>> Hi, I'm Lewis Howes, New York Times best-selling author and entrepreneur.

And welcome to "The School of Greatness," where we interview the most influential minds and leaders in the world to inspire you to live your best life today.

In this episode, we sit down with sleep expert Matthew Walker.

He is a professor of neuroscience and psychology, as well as a best-selling author.

And today, he shares the importance of sleep and how it affects you when you don't get a sufficient amount.

He shares how dreams are helpful, how relationships and diet impact your sleep, and the most important habits to allow you to get a full night's rest.

I'm so glad you're here today.

So let's dive in and let the class begin.

And I'd love to start with asking the question about if we sleep poorly, how does this impact our brain?

If we just sleep poorly one night or over and over and over again, how does that impact the brain chemistry?

>> Yeah, so, I think, firstly, in response to the general question, sleep is probably the single most effective thing that you can do to reset both your brain but also your body health, of course, as well.

And I don't say that flippantly against the notions of diet and exercise.

Of course, both of those are fundamentally critical.

But if I were to take you, Lewis, and I were to deprive you of sleep for 24 hours, deprive you of food for 24 hours, or deprive you of even water or exercise for 24 hours and then I were to map the brain and body impairment that you would suffer after each one of those four, hands down, by a country mile, a lack of sleep will implode your brain and body far more significantly.

>> Really?

>> The only one I would probably lose out on is oxygen.

>> Of sleep, food, and water, sleep is the most important thing.

>> I would -- Yeah, you know, I used to say that sleep was the third pillar of good health alongside diet and exercise, but I think the evidence has suggested that I was utterly wrong, that sleep, in fact, is the foundation on which those two other things sit.

And you can do wonderful things in those two domains, but if you're not getting sufficient sleep, those things tend to be far more futile as a consequence.

>> Yeah.

And, so, what is sufficient sleep then?

>> So, right now, we recommend somewhere between 7 to 9 hours for the average adult.

Once we know that you go below seven hours of sleep, we can start to measure objective impairments in your brain and your body.

And, in fact, the number of people who can survive on less than six hours of sleep without showing any impairment, rounded to a whole number and expressed as a percent of the population, is zero.

>> Why is the -- Why are the majority of people bad at getting good sleep?

Is it -- is it we're distracted?

Is it we think we need to be doing more?

Is it we're stressed and worried about the past and the future?

Is it, you know, we just want to work harder?

What is the main cause of why we get poor sleep?

>> So, I think the first -- And I've thought about this a great deal.

Why are we suffering this global sleep-loss epidemic that we're under right now?

I think the first thing is that, unfortunately, sleep has an image problem, that, you know, the P.R.

agent for sleep should be fired, because we associate sufficient sleep with this concept of being lazy, of being slothful.

And that's a terrible disservice to this thing called sleep.

But we have the very opposite.

We have this almost -- You know, well, "we."

We don't.

Some niches of society have this sleek machismo attitude, you know, this kind of "you can sleep when you're dead" mentality, which, by the way, based on the evidence, is mortally unwise.

Yeah, it will lead to both a shorter life and a life that is significantly less healthy.

So I think the first thing is, we need to change our cultural appreciation of sleep from something that is a waste of time to something that, in fact, is an incredible investment.

It is probably the very best and the most freely available democratic and painless health-insurance policy that I could ever imagine.

But then there are plenty of people who give themselves the opportunity to get enough sleep, but they can't obtain it.

We know that one of the principal roadblocks to getting this thing called a good night of sleep is anxiety.

>> Stress, worry, anxiety, regret, all those things, resentment, holding on to all that stuff.

>> It is.

That is toxic to sleep.

You're absolutely right.

And, in fact, anxiety and physiological stress is our principal model for the explanation of insomnia right now.

It's not the only cause, but it seems to be one of the principal causes.

And in modern society, it's become so easy -- And I'm not finger-wagging.

You know, I'm just as guilty.

We are constantly on reception, but rarely do we do reflection.

And, unfortunately, the time when most of us do reflection is when we turn off the light and our head hits the pillow.

And that's the last time -- >> That's the worst time.

>> Oh, you know, because I don't know about you, Lewis, but, you know, at night, in the dark, thoughts are not the same thing.

You know, concerns become twice as big or you 10x the size of concerns.

I start to worry.

I ruminate, I catastrophize.

Yet, in the light of day, those things seem very different.

And, so, we can speak about sleep tips, perhaps, later on, but, certainly, getting right with your emotions and your anxiety is key to good sleep.

And that's one of the things that prevents sleep.

>> Can you talk about dreams and the importance of dreams?

>> When we are dreaming, it is more consciously energetically demanding than not dreaming is my assumption from a brain-based perspective.

And any time Mother Nature burns the most valuable unit in your body, which is called an ATP molecule, an energy molecule, then it usually has some evolutionary advantage to it.

In other words, if dreaming is metabolically more active and you could have REM sleep without dreaming, but she still added dreaming atop of REM sleep, then it must serve some benefit.

And we've now discovered that it serves at least two vital functions.

>> Really?

>> The first is that dream sleep provides a form of almost overnight therapy, that dream sleep is emotional first aid.

>> Interesting.

>> And it's during dream sleep at night that your brain takes those difficult, emotionally charged experiences, sometimes even traumatic memories, and it acts like a nocturnal soothing balm and it just takes the sharp edges off those painful, difficult experiences so that you come back the next day and you feel better about those experiences.

And, in that way, it's not time that heals all wounds.

It's time during dream sleep that provides emotional convalescence, as it were.

And it's not just dream sleep.

It's also even what you dream about, not just that you dream.

In other words, I'm talking about your dream content being important.

Because there was a study done several years ago, and they looked at people going through a really tough time, a traumatic experience, such as a really painful and bitter divorce.

And at the time when that was happening, they were recording their dreams.

And then they tracked those individuals for a year.

And one year later, about half of them had clinical resolution to their depression, and the other half did not.

And then they went back and they separated the dreams of those two different groups.

And what they found is that those people who were dreaming but not dreaming about the emotional events themselves, they didn't get clinical resolution one year later.

Those people who were dreaming but dreaming of the event, they got the clinical resolution.

So, in other words, dreaming is necessary, but it's not sufficient.

You need to be dreaming of what those events are to process those.

>> I want to ask you about the impact of love and sleep.

When someone feels an overwhelming feeling of love, connection, intimacy with a partner, does that support their sleep and improve the quality of their sleep?

Does it hurt the quality of their sleep?

And is there a difference if they're actually hugging and feeling love and connection to their partner, feeling, you know, that heartbeat or that warmth or whatever it might be that they're feeling?

Is there a difference if they're just feeling it but they're not next to them in the same bed?

What's your thoughts on this topic?

>> I think the best answer is, it's complicated.

But let me pick it apart.

Firstly, what we know is that couples who have a strong, loving relationship typically have overall significantly better sleep, both quantity, as well as quality.

When that relationship deteriorates and there is conflict, typically, sleep is worse.

We also know that there's just a very strong relationship between sleep and sex for the following reasons.

Firstly, we know that your sex hormones are powerfully affected by sleep.

So if I take a healthy young man and I put them on four hours of sleep for one week, they will have a level of testosterone which is that of someone 10 years their senior.

>> Eeh!

>> So a lack of sleep will age a man by a decade in terms of that critical aspect of wellness and virility.

You see exactly the same profile in women.

We see that insufficient sleep is linked to a reduction in estrogen, in luteinizing hormone, and also in follicle-stimulating hormone, all of which are critical for female sexual health and reproductive health, as well.

What we've also found is that when, for example, a woman gets an extra hour of sleep, her desire to be physically intimate with her partner increases by 14%.

What we've then found at the psychological-relationship level is also interesting.

When couples aren't sleeping well, firstly, they have more conflict.

Secondly, not only do they have more conflict, they don't resolve that conflict as well.

And part of the reason that they don't is because they lose empathy.

>> Right.

They're just moody.

>> Right.

They become more self-centered and less compassionate towards the other.

>> Yeah.

>> So, for all of those reasons, you can see this bi-directional relationship.

Regarding sleeping together in the sense of physical sleeping in the same bed, the data is very interesting.

What we know is that about 30% -- It depends on what survey you look at.

But about 30% of people surveyed anonymously -- and it usually has to be done this way -- will report not sleeping in the same bed.

Of those who do sleep in the same bed, a significant proportion of them, up to 40% of them, will report waking up in a different location for whatever reason.

And this is what we've then -- Because the stigma first is that if you're not sleeping together, then you're not sleeping together.

But the opposite seems to be true for those specific couples for whom it works.

When they start to sleep apart, firstly, because their sex hormones improve and the desire for each other increases, typically, their physical, intimate relationship is improved by way of what we call that sleep divorce.

So a sleep divorce can actually help you prevent a real one in that sense.

>> Wow.

>> But it's not a one-size-fits-all.

I'm not suggesting that by any means.

For some people, sleeping together works very well, that, overall, what we know is that when people sleep together, objectively, the quantity and the quality of their sleep is worse.

On average, it's worse.

>> When people sleep in the same bed, objectively, the quality and the quantity gets worse.

>> The quality and the quantity of their sleep is worse.

However, if you ask them what they felt their sleep was like in terms of their satisfaction with sleep, on average, they will say that they felt more satisfied by their sleep when they were sleeping together.

Now, that could just be because of this sort of stigma and this bias towards how we think we should sleep as couples.

But I want to give people the permission to undergo at least this exploration with your partner, because there are many reasons -- sleep disorders, such as sleep apnea, snoring, tossing and turning.

We know that when one partner starts to toss and turn, it has a knock-on effect like a domino, causes the other to have a bad night of sleep.

There are several ways that you can think about this.

Firstly, have a conversation.

And you don't have to admit it to the outside world if you don't want.

I've admitted to this before, having a sleep divorce.

I would say that it's fine to tell people, "I love you.

I care for you.

I don't sleep well when we're together often.

And I think I would be a better partner if I could try to sleep in a separate location."

However, the funny thing is, most of us, for the majority of that nighttime period, were non-conscious, so we're actually not aware of the other partner.

What we miss, I think, is the bookends of sleep.

It's getting into bed, saying "good night," having a cuddle, and then it's waking up and saying -- So, you can kind of hack the system.

So, whoever goes to bed first, depending on chronotype -- morning type, evening type, somewhere in between -- And we can speak about that, too.

Whoever goes to bed first, it's the job of the other person to come through, and as they -- They can send them a text and say, "Look, I'm about to turn the light off.

Can you come through?"

And you go through and you give them a kiss and a cuddle and you have your little sort of bedtime moment at the front end.

Lovely.

And then, on the back end, whoever wakes up first, they, you know, get to the kitchen and they start making their tea or coffee, whatever it is.

And then the other person, as they're waking up, they text them and say, "I'm just waking up.

Come through."

And you can go through to the bedroom and you can have your back-end bedtime sort of union when they wake up.

It sounds like a lot of work, but the the cost benefit that you get in terms of healthy sleep and how good you will feel and how much better the statistics tell us relationships are when couples are well-slept, I think, is worthwhile at least exploring that.

So, it's not a one-size-fits-all.

I'm not suggesting that.

Different people find different -- Some people find it very safe to sleep with another partner because there is a degree of threat for whatever, you know, historical psychological reasons, or they just feel better about having someone else there from a threat perspective, which I totally understand, too.

So, just explore it with your partner.

>> And what about sugar and the standard American diet, the SAD diet?

How does this impact our sleep?

>> There is a very strong link between your sleep and what you're eating, and there is an equally strong link between what you're eating and how you sleep.

And we can maybe take both of those.

There is less evidence, actually, regarding your first question, which is, "How does what you eat impact your sleep?"

What we do know for certain is that diets that are high in sugar and low in fiber will typically result in worse sleep.

And part of -- Especially if you're having sugar intake in the last couple of hours of sleep.

And part of the reason I believe this is true, although we don't yet have the evidence, is that sugar is a very good way to release energy and increase your core body temperature.

>> Yeah, man.

>> And what we've just spoken about is that when you go to sleep, you need to drop your core body temperature, and that can be one of the many, I think, consequences.

>> So if you're going to have sugar, try to wait and do it 2 or 3 hours before, at the latest, when you sleep.

>> Would be -- advise it, yeah.

>> And don't have it at midnight and then wait three hours of sleep, like -- >> No.

That would be ill-advised, as well, from my scientific knowledge.

>> And what about food in general?

Is there a time where you should stop eating before you sleep?

>> Great question.

And, in fact, that's kind of a bit of a myth when you look at the data, that you could bust -- You know, people will say, "You should really cut yourself off, you know, 3 or 4 hours before bed, and that's the optimal."

If you look at the studies, you can go as close as to one hour before bed eating, and it doesn't seem to have an impact.

Once you get closer than one hour, it does seem to have that negative consequence.

Also, just be mindful of acid reflux.

That's the other thing.

If you have a large meal and then you lie down, a lot of people will get that reflux that will wake them up throughout the night, and that's another reason, that cost of eating too big too late.

>> What would you say if there were three things someone could do to improve their sleep tonight?

Only three things.

What would those three things be for you?

>> Firstly, regularity.

If there's one thing that you take from this podcast regarding sleep, it's regularity.

Go to bed at the same time and wake up at the same time, no matter whether it's the weekday or the weekend.

>> Really?

>> Regularity is king.

And I don't like giving rules.

People don't respond to rules.

People respond to reasons, not rules.

And so I'll try and explain the rule, as it were.

The reason is because your brain has a master 24-hour clock inside of it.

It sits right in the middle of your brain.

It's called the suprachiasmatic nucleus.

And it expects regularity and thrives best under conditions of regularity, including regularity of your wake-sleep schedule.

And if you give it regularity, regularity is king, and it will anchor your sleep and improve the quantity and the quality of your sleep.

>> Okay.

>> I think the second piece of advice I would have is, have a wind-down routine.

You know, many of us think of sleep almost like a light switch, that we are racing around during the day, we're desperately busy, we jump into bed, we switch the light out, and we think that sleep should be like that same light switch.

Sleep is much more like landing a plane.

It takes time for your brain to descend down onto the terra firma that we call good sleep at night.

And we do this with kids, of course.

You know, we have to -- We go through the routine.

>> Read the book.

Yeah, yeah.

>> Yeah, we sort of give them a bath and then we sort of get them out and then put them into bed.

Then we read to them and then gradually -- And if you deviate from that routine, from that wind-down routine, bad things are going to usually transpire.

>> How long should that routine be?

Can that be 10 minutes?

Can it be an hour?

I mean, what does it matter?

>> I would say find what works for you.

I would say, usually try to think about some kind of a 30-to-20-minute routine, whether that's taking a bath.

I've found meditation to be incredibly powerful.

I really enjoy the app Headspace.

And I know you've had Andy on the show before, too.

Fantastic, wonderful individual doing great things.

So, meditation before bed, you know, stretching, some kind of a wind-down routine.

The other thing you can do is have a worry journal.

Just sit down, and usually two hours before bed -- don't do it right before bed -- with a pad of paper and a pencil, write down everything that's on your mind.

And it's catharsis and it's just like vomiting out all of your anxiety onto the page.

>> Right, right.

>> And that seems to help sleep, too.

>> Don't sleep with it, yeah.

>> So you don't sleep with it.

So you can have that as part of your wind-down routine.

Find something that works for you, but a wind-down routine is critical.

>> Yeah.

>> The last piece of advice I would give, the third piece, is that after a bad night of sleep or if you're struggling with a bout of insomnia, the very best advice that I can give you is do nothing.

And what I mean by that is, don't wake up any later, don't go to bed any earlier, don't nap during the day, and don't drink more coffee.

And I'll explain each of them.

>> Why?

Yeah.

>> Yeah.

So, if you wake up later in the day because you think, "Well, I had such a bad night of sleep, I need to sleep in a little bit to compensate."

Because you're waking up later, when it comes time to your normal bedtime later that evening, because you've only been awake for less ti-- you've been awake for less time than you would do normally, you're not as tired.

So what happens?

You get into bed because you think, "I had a bad night of sleep and I want to sort of make this one a good one."

And now you're tossing and turning and you have another bad night because you woke up too late in the morning.

The same is true for going to bed too early.

You think, "Well, my bedtime is normally --" You know, let's say it's 11:00 in the evening.

"I'm going to get to bed at 10:00 tonight because I had such a bad night of sleep."

Resist.

Don't do that.

Because your circadian rhythm, your natural 24-hour rhythm, will not typically want you to go to bed until 11:00.

But you get into bed at 10:00 and then you're wide awake and now you have another bad night of sleep.

>> Mm!

>> Napping we've already spoken about.

Just takes that edge off your sleep desire.

And then don't, obviously, try to compensate with caffeine, because you'll just have more caffeine in the system, which means, that following night, you're going to be more alert and more awake.

So, it sounds strange to say, but after a bad night of sleep, stay the course.

Just do what you normally do.

And, by the way, the other tip is a strange one.

Many of us have a wake-up alarm.

Why don't we have a to-bed alarm?

>> Mm.

You mean like an alarm that tells us, "Time to go to bed."

>> Yeah.

Just, you know, set it for, you know, 30 minutes before bed, and it just -- >> And that's your wind-down time, yeah.

>> And that's your wind-down routine.

And even if it just means that two out of the seven nights a week, you end up just being nudged to go to bed a little bit earlier -- or on time, I should say -- then that is a great hack.

The other thing, too, is, I would say remove all clockfaces in your bedroom, because if you wake up and you're having a bad night of sleep, knowing what time of night it is is not going to help at all.

It's not going to change anything.

You know -- And, so, remove all clockfaces, have a to-bed alarm.

The other thing you can do, by the way, is get ready for bed.

You know, most people finish up their Netflix and then they start brushing their teeth, you know, take their makeup off, get changed.

Instead, before you sit down for television, brush your teeth, floss, get changed, get ready for bed.

And then what's great is that when you feel sleepy on the couch and you turn the television off, you go straight to bed and you've already hacked back 10 or 15 minutes of extra sleep.

Add that up night after night, month after month, it's like compounding interest on a loan.

>> Couple final questions for you before we wrap things up.

This is called the Three Truths question.

Hypothetical scenario.

I'd love for you to imagine it's your last day on Earth many years away from now.

You've slept your way to 200 years young and done all the right things and you have accomplished all your greatest dreams in life.

You've seen everything come true that you want to have come true, Matt.

And for whatever reason, all of the content you've created and put out into the world, it has to go with you or it goes to another place, but no one has access to the information anymore.

It's a hypothetical scenario.

>> I love it.

>> But you have a piece of paper and a pen and you get to write down three things you know to be true, the big lessons you learned in your life that you would leave behind.

And this is all we would have as information that you would leave behind.

What would you say would be those three truths for you?

>> Oh, gosh, what a great set of questions.

I would say acceptance over denial.

I would say questions over advice.

And I would say self-compassion over self-brutalization.

>> Mm!

Those are powerful ones.

And my final question for you is, what's your definition of greatness?

>> Astonishing service to others.

>> There you have it.

Dr. Matthew Walker, thank you so much for being here.

I appreciate it.

>> Thank you so much for having me.

It's just a privilege and a delight to speak with you, Lewis.

Thank you.

>> We hope you enjoyed this episode and found it valuable.

Stay tuned for more from "The School of Greatness" coming soon on public television.

Again, I'm Lewis Howes.

And if no one has told you lately, I want to remind you that you are loved, you are worthy, and you matter.

Now it's time to go out there and do something great.

If you'd like to continue on the journey of greatness with me, please check out my website, lewishowes.com, where you'll find over 1,000 episodes of "The School of Greatness" show, as well as tools and resources to support you in living your best life.

>> The online course "Find Your Greatness" is available for $19.

Drawn from the lessons Lewis Howes shares in "The School of Greatness," this interactive course will guide you through a step-by-step process to discover your strengths, connect to your passion and purpose, and help create your own blueprint for greatness.

To order, go to lewishowes.com/tv.