WHOOP Podcast - Inside The Rise Of Wearable Tech: How WHOOP Can Improve Your Health with Dr. Greg Grosicki

Episode Date: July 16, 2025

What happens to your body—and your behavior—when you start wearing WHOOP every day?In this episode, WHOOP Global Head of Human Performance, Principal Scientist, Dr. Kristen Holmes is joined by WHOOP Senior Research Scientist, Dr. Greg Grosicki to break down the results of a groundbreaking new study conducted by WHOOP, analyzing the data from 12,000 WHOOP members over 12 weeks. The study reveals a clear relationship between WHOOP wear frequency and improvements in key health and performance metrics like sleep consistency, duration, and quality, RHR and HRV, and overall physical fitness. Dr. Holmes and Dr. Grosicki break down the study, science, and implications of the findings on long-term health and longevity.The Study:Wearing WHOOP More Frequently Is Associated with Better Biometrics and Healthier Sleep and Activity PatternsRelated Episodes:Understanding GLP-1: The Latest Research From WHOOP with Dr. Greg GrosickiSpotifyAppleYouTubeImproving VO₂ Max For Longevity and Performance with Dr. Greg GrosickiSpotifyAppleYouTubeSupport the showFollow WHOOP: www.whoop.com Trial WHOOP for Free Instagram TikTok YouTube X Facebook LinkedIn Follow Will Ahmed: Instagram X LinkedIn Follow Kristen Holmes: Instagram LinkedIn Follow Emily Capodilupo: LinkedIn

Dr. Grisicki, welcome back. Kristen, or Dr. Holmes, should I say? I'm pumped to talk about this research. So before we get into this awesome study that was drawing on nearly a million days and nights of data across almost 12,000 Woot members and showed this super cool dose response relationship to wearing Woot more, greater gains in sleep quality and physical activity. and other key biometrics like resting heart rate and our heart variability. It was just a really cool study. I love, Greg, for you to talk about how do we go about these type of analyses? We're scientists. So we have an oath, right, to do things honestly, you know, follow scientific method and be rigorous and transparent in how we approach all aspects of the scientific method.

So I'd love for you to talk through how we think about this process as a scientist. And we obviously, we work for whoop, right? So there is a conflict of interest there. But I think our team does everything that we possibly can to make sure that we are not allowing those conflicts to enter into our process. Yeah. So I wanted to start by kind of relaying a conversation I had when I was chatting with Finn and Elena on marketing about these results. They're really exciting. This is a study that we've known the

answer to at WOOP for a long time. We know that WOOP is designed to be this 24-7 wearable, that it is always on and we want it to be always on you, and that theoretically those who wear Woop more will get entrained in this feedback loop whereby it will encourage positive lifestyle behaviors and make them healthier, right? But we, until really now, didn't really have great quantitative evidence for that. And one of the products, and we'll talk far more about this in this discussion, one of our big findings is that resting heart rate is lower in people who wear who weep more. And that's great. But let's quantify it. And if we're trying to market that, just for instance, when we compared people who wore whoop every day to those who

war whoop less than five days per week. Resting heart rate was almost five beats per minute different in those two groups. Now, it would be really easy for me just to give that information to marketing and let them post it on the website because that sounds really cool. It's like resting heart rate is obviously massive, right, when we're looking at that from a longitudinal perspective, right? It's huge. It's big.

It's 10%, right? I would love, I don't know, mornings I wake up with my resting heart rate five beats for minute lower. I'm like, whoa, this is really cool. It's meaningful for me for me, for my life. Right? Like, I don't know about you, but when I wake up, I'm like, what did I do yesterday? Exactly. Yeah. But that's not the data we gave because that's not the most robust.

Instead, we controlled for as many things that we could possibly think of that could be different and that we noticed were different in between those two groups. Right. And that move around, rest of the part rate. Things like age, things like BMI, things like biological sex, even things that people don't even think about. things like what month was it they were wearing who. Right. There's a seasonal effect that we see very reliably in our data analysis. What day of the week and how many Mondays versus Saturdays were people wearing whoop? In addition to what was their baseline values coming into the study? How did those look like and trying to normalize for all of that? And at the end of the day, it was about a one beat per minute difference, which might not seem like a lot, but

what I'd give to wake up with my heart rate a beat per minute lower. And if it's as simple as wearing whoop more, then that's pretty cool. I think that just kind of provides a nice context to what you were saying in regards to we're delivering a answer that's academically rigorous, but also informational. Right. And this is a study that has moved through peer review, which is also important to call out that, you know, whenever we declare something and make a claim of this nature, it is going to go through peer review. And that's, obviously, Obviously, I think in large part, like what our team does performance science is we're looking to publish. So in order to make that happen, there's no way that we can cut corners because it's just it's not going to end up published.

Yeah, particularly when you have academics who are reading our work. Yeah. Who have the highest level of suspicion about what we're doing. Exactly. They're skeptical already of industry type of research. So yeah, so that just our bar is even higher in some ways. So that's okay. That's how it should be, right? Yeah. Yeah. And it's we, we welcome that. You know, it's not something that we're shy. And we can back the work that we do because, you know, we, I think have a world class team that that's able to go about the analysis and everything in between in a way that I think is honest and rigorous. As well, as a product that works. Exactly. Let's just do like a quick overview of just the design of the study and kind of what made it unique.

Yeah. So the study started with a very innocent question. from marketing we're interested in data showing that we're in more may or may not be beneficial is there any this is something we've kind of trying to been get at for a very long time and it was you know posed to fin and i and we're like all right this is like a very cool question but this is not something i can get to you next week or the week after probably not even the week after that but if you give me some time i think we can cook up and do a very robust and rigorous analysis we'll see what it shows and to be totally honest with you I was not expecting the data to be as compelling as they were.

I was not expecting it at all. I even told marketing, I was like, just realize I may do this, and we may not have anything that's usable here, but we did, right? And in fact, it was way more usable than I could have imagined, which is really cool. So what I did, and I, like, outlined this, I thought about it, I chatted with Finn. I was like, here's what we're going to do. I'm going to get 12,000 people who began using WOOP in 2024. for. We're going to make sure they're evenly split by biological sex because we want

whoop to work equally as well for males and females. We said, I'm going to get 84 days of data for each of those people. Now, each of those people needs to have a day the first week when they started wearing whoop, and they also need to have a day of data the 12th week. Other than that, there's no conditions. If they wore whoop twice, once the first week and once the 12 week, that's fine. But if they wore it 84 days, then that's fine too. And we spread split them across 2004. So we made sure we got an equal distribution of those members by month

because we know there's seasonal effects and where people are more likely to engage in exercise and sleep better in the summer than they do in the winter. So that's kind of where we started. I think it's important to call out motivation. You know, because that's, I think, something that we're not able to

disambiguate and that is kind of a confounder or a limitation. Maybe just talk through that quickly. Yeah. And that's kind of one of the interesting things. And it goes back, again, this is going to be very honest, with one of the key limitations of our study is that we don't know for the life of us what people were doing before they started wearing their right. Right. We don't know what their resting heart rate was. We don't know what their activity was. We don't know how much they were sleeping if they were sleeping. And so one of the first things we did

with this analysis is I started just by first answering the question, how much on average did this this group of 12,000 people wear who. And on average, it was about a little over six days a week. So that's great. That's like pretty cool. Yeah. But we did see more than 2,000 people who were wearing it less than five days a week, five days a week or less.

And so, okay, let's just start by breaking this into groups, less than five days, five to six days, six to seven days, and then seven days, the perfect wearers. And let's just look the first week of data, what those people's data look like. And already we saw these stark differences. emerge in these cohorts. Interestingly, the people who war who war whoop every day, they had a lower BMI, they had a

lower resting heart rate, they had a higher heart rate variability, they had more physical activity. And I showed it to you and you're like, oh, well, this all comes down to conscientiousness of these people. And I like, you know, as an excess physiology, I'm like quickly Googling conscientiousness. Like, how does it play into this, right? And I'm like, thank God I work with people who know something about psychology. But you can talk maybe a little bit about that, maybe.

Yeah. This is, I think, one of the challenges, right, with not having some of this context when we're doing this type of research is that we don't really understand the motivation behind why people are doing what they do, right, and how that moves around these biometrics, these objective data, physiological data. One of the things that we try to do in our research is we try to have an understanding of personality. We try to have an understanding of psychological kind of functioning and in every study we're not able to do this. You know, this is a retrospective analysis, right? Not a perspective. And we don't really have in our data a lot of this trait kind of information. So it does create a limitation for us in terms of being able to really understand or create a profile of people who actually get fit on our platform versus not. But I think this is an amazing start to really just say, hey, at a base level, if you wear whoop more, the chances of getting more fit are there for you.

And I think, you know, at the highest level, that's what we're able to see. But I think it's important just to call it the fact that we don't really understand the motivation behind why people are doing what they're doing, why they're wearing it. And I think if we're to hypothesize, well, yeah, those folks are probably more conscientious, right? Right. And just baseline when they're coming into wearing who, those who are more likely to wear whoop seven days a week probably are more fit. Right. But also tells us that those behaviors maybe go hand in hand, right? Yeah, totally.

And so if you see being more physically active or working on sleep consistency, it's a big hurdle. It's like, well, maybe you could start with something that's way more simple. Yeah. Keeping whoop on your wrist for seven days ago. What's up, folks, if you are enjoying this podcast or if you care about health, performance, fitness, you may really enjoy getting a whoop. That's right. You can check out whoop at whoop.com. It measures everything around sleep, recovery, strain.

and you can now sign up for free for 30 days. So you'll literally get the high performance wearable in the mail for free. You get to try it for 30 days, see whether you want to be a member. And that is just at whoop.com. Back to the guests. You know, when people are trying to improve their body composition and are weighing themselves every day, that helps. Yep.

Right? That is irrefutable at this point, right? That weighing yourself is going to help you achieve your body composition goals faster than not being aware of those numbers. And I think we can kind of use that as a really good analogy for being able to kind of see your recovery data and your sleep data and getting insight from strain coach, you know, and saying, hey, this is your target strain today. Based on your recovery, this is how hard you can go. We also see that in the data that people who listen to strain coach actually get fitter on our platform, right? So there's this really important relationship

between recovery and your capacity, right, that we call out very, very clearly to our members. And when people follow, they play better golf, they play better golf, which will be another podcast soon. More to come on that one. This has been like such a, that was a really fun analysis. But, you know, I think what we're kind of doing is, is actually starting to put this puzzle together. And I think for folks starting out, if you have made this investment, you are paying a subscription on whoop, wear it, pay attention to the data and see what happens. Chances are you're going to improve your cardiorespiratory fitness. That's what we see.

That's what these data show. Yeah. Yeah. And it starts with the lifestyle behaviors, right? And that was maybe one of the key findings of the study, I would say, was that we saw that, but the improved lifestyle behaviors. Now, again, keep in mind, this study was 12 weeks. So we're only looking at 84 days of data. And we saw improvements in sleep consistency, which I'm not sure has ever been shown with using a wearable.

Definitely not. Or really any intervention is improving sleep consistency because it is just such a new and emerging indicator of health. And frankly, I would be willing to bet that most people, when they come on whoop, don't even really know what sleep consistency is or have any understanding of the importance of it. So I think that's a worthwhile thing to talk about. And I think the realization that sleep duration is so important is it's now well known. The American Heart Association brought it into their life's essential eight along with things like not smoking and being more physically. active and maintaining body weight and maintaining a healthy glucose, but now healthy sleep has come in there. But when you look at the detailed instructions, it says sleep between seven to nine

hours a night. But you and I know, the science says that that actually isn't the most important aspect of sleep. It's really sleep consistency, because that's the primary driver of sleep quality. We can talk about the data that exists. You know, now I feel like there's more evidence coming out, you know, every, every quarter, I feel like there's a new paper published around sleep regularity and sleep consistency. And we know from Daniel Widger's paper that was published in January of 2024 that looked at, that looked at mortality risk. They found in that study that sleep regularity, what we call sleep consistency, was a greater predictor of all-cause mortality or mortality risk than sleep duration. So just to emphasize your point that, yeah,

duration matters, right? You need to be getting the right amount of sleep cycles. But if you can focus on sleep consistency, and again, wearing whoop, it's going to be very obvious to you that sleep consistency, it is an input to health span, right, for all the reasons that we're talking about. We know that it ladders up to all-cause mortality and mortality risk. So it's something that you should be aware of in measuring, right? So if you want- It's now a key player in our sleep performance, right? Yeah. Now it's finally a key player in our sleep performance. So when you're looking at your aggregate score of how well you're sleeping. Sleep consistency is now part of that algorithm. So, you know, you want to try to keep your sleep consistency around 85%. This should be kind of

the target. And that is going to contribute positively to your health span. And we see people who wear who whoop more improve their sleep consistency. And again, it's just by being peripherally aware of these data points, they kind of nudge you in the right direction. And we see, you know, we saw in another paper that we have in peer review right now with sleep. Our core four challenge is another paper where we see that these four behaviors, zone two, breathwork, morning sunlight, and time restricted eating, all of which kind of have this circadian component drive sleep consistency. Right. So it's, and a lot of these, these behaviors are things that we're nudging you toward in the coaching experience on our platform. So, you know, I think it's,

it's a matter of when we think about reducing all of the noise that is out there around, what are the things that you should be focusing on to improve your health? I think we have done a really elegant job of wrestling to the ground. What is most important for your health span? And a big piece of that is just wearing the sucker so you can get that insight. Yeah, yeah. And packaging that, you know, the latest science into it. The Winderd paper you were talking about UK Biobank, 2002, and it's already in the app and

we're already driving people towards it, right? Yeah. And sure enough, people come in. They probably don't know about sleep consistency. The nice thing about sleep consistency, and this is something I talk about all the time, is I can want to sleep more, and I just, you can't will it.

I can't go to bed at night and say, tonight is going to be the night where I am going to get nine hours of sleep because the truth is my body doesn't sleep nine hours. It just isn't going to happen. But what is really easy is for me to say, at 9 o'clock, I'm going to get in bed and shut my eyes. And I may fall asleep or I may not,

but that's besides the point. And then at 6 a.m., when my alarm wakes up, I'm actually going to get up and get out of bed. Those are very actionable, easy things to do. And in the golf paper, we see that within person, in athletes who slept more one year than the other, their performance didn't improve at all. However, those who slept more consistently, their score went down, they had fewer poor shots, and they were playing better golf, right?

So our data is supporting this body of literature, and it's just going to keep coming out. And one of the really unique things and cool and insightful things about this recent analysis, as we showed, that over the 12-week period, on aggregate, the group increased their sleep consistency. And that's never really been shown before. And so that's pretty cool. It's so cool. And I think it's worth spending this time on sleep consistency because, you know, I think we're really working hard, given what we know in terms of relationship between health and performance, it is a, it is the driver, right? It is the behavior. I think it's worth us spending a little bit time. How do we actually back into sleep consistent?

To your point, I can have the best intention to fall asleep at 9.30 or 10 o'clock at night. But if I am not creating conditions during the day that enable me to feel sleepy at that time, I am never going to be able to achieve sleep consistency. And I know when people look at health span, the number one mover of health span is sleep consistency, right? So people need to understand how do they actually improve sleep consistency, given that it's the number one input to your pace of aging. It's going to age you faster the more variable your sleep wake time, okay? Bottom line. So how do we actually fix it? So if you think about, all right, this entire month, what time can I get up every single day reliably? And you want to try to stay within a half hour window left or right of that. You can control when you wake up, okay? To your point, Greg, you can't control when you fall asleep.

So you set your alarm, let's say, for 6.30 a.m. That's the time that I can wake up, you know, for the rest of the month. And you get up at that time. and you view as much artificial light, natural light as you can at that time. And that's going to basically set your circadian rhythm and help you feel sleepy about 15, 16 hours later. It's a very simple behavior that you can do. But that is the way to get yourself to create a condition that allows you to fall asleep at a regular time. The other piece to that is after the sun goes down, you need to start restricting light. It doesn't mean you have to be in complete darkness. But half an hour before you want to fall asleep, you need to be in very dim light.

that is what is going to release your melatonin, which is that hormone that is going to help facilitate sleep onset. So those are really the two big things that you need to do. There are more things that you can do, but those are the kind of the non-negotiables. If you are interested in stabilizing when you go to bed and when you wake up, i.e. sleep consistency. Yeah. And there's great data from the group that I think it's in Australia that showed that athletes who slept more consistently, slept more efficiently. Monash. Monash, that's it. Yeah. Yeah, 100%. Yeah. And so, again, you're fixing something that's actionable, what time you go to bed and what time you wake up, and you're improving things that aren't necessarily actionable. Yeah. Or they are, but only indirectly.

Yeah. And this is the other, I think, the group at Monash found this. There's other evidence that sleep consistency is really the big driver of sleep quality, right? And that's when all this restoration happens. Yeah. Was it Charlie Sargent's paper that you're referring to? Because Yeah. Oh, that's, yes. He's from Suki, Central Queensland University. Yeah, yeah, so Charlie. And then, but I think there are some folks from, I think, Elise, Faster Child was on that paper, too, from my gosh. Yeah. Yeah. But yeah, it was, it was a great group. It was a great paper. And again, I think it's just, the literature just keeps piling up, the evidence keeps piling up that soup consistency is, is the big needle mover, which I feel really grateful for, because I've been talking about this since 2017. I feel like it. Now we just got to get it in the American Heart Association's healthy eight, right? Seven and nine. nine hours and consistent sleep, but it's coming. It's coming. The evidence is mounting. It will be there. And I think that's where what I love about Woop is that we get at some of these nuances, right? Like you hear just these very general recommendations like, get seven to nine hours of sleep. Well, yeah, it's a little bit more than that. If we're really trying to kind of show up

every day and have as much kind of capacity and alertness and presence with the people we care about and love, there are some nuances to that, right? And it's. if we just know them, then we can move toward them in a more strategic manner, as opposed to just trying to guess, right? There's, we're kind of getting to a place in human history where we don't actually have to guess, right? That said, kind of going against the grain of modernity is not easy. And that's part of the challenges, right?

Like modern life in a lot of ways isn't set up for us to practice sleep consistency. So we kind of have to override some of that. and I think accept, well, we have to recognize the challenges and just kind of design a life that fits within our constraints, but honors our biology. And that's kind of what we're after with consistency. Yeah. And we improved it. So that's always good, right? The other one, we increased the amount of physical activity people were doing. Admittedly, this is great. It's not like entirely unique to Woop. It's well known that people who wear an activity monitor are going to be more physically active. But those are the two things that end the population, we moved as an

aggregate. So I think that's really cool and worth mentioning. And there are probably a lot of people who are thinking about using WOOP as this accountability partner, right? Yeah. And these data show that it is effective at doing that. Yeah. And the biometric and health span changes that will follow that will certainly come. Yeah. And I think, you know, I hear, you know, some influencers online, you know, talking about, you know, data takes you further away from yourself. And, you know, it's like you don't, you can't feel your body. And I'd push back on that. Of course, I'm very biased. And I think a lot of this, this sentiment, I think, comes from people who, who maybe were former athletes and are very connected to their body. But a lot of folks are not super connected to their body and are trying to figure out how to apply their effort, right, in terms of getting to a better. position in terms of health span, trying to reduce illness and injury burden. And these data are, you know, can you get by without them? Of course. But why would you want to? Right. Like it's like such a powerful source of insight into whether or not your behaviors are

contributing positively towards your health span, i.e. being in a position when you are 70 or 80 to get down on the ground with your grandchildren to be able to, you know, party it up at your kid's wedding, like, whatever it might be, right? Our behaviors every single day are going to contribute to that positively or not, right? And in the data just give us insight into how close or how far are we from that future self. Yeah. And the truth is you can't optimize what you're not measuring. I'm sorry. It's just the reality of the situation. And we provide that measurement tool. And one of the unique things I think about our research that I see folks like Marco Altini, who's a legend in the field of heart rate variability,

and he does great work, and he writes great blogs. I think he's a fantastic scientist. Super rigorous, yeah. But one of the things he will frequently call wearable tech out for, and it's true, is that when we design our algorithms, a lot of the times we'll focus on population-level trends, basically between-level effects. But I think one of the really unique things about our research, particularly at WOOP, is that we don't stop by looking at population level trends,

and we didn't stop at that for this analysis. In person effects. We looked at within person effects, right? And that's one of the very unique things about having a longitudinal data set like this is what we did for this particular study was we grouped people. We defined people, characterized them by a week. So we said, okay, for Kathy, we didn't have her name, obviously. We said for subjects, one, two, three, four, five.

This is what their data looked like in week one all the way to week 12. And so we looked at their resting heart rate, their heart rate variability, their sleep duration, their sleep consistency, their physical activity both over the course of the week, and then how much physical activity they were doing each day that they were active. And we also were curious as to how many times did subject one, two, three, four, five, where whoop over that week? And so we were able to say, okay, starting kind of broadly, high level, and this is what wearables will get criticized for, did people who war whoop

more, on average, have better metrics, a lower resting heart rate? That's great. But what we're not really getting that with that is did weeks where, subject one, two, three, four, five, where wooop more or less than usual was that and how was that associated with their personal data? And so one of the things we do and look to do in all of our studies is to tease out not only what are these population level trends, the wearables are criticized for, and rightfully so. Yeah. But also what happened at the individual level. And that's one of the unique things about recovery score, right? Is that recovery score isn't a population level trend. And that's very important when you look at things like heart rate variability. Yeah. Where me comparing my heart rate variability to anybody comparing their heart rate variability between people, is a horrendous idea. Yeah, strain as well. It's just different.

Yeah. It's just different. It needs to be analyzed within an individual. Yeah, such an important call out. And I feel like I talk about that ad nauseum, you know, because I think that the assumption is that we're just giving population averages. And I'm like, no, you know, of course people aren't reading the papers necessarily, right? But I think, you know, we can't say that enough and educate folks on what that actually means in terms of the rigor of the analysis. and the utility of the of the findings you know i think it it changes the usefulness of the findings

and i think really important ways right it's far different to say that you know uh christin has a white hat and that people who wore a white hat their heart rate was one beat per minute lower it's like oh that's great but what happens if i put on that white hat what happens to my resting heart rate and that's one of the things we looked at here in the analysis i'm just going to talk about the resting heart rate and heart rate variability findings because i think those are interested And so between individuals, we compared resting heart rate and heart rate variability in individuals who wore it every day. It was really six to seven days, five to six days, and then less than five days. We showed that individuals who wore it every day controlling for

everything, age, sex, BMI, season, day of week, we even controlled for what their values were at baseline, had a resting heart rate that was one beat per minute lower. Interestingly, and maybe not surprisingly, heart rate variability was not different, which this again calls into the danger of comparing heart rate variability between people. If you have a heart rate variability of 50 and your buddy has one 150, it doesn't mean that he is any more or she is any more or less healthy. It should not be compared. But where it is really valuable is looking at within. And so interestingly, we show that on weeks where individuals wore their route more than usual, their resting heart rate was two beats per minute lower, which is more than what we saw

in the between person comparisons. And their heart rate variability was significantly higher. and again that speaks again to that very important aspect of comparing not only between people who are wearing white hats but if I put on that white hat what's actually happening my wrestling heart rate gets lower and my heart variability goes up and it helps to eliminate all these different confounders and that's not to say that I'm training for a marathon when I'm wearing my white hat because that's it that possibly exists right but it does help to parse that out a little bit yeah and these within person effects are are really exciting, you know, when we, when we think about the potential for just actioning these data, daily, you know, and kind of, I'm not suggesting you need to calibrate your life around these data points necessarily. I mean, many of our elite athletes do, because that's kind of their job, you know, but it's not, that's not practical for most folks. But I think just as a guide to just understand, you know, at a really high level, like, okay, I'm red today, you know, and just stepping back and just evaluating.

what might be going on in your life that's contributing to that. You know, it just accelerates your wisdom. Yeah. I think this study really shows exactly that, that there's a wisdom, a potential for these data to help accelerate your wisdom. Yeah. And, and I think we see that in these within-person data. You're invited to join the waitlist for WOOP Advanced Labs. Advanced Labs delivers clinician reviewed lab results right into your Woop app for the most complete view of your WOOP app for the most complete view of your biomarkers and biometrics and the most comprehensive understanding of your health. Unlike other tests, WOOP integrates your lab results with your WOOP data. See how your habits and behaviors influence your biomarkers and get clear guidance on what

to change to improve your results. To join the weight list, visit our website or the Health tab in the Woop app. To speak about more of the within-person findings, if I may, because I think those are particularly exciting. Yeah. So we talked about resting heart rate and heart rate variability. and I think most of our listeners probably have a pretty good understanding of what those are. We also looked at sleep duration, of course, because we can't not.

But, you know, perhaps more exciting to us was sleep consistency. And what's really cool is when the between and within person effects kind of line up. And in this particular situation, they did. And they don't always, which is sometimes even more interesting. We showed that people who wore their whoop every day compared to less than five days a week, slept for over 20 minutes longer per day. So almost two and a half hours more of sleep per week than those who are wearing it less than five days? Yeah, it doesn't sound like a lot, but 14 minutes is clinically significant. Yeah. And when you get to 20 minutes, yeah. Yeah. I mean, that's,

and that adds up, you know, has a compound. I would kill for an extra 20 hours of sleeping. Too bad. Too bad I can't extend the week to 14 days. I know. I know. And within person, we saw the same thing. They slept for 15 minutes more. So it's not that much different. They're sleeping longer. They're also sleeping more consistently. People who war-whoop every day, and this gets into that, you know, the traits that are associated with it, their sleep consistency was five percentage points higher. But also within person, their sleep consistency was about four percent higher on weeks. They were more than usual. And so we see it guiding those targets and key outcome variables as well. I think there is a circadian component there.

You know, when you're really active during the active phase of your circadian rhythm, you are going to feel sleepier during the inactive phase. of your circadian rhythm. You know, so there's like, I think, a really nice synergistic effect, you know, when we are kind of aligning what we're designed to do, it is going to make a difference. And I think that's probably one of the reasons why we reliably see sleep consistency improve in parallel to activity levels. Yeah.

I think it's time for a sleep consistency study. What do you think? Yes. It's a good thing. We have another meeting coming up. I know. It's so funny because these conversations just generate ideas for like, our next yeah tell fanny is going to lose his mind i know just another study for him i know i know

but i think that this is really i think in the end and this is i think basically our job gregg is to is really to find the signal in all of this noise you know so people are not wasting their time trying you know experimentation is is fun but you know i think in terms of like this foundational stuff and again if if people have the goal of being able to kind of show up be present reduce sickness reduce injury, then there are some things that we can do, some principles that we can deploy as often as possible that are going to put us in a position or create conditions that allow us to show up consistently. And I think that's, you know, when we get excited about, you know, some of these research possibilities, I think that's really what drives our excitement is this

idea that we can reduce the confusion for our members. Yeah, I think one of those is like figuring out what to expect with some of these behavior changes. And one of the kind of unique things about this analysis is we saw also improvements in activity that were associated with this, right, both between and within people. But one of the questions that I had, and I have a huge bias going into analyses like this. In fact, I think when I told you the results, I was like, I don't believe them, so I'm doing it again. Yes. We saw that people's heart rates were lower in weeks. And these are the, again, so we're getting at the within person effects, right? So in weeks where people wore whoop more, their heart rate was about two beads per minute lower. And so

I'm trying to tease out, is that aligned with their behavior? We know that weeks they're wearing whoop more, they're also sleeping more, and they're doing more exercise. And so the very biased exercise physiologist and me immediately, well, it's because they're doing more exercise, of course. So we use this multiple mediation analysis to look at these within person effects. And I ran the models, and I was like, I can't believe this. Like, it turned out that actually sleep was partially mediating the association between wearing more and the resting heartlight getting lower and exercise wasn't a predictor. And I'm like, something's broken here. Like, what is happening? How do I fix this? Right? And it's ran it again. Sure enough. And then, you know, you take a step

back and you look at it and you're like, okay, well, let's think about what is actually physiologically going on. What's the mechanism behind this? When people are sleeping more, they're probably in a more rested state. They're more recovered. And so it makes sense the resting heart rates. going lower. But as an exercise physiologist, we also know weeks when we're working out more than usual, we're putting extra strain on the system. And so we shouldn't maybe expect a decrease in resting heart rate when we're working out more. And so that didn't necessarily. And now maybe we will see that in the future and I would expect we will. But I think kind of aligning, you know, behavior change with expectations, it's like, okay, I'm going to sleep more. My resting heart rate

might come down immediately. I'm going to exercise more. It may not. It may be a couple weeks delay and like that was a mistake I made I was like oh this is going to be really cool we're going to show exercise beats sleep again right because I can exercise but working on my sleep is a harder thing to do but I wasn't actually how it worked out oh yeah that I'm so happy that you remember to share that yeah yeah it's really cool I almost didn't want to because you know exercise is king but I know I know it's it's more complex than that you know but I think that that's what this research really allows us to do is to understand what the the big mediators are actually what's driving what's driving we're seeing right great so understanding kind of

how we can predict future health improvements it'd be really good for you to take us through kind of causality analysis and and how we use that as a way to predict future improvement yeah yeah yeah so this is a paper that started with marketing giving me an idea and slack and then us as a team trying to design the study to figure out how to answer it and it was completed by, or it was greatly supplemented by a recommendation from Maria in data science when I was chatting with her about it. And she goes, you know, have you considered any sort of causality analysis? And I'm like, Maria, I don't know what you're talking about. And she's like, well, like, take a look at Granger causality. It's like, okay, so I did a little bit of research on it. And essentially,

it's pretty simple. The Granger causal model basically says if we were to take variable X in the past in the circumstance for this study we set that up is how frequently did people wear their whoop? Can we look at variable X in the past and use that to predict variable Y in the future, which in this case we set up as resting heart rate? I thought that was particularly interesting. And so what we did is I focused this analysis on,

again, just for the sake of transparency, a subset of the sample that were whooped less than five days a week, five days a week or less, because there needs to be some variability in X Totally. Otherwise X isn't going to predict one. So we focused on that portion of the sample and we said if we use a seven day rolling average where they either wore it or they didn't, their whoop strap, can we use that to predict their resting heart rate in the future? In over 12% of the people, that actually emerged as the case, that we were able to use their past wear of whoop to predict their resting heart rate in the future. Anyone who's worn who who has worn whoop or has friends who warn who equally know that when our metrics aren't trending in the right direction, it can be tempting. to take it off, right? 100%. And so we actually reversed it too.

Or when you're doing a lot of naughty behaviors. Right? Well, people, we know, again, going back to the weekday versus weekend, people aren't wearing it. And we saw that in this case, right? Yeah. There was a big difference if we looked at the percentage of weekday versus weekend. I want to bring their baseline down. We know who you are.

Yeah, yeah. And so we ran it in reverse as well. And while we did see some signal, there was about seven or eight percent of the people were able to predict it. That's not nearly as strong as where password predicts. future resting heart rate versus vice versa where it was like, does resting heart rate in the past predict where time in the future? It wasn't as strong. But that does give us at least some good indication. It doesn't definitively prove causality that people are wearing their woup

may or may not be theoretically as modifying their behavior in ways that is yielding a lower resting heart rate in the future. And that could be through sleep. It could be through activity. it could be something as simple as having no or less drinks at night yeah whatever it could be improved sleep consistency but i think that was one thing that some combination of all of those things probably yeah and i think that was one thing that really made this study impactful and so that was a really great addition i love it well gregg this has been another fabulous uh discussion uh appreciate your expertise and insights into these data and uh so fun that we were able to, I think, collaborate with so many folks in the company, you know,

with marketing and data science, to really tackle this question, you know, which is, I think, a really cool and important question, certainly for our company, you know, but I think for just wearable tech in general. Yeah, no, for sure. Pleasure to be on the conversation and obviously to work for a company that cares about their science like this. Love it. Thank you so much.

Thank you. If you enjoyed this episode of the WOOP podcast, please leave a rating or review. Check us out on social at Woop, at Will Ahmed. if you have a question what's answered on the podcast, email us, podcast at whoop.com. Call us 508-443-4952. If you think about joining whoop, you can visit whoop.com, sign up for a free 30-day trial membership. New members can use the code will, W-I-L, to get a $60 credit on Woop accessories when you enter the code at checkout. That's a wrap, folks. Thank you all for listening. We'll catch you next week on the WOOP podcast. As always, stay healthy and stay in the green.

Thank you.