RHR: How Sleep Temperature Improves Your Rest, with Tara Youngblood

Getting enough sleep is one of the most important things we can do for our health, and optimizing your sleep temperature can have a major impact on the quality of your rest. In this episode of Revolution Health Radio, I talk with Tara Youngblood about the science of temperature regulation as a means of improving your sleep.

In this episode, we discuss:

• How temperature regulation improves sleep
• What’s wrong with the way we’re sleeping?
• The benefits of sleeping colder
• Optimal sleep temperature
• How sleep temperature devices work

Show notes:

Hey, everyone, it’s Chris Kresser. Welcome to another episode of Revolution Health Radio. This week I’m very happy to welcome Tara Youngblood. She is the founder of ChiliPad, which is a device that has had one of the biggest impacts of anything that I’ve ever tried for improving my sleep. And as you know, I’m all about improving my sleep. I think getting good sleep is one of the most important things we can do to optimize our health and prevent and reverse disease. And this is, of all of the things I’ve tried, definitely one of the most potent interventions. It’s so potent that I actually became an investor in the company and really believe in what they’re doing.

So Tara’s spent over 10,000 hours studying the science of sleep since launching this company. And she has applied her analytical skills from her physics and engineering background to shape the future of sleep-driven health by making sleep easy and drug free. So we’re going to talk about the science of temperature regulation as a means of improving sleep, so there’s a little hint there about what this device does, among many other topics. And I hope you get a lot out of the show. So let’s dive in.

Chris Kresser:  Tara, thank you so much for joining us. Pleasure to have you on the show.

Tara Youngblood:  Yeah, it’s great to be here.

How Temperature Regulation Improves Sleep

Chris Kresser:  So let’s talk a little bit about your story. How did you get interested in temperature regulation as a means of improving sleep? Maybe not the first thing that people think about when they think about how to improve their sleep. So how did that come about for you?

Tara Youngblood:  So, Todd and I are in business together, my husband, and we have brought over a hundred different products to market. And right about the time that Tempur-Pedic and Select Comfort were talking about pressure and that was really a big thing, we thought, “Well, we should be able to adjust temperature.” And we sort of started it with a comfort thing. Todd has always slept really hot; I like to have a warmer bed. And we usually ended up with this wall of pillows in between us to separate our temperature so we could be comfortable.

Chris Kresser:  Oh, yeah, I’m familiar with that.

Tara Youngblood:  Yes. So, and his uncle invented the waterbed, so we had sort of played around with waterbeds a lot, obviously. So I think it was a natural evolution to see what we could do to create these dual-zone temperatures. So it started, really, with comfort, and it really, by customer feedback, it started coming back of like, “This is changing my life.” People started tracking it. And, like, “Wow, my resting heart rate is dropping. I’m getting more deep sleep.” And as these trackers came online and really started looking at what was happening with this temperature, it’s kind of opened up this whole new window of, like, “Wow, this is really changing sleep, not just making people more comfortable. People weren’t waking up as much at night, and it was really making a difference.”

So I really, my background is in physics. I was a physical trainer, the sports trainer for Todd’s football team. So kind of a weird mix of interests there. And so I was like, I really need to figure this out. There hasn’t been a lot of research on what temperature has done in sleep because it’s hard to manipulate the temperature for people. So when you start looking around, there are a few. And the ones that are out there are an amazing result. So one of the leading researchers right now is Saper out of Harvard and he’s really coined the term “sleep switch.” And temperature is one of those things that activate those neurons and helps put you to sleep and helps wake you up.

Chris Kresser:  Yeah, yeah, absolutely. And it kind of makes sense from an evolutionary perspective, which of course we talk a lot about on this show. We evolved in an environment where we’re typically sleeping on the cold ground or earth, not a really warm surface that was reflecting our heat back.

Tara Youngblood:  Yeah, so, part of the problem is our wonderful comfort mattresses come back and they’ve got all this foam and man-made materials in it. But what they do is they reflect our heat back at us. And our circadian rhythm does follow that outside weather pattern as you described, where once the sun goes down, it tends to be cooler. And once the sun starts to come up it tends to warm up. And our own body rhythm matches that. But these man-made materials are basically counteracting that and heating us up when we really want to be coolest.

Chris Kresser:  I always notice before I even knew a lot about this stuff that one of the biggest differences between a higher-quality mattress and a poorer-quality mattress was its ability to absorb heat and not reflect it back. Like, when I would travel and if I was in a country where maybe the beds weren’t as nice, I would always wake up super hot and it would really interfere with my sleep. And so I’ve been aware of this for some time, even before I became an investor in Kryo and ChiliPad and started using it myself. It’s something that has been used to kind of differentiate between the quality of mattresses.

Tara Youngblood:  Yeah, that breathability in a mattress, that ability to move the air and get that circulation around you, really changes depending what material is in that bed.

Chris Kresser:  So what is the research focusing on now? You mentioned that guy at Harvard. Are they looking at like how temperature affects different sleep cycles, REM and deep sleep? And sleep duration and quality and all of that? How are they approaching it?

Tara Youngblood:  So, most of his studies right now that are in mice, and they’re looking at mice being able to actually go into non-shivering thermogenesis, which is really pretty chilly in mice. It’s almost that borderline hibernation state. When you’re in deep sleep, you actually don’t register temperature in the sense of comfort or whether you’re going to wake up.

In REM sleep and light sleep you do, so that’s when if you are too hot, you’ll wake up in those. If you get too cold as well, you can wake up in those. So there’s a delicate balance, at least for people in managing that. And a lot of our patent-pending IP that we have is around that, manipulating of those sleep cycles of really optimizing for deep sleep. Because that’s really where the cold makes a big impact for sleep.

What’s Wrong with the Way We’re Sleeping?

Chris Kresser:  Right. So we’ll come back to that. I have some questions and observations from my own use that I want to run by you. But let’s back up a little bit and talk in a more general sense about what’s wrong with how we’re sleeping in the modern world. And temperature is obviously a big part of that.

Tara Youngblood:  Well, some of it starts with the fact that we’re not outside. We’re not in a variation of temperature throughout the day. We’re in these temperature-controlled environments for most of our time. So there’s no natural dip. There’s no signaling to the hypothalamus, to those ,neurons we were talking about of saying, “Okay now it’s time to go to sleep.” We’re maintaining lights.

All those things around us are sort of giving us an artificial sunrise or sunset that is way later than we would normally expect it to be. So all the natural triggers are not happening. And so, by keeping that consistency during the day, it’s really kind of messed us up to be able to use temperature naturally as it would cool off during the day to trigger us to fall asleep.

Chris Kresser:  Yeah, it’s just another unintended consequence of the modern world, right. And there are obviously some benefits to the way we’re living now versus how we did in our natural environment. But I’m always struck by these unintended consequences. The things we may not have predicted would happen from the improvements that we’ve made in our quality of life.

Tara Youngblood:  Yeah. A lot of the people that suffer from insomnia, 98 percent of the time their circadian rhythm, that drop in core body temperature, is not happening when it should at night. And that’s one of the reasons why they have such a hard time falling asleep.

Chris Kresser:  And why is cooling the temperature of the bed versus just cooling the ambient temperature in the room important?

Tara Youngblood:  So once you get in that bed, most of us anyway like to pull up the covers and we insulate ourselves. We run approximately 98 degrees, give or take on the person, and you have all those foams and all those things that make us comfortable. And so we heat up this little cocoon, our little cave to be much hotter even than our body temperature. We’re naturally, we’re engines. We’re creating heat in that environment. And so whatever temperature you set your room at night helps us some. But all of that heat generally has to vent through your head.

So a lot of people end up flipping the pillows so they feel like their head’s hot. But most of that is just, that’s the only place your body can vent that heat. So the way the ChiliPad works, and OOLER as well, is by running these coils of water consistently at whatever temperature you set underneath you. You’re basically creating at least thermal neutral to cold. So even if it’s just neutral and you’re not able to add any heat to the equation and you at least keep it from heating up, for some people that’s enough. That’s why they set it warm and it’s okay. But it’s still cooler than their body temperature.

But for a lot of us, we’re used to that ambient temperature. So if 68, 70, whatever you’re setting a room at, we really want that to maintain that same. Because our body’s gotten used to it. And then it’ll actually do its core body temperature drop of the two degrees it would normally do.

Chris Kresser:  Yeah, I’m familiar with this from surfing. It’s interesting, like go to a place like Costa Rica where the water’s 80 degrees, which is quite warm, it feels quite warm, but I still get the benefits of cold, because 80 degrees is cooler than 98 degrees. My body temperature and being in the 80 degree water for a significant period of time still has that impact on my body.

Tara Youngblood:  Yeah, we do see, we’re looking at metabolism in some of the studies we’re starting. And the early results really show that there is some metabolism boost that you’re getting. You’re at least getting part of that recovery of just circulation and metabolism that you would similar to being in a little bit colder pool. That cold temperature does seem to be helping your metabolism.

Chris Kresser:  Yeah, that was actually going to be my next question. Because I was thinking there must be some metabolic benefit there. Because as you were talking about the drop in body temperature, I was thinking about the research on cold thermogenesis and metabolic benefit. So it’s good to know that there’s some work being done there so far. Because that just makes sense to me that that would happen, and given my experience as well just in swimming and surfing in even warm water, and how much that promotes weight loss.

When I’m surfing a lot, I have to eat massive amounts of calories just to keep the weight on. And I know from a lot of people who are swimming and surfing and able to lose quite a bit of weight that way. So what are some of the other therapeutic benefits of sleeping colder, at least not warm? What you’re saying, you get the benefits, not just from cold, but even just maintaining your normal body temperature instead of going up.

High-quality sleep is a must-have for good health, and optimizing your sleep temperature can go a long way toward ensuring you get enough shut-eye. Find out how temperature impacts your sleep in this episode of RHR. #healthylifestyle #wellness #chriskresser

The Benefits of Sleeping Colder

Tara Youngblood:  So one of the sort of easiest things to look at is, temperature is one of those things that gets crazy pretty quickly. That’s one of the reasons you run a fever when you get a cold or aren’t feeling well.

So temperature is a symptom of trouble for lots of different diseases or illnesses. So one of the earliest benefits is just helping to maintain thermal neutral while someone’s going through that. So we have cancer patients that are going through chemotherapy or even post-chemotherapy, because it messes with their thermostat so badly. We have a study ongoing with menopausal women. Early results are that if you maintain that coolness throughout the night, they stay asleep. They actually have less hot flashes during the day as well.

Diabetes, MS, a lot of those diseases people struggle with maintaining their temperature. But for the average user, they’re going to see, if you’re tracking it, your HRV, that heart rate variability, your resting heart rate, those are all really easy to see. Those sort of readiness scores in the sense of how well you feel, how well you recover, how you feel like you can work out the next day. How you feel like you’re going to have a cognitive load or memory load if you’re studying or whatever. All those measurements is improvement across the board in all of them.

Chris Kresser:  How about the benefit of saving your marriage? I assume when I read some of the reviews on the ChiliPad, it’s funny to read some of them. Because you get a lot of people say, “Oh, my gosh,” and this was true for, not for us and to the point of our marriage being in peril, but it’s pretty common in a couple, one person will sleep hot and one person will sleep cold. And there’s no really easy way to deal with that.

Tara Youngblood:  No, there isn’t. Actually, my favorite review at the moment was a woman that defended her ChiliPad to the point where she would trade her husband before the ChiliPad. So I think that helps.

Chris Kresser:  That’s a good testimonial to have.

Tara Youngblood:  In the odd category. You don’t advocate keeping the ChiliPad over husbands. We’re not saying that.

Chris Kresser:  Yeah, yeah.

Tara Youngblood:  But it’s definitely funny.

Chris Kresser:  Yeah, right. There’s no need to choose. Just get two.

Tara Youngblood:  Exactly.

Chris Kresser:  Right. Or one that covers both sides of the bed. Yeah, I mean it’s interesting. Like for me, my wife’s temperature doesn’t seem to be as much of an issue for her sleeping, but for me it definitely is. And so, and I tend to sleep hot. Actually, I have a mixed kind of pattern. Like I definitely go to bed hot and used to tend to wake up in the earlier part of the night feeling hot. And then I would wake up, and then I would like throw off the covers.

So I just had the sheet on. Or sometimes not even the sheet. And then I’d wake up at four in the morning really cold. And it was just really challenging because whatever, going to bed, whatever temperature was right when I went to bed was not right later on in the night. And we can talk a little bit more about the difference between the ChiliPad and the OOLER, and this will sort of point to that. But I even found it difficult to use the first iteration of the ChiliPad because the temperature that was perfect for me going to bed was not perfect for me at three or four in the morning. It was too cold. And so does each person have an optimal sleep temperature? And is it the case that that could change throughout the night for different people?

Optimal Sleep Temperature

Tara Youngblood:  So, most people do change throughout the night. That part is pretty universal. And that’s part of that, as you start to go to sleep, your core body temperature wants to drop. And about 4:00 in the morning, depending on when you go to sleep and when you wake up, that core body temperature is about two degrees colder than it started at. So if you started at 98, you’re about 96.

And again, there is variation on that depending on the person. But then it really wants to start warming up. It wants to get closer to that morning sunrise warmth. It’s expecting that. So if it’s still really cold, that’s where you’re going to wake up from the cold usually. Because you’re no longer in deep sleep. Most of your deep sleep happens in the beginning of the night. The first few cycles are very heavy on deep sleep, so that’s when it feels really good to be cold then.

But then in the morning, your cycles tend to be heavier on REM sleep and you are feeling that temperature, and that’s where it’s going to want to wake you up if it’s too cold. And some of that really changes throughout life. Women, especially, between pregnancy, menopause, even monthly hormonal cycles will change and vary. And different women will have different results on that. Men will have sort of, seem to have more of a profile. Whatever they start at, they tend to stay that way until they get to a much older age where they’re having different sleep parameters. And some of that comes from everybody loses deep sleep as they age, typically.

A 20-year-old may be getting sort of 20 to 30 percent and an 80-year-old may get none. So some of that also goes back to that temperature realization of if you’re not getting any deep sleep, if you’re not looking for that coldness because of your age, you may feel cold and you may wake up. So you may want a warm ChiliPad to keep you warm.

How Sleep Temperature Devices Work

Chris Kresser:  Yeah, that makes sense. So let’s talk a little bit about the devices, the ChiliPad and then the OOLER. And my understanding, the OOLER, which I’ve been trying out recently, and thank you for sending that unit to me to try, because it really made a big difference for my ability to use it successfully because I am one of those people who experienced that temperature shift maybe even more significantly than average. And the ability to schedule has been a game changer for me. So tell us a little bit about the OOLER.

Tara Youngblood:  Yeah, so the OOLER for me was a really big difference. To Todd obviously, he sleeps hot in a way that he could pretty much set it and if he has it all night at the same temperature, it doesn’t seem to bother him the same way. I really want to still go into bed into a relatively warm bed, somewhere south of body temperature, but still warmer than room temperature. I want to snuggle in, but I still need it cold or I’ll wake up in the middle of the night. And I do love right after 4:00 being just a little bit warmer. The other feature of OOLER that I really like is the warm awake.

Chris Kresser:  Yes.

Tara Youngblood:  It’s a patent-pending feature that is amazing, and again it mimics that circadian rhythm. But waking up that way, no matter where you are in your sleep cycle, it just naturally, you wake up and you’re like, “Oh, it’s time to wake up.” And again, it’s just a little bit of that bump in your core body temperature. There’s enough of a variation in temperature that it causes that switch, that sleep switch to turn back to awake.

Chris Kresser:  So maybe we should back up a little bit here and just describe the device and how it works. I realize we just dove right into the science and the finer tips and tricks for how to use it. But I think maybe even people who are listening might not know exactly what we’re talking about. So if you could just give a kind of basic overview of what it is and how it works and what the features are, that would be awesome.

Tara Youngblood:  Yeah. So the ChiliPad and OOLER, they both start with water. So water’s 25 times more effective at cooling than air. So we do get, “Well, what about a fan? What about sort of that air conditioning feel?” You’re not going to put your hand in boiling water, but you can kind of put your hand in an oven is how we look at it. So we’re looking at taking away that thermal load and really being able to affect that core body temperature.

So we’re able to change off of ambient temperature about 12 degrees, sometimes more, depending on the temperature. So what happens is we have a mattress pad that goes on, you can have it go on one side of the bed. Or you can have it two zones for both sides of the bed and then you have two control units. But we basically have water circulating through the bed. So there’s, neither unit has EMFs inside the bed at all. So it’s just water tubes circulating water, kind of like a radiator does in your car. But for you, the human body. So it actively maintains the temperature that you set it at.

ChiliPad uses a remote; that’s the legacy product. You set your remote similar to your standard thermostat in your house where you would set it and forget it, and it’s all one temperature until such time as you move the dial. ChiliPad kind of works like that as you described. It’s one temperature and it runs that way all night. For some people, in fact, it’s surprising to me, they are very excited to just have the remote and it’s simple and easy.

OOLER, on the other hand, is more like the nest, where you’re able to program it. You’re able to utilize the energy and temperature, sort of scheduling to really match your rhythm. It’s a little more interactive with the app. You’re able to adjust the fan speed. ChiliPad has one fan speed. It runs on a TEC chip with a heat sync. So there is a small amount of noise. But the OOLER allows you to have three different speeds on that fan. It also has a UV lamp in it for cleaning the water and just some of those little upgrades. Most of it is customer feedback that we’ve gotten over the years, that we’ve sort of put that into the OOLER unit.

Chris Kresser:  Yeah, I really appreciated those upgrades. The unit is definitely, not only quieter, the sound is more like white noise to me, to my ear.

Tara Youngblood:  Yeah.

Chris Kresser:  It’s not as intrusive,, and the scheduling, I’ll describe how it works for people who are listening. Because it was such a big game-changer for me. Basically, you can set, connect it to the app, and connect your phone to the unit. And then you can set a time for it start cooling. That was a big improvement. Because with the ChiliPad, you had to remember to turn it on before bed.

So this now, the machine will turn on on its own and start cooling before I even go up to my bedroom so that it’s ready. And then if I set it at, let’s say 64, which is the temperature that I’m using to go to sleep, then I can set another time point for however far ahead of when I’m going to bed to start increasing the temperature. So I think I’ve chosen two more time points between when I go to bed and when I have the warm wake feature happening. Maybe one at like three in the morning and one at four in the morning. And I’ve just set it a little bit warmer.

So I think it goes up to 65 at three and then, like, 66 or 67 at four. And then I have the warm wake at, like, 70 or something like that. And that, I’ve been tweaking and fiddling with it a little bit. I’m not sure I totally have it yet, but that has, I’m very close to being there. Because that seems to be really great for me. And the app, I mean I can just keep customizing and tweaking it if I need to, which is really cool. And then I think you mentioned this briefly, but there’s another mat coming with the OOLER, is that right?

Tara Youngblood:  Yeah. So the mat’s evolved in an incremental way where we have a little different material on it, with a waterproof layer on the bottom. We’ve not really had leaks, but it’s just one of those things that people have expressed concerns about and would like to have. Some people have a waterproof layer on there already.

So this sort of combines that in there. It also has some far-infrared material in it, so you get a little bit of that far infrared healing happening at the same time. Really our push is to make sleep the future of health, and by putting that far infrared there, it’s just a little extra burst of muscle recovery and other recovery kind of help push that forward.

Chris Kresser:  Cool. And I know that as far as I know, you’re the only company that’s doing this right now. Are there any other, anyone else out there trying to attack this temperature regulation space?

Tara Youngblood:  Yeah, so, we have pending IP and some IPA that covers a fair amount of this space. There is a new mattress coming out from Eight Sleep. It doesn’t have the same degree of temperature efficacy, and that’s one of the things that we continue to push with ChiliPad is being able to manage that thermal load in such a way that we can affect core body temperature. And so it really stays more in that, a little bit more comfortable category of there’s some temperature regulation. But it’s not managed to really match thermal load.

And that’s really what makes the big difference for that deep sleep number. So we’re seeing with ChiliPad users and now OOLER users that deep sleep number is able to double or, like, in the case of my father, who’s 80, he would normally not be getting any deep sleep, or very little. And he’s able to still get that 20 percent number. So he’s a guy with arthritis and some other issues, and what it does for pain and recovery for him is an amazing difference for him to actually get deep sleep. Which is really unheard of at his age.

Chris Kresser:  Yeah, I mean, that’s worth it alone. It’s incredible. I have an Oura ring and I track my sleep. And I’ve done lots and lots of different sleep interventions over the years. And deep sleep is my biggest challenge and I’ve been able to probably double it fairly consistently, especially now that I have the scheduling and I’ve been able to kind of work out the rhythm.

And, I mean, that is just, it’s hard to overstate the value of that, because so much happens in deep sleep that we need for health, from tissue regeneration and repair to resolution of inflammation to gut healing. The list goes on and on. So I think it’s pretty amazing what you guys have done. I know, I mean, everyone that I’ve turned on to this ChiliPad and now the OOLER has been, had a phenomenal experience with it. It’s been pretty transformative. So thanks to both you and Todd for doing this important work in getting this out there.

Tara Youngblood:  Yeah, well, we do it really for the testimonials. We get calls and emails and letters regularly from people where it’s really changed their life. As I said earlier, we didn’t go into this thinking it would be as transformative as it is. As an intervention, you pretty much set it up and maybe you tweak your schedule or you set your temperature. But in the scheme of things, there’s no willpower, there’s no remembering to take it, there’s no side effects.

When we do studies, it’s almost humorous when we lay out the parameters of, like, there’s no side effects. This is not something that you have to do. So when we do the, there’s NIBR guidelines you have to lay out, like there’s no side effects for this. There’s no really difficult things. Honestly, we pair with Oura for a lot of our studies. And the tricky part is setting up their rings and getting them started. But once people sleep on it, we have a satisfaction guarantee. But we get so few back. And people often call it being addicted to it. They can’t sleep without it.

Chris Kresser:  I know, it does make travel kind of a bummer.

Tara Youngblood:  I know. Then the next evolution will have to include a travel one because we get that all the time.

Chris Kresser:  It’s true.

Tara Youngblood:  That’s the trickiest part. But it does seem to change your sleep habits. So a lot of people that have slept on it regularly still get some benefit when they travel, because their sleep is just more consistent.

Chris Kresser:  Yeah, yeah. I think that’s true. And when you’re able to bank up good deep sleep for a while in a row when you’re at home, then you’ll be more resilient and able to withstand a few nights of less-than-ideal sleep too when you’re traveling.

Tara Youngblood:  Yeah. And as you mentioned that the long-term health effects, I think the studies continue to come out on deep sleep being attached to Alzheimer’s and memory loss and autoimmune and just stress recovery. So to me the impact of being able to do something simple like this is, it’s really heartwarming when we get that kind of feedback.

Chris Kresser:  Great. Well, Tara, thank you so much for joining me on the show. And where can people learn more about the OOLER and pick one up if they want to do that?

Tara Youngblood:  Yeah, so we are in the B8ta stores. There’s some of those around the country if you want to touch and feel it. But the easiest way is probably just to go to our website. And that’s ChiliTechnology.com.

Chris Kresser:  Great, well, thanks again for joining us on the show and keep up the great work.

Tara Youngblood:  Great, thank you for having me. It’s been great being here.

Chris Kresser:  Okay, everybody, thanks for listening. Send in your questions to chriskresser.com/podcastquestion, and we’ll talk to you next time.

Do you sleep hot or cold? Have you considered using tech to optimize your sleeping temperature? Comment below and let me know.