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 those 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, you're thinking, 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.

And 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 an 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, this is more than one kind of 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 than 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.