The Peter Attia Drive - #193 - AMA #31: Heart rate variability (HRV), alcohol, sleep, and more

Episode Date: January 31, 2022

View the Show Notes Page for This Episode Become a Member to Receive Exclusive Content   Episode Description:   In this “Ask Me Anything” (AMA) episode, Peter and Bob first answer a variety of questions related to heart rate variability (HRV): what it means, why it matters, and how to measure, interpret, and potentially elevate it. Next, they dive deep into the topic of alcohol, beginning with a discussion on the negative impact that it can have on sleep. They then break down the confusing body of literature suggesting potential health benefits to moderate levels of drinking compared to complete abstinence and point out the limitations of these studies. Finally, they conclude by analyzing data on the impact of moderate and heavy drinking on the liver and on risk for Alzheimer’s disease and dementia.   Please note: this AMA is audio only. If you’re not a subscriber and listening on a podcast player, you’ll only be able to hear a preview of the AMA. If you’re a subscriber, you can now listen to this full episode on your private RSS feed or on our website at the AMA #31 show notes page. If you are not a subscriber, you can learn more about the subscriber benefits here.   We discuss: What is heart rate variability (HRV), and why do we measure it? [2:10]; The association between low HRV and mortality risk [10:00]; What high and low HRV means and why athletes strive for a high HRV [15:30]; Factors that can raise or lower HRV [18:00]; How and when to measure HRV, and the best wearables [19:15]; Interpreting your personal HRV number and why there’s so much individual variation [23:15]; How Peter’s morning HRV reading impacts his decision to train [28:30]; Alcohol’s impact on sleep [31:30]; Metrics to track the impact of alcohol on your sleep [34:00]; Alcohol’s impact on the need to urinate during the night [39:00]; Alcoholic fatty liver disease (AFLD) [41:30]; Individual differences in the way people metabolize and react to alcohol consumption [44:15]; Analysis of epidemiology studies suggesting moderate alcohol consumption lowers mortality risk [52:00]; Alcohol consumption and Alzheimer’s disease [1:05:15]; Heavy alcohol consumption and risk of dementia [1:08:30]; Chronic effects of alcohol on the liver [1:17:45]; The relationship between alcohol, sleep, and automotive deaths [1:20:45]; and More.   Sign Up to Receive Peter’s Weekly Newsletter   Connect With Peter on Twitter, Instagram, Facebook & YouTube

Hey everyone, welcome to a sneak peek, ask me anything, or AMA episode of the Drive Podcast. I'm your host, Peter Atia. At the end of this short episode, I'll explain how you can access the AMA episodes in full, along with a ton of other membership benefits we've created. Or you can learn more now by going to PeterittiaMD.com forward slash subscribe. So without further delay, here's today's sneak peek of the Ask Me Anything episode. Hey everyone, welcome to Ask Me Anything episode number 31. I'm joined once again by Bob Kaplan, although as you'll learn at the end of this episode, this will be the last time we're joined by Bob Kaplan. But let's not get ahead of ourselves. In today's episode, we talk about really two things in detail.

One is HRV, heart rate variability. We've had so many questions on this subject for the past couple of years, and we've just been slowly kind of collecting questions until we thought we had enough to do kind of one of our thematic shows on it. And the second thing we talk about is ethanol. All things related to ethanol. So how does it affect HRV is really our segue, but then also what are the effects of alcohol on sleep?

And we really go after mortality, probably where we spend most of our time, and we talk about it through the lens of all of the epidemiology as most of you or may some of you know, there's a confusing body of literature out there that suggests that maybe some alcohol is good for you and no alcohol is not as good for you. And so we go really deep on this subject matter. So again, if you have any questions about alcohol or if you drink at all, or if you don't drink and you're wondering, if you should be drinking, I think this episode will be very helpful for you. So one thing I want to point out for this episode, this episode was just due to some limitations of timing when we recorded it.

This was not recorded in video, so we will only be doing this in audio. That might make the show notes a little more important, although we didn't really have a lot of content here that necessitated being able to see. So I think you're gonna be fine listening to this in audio, but obviously the show notes will have any of the graphs and other images that we talk about. Now, if you're not a subscriber, of course, you can get a sneak peek at this as usual,

then you'll have to obviously subscribe if you want to enjoy the full content. So without further delay, I hope you enjoy. AMA number 31. [♪ OUTRO MUSIC PLAYING [♪ [♪ OUTRO MUSIC PLAYING [♪ Hey Bob, how's it going today? Going well, Peter.

How are you? It's good. It's a little unusual today. We're doing this a little bit on the old school tip. No video today. We're going to be a little bit more descriptive in our terms since people can't watch our facial expressions, although that somehow provided any value. We won't do any screen sharing.

I think we can manage. What do you have in store for us today? So I aggregated a whole bunch of questions around HRV, heart rate variability, and alcohol. Many questions on both those topics. I know this has been something you've been asking me about for a year. Why don't we go to do one on HRV? Why don't we go to do one on HRV? So I think the answer is now. All right, we'll dive in. First question seems relevant.

What is HRV? And it's funny. This is a tougher question to answer without an image, but I'll do my best. So as you pointed out, a second ago, HRV stands for heart rate variability. And that's a pretty descriptive term because what it measures is the variation in time between heartbeats, and that's measured in milliseconds. So a thousand milliseconds is one second. So if a person's heart is beating 60 times per minute, you might say,

well, there's a thousand milliseconds between every beat, but it turns out that it's not really that way. You see, even if your heart is beating 60 times per minute or once per second. Between the first beat and the second beat, it might be a thousand ten milliseconds. And between that beat and the next beat, it might be nine hundred and sixty milliseconds. And between that beat and the beat thereafter, it might be a thousand twenty seven milliseconds. When you start looking at this thing at the level of thousands of a second, you realize that there is actually some variability. If anybody has ever seen an EKG, which I'm sure everybody has seen, but maybe you haven't thought so much about what all the little squiggly lines mean, without going into the details

of what the P wave and the QRS and T waves mean. I think most people will recognize that there is a very big spike for each of those beats, and that's actually the r spike. If you now measure the distance between the rs we call that the r r interval and you take the root mean square of the successive differences between the heart beats. So that means you calculate the time difference between each rr interval. Each of those values is squared, so multiplied by itself, and the result is averaged before the square root of the total is obtained. So it's just kind of a mathematical method for trying to approximate differences. You get what's called the RMSSD.

Again, if you just think about that in units, you took something that was in milliseconds, you squared it, so it became milliseconds squared. You added them all up. It was still milliseconds squared. You took the square root of it. It's back to milliseconds. So RMSSD is reported in milliseconds. If anybody's been paying attention to wearables, a number of these

things will calculate your heart rate variability, typically while you're sleeping, and you'll notice it gives you a number in milliseconds. I think prior to the advent of wearables, this was typically just done with an EKG, or another sort of chest strap-like device that was very accurately measuring the electrical activity of the heart. The next question is probably why do we measure HRV? So you talked about heart rate, I think people would understand measuring heart rate and maybe why that matters, why you might want a lower heart rate in general. Why do we measure HRV?

What does it tell us? Or what can it tell us possibly? As I alluded to above, the heart, even when your heart rate is not changing, and if you're at rest, which is when we measure HRV, so we don't really measure HRV when you're out and about moving around because just the movement itself that you're undergoing is going to change your heart rate. So if I stand up from my desk and go and walk over to the kitchen and do something, well, that's going to increase my heart rate just because I stood up.

And if I'm exercising, obviously, my heart rate is changing quite a bit. So this is really something that we care about when you're at rest. But as I said, there is variability between those beats. And it turns out that that variability is heavily influenced by which of the autonomic nervous systems is most dominant. So this probably warrants a slight detour. So we have broadly, broadly speaking, two nervous systems. We have one that is under our control and one that is not under our control. And that's a very good thing. If

you want to reach for and grab a pencil or walk, obviously that requires voluntary control. You want to be in control of those nerves, firing and making muscles do their thing. But you certainly don't want to have to be thinking and consciously making things happen that need to happen constantly. You certainly wouldn't want to have to think about breathing.

You certainly wouldn't want to have to think about your heart beating. You certainly wouldn't want to have to think about digesting food. You certainly wouldn't want to have to think about your heart beating. You certainly wouldn't want to have to think about digesting food. You certainly wouldn't want to have to think about a lot of things that take place beneath the surface. All of those things are regulated by this thing called the autonomic nervous system. We further divide this autonomic nervous system into two branches.

One is called the sympathetic system, and the other is called the parasympathetic system. The parasympathetic system, the way we would always learn to remember this in medical school, was this was the rest and digest system. So this is the down regulating system. It conserves energy. It aids in digestion. It slows heart rate. Our favorite little fact was it was responsible for erections, but not ejaculation. ejaculation somehow came from the sympathetic system. So the sympathetic system, of course, is the fight or flight system. So it's making energy more available. It's dilating the pupils, right? It's getting you ready to see as much information as possible. It's slowing digestion and peristalsis, meaning it's

slowing down anything that's not essential and it's increasing heart rate. Let's just think about what this looks like. From a practical standpoint, if you're laying in bed and you hear a loud bang in your house, you have no idea if it's an intruder or if a picture fell off the wall, but you don't even have to worry about your brain isn't going to even force you to make that decision. It's going to make the decision for you, which is this is a threat. And so your heart rate is going to shoot up. Your pupils will dilate any amount of digestive energy going on right now. We'll cease and your liver is going to start cranking out glucose and making you available for fight or flight. Okay.

So what does this do with HRV? It turns out when the sympathetic system is revved up, H-r-v goes down. And when the parasympathetic system is in control, H-r-v goes up. And I think it's easy to think about this, right? As the heart rate speeds up, which is what's happening under sympathetic tone, there's less variability between the beats. When the heart rate slows down, when the body is relaxing, there's more variability between beats. I don't know if that's intuitive or not. I was thinking

about that. If you have over the course of a minute and your beats per minute is say, you're, I don't know, Lance Armstrong when he's at the height of his powers. I don't even know what that is. Probably 30 beats per minute. 30 and then you've got somebody else who has 100 beats per minute. Just the RR intervals, whatever you call it, there's just less time between them. Intuitively, I would think there would be less room for variation between each beat. That makes sense. Yeah. I mean, I don't know how strong the correlation is between resting heart rate and HRV.

It's almost undoubtedly positive, but I don't know what the R squared is on that. Is that a fair explanation, Bob? Does that make sense on why we would care about HRV? Yes, I think so. As a knock-on to that, when you get your HRV output, if it's higher low, what is that telling us, or how does that inform us? What do we do with that information? Thank you for listening to today's Sneak Peak AMA episode of the Drive.

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