The 8 Hours of Sleep Myth for Longevity and Muscle Building After 40
Do you actually need 8 hours of sleep to build muscle after 40?
We put that claim under the microscope and separate what sleep research actually shows from what fitness culture spreads online.
Learn about the simple rules that protect your strength training, fat loss, and daily energy even when your night falls a bit short:
Where the 7+ hours of sleep guideline comes from and what it does and does not cover
The effect of sleep restriction on a calorie deficit, including fat loss vs fat-free (lean / muscle) mass loss
Why “short sleep kills your gains” is not supported by direct lifting trials, and what mechanistic data suggests instead
How cutting sleep often affects your sedentary time more than gym performance
Why sleep regularity can matter more than duration for long-term health outcomes
Wow to use wearable data without letting sleep scores drive stress and bad decisions
3 practical rules for bad sleep days
The simple movement targets that offer big returns and 2 quick strategies to offset extra sitting (which is connected to sleep)
If you want to stop treating sleep as the thing you have to fix before anything else works, hit play.
Try Fitness Lab, the AI coaching app that reads your data, coaches you on your patterns, and keeps you consistent for adults over 40 who want to lose fat and build strength. Get a free custom fat loss and muscle building plan before you buy anything.
Wits & Weights is the evidence-based podcast for strength training over 40, muscle and longevity, body recomposition, fat loss over 40, and healthy aging. Hosted by Philip Pape, creator of Eat More Lift Heavy and Fitness Lab.
Timestamps:
0:00 - Why you skip the gym after a bad night
3:31 - Where "8 hours of sleep" came from
6:41 - What we know about lifters on short sleep
7:26 - 5 nights of 4 hours in bed
8:27 - 6 weeks of less sleep
10:16 - Where the appetite research disagrees
11:10 - Sleep vs. strength training
13:11 - Rule 1: Never let a bad night be the excuse
14:34 - Rule 2: Sleep regularity vs. hours in bed
16:17 - Rule 3: What your ring is bad at measuring
17:50 - The biggest single sleep lever
18:36 - Steps, lifting, and mortality
19:24 - Sleep, food, and movement
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Why you skip the gym after a bad night
Philip Pape 0:00
If you've been told you have to have eight hours of sleep or your training and fat loss just won't work, or you've skipped a session after a bad night because of it, this episode is for you. Today I am evaluating that claim. And that includes a randomized crossover trial where they actually cut people's sleep and measured what happened. You'll learn what a bad night really costs you in the gym, what it costs you for the rest of your day, which is a little bit bigger actually, and one change to make tomorrow that covers both of them. Welcome to Wits and Weights, the show that puts a popular piece of fitness advice under the microscope, finds the hidden reason it doesn't work, and gives you the deceptively simple fix that does. I'm your host, certified nutrition coach, Philip Pape, and today we're gonna revisit sleep. And I've often said, hey, sleep is a foundation. Sometimes I've put sleep on the biggest pedestal as the root of all evil when it comes to your inability to achieve certain goals. And sometimes I don't even talk about it. So what we're gonna talk about today is where does this all fit in? How much do you really need? How much impact does it make? Because at the end of the day, what I care about is practicality. I don't want to tell people on this podcast, you need to optimize everything and here's the perfect way to do everything, because that's just not gonna work. You're not gonna do it, I'm not gonna do it, and you know, don't always need to, right? There's a point of diminishing returns. Now, if you're listening, you're probably on the older side, at least into your 30s and 40s, maybe over 50 or 60, and your sleep is not what it was in your 20s. I mean, I know as a teenager, I could sleep 12 hours, I could sleep till 11 or 12 during college. I could sleep to, you know, all hours of the day, no problem. I never had to get up to go to the bathroom. And as I got older and as I had kids and as stress starts to build and all of these other things, your patterns change. Hey, you're up at three in the morning for no reason. Maybe it's to go to the bathroom, maybe not. Maybe you've got some insomnia, maybe you have issues with falling asleep, maybe you have issues with snoring and things like sleep apnea. And maybe you got seven or eight hours of sleep and then don't feel like you slept, all of those things. Then we have our smartphones, we have our screens, we we get obsessed over our numbers, like on our aura ring or our watch, where it gives us this indictment, this grade, this sleep score, and you know, our recovery is X percent, 41, 89, whatever the number is. And now you're kind of obsessed over that. Maybe you're inconsistent with the gym, or maybe you are going to the gym, but now you don't have enough time to sleep. And I'm just kind of laying it all out there that these are the problems that you, dear listener, have talked to me about and that I've experienced myself. Underneath all of it is are these rules about sleep. And it goes something like this Hey, if you didn't sleep, maybe you shouldn't go to the gym because you're not gonna recover as well. Or hey, if you don't get at least that like solid eight hours of sleep, that is the one thing you have to fix above all else. And there's different variations of that. So in today's episode, we are gonna talk about what the actual sleep guidelines say. Secondly, we're gonna talk about what a short night of sleep does to you. Like what is the cost, both with your session and in the time after that, of the 14 hours after it to be precise. And third, we're gonna go over three rules that I would actually use. And none of them has to do with the number of hours. Stick around to the end because I have a specific number for what a very short night costs in the hours afterward. It's even bigger cost if you're a woman past menopause, and two ways that are pretty simple to offset that and be in a much better position.
Where "8 hours of sleep" came from
Philip Pape 3:31
Okay, so let's start with where something like eight hours came from. It's kind of like the 10,000 steps. It's like, where did that come from? Oh, okay, it came from some Japanese company years ago, right? But from the sleep perspective, it comes from the American Academy of Sleep Medicine and the Sleep Research Society. Back in 2015, they got together a panel of 15 experts. They ran this formal consensus process, and they published that adults should sleep seven or more hours a night on a regular basis to promote optimal health, and that six or fewer is just not adequate to sustain health and safety. So that's the guideline. That's where we get these seven or more hours. So if you're getting seven and change, and you know, you feel like it's not enough because you should be getting eight or something like that. No, you're actually doing pretty good according to those guidelines. And I personally, this is a struggle of mine, even when I work really hard on my routine and moving things around and talk to my wife and like trying to make the schedule work. You know, you get into parts of your life, times in your life where sleep is just hard to come by. Now, notice that there's no upper limit on that one when they say at least seven hours. And of course, they're not going to talk about other activities like exercise, lifting, building muscle, because these groups tend to focus on one thing, right? The sleep groups here were evaluating population health outcomes, things like cardiovascular disease, mortality, even driving accidents, accidents while people driving their cars. They weren't evaluating how it affects lean mass, body composition, things like that, right? They they almost never do that. So let's start digging into the research, shall we? There's a study by Nedelcheva and colleagues, 2010 in the Annals of Internal Medicine, where there were there were just 10 people in the design. Okay, just 10, three women and seven men, average age 41. They were overweight, sedentary, they were not lifters. And it was a crossover study, which are pretty cool. I find that crossover studies work well when you have the smaller sample size because everybody does both conditions. And in this case, it was for 14 days on each condition, one on a moderate calorie deficit with either eight and a half hours of sleep or five and a half hours of sleep. So interesting. They they isolated it to the length of sleep. And they found that total weight loss came out the same, about three kilograms either way. But what the group that, not the group, but because everybody did both, but when they got adequate sleep, they lost 1.4 kilograms of fat. And when they were sleep deprived, they lost only 0.6 kilograms of fat. And then the other way, they lost 1.5 kilograms of fat-free mass. So that's lean mass, what we don't want to lose, on adequate sleep, but then they lost even more on restricted sleep. So the share of the weight that came off as fat dropped by more than half. And the fat-free mass loss went up in the sleep-deprived group. So the body composition movement was not good when you didn't get that much sleep. Now, that's just one study, again, just 10 people, and you have to take it with a grain of salt, as always. So when we throw around specific numbers, it's because that's what's been studied at various thresholds. But I think many can agree that, hey, getting seven
What we know about lifters on short sleep
Philip Pape 6:41
and a half or eight hours of sleep versus five and five hours of sleep, there's a meaningful difference there for most human beings. Now, what happens to people who lift weights when they sleep less? Well, I don't think there's a study on that. There's no trial of resistance-trained adults on chronic sleep restriction where muscle growth is the outcome. Not even a small trial, not even a badly designed trial. I couldn't find it. If you know different, let me know. It's always difficult to find things, or when you find them, you think it's on this and it's really on something else. So when anybody says that like short sleep kills your gains, it's not based on research. Okay, but it probably is based on a lot of anecdote and coaching and you know, years and years of experience, plus personal experience when people understand that, hey, when I don't get enough sleep, it's gonna affect everything in my life.
5 nights of 4 hours in bed
Philip Pape 7:26
What we do have is though, is mechanistic work. There's one that I really like from Seyner and colleagues in 2020 in the Journal of Physiology. They took 24 healthy young men with five nights of four hours in bed, which is awful. I would not want to be one of those guys. Just four hours of bed five nights in a row, and they measured myofibular protein synthesis. That's the muscle-specific protein synthesis, and it decreased under sleep restriction. But there was a third arm in the study where people did high-intensity interval exercise during those nights. And in that group, their protein synthesis was maintained at control levels. So the thing that protected the muscle for the sleep-deprived group was the training. And when I say training, in this case, again, it's cycling intervals. So we're not talking about lifting weights, but I think the general idea that you are moving your body and using it, there's something
6 weeks of less sleep
Philip Pape 8:27
to that. Now, the best chronic evidence we have actually came out this year from Zureikot and colleagues in the annals of internal medicine. They pulled together two randomized crossover trials of 95 adults. All of them have habitual seven plus hour routines for their sleep. And were these people were at elevated cardiometabolic risk. The phases in the trial were six weeks long. And in the restriction phase, they cut time in bed by an hour and a half. So in re but so in reality, it worked out to sleeping about 78 minutes less. In reality. So, in other words, the manipulation of their sleep time worked, which sometimes doesn't happen in research. Research on calories are like, yeah, we decreased our calories by 500, but in reality, they were only down by 100. Or in reality, they stayed at maintenance, right? So in this case, they in reality slept on average 78 minutes less. What happened? Their body weight went up by about half a kilogram, so call it a pound over six weeks. Waste circumference went up by about a half a centimeter. Now, they're small, but they're consistent, and they go in the direction that you would expect when you are sleep deprived, you know, relative to your baseline, because again, it's compared to what they were doing before. However, energy intake did not go up measurably, and total daily energy expenditure didn't change either. And I say that because there are studies that show big differences in an ad limitum consumption of food. Like you tend to eat more when you're sleep deprived. And again, that's usually comparing something like five and a half to eight hours, so big, big difference. And in this case, again, they dropped by 78 minutes. But what did go up was their sedentary time. These people just sat around more. And that's probably why they gained a little weight, right? Even though it seems like their daily energy
Where the appetite research disagrees
Philip Pape 10:16
expenditure was unchanged. Um, and we're gonna actually come back to this at the end of the episode because I have some practical tips around this that you're gonna find interesting. Now, this seems to somewhat disagree with the research from 2017 that I've brought up multiple times about sleep deprivation raising energy intake, like you eat three or four hundred more calories a day without a rise in expenditure. But some of these studies are measured over days rather than weeks. Though that one was in a lab. Also, the variability between individuals is much larger. Some people were eating like 800 calories less to 1400 calories more. So there's a lot of variation. So I'm not going to compare them. I'm gonna say that no matter what, it seems like, you know, over the short term, being sleep deprived can definitely cause you to eat more. And over the medium term, we think that maybe it causes you to move less as well. So it just tends to cause all sorts of bad things that we don't like.
Sleep vs. strength training
Philip Pape 11:10
Now, I want to quickly mention my app Fitness Lab because it's highly relevant here. Because Fitness Lab has an evening debrief every day where it asks about your sleep and your energy, your hunger, your stress, your soreness on a one to 10 scale. And it measures things like your movement and your sitting time, which is really the whole thing this episode is about. It's not just about sleep, it's about how sleep interacts with all the other things you're doing to help or hurt your goals. Now, if you're using an iPhone, Fitness Lab can pull up to 85 Apple Health metrics. So it's actually pulling in a lot of your sleep and recovery data there. If you use an Android, we're working on it, we're working on Google Health. It takes a long time for Google to approve it. So just stay tuned. But you can still use the app and the evening check-in and answer it manually. And it's still highly, highly powerful to do that. Now, why am I bringing this up in an episode that is arguing against being obsessed with your sleep? Because I don't want you to be obsessed with it. I simply want you to track things and be able to make simple behavior choices based on it, as opposed to getting overly consumed by things like sleep scores and HRV and stuff like that. So Fitness Lab, which by the way, go to winsonwaits.com/slash app to check it out. Before you buy anything, you can get a free custom fat loss muscle building plan. The app doesn't, you know, judge you for any of this stuff. It helps you use that data so that you can train better. So, like when you log a training session and asks whether movement felt easier or harder, and it said it sees that you slept badly and you were stressed or you sat around all day, it's going to correlate that data and over time understand your patterns and what you should work on that will move the needle the most. Right. And as much as I love the aura ring and the Apple Watch and all the data you get from that, the problem with all this data flowing in and like a fire hose is like, what do you do with it? What do you actually do with it? So go to witsawaits.com slash app if you want to take a look at how that works, wits and weights.com slash app. And it's a great tool to put your sleep next to your training and have them work together. All right.
Rule 1: Never let a bad night be the excuse
Philip Pape 13:11
So what would I actually do when it comes to sleep? Three things. Okay, three things, make sure to take notes because this is where you're gonna have some actions. First, and this is the big one, never let a bad night be an excuse not to train the next day. There's actually a systematic review and meta-analysis from Grandau and colleagues in 2022. It's in sports medicine, if you want to look it up. And what it shows is that acute partial sleep loss produces small strength decrements or decreases on the order of a few percent. And those decrements get bigger as the bad nights stack on top of each other. Now, a few percent isn't nothing, but it's also strikes me as a big excuse you can use that I don't want you to. All right. The day after you have a bad night of sleep, keep your training session scheduled, keep the load where it is, don't try to change everything, don't make an excuse to slack off or not train with effort or to reduce the reps or sets or whatever. You may be surprised when you go in that you just feel great. You feel strong. I mean, I've gone into a gym and felt kind of weak and tired when I had a great night of sleep, and vice versa. Just showing up and getting that stimulus moves the needle tremendously. And guess what? Here's the cool thing training itself is doing something specific even when you are underslept. And wouldn't you rather have that than not having that and being underslept? Okay, that's the first thing.
Rule 2: Sleep regularity vs. hours in bed
Philip Pape 14:34
The second thing to do is I want you to focus on regularity, right, or consistency instead of sleep duration. For many, that's often the place where they can get that aha moment and really fix some of these issues for them. There's a study from Windred and colleagues in 2024 in the journal Sleep, great name for a journal about sleep. And it was a big one, almost 61,000 people in the UK biobank, and they used accelerometer data. They built something called a sleep regularity index, which essentially is how similar your sleep and wake timing is from one day to the next. So are you going to bed and waking up at roughly the same time? How much variation is there? And the people in the more regular groups had around 20 to 48% lower all cause mortality than the least regular group. And then in their model comparison, that this regularity, this consistency predicted mortality better than hours in bed did duration. Now, this is observational. It's an association, right? It's a correlation, it's not necessarily cause and effect. And it's from the UK Biobank, Biobank with all the problems that come with that. Okay, I'll get those in a minute because I do think they matter. But I always care about things you can control. And duration, even though you can technically control it, it's often hard, harder to control it. And some parts of it you can't at all. Like even if you intend to sleep eight hours and you have you're in bed long enough, sometimes you just don't, or you can't, if that makes sense. But you can decide what time to go to bed and wake up. And that seems to benefit people when they do that regularly, even on the weekends,
Rule 3: What your ring is bad at measuring
Philip Pape 16:17
all seven days, including Saturday, right? Instead of, yeah, I don't like I don't want you sleeping 10 hours on Saturday, but then five hours Monday through Friday, that's gonna really wreak havoc. So that's the second one is that regularity. The third one is to stop grading yourself based on your sleep scores from wearables, like from your ring. Hey, I have an aura ring, I have an Apple Watch, I love data too, but we have to be balanced with how we use this stuff. There was a clinical sleep lab comparison where the aura ring came in around 50% accurate across all four sleep stages. Now, I'm sure they're getting better. I know they are. Again, I have one, so it's not a knock on them. I'm just trying to be honest with like what the data shows. I think it's great at telling you whether you were asleep or awake and measuring like objective things, of course, like HRV, oxygen, um, temperature, things like that. And and the differences between those can tell you about whether your sleep is better or not. I'm not sure it's very good at the sleep stages, though, which is uh what a lot of us rely on it for. And therefore, if you see that the deep sleep is like nowhere near it supposed to be, and you get freaked out by that and stressed out, maybe you shouldn't be. If it's 53% accurate, that's like a coin flip. So be careful. That's all I'm gonna say. You know, they're gonna push it hard. They're talking about all their improvements and new upgrades and everything and the shiny new versions and all that. I get it, I get it. I'm beholden to that, just like the next person. There's mattresses, there's magnesium blends, there's, you know, all the things that say that they're gonna help you with sleep. Just be careful and make sure it moves the needle, as much as the easy things you
The biggest single sleep lever
Philip Pape 17:50
can control, like when you go to sleep and wake up. Now, there were quite a few other studies that I looked at for this episode, and I honestly don't want to bore you to death. I think one thing we're seeing from research over and over again is that activity is the biggest single lever when it comes to the interaction here with sleep. And that the optimal sleep is probably somewhere around seven or seven and a half hours. It's not necessarily eight hours, right? For many, many years, me growing up in the 80s, the eight seem to be the magic, like at least eight, but now it's probably at least seven or seven and a half, and that all of these things are bidirectional. Like sleep affects your training and your movement. Your training and your movement also affect your sleep. We really, we do have some really good fit data that I did want to share though on steps.
Steps, lifting, and mortality
Philip Pape 18:36
So regarding steps, Pollock and colleagues in 2022, they took 15 separate studies with more than 47,000 adults, and they saw that the mortality benefit of steps plateaued around 6 to 8,000 steps a day for adults 60 and older, and 8 to 10,000 a day for those under 60. We also see that muscle strengthening activity, fancy word for lifting weights, is associated with a 10 to 17% lower all cause mortality, independent of exercise, and the dose response starts to peak around 60 minutes a week. So 60 minutes a week is not very much to hit. This is why I tell people going from nothing to a couple training sessions a week is gonna be massively beneficial. And sleep
Sleep, food, and movement
Philip Pape 19:24
has nothing to do with whether you can get into those sessions in the gym, but sleep has other effects, and then whether you go to the gym and whether you move enough also affect your sleep. So sleep and movement and food all work together as like one combined dose, I'm gonna say it's like one big dose of your fitness lifestyle, right? If one of them is down for the count, okay, if your sleep was terrible last night, hey, the other two are still available to you. Don't make the excuse. Go after those, still eat well, still train, all right? And you're gonna be far better off in the long term from a consistency basis, which is the piece I want I kind of started this episode with is like not trying to be perfect, but doing your best to kind of keep these things fairly regular. Now, before we wrap up, I have that number related to sitting that I promised you earlier, and two specific ways to offset how bad sitting too much can be for your health. Okay, we'll talk about that in a second. But if this episode hits you in terms of maybe making you feel a little bit better about what actually moves the needle with sleep and the fact that you don't have to be perfect with this, that you can make it work. And I'm not even getting into all the little sleep hacks that people focus so much on, because there are really some simple things to start with, one of those being the regularity, and the other one being to have your other things in order, like training and movement. If someone else needs to hear this, just text it to them. Text it to a friend, him or her. That is a great way to support the show. Not only that, if you give me a review, five-star review, that can help as well, but just text this to a friend if you think they'll find it interesting. Okay, so here's here's a really cool number that comes from the research related to sleep. When people researchers cut people's sleep by about 78 minutes a night, which we talked about in the study earlier, they did not eat more, but they sat more. So I mentioned that earlier. The details are that they sat 17 extra minutes a day and close to 30 extra minutes a day for men and post-menopausal women. So to offset this, all we need to do are some very simple things. One is take two 10-minute walks after meals. Walking after meal is one of the best things you can do for your health, for your digestion, for your blood sugar, and for your steps. It's really one of the best times to actually do your walks. So a 10-minute walk after breakfast or lunch, a 10-minute walk after dinner. And then in other trials, when they looked at sedentary breaks, like taking a break while you're sitting a long time, five minutes of light walking every 30 minutes. And I've talked about as little as two, like even just getting up and walking around for a couple minutes can make a massive difference on your postmeal glucose, your blood pressure, your blood flow, your inflammation, your muscle protein synthesis. Like there's a lot of benefits to that that we're finding out. Kind of like anti-inflammatory, if you will, whereas sitting is inflammatory. And the older you are, it seems to have an even better impact. And that could simply be because older people are even more sedentary. So it's and it's not just standing up either. If you have a stand-up desk, that's great, but you have to be moving around and walking. So I would say 10-minute walk after meals, get up every 30 minutes for two to five minutes walk. That's it. All right. Until next time, keep using your wits, lifting those weights. And remember that sleep and movement and food are one combined dose. So when one of them is off, the other two can somewhat make up for it. I'm Philip Pape, and I'll talk to you next time here on the Wits and Weights podcast.
