Why You're Always Tired - 7 Myths Ruining Your Sleep

Summary

このビデオは、睡眠に関する7つの誤解を解くことを目指しています。アメリカの成人の平均で週に3日間は眠気が感じられ、30～48％の成人が睡眠障害を経験しているとされています。しかし、多くの場合、問題は睡眠時間の不足ではなく、様々な誤解に起因する睡眠に対する不安です。ビデオでは、オックスフォード大学のラッセル・フォスター教授のポッドキャストでのインタビューを通じて、睡眠の科学について語ります。フォスター教授は、体内時計のリズムに従って睡眠をとることが大切であると述べ、また、睡眠時間を強制的に8時間に押し込む必要はなく、個人差があると説明しています。また、青色光の影響や睡眠アプリの有効性、メラトニンの助益、そして多相睡眠の生産性に関する誤解についても触れています。このビデオは、睡眠についての誤解を解き、より良い眠りを得る手助けを提供することを目指しています。

Takeaways

• 😴 米国の大人は週に平均3日間疲れを感じており、30～48％が睡眠に問題を抱えています。
• 🔍 睡眠の質が悪い原因は睡眠時間ではなく、睡眠にまつわる不安や迷信に起因することが多いです。
• 📚 マシュー・ウォーカーの著書「Why We Sleep」は良書ですが、睡眠に関する過度の心配が睡眠不安を引き起こす原因となっています。
• 🕒 睡眠のタイミングが重要であり、サーカディアンリズム（体内時計）が私たちの健康に大きく影響しています。
• 🌞 体内時計は光を感知する特定の眼内細胞によって調整され、日中は活動し夜は休むように促されます。
• 🕊️ 個人によって体内時計の設定が異なるため、朝型人間や夜型人間などの概念が存在します。
• ⏰ 睡眠時間には個人差があり、必ずしも8時間が全員に適しているわけではありません。
• 🌙 青色光は睡眠に悪影響を及ぼすとされていますが、その影響は生物学的にはわずかで、大きな問題ではありません。
• 📱 睡眠アプリは客観的なデータを提供するものの、それに依存することは避け、自身の体の信号を重視すべきです。
• 💊 メラトニンのサプリメントは睡眠の質を向上させるとされていますが、その効果は限定的であり、睡眠障害の改善には不十分です。

Q & A

平均的な大人は何曜日に疲れを感じる傾向がありますか？

調査によると、アメリカの大人たちは平均して週に3日間疲れを感じています。

睡眠に関する誤解を抱くことによって生じる不安を何というのですか？

睡眠に関する誤解を抱くことによって生じる不安は、睡眠不安と呼ばれます。これは睡眠を心配したり、心配しているという感じで、睡眠を妨げる悪循環を作り出します。

マシューズ教授のポッドキャストで話された7つの睡眠の神話とは何ですか？

マシューズ教授が話した7つの睡眠の神話には、人は毎夜8時間の睡眠が必要である、睡眠は年齢と共に減少するべきである、睡眠剤が安全である、等が含まれます。

Outlines

00:00

😴 睡眠の誤解を解く

この段落では、アメリカの大人の平均的な疲れ感や睡眠問題、そして睡眠に関する誤解とその解明方法が紹介されています。特に、マシューズ・ウォーカーの本「Why We Sleep」の話題を通じて、睡眠時間と認知症や心臓病の関連性について触れています。また、睡眠不安という概念も説明されており、これは睡眠に対する不安感が睡眠を妨げる悪循環を作り出すとされています。また、ロッサム大学のラッセル・フォスター教授のインタビューも取り上げられており、彼は体内時計と呼ばれる生理リズムの専門家です。

05:00

🛌 睡眠の7つの誤解

このセクションでは、睡眠に関する7つの一般的な誤解と、それらを解くためにフォスター教授が述べている事実が説明されています。具体的には、睡眠のタイミングが健康に与える影響、睡眠時間の個人差、同じ時間に起きることが望ましい理由、青色光の影響、睡眠アプリの有効性、メラトニンの効果、そしてマルチフェーズ睡眠の生産性に関する誤解が取り上げられています。各誤解は、科学的根拠に基づいて分析されており、睡眠の質と生産性の向上に役立つ情報を提供しています。

10:03

📚 睡眠の科学と生産性

最後の段落では、マルチフェーズ睡眠と生産性に関する誤解が詳述されています。マルチフェーズ睡眠は、1日の中で複数の短い睡眠時間をとることを意味していますが、実際には生産性や創造性に悪影響を及ぼす可能性があるとされています。また、学生の試験成績に関する研究結果も紹介されており、通常の単一フェーズ睡眠よりもマルチフェーズ睡眠の方が生産性が低いとされています。このセクションでは、視聴者がフォスター教授のポッドキャストのインタビューをチェックしてみることを促しており、さらに深く眠りの科学を学ぶことができます。

Keywords

💡睡眠焦虑

睡眠焦虑是指对睡眠感到恐惧或担心的一种情绪状态，这种焦虑反而会加重失眠问题，形成恶性循环。在视频中，提到睡眠焦虑是由对睡眠的各种误解和神话所引起的，这些神话被用来说明如何通过消除这些误解来改善睡眠质量。

💡昼夜节律

昼夜节律是身体内部的时钟，它指示身体在特定时间需要什么。视频中提到昼夜节律几乎影响我们健康和幸福的每一个方面。例如，昼夜节律决定了我们在明亮的外部环境下保持清醒，在黑暗环境下睡眠，这与我们的眼睛中负责检测光线的细胞有关。

💡chronotype（时间类型）

chronotype是指个人自然倾向于在一天中特定时间睡觉的类型。视频中提到，根据个人自然醒来的时间和感到最高效的时间段，可以将人们分为早晨型或夜晚型。了解个人的chronotype有助于安排日常活动，以适应个人的生物钟。

💡8小时睡眠规则

8小时睡眠规则是一个普遍的信念，认为每个人都需要每晚睡8小时。然而，视频中指出人们对睡眠的需求有相当大的变化，健康睡眠的时间可以从6小时到10或11小时不等。因此，不必过分担心每晚获得的睡眠时间，而应关注睡眠质量和个人的身体信号。

💡蓝光

蓝光是波长较短、能量较高的光。视频中提到，有关蓝光影响睡眠的担忧是基于假设蓝光以某种方式影响眼睛，使入睡变得困难。然而，研究表明蓝光对睡眠的影响可能并不像人们想象的那么大，例如使用带有背光的Kindle阅读并不会显著延迟入睡。

💡睡眠追踪应用

睡眠追踪应用是设计用来监测和分析睡眠模式的工具。视频中提到，虽然这些应用可以提供睡眠数据，但它们并不总是准确的，也不应成为评价睡眠质量的唯一标准。个人的主观感受，如醒来时的感觉，以及白天的精神状态，是更重要的睡眠质量指标。

💡褪黑素

褪黑素是一种被广泛用作补充剂的物质，人们认为它可以帮助改善睡眠。然而，视频中提到，褪黑素对于缩短入睡时间的效果有限，最好的研究结果表明它可能只将入睡时间缩短30分钟。对于大多数人来说，褪黑素对日常睡眠的帮助并不显著。

💡多相睡眠

多相睡眠是一种将一天的睡眠分成多个时间段的睡眠模式，与单相睡眠（即传统的一夜睡眠）相对。视频中指出，尽管多相睡眠理论上可以增加清醒时间，但实际上它可能会导致工作效率和创造力下降，因此并不利于提高生产力。

💡Russell Foster教授

Russell Foster是一位睡眠专家，他在牛津大学拥有自己的实验室。视频中提到了对他的采访，他对于睡眠的科学有深入的研究，并在视频中提供了关于睡眠神话的科学解释和建议。

💡睡眠建议

视频中讨论了关于睡眠的各种建议，包括睡眠的持续时间、睡眠的质量和睡眠习惯等。这些建议旨在帮助观众识别和避免关于睡眠的常见误解，从而改善他们的睡眠质量。

💡睡眠神话

睡眠神话是指关于睡眠的一些普遍但错误的信念。视频中列举并反驳了七个关于睡眠的常见神话，如睡眠时间的长短、蓝光对睡眠的影响、褪黑素的作用等，目的是帮助观众建立更科学的睡眠观念。

Highlights

成年人在美国平均每周有三天感到疲劳，30%至48%的成年人存在睡眠问题。

许多人的睡眠问题不是睡眠时长，而是围绕睡眠的焦虑，这由相信各种睡眠神话引起。

睡眠焦虑会进一步导致无法入睡，形成恶性循环。

Russell Foster教授的研究表明，睡眠时机与我们的生物钟，即昼夜节律，密切相关。

昼夜节律几乎影响我们的健康和幸福的每一个方面。

我们眼睛中的某些细胞只负责检测光线，帮助调节我们的内部时钟。

昼夜节律的紊乱，如时差或夜班工作，会增加压力激素，增加心脏病风险，并导致更频繁的疾病。

97%的夜班工作者无法适应夜间工作的需求。

不同的人有不同的内部时钟设置，这与所谓的“生物型”有关。

睡眠需求在个体间存在很大差异，健康睡眠时长可以从6小时到10或11小时不等。

应该根据自然醒来的情况，而不是闹钟，来判断是否获得了足够的睡眠。

每天同一时间醒来有助于调节生物钟，但偶尔的变动并不会有太大影响。

蓝光对睡眠的影响被夸大了，研究表明使用蓝光设备对睡眠的延迟并不显著。

睡眠追踪应用的数据应该谨慎对待，因为它们并不总是准确的。

褪黑激素作为补充剂对改善睡眠的帮助有限，最好的研究也只显示减少入睡时间30分钟。

多相睡眠，即一天中多次睡眠，对提高生产力并没有帮助，反而可能导致效率和创造力下降。

Transcripts

If you're feeling like you're always tired,

you're not alone.

Surveys have shown that on average,

adults in the US feel tired for three days of the week,

and 30 to 48% of adults have trouble sleeping.

But for a lot of us,

the problem isn't how much sleep we're getting,

it's actually the anxiety around our sleep

caused by believing various myths,

which is what we're gonna debunk in this video.

Now, I've been looking into the science behind sleep

for quite a while,

but even as someone with a medical background,

things can get super confusing.

And generally, when I talk to people in this area,

it's hard to figure out what's actually good advice

to follow and what is bad advice to ignore.

Like for example, Matthew Walker's book,

''Why We Sleep'' is very good,

but there was this whole craze around,

''Oh my God, I need to get my eight hours,

otherwise if I don't get my eight hours,

I'm gonna develop Alzheimer's disease

and all this cardiovascular problems.''

And all of this feeds into this thing called sleep anxiety,

which is the feeling of being scared or worried

or concerned about your sleep,

which paradoxically actually further contributes

to you being unable to sleep,

and this creates this kind of vicious cycle,

which is not very good.

Anyway, recently I interviewed Professor Russell Foster

on my podcast, Deep Dive.

He is a sleep expert who runs his own lab

at the University of Oxford.

Now, if you want,

you can check out the long form interview completely for free

on any podcast app that you like,

including iTunes and Spotify and Apple Podcasts,

all that kind of fun stuff.

But in this video,

I wanna talk about the seven sleep myths

that the interview with Professor Foster debunked.

And so if you like me have fallen into believing

some of these myths,

then hopefully this video should hopefully help you out

and help you get a better night's sleep.

Let's get started.

Myth number one,

it doesn't matter when you sleep,

as long as you sleep enough.

But it turns out that when we sleep

is actually super important as well.

And that's all because of this thing called

the circadian rhythm.

Circadian rhythms underpin almost every aspect

of our health and wellbeing.

And that was the bit I wanted to get across

within lifetime.

So the circadian rhythm

is essentially your body's internal clock

that signals to your body what you need at a given time.

In the 1990s,

Russell and his research group discovered

that there's a bunch of cells in our eyes

that are only responsible for detecting light

rather than helping us to see images.

This light detection mechanism in our eyes

tells our brain what time of the day it is

and helps regulate our internal clock.

Now, since our internal clocks are sensitive to light,

it means that generally we wanna be awake

when it's bright outside

and we wanna be asleep when it's dark outside.

And actually for the last few years,

Russell and his research group

have been working on what happens

when the circadian rhythm is affected,

i.e. when you sleep at weird times.

For example, if you've got jet lag

or for example, if you're working night shifts.

And they found that in these sorts of people

that have this disruption to their circadian rhythm,

you get an increase in stress hormones,

you get an increase in the risk of heart disease

and these people get sick way more often

and they're also more prone to emotional and cognitive

problems.

97% of night shift workers do not adapt

to the demands of working at night.

So they're working against an entire biology,

which is saying you should be asleep.

Now, it's important to realise that even though

we all have an internal clock ticking away

inside of ourselves,

not all of our internal clocks

are set in exactly the same way.

And so when you hear people saying,

I'm a morning person or I'm a night owl,

that relates to something called your chronotype.

Based on a natural inclination to sleep at a certain time,

scientists can bucket us into something called chronotypes.

For example, someone who naturally gets up early

and finds the morning to be the most productive hours

of the day probably has a morning chronotype.

And there's a questionnaire in the book

and on Russell's website,

we'll link that down below where you can answer

a few questions and it'll help you figure out

what your own chronotype is.

But once you figure this out,

then you might wanna try as best as you can

to organise your activities around,

kind of fitting around your chronotype.

For example, if you're more of a morning person,

you might find that it's better to put your creative

or your kind of highest focus related activities

in the morning.

Whereas if you're a night owl, that's totally fine.

If you can control your schedule,

it's generally worth trying to tweak things around

so that you're doing focused stuff at night, for example.

I've personally tried really hard

to become a morning person.

I attempted to wake up at six in the morning

and go straight to the gym,

but I always found like I had this like,

it's like absolute nightmare.

And so I wake up at a reasonable hour.

I wake up around seven, 7.30.

I think I'm a fairly middle of the day kind of guy.

And generally I try and get my book writing stuff done

in the morning and then do more chill things in the evening.

Myth number two, everyone needs eight hours of sleep.

Now the reality is that there's actually loads of variation

across like how much sleep people actually need.

One of the sort of slight frustrations that's emerged

is that an average value is taken

as the optimum value for all of us.

And of course it isn't.

Healthy sleep can range from six hours,

maybe slightly less than that, out to 10 or 11 hours.

Yes, there is an average,

but actually there's so much individual variation.

So rather than overly worrying

about the number of hours of sleep that you got

and then looking at your thing and,

oh, I only got seven hours of sleep tonight.

I'm gonna have a terrible day for the rest of the day.

There's a few other things that you can think about

to optimise your sleep.

Firstly, you might like to ask yourself,

did you wake up naturally in the morning

or did you need an alarm to wake you up?

Generally, if you wake up naturally,

you've got a pretty reasonable amount of sleep.

You might ask yourself,

did it take you a long time to wake up?

And did you feel the need for caffeinated drinks

when you woke up to help you become more awake?

That might be a sign that actually

you didn't necessarily get enough sleep.

And you can even check out your behaviour.

Like if you find yourself doing like stupid things

or being mean or unempathetic

or just being a bit annoying to people around you,

it might actually be because you didn't get enough sleep

the night before.

Myth number three,

we should wake up at the same time every day.

Now this isn't entirely a myth,

but what Russell said in the interview is that,

yes, it's generally good to wake up

at the same time each day,

but you don't really need to be overly pedantic about it.

It reinforces all of the sort of signals

that regulate the circadian system.

So eating at the same time,

getting light exposure at the same time,

that all acts to stabilise.

However, having said that,

you know, there's gonna be an occasion

where you have a party,

you're gonna get up late, you know,

and sleep is very dynamic.

And the other thing to keep in mind

is that our circadian rhythms can change

over the course of our life cycle.

So it's really common for teenagers, for example,

to have more of an evening chronotype,

which is why teenagers really struggle

to wake up in the morning.

And then as we age,

we sort of move to a more morning chronotype.

The time we're in our late fifties, early sixties,

we're getting up and going to bed.

At about the time we got up and went to bed

when we were 10.

Myth number four,

you should avoid blue light before sleep.

So where does this come from?

Well, blue light is light that has a short wavelength

and short wavelengths of light generally have more energy.

And so scientists have hypothesised that,

hey, blue light reacts to the eye in some way

and makes it harder to fall asleep.

For example, these glasses that I have

have a blue light filter to them

because the optician that I went to said,

hey, do you wanna pay an extra 100 pounds

for a blue light filter?

It's better for your sleep.

I was like, all right then, why not?

But apparently that's a bit of a myth.

So the Harvard group got people to look at a Kindle

on its brightest intensity for four hours

just before bedtime on five consecutive nights.

And it just statistically delayed sleep onset by 10 minutes.

Well, it may be statistically significant,

but it's biologically meaningless.

Which was pretty nice for me to hear

because now I can read on my Kindle

with a backlight on my Kindle

and not worry too much about like,

I'm getting too much blue light into my eyes.

By the way, if you're enjoying these myths so far,

I would love it if you can hit the like button

for the YouTube algorithm.

Apparently it really helps.

Myth number five,

sleep apps help you sleep better.

Now I got into this whole sleep tracking thing at one point.

I got the Aura Ring.

I currently use an eight sleep mattress,

which is admittedly quite good.

And I used to kind of keep track

of all of my kind of sleep data.

But what I would find is that I wake up in the morning

and be like, oh, my sleep readiness score is 54%.

I was like, oh, but I was feeling reasonable.

I guess I'm not actually feeling reasonable.

I guess my sleep score is 54%.

So I guess I should be having a bad day.

And it's like, I ended up sort of weirdly placebo

affecting myself in a negative way

because of what these various sleep tracking apps

were telling me about the quality of my sleep.

But as Russell said in the interview,

we should take a lot of this sleep app data

with a bit of a pinch of salt.

Worth bearing in mind at the moment,

no sleep apps are endorsed by any of the sleep federations

or FDA approved.

And of course, you know,

when you look at the validation of many of these apps,

you'll go into the paper

and you'll see it works perfectly for eight undergraduates,

you know, in California.

And that's about it.

But of course, the point I've just made

is that sleep changes as we age and between individuals.

And so one algorithm is also not appropriate

for telling us what good sleep is.

And so the bottom line that I took away from this is,

yes, it's nice to see what your sleep score is

if you're one of those people that loves to optimise

every little thing about your life,

but actually the biological and psychological signals

that your body is giving you,

like how it felt when you woke up,

did you feel well rested?

Did you need to wake up with an alarm or without?

How are you feeling the rest of the day?

Those signals are way more important

than an app telling you exactly

what your sleep fitness score might be.

Myth number six, melatonin helps us sleep better.

So you might've heard of melatonin.

It's a supplement that a bunch of people take.

It's really popular in the US apparently.

A bunch of people take it to kind of combat jet lag,

but also people have started taking melatonin

just to help with their sleep if they have bad sleep.

The best studies ever undertaken,

taking melatonin before you go to bed

can reduce the time it takes to get to sleep by 30 minutes.

And I stress, that's the best study ever undertaken.

Many studies showed no effects whatsoever.

Now this best study that Russell is referring to

is a study that was done in 2007 on autistic children.

And they found that the children

who were taking regular small doses of melatonin

every day for three months,

eventually ended up being able to fall asleep

30 minutes sooner.

But a few years later in 2013,

there was a meta analysis

about whether melatonin really helps your sleep.

And the researchers who did that study

found that on average,

melatonin reduces your time to fall asleep

to by about seven minutes,

which is not particularly impressive.

And if you're looking for something

even more recent than that,

this book, Lifetime, it's really good.

I listened to it on Audible, came out in 2022.

I even have a nice little signed copy right here.

But this talks about kind of the most up-to-date stuff

around melatonin.

And it's basically what Professor Foster says

because he wrote the book and is a sleep professor

that it doesn't actually make that much difference.

Maybe it might help with jet lag,

but not generally in day-to-day life.

Oh, and by the way,

if you've gotten to this point in the video,

you're probably interested in sleep.

And so I'd love to hear in the comment section below,

what is something that you've tried to improve your sleep

and did it work or didn't it work?

Like it would be cool to crowdsource

some different tips that people have

for improving their sleep.

Myth number seven, polyphasic sleep

is good for your productivity.

Now, polyphasic sleep schedules were a big thing,

like I think like 10 years ago

in sort of the biohacking community.

They've started to kind of have a bit of a resurgence.

Basically, the idea is that you sleep at multiple times

throughout the day.

Like maybe you'll sleep for four hours

and then you'll get up a bit and do some stuff

and then you'll sleep another four hours.

It's like, there's more than one period of sleeping

You have these various patterns whereby there's a total of something

like four or six hours of sleep.

It may be two hours at night with various fragmented sleep during the day

And all of the data suggests that this is a really bad idea.

So even though polyphasic sleep in theory gives us more waking hours in which we can be productive.

Actually what Professor Foster says is that the quality of work

that we can produce in those hours,

it's generally lower because we tend to be more exhausted and

therefore less productive and less creative during those hours.

And there's even been a couple of studies that show that students

who are on a polyphasic sleep schedule

do worse in exams compared to the students who are in a normal

monophasic sleep schedule.

So overall the evidence does seem to suggest, at least according

to the experts,

that actually splitting your sleep up into polyphasic blocks

doesn't actually help your productivity

as much as blogs like Lifehacker might like to run stories and

pretend that it might.

Anyway, if you enjoyed this video you might like to check out

the full interview that I did with Professor Foster.

You can check that out over there or in any podcast app.

Thank you so much for watching and see you later. Bye bye.