[0:00] What if I told you the single most underrated 
thing damaging your heart right now is not what  
[0:06] you eat. It's not how much you exercise. It's 
how you sleep. Maybe your doctor has never told  
[0:12] you we need to fix your sleep. But here's what the 
science is showing us. People with poor sleep have  
[0:19] up to twice the risk of dying of heart disease, 
even if they sleep the same number of hours. A lot  
[0:25] of people think that good sleep means getting 
eight hours of shut eyee, but the scientific  
[0:30] evidence tells a very different story. And I've 
often been surprised by it. And I think it's  
[0:35] going to surprise you. The main issue is not how 
many hours of sleep you get. It's whether you're  
[0:41] getting the right kind of sleep that's actually 
restorative and helps preserve your heart health.  
[0:48] I'm an MD and a research scientist and I started 
studying neurobiology in 2012, 14 years ago. I've  
[0:55] always found the science of sleep fascinating and 
I've actually applied it in my own family life.  
[1:02] A very close family member had a devastating 
case of insomnia. I mean, could not function,  
[1:07] just a zombie. And when we applied everything 
I've learned from the neurobiology of sleep,  
[1:13] the 10 strategies I'm going to share with you 
in this video, her sleep improved dramatically.  
[1:18] I mean, it's night and day, pun intended. 
So, our scientific understanding of sleep  
[1:23] is incredibly powerful, and it's not just some 
ivory tower theory. They're actionable things.  
[1:30] So, my plan is to give you all of the tools that 
I've learned over the years that have reframed how  
[1:36] I think about rest so that you can start improving 
your sleep tonight. If you're interested in videos  
[1:41] like this that look at scientific evidence and 
put it in language that anyone can understand,  
[1:46] subscribe. We have a lot more material on heart 
health, sleep, longevity, and many other topics.  
[1:52] Let's look at a really common sleep myth that 
we've all heard. As we're going through these  
[1:57] myths, I want you to ask yourself a question. Do 
you consistently wake up feeling well-rested and  
[2:04] energized? Because a lot of us in our society 
do not. And I'm about to show you how you can  
[2:09] change that. So, let's start with the 8our myth. 
We've all heard this. You've heard this. We all  
[2:14] need 8 hours of sleep. In reality, it's much 
more variable than that. Most people need at  
[2:19] least 7 hours, but it can vary between 7 and 9. 
Some people with genetic mutations even feel well  
[2:26] rested with less than that. They're natural short 
sleepers. They're totally fine with somewhere  
[2:33] between four and 6 hours, although that's unusual. 
So, it's not true that everybody needs 8 hours.  
[2:39] That's about the average in the population, but 
individually, you might not need 8 hours or you  
[2:45] might need them or 8 hours might not be enough 
for you. But here's a second myth that has become  
[2:50] very pervasive and that is that both sleeping too 
little and sleeping too much is bad for you. And  
[2:58] this comes from studies showing a U-shaped curve. 
These studies report that the risk of death or  
[3:04] disease is lowest in people sleeping about eight 
hours a night and both sleeping less and sleeping  
[3:11] more correlate with higher risk. But this idea 
has been questioned by scientists in this field.  
[3:18] First of all, some studies find that pattern, that 
U-shaped pattern. Other studies do not. Second,  
[3:24] genetic studies, which are more robust generally 
don't find this pattern. For long sleepers,  
[3:30] they don't find increased risk. So, what's going 
on here? Well, the prevailing view in the field is  
[3:36] that people who report sleeping longer often have 
health issues. Other diseases that lead them to  
[3:44] spend longer in bed and so they overestimate how 
much time they actually spend sleeping. And those  
[3:51] diseases that they have explain the increased 
risk of mortality rather than sleeping a lot per  
[3:57] se. As for the short sleepers, those are likely 
to be people who are sleepdeprived, who are not  
[4:03] getting enough sleep for their needs. As opposed 
to the natural short sleepers that we talked about  
[4:08] that only need four, five, six hours a night, we 
don't have compelling evidence that those folks  
[4:15] are at higher risk. And those people are much less 
frequent anyway. Whereas people who get five or 6  
[4:21] hours because of life constraints but who really 
would like to get seven or eight, that's almost a  
[4:27] norm in our society, right? Unfortunately. Now, as 
you're watching this, you might have picked up on  
[4:33] a pattern. Studying sleep scientifically is really 
hard because we can't mess up people's sleep for  
[4:40] years just to see what happens. It wouldn't be 
ethical. And also, would you sign up for that  
[4:45] study? So, we have to piece together what we know 
from observing people's natural behaviors and the  
[4:52] outcomes, the consequences, as well as genetic 
studies, as we said, and also the occasional  
[4:57] randomized trial, which we'll look at in a second. 
And generally, they're kept pretty short because,  
[5:02] as we said, there's only so long you can 
torture someone for the sake of science. Okay,  
[5:07] so here's where we are. We saw that the famous 8 
hour rule doesn't really pan out. Now, we're going  
[5:14] to look at the flip side of the coin. And this is 
something that people almost never get told and  
[5:19] that applies directly to you. Even if you sleep 
the famous eight hours, let's say you get eight  
[5:26] hours of sleep on the dot every night and you 
wake up naturally after eight hours, not with the  
[5:31] alarm clock, not with some external interruption. 
Does that mean you're good? This is a huge myth  
[5:37] in itself because the truth is you can sleep eight 
hours and still have serious sleep quality issues.  
[5:45] Large studies following thousands of people 
over many years have found that those that  
[5:51] have fragmented sleep, that means they repeatedly 
wake up over the course of the night, even if they  
[5:58] don't remember waking up because often this is 
not conscious. Those people have a higher risk of  
[6:03] dying of heart disease. This effect was especially 
strong in women where the risk of dying of heart  
[6:09] disease was up to twice as high as the folks who 
do not have fragmented sleep. And here's the key  
[6:16] detail. This held even after sleep duration was 
matched. So same total number of hours slept,  
[6:25] radically different outcome. And these studies 
don't just ask people how they slept. They use  
[6:30] techniques like polyomnogs. It's a device with 
electrodes that actually measures brain activity.  
[6:37] So, it monitors sleep patterns objectively. 
It's much more robust than self-report. So,  
[6:44] this introduces a key concept of sleep quality. 
Your body doesn't just need time asleep. It needs  
[6:52] the right kind of restorative deep sleep so that 
your blood pressure can drop, your heart rate can  
[7:00] come down and your cardiovascular system can 
actually rest. In fact, scientific evidence  
[7:06] indicates that sleep quality may matter just as 
much, if not more, than sleep quantity. And don't  
[7:13] worry, we're going to cover specific actionable 
strategies to improve your sleep quality. For now,  
[7:19] just hold on to this concept. sleep quality versus 
sleep quantity. The main thing to focus on is not  
[7:25] so much how many hours of sleep you got. That's 
often overemphasized. It's whether you wake up  
[7:32] naturally and how you feel when you wake up. If 
you naturally wake up after 7 hours or even less  
[7:39] than that for some people and you feel rested 
and energized consistently, then that's likely  
[7:45] all you need. But if you have difficulty waking up 
in the morning, it takes an alarm clock or three,  
[7:52] right? And you feel tired, you feel groggy, you're 
out of it all day, and you're nodding off at work.  
[7:58] We all know that feeling. Then even if you got 
eight hours, that's a strong sign that you're  
[8:03] not getting enough or not enough of the right kind 
of rest for you. Okay, here's the second reframe,  
[8:10] and this one surprises most people. Sleep timing 
is also a key factor. So, you could be sleeping  
[8:16] 8 hours a night and still be quietly damaging 
your heart, not because of how much you sleep,  
[8:22] but because of when you sleep. If you're 
awake when your body expects to be asleep,  
[8:28] we call that circadian misalignment. And this 
causes insulin resistance. This causes your blood  
[8:34] pressure to go up. This causes your inflammatory 
markers to rise. The typical case are, of course,  
[8:39] shift workers. They work at night and they sleep 
during the day. We've known for a while that  
[8:44] shift workers have a higher risk of heart disease 
and high blood pressure. But is that because of  
[8:50] their circadian rhythm or is it something else 
about their jobs or something else about their  
[8:55] lives? A team of scientists set out to test 
this idea by actively changing the circadian  
[9:01] rhythm of participants. They found that when 
they inverted their habits, awake at night,  
[9:07] asleep during the day, their blood pressure 
and their inflammatory markers went up. So  
[9:12] scrambling your sleep patterns by itself can have 
harmful physiological effects. Why is that? Well,  
[9:18] they found that the participants that were forced 
to stay up at night, they ended up sleeping less  
[9:23] overall. And that was part of the problem. Their 
sleep quantity was reduced. But they also found  
[9:29] that some of the harmful effects were independent 
from sleep duration, from sleep quantity. So even  
[9:35] if they slept the same number of hours, there 
would still be an issue. So what this is saying is  
[9:40] that if you sleep at weird hours that don't match 
your natural circadian clocks then your body is  
[9:47] building up damage even if you end up sleeping the 
same total number of hours. Now one limitation as  
[9:53] we said is you can't mess up people's sleep for 
years. So these trials are pretty short usually  
[9:59] a week or two. So can our bodies adapt to these 
weird sleep schedules after a few months for  
[10:05] example? Well, in shift workers, risk of heart 
disease actually goes up for every five years  
[10:11] on the job. So, if anything, the evidence shows 
this seems to get worse with time. Now, I know  
[10:17] what you're thinking. I'm not a shift worker, so 
I'm in the clear. This has nothing to do with me.  
[10:21] But there's actually a much more common way that 
you and I are exposed to circadian misalignment.  
[10:27] Let me know if this sounds familiar. On week 
nights, we stay up a little too late. Then,  
[10:31] we have to get up early to work. We sleep a 
little bit less than we would have liked to  
[10:36] over the course of the week. We get increasingly 
tired. Then on the weekends, we sleep in. Then  
[10:42] Sunday night, it's hard to fall asleep again. We 
end up going to bed really late. Monday morning,  
[10:47] we're really tired. We're out of it. We call 
this pattern social jet lag. And millions and  
[10:54] millions of people go through this week in 
and week out. When you do this, the part of  
[11:00] your brain that controls your circadian clock, 
the superchismatic nucleus, is scrambled. It  
[11:06] expects a certain consistent rhythm. And by 
constantly changing, you're basically giving  
[11:11] yourself jet lag without traveling. And your 
cortisol, your melatonin, everything shifts with  
[11:17] some harmful physiological consequences. And the 
scientific evidence is showing us that the idea  
[11:23] that I'll just catch up on sleep in the weekend 
is basically a big myth. In a fascinating trial,  
[11:30] scientists simulated social jet lag by restricting 
the participants sleep to 5 hours a night. Pretty  
[11:37] similar to what a lot of people do during the 
week. And what they saw was these participants  
[11:41] started eating more after dinner. They started 
snacking more later during the day and they put on  
[11:48] more weight. And it was a big difference. Almost 
a kilo and a half, which is about 3 to four pounds  
[11:53] in less than two weeks. So, it's not nothing. 
And their insulin resistance also went up. All of  
[12:01] this compared to a control group that got to sleep 
all they wanted. But then they had a third group,  
[12:07] people that were sleeped for 5 days, then got 
two days of sleep recovery, sleep all you want,  
[12:13] and then started sleep restricting again. similar 
to a lot of people's typical schedule, right?  
[12:20] And these guys gained weight similar to the ones 
that were just restricted, no period of recovery,  
[12:26] and their insulin resistance also went up. So, 
what this is saying for you and me is that this is  
[12:32] likely not a healthy lifestyle. Even if we try to 
catch up on the weekends, it's not the same as a  
[12:39] regular sleep schedule. I've actually experienced 
this myself. I'm a night owl. I function better  
[12:45] later in the day. It's always been hard for me 
to get up really early. So, I did the social jet  
[12:50] leg thing throughout school when I was a kid. But 
later, I realized the importance of sleep. And so,  
[12:56] now I work pretty hard at structuring my life so 
that I get enough sleep consistently night after  
[13:03] night. More on that in a second. But this leaves 
open a different question. Let's say that you're  
[13:08] sleeping all the hours that you need, regular 
times, same time every day, but it's shifted late.  
[13:15] So, you go to bed late, you wake up late. Let's 
say 2 am to 10:00 a.m. A typical night owl. Is  
[13:23] that harmful? Well, let's look at this question 
real quick before we go to the 10 actionable  
[13:27] strategies to improve sleep quality because 
this is a fascinating part of this field. It's  
[13:33] something that I've tried to investigate myself 
because it's my natural tendency and I just wanted  
[13:39] to know what's healthier. I'll try to change 
if the evidence justifies. So in sleep research  
[13:45] they call this a late chronotype. That's the 
technical name for night owls. And we know that  
[13:52] there's a genetic component to this. It's not just 
habit. So depending on your genetics, you might be  
[13:58] prone to having a later chronotype or an earlier 
chronotype or an intermediate chronotype. In fact,  
[14:06] the first genetic mutations controlling circadian 
rhythm were identified by my PhD adviser, the late  
[14:13] Seymour Benzer, and the scientists that followed 
up on that work and later cloned the gene. It's a  
[14:19] gene we now know by the name of period. They ended 
up getting the Nobel Prize for that work. So,  
[14:24] we know this is partly genetic. It's not all 
habit. It's natural human diversity. But that  
[14:31] doesn't tell us if this is harmful or not. For 
that, we want stronger evidence. And when we look  
[14:36] at night owls, the late chronotypes, that does 
correlate with a slightly increased risk of death,  
[14:43] even when the total sleep duration is matched. 
Scientists have also found that late chronotypes  
[14:49] also have more psychological disorders, more GI 
disorders, more diabetes, even more respiratory  
[14:57] disease. Yeah, my night owls are a mess. They're 
also more likely to drink alcohol and smoke and  
[15:03] exercise less and be more obese. So, a different 
idea has arisen in this field. Maybe it's not  
[15:10] sleeping late that's harmful per se, but night 
owls are forced by societal structures to function  
[15:18] at a rhythm that is not natural to them. They have 
to go to work at a certain time. They have to drop  
[15:22] off their kids and go on errands when everybody 
else is awake, right? And maybe it's this constant  
[15:30] circadian misalignment that causes all the issues, 
the drinking, the smoking, the not exercising,  
[15:37] the eating a worse diet, and eventually all the 
diseases. In an absolutely fascinating study,  
[15:43] scientists asked if this higher risk we see in 
shift workers depends on people's chronotype,  
[15:51] whether they're night owls or morning birds. So 
they followed 65,000 nurses which often are shift  
[15:58] workers. And they found that the early birds, 
the early chronotypes, they had a higher risk  
[16:03] of diabetes when they did shift work, when they 
had night shifts for many years in a row, more  
[16:09] than 10 years. But the late chronotypes, the night 
owls, they had the highest risk of diabetes when  
[16:15] they worked daytime shifts. So the key seemed to 
be matching the work schedule to their chronoype,  
[16:22] matching the lifestyle to their nature. And this 
has led some of the leaders in this field to write  
[16:28] that it is the conflict with the time constraints 
imposed by society that at least in part may  
[16:35] explain the higher risk of late chronotypes. Night 
owls may be forced to sleep less overall or be in  
[16:42] constant circadian misalignment, be mismatched 
with their own internal clocks. Now, I want to  
[16:48] be clear that this question is not completely 
settled. There's still some debate. We don't have  
[16:52] that many studies on this specific question. So, 
this could still change. If you've made it this  
[16:57] far in the video, congratulations. You already 
know more about sleep than the vast majority of  
[17:02] people, including most doctors. But everything so 
far, the 8hour myth, the sleep quality paradigm,  
[17:10] the timing issue, all of that is the foundation. 
Here's what you can do with that knowledge. I'll  
[17:15] share with you guys what I personally do based 
on everything we know and you can adapt that  
[17:20] to your personal chronoype and then we'll wrap 
up with the 10 actionable strategies to improve  
[17:25] sleep quality. I try to structure my whole life 
around my natural circadian rhythm. So meetings  
[17:33] and commitments mostly shifted to the afternoon 
and evening and I go to the gym in the evening and  
[17:38] I work later than most people. I start later, 
I end. If you're an early bird, it would be  
[17:43] the same rationale just shifted. So most of the 
commitments and the activities in the morning,  
[17:48] maybe you work out before you go to work, but 
same logic. But and this is the important part,  
[17:54] I try to be pretty consistent with bedtime and 
wake up time. And this is actually the first  
[17:59] of the 10 evidence-based strategies for sleep 
quality. Keeping a consistent sleep schedule. Try  
[18:06] to go to bed and wake up within 30 to 60 minutes 
of the same hour every day because your super  
[18:12] kismatic nucleus needs that regularity to function 
properly. Now, obviously, we've all got different  
[18:19] lives, different constraints. So, you do what 
you can, but we're talking about the rationale. I  
[18:24] generally sleep between 2 am and 10 am regardless 
of whether it's a weekday or a weekend. I try to  
[18:31] be pretty consistent. Now, it's not a robotic OCD 
thing. If there's one day an event or a trip or  
[18:39] something like that and it changes, no big deal. 
But in general, I try to be consistent so that  
[18:44] it's not a roller coaster every 3 days. Strategy 
number two, try to get some sunlight soon after  
[18:51] waking up, within 30 minutes or an hour of waking 
up. This is actually the strongest circadian  
[18:58] signal your body has. I try to go for a walk first 
thing on most days, I feel more energized and I'm  
[19:04] able to sleep a little earlier. Whereas, if I just 
stay inside and only go outdoors later in the day,  
[19:09] which is kind of my natural propensity, my sleep 
starts to go crazy. I start to sleep at 3:00 a.m.,  
[19:16] 4:00 a.m., 5 a.m. It's insane. Number three, if 
you have a sleep condition or a disorder that  
[19:22] affects your sleep, sleep apnea is one of the most 
common ones. You need to get it treated. Sleep  
[19:28] apnea is one of the most common causes of sleep 
fragmentation. Taking care of that is the highest  
[19:34] impact intervention for anyone suffering from 
that condition. The irony is that a lot of people  
[19:39] who suffer from sleep apnea don't know they have 
it because it's not conscious during the night.  
[19:45] So you if you consistently wake up feeling tired 
with headaches, you have daytime fatigue, ask your  
[19:51] doctor about it. Strategy number four, you want 
to start dimming your lights a couple hours before  
[19:57] bedtime because this helps your melatonin go up. 
Melatonin is your sleep hormone. You want to avoid  
[20:03] most electronic devices in this period because the 
blue rich light from cell phones and laptops shuts  
[20:10] down melatonin. If you're reading a book under a 
light that's not super bright and is not shining  
[20:15] directly into your eyes, that's fine. Electronic 
readers like the Kindle, they're a little better  
[20:20] than cell phones because the technology, the 
way they emit light, they shine less light into  
[20:25] your eyes than a cell phone or a laptop, but 
they're not quite as low intensity as actual  
[20:33] oldfashioned paper. The good thing is with a lot 
of these electronic readers, you can regulate the  
[20:37] intensity and the type of light that they emit. 
And that's it. Just dimming the lights. You don't  
[20:42] need these special glasses that influencers 
sell. It's a gimmick. Save your money. just  
[20:47] dim the lights. Strategy number five, no caffeine 
or alcohol near bedtime. In fact, for caffeine,  
[20:54] it's actually good to stop it earlier than a lot 
of people realize because the halflife of caffeine  
[21:00] is about 5 to 7 hours. So, if you have trouble 
sleeping, that cup of coffee you had at 3 p.m.  
[21:07] might still be having an effect. Try to aim for at 
least eight hours before bedtime for the last cup  
[21:13] of coffee. And some people may need even more. 
And alcohol is a double-edged knife because it  
[21:19] helps people fall asleep as we all know, but then 
it suppresses your REM sleep and it fragments your  
[21:26] sleep architecture. So, drinking alcohol to fall 
asleep is a crutch. It's not good. It's not the  
[21:32] same as actual quality restorative sleep. Strategy 
number six, you want to control your environment,  
[21:38] your bedroom environment. You obviously want it 
dark. You want it quiet. And the temperature also  
[21:43] matters. You want to keep your bedroom a little 
cool. So 17 to 20° centigrade is ideal, which is  
[21:52] about 63 to 68 Fahrenheit. And this is because 
your core body temperature needs to drop for  
[21:59] sleep onset to happen properly. Strategy number 
seven, you want to avoid exercise before bedtime,  
[22:06] especially intense exercise because it raises 
your adrenaline and your core body temperature.  
[22:12] So that makes it harder to fall asleep. Number 
eight, you want to avoid eating especially large  
[22:17] meals close to bedtime. Digestion raises your 
body temperature. It can also cause reflux and  
[22:23] it can worsen sleep quality. Number nine, you 
want to address any stressful activities or  
[22:28] experiences before bedtime. Even 10 minutes of 
wind down with some low stimulation activity,  
[22:35] mindfulness exercise, meditation, reading a 
book, especially a boring book, not a super  
[22:41] exciting book, that helps lower your cortisol and 
makes it easier to fall asleep. And number 10,  
[22:47] if you suffer from insomnia, if you have trouble 
sleeping, chances are your instincts and your  
[22:52] sleep hygiene are all wrong. Because here's the 
counterintuitive thing about sleep that nobody  
[22:58] tells people with insomnia. When you have a hard 
time sleeping, your natural instinct is to go to  
[23:04] bed early. Every bone in your body wants to get to 
bed as early as possible to catch up on sleep. But  
[23:11] this is exactly the wrong instinct. Spending time 
awake in bed builds a mental association between  
[23:18] your bed and your bedroom and wakefulness. Your 
brain starts treating your bed like the place to  
[23:23] be alert and to be analyzing and thinking about 
the day and what you have to do tomorrow. On a  
[23:28] personal note, I saw this firsthand with my family 
member who would lie in bed awake for hours,  
[23:34] but then if she moved to the couch, she would 
fall asleep instantly. So, she didn't have a  
[23:38] physiological difficulty falling asleep. It was 
a mental association with the bed and the bedroom  
[23:45] environment. So, the evidence-based approach 
is exactly the opposite. You want to reduce  
[23:50] the time you spend awake in bed to an absolute 
minimum. Our beds are for two things and two  
[23:56] things only. Sleeping and sex. It's not for lying 
awake for hours, for reading an entire book or for  
[24:03] sitting on your laptop doing work. So, you want 
to delay going to bed. And this feels so wrong to  
[24:08] the insomniac. It just feels stupid. But you want 
to delay going to bed until you're really tired,  
[24:16] until you're nodding almost, and as soon as 
you hit that head on the pillow, you're out. If  
[24:21] you need five or 10 minutes of reading in bed to 
sleep, that's fine. But what you don't want to do  
[24:26] is spend 40 minutes, an hour, an hour and a half 
waiting for sleep to come and then when you wake  
[24:31] up, exactly the same logic. You want to get out of 
bed ASAP. You don't want to wait awake in bed. The  
[24:37] person with insomnia wants to stay in bed because 
they feel tired and they think, "If I just wait a  
[24:42] little longer, maybe I'll fall asleep again." 
This is exactly the wrong strategy. Exactly  
[24:46] the same with middle of the night awakenings. If 
you wake up and you can't fall asleep within 10,  
[24:51] 15 minutes, get out of bed. You want to do some 
boring activity in dim light. Organize your  
[24:56] sock drawer or count silverware in the kitchen 
drawer. Don't get on your phone. Reading a book,  
[25:01] ideally a boring book on paper or on a Kindle is 
fine, too, but do that outside of bed, outside  
[25:08] of your bedroom. Then when you feel sleepy again, 
you go back to bed. And if you can't fall asleep  
[25:12] within 10, 15, 20 minutes max, you get out of bed 
again. This feels so wrong at every level, but it  
[25:19] actually works. It's an evidence-based approach, 
and the goal is to prevent your brain from forming  
[25:25] the habit of being awake in bed. I watched my 
relative resist this advice for months on end. It  
[25:32] just was against everything her body was screaming 
for her to do. But when she finally committed to  
[25:38] it and did it, the improvements were dramatic and 
pretty quick. Within a few weeks, we saw palpable  
[25:44] improvements. And we were also able to reduce 
her medication a lot, her sleeping medication,  
[25:49] as her sleep quality improved. So, this is what's 
possible with an evidence-based approach. If you  
[25:54] find this information useful, please consider 
sharing it with someone who's tired all the time,  
[25:59] who has trouble sleeping, and maybe they think, 
"Hey, I'm sleeping 8 hours every night. I don't  
[26:04] know why I'm so exhausted." And subscribe for 
more videos on the science of what actually  
[26:08] protects your heart and your brain. This is a 
content I wish people had shown me 10 years ago.