentally /ˌæk.sɪˈdɛnt(ə)li/, altogether /ɔl.tuˈɡɛð.ɚ/, irregular /ɪˈɹɛɡ.jə.lɚ/

日本語話者が苦手な音：

/r/ と /l/ の区別 — /l/ は舌先を歯茎につけ、/r/ はどこにもつけない: relax /ɹɪˈlæks/, regulation /ˌɹɛɡjʊˈleɪʃən/, roughly /ˈɹʌf.li/, rely /ɹɪˈlaɪ/, vulnerable /ˈvʌln(ə)ɹəbl̩/
/v/ — /b/ にならないように、上の歯を下唇に当てる: evolve /ɪˈvɑlv/, evolution /ˌiːvəˈluːʃ(ə)n/, vital /ˈvaɪtəl/, vary /ˈvɛəɹi/, vulnerable /ˈvʌln(ə)ɹəbl̩/
/f/ — 「フ」ではなく、上の歯と下唇で出す: dolphin /ˈdɑlf.ɪn/, roughly /ˈɹʌf.li/, glymphatic /ɡlɪmˈfæ.tɪk/

この動画での練習方法

まず声を出さずに動画を最後まで聞き、知らない単語をメモします。
まず0.75倍速で一文ずつシャドーイングし、慣れてきたら通常の速度に戻します。
自分の声を録音して元の音声と比べます。awake, muscle, asleepなどの単語に特に注意しましょう。

シャドーイングとは？英語上達に効果的な理由

シャドーイング（Shadowing）は、もともとプロの通訳者養成プログラムで開発された言語学習法で、多言語習得者として知られるDr. Alexander Arguelles によって広く普及されました。方法はシンプルですが非常に効果的：ネイティブスピーカーの英語を聞きながら、1〜2秒の遅延で声に出してすぐに繰り返す——まるで「影（shadow）」のように話者を追いかけます。文法ドリルや受動的なリスニングと異なり、シャドーイングは脳と口の筋肉が同時にリアルタイムで英語を処理・再現することを強制します。研究により、発音精度、抑揚、リズム、連音、リスニング力、そして会話の流暢さが大幅に向上することが確認されています。IELTSスピーキング対策や自然な英語コミュニケーションを目指す方に特におすすめです。

シャドーイングのやり方: ステップ別の完全ガイドを読む →

シャドーイング練習: Why Do We Actually Need Sleep?? - 動画で英語スピーキングを学ぶ

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