When it comes to how we sleep, the internet is full of seemingly endless contradictory advice. Sleep on your back. Don’t sleep on your back. Sleep on your stomach. Definitely don’t sleep on your stomach. Sleep on your right side. No, your left side!
So, what’s actually the best sleep position? In a new episode of Popular Science’s Ask Us Anything podcast, we explore just that.
Ask Us Anything answers your most outlandish, mind-burning questions—from the everyday things you’ve always wondered to the bizarre things you never thought to ask. So, yes, there’s a reason cats love boxes and no, hot workout classes usually aren’t better. If you have a question for us, send us a note. Nothing is too silly or simple.
This episode is based on the Popular Science articles “The best sleep position, according to science” and “Can tracking make my sleep worse? The quiet torment of sleep tech.”
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Full Episode Transcript
Sarah Durn: Quick question, what position do you sleep in?
Person 1: I like to sleep on my side, usually cuddling a pillow or my partner.
Person 2: I sleep usually on my sides or laying down on my back, very rarely on my stomach. I like sleeping with a stuffy ’cause that helps me feel like I’m not alone in the room, ’cause that’s creepy.
Person 3: I sleep basically like a vampire. I’m flat on my back, my legs are straight, my arms are either straight by my sides or my hands are clasped together on my stomach. It’s pretty weird.
SD: Okay, but here’s the real question: Is one of us actually sleeping wrong?
Welcome to Ask Us Anything from the editors of Popular Science, where we answer your questions about our very weird world, from “Why do we need braces?” to “What would happen if Yellowstone’s super volcano blew up?” No question is too simple or surprising. I’m Sarah Durn, an editor at Popular Science.
Annie Colbert: And I’m editor-in-chief Annie Colbert, and I am also dealing with a head cold today.
SD: Oh, no. Here at PopSci, we’re always pondering quirky questions.
AC: And this week we’re wondering, what’s the best sleep position?
SD: Which feels like it should have a pretty simple answer, right?
AC: Absolutely. What, we’ve got three main options, back, side, stomach. Just pick a winner.
SD: Yeah, except the answer is a little trickier than just picking a single winning sleep position.
AC: Okay, but why?
SD: Because the position you sleep in can affect some surprisingly important things happening in your body overnight. How easily you breathe, how aligned your spine is, even how your blood circulates.
AC: Okay, so now I’m suddenly very aware of how I spend eight hours every night.
SD: Right? Me too. And there are all these things you hear.
Sleep on your back. Never sleep on your back. Sleep on your left side. Actually, sleep on your right side. Put a pillow here. Put a pillow there.
AC: So which one is true?
SD: Well, there is a best sleep position.
AC: Aha.
SD: But it might not be the same one for you as it is for me.
AC: Oh.
SD: I know. Because figuring out your best sleep position has less to do with declaring one position the universal winner and more to do with figuring out what your body needs while you’re asleep.
AC: Okay, now I want to know what mine is.
SD: And we’re going to figure that out.
AC: Mm. So by the end of the episode, I’m going to know whether I’m sleeping wrong?
SD: You might.
AC: Hmm. Okay. That is both exciting and slightly threatening. And I am also sure that I am 100 percent sleeping the incorrect way. I just know it.
SD: Yeah, somehow I feel like I am, too.
And we’ll also get into whether you can actually change the way you sleep. But first, we want to hear from you. What questions are keeping you up at night?
AC: If there’s something you’ve always wanted to know, submit your question by clicking the “Ask Us” link at popsci.com/ask.
SD: Send us your questions.
AC: Yes, send them, especially if they’re keeping you up at night.
SD: Especially.
AC: Yes. Coming up, what actually happens to your body when you sleep on your back, your side, or your stomach?
SD: And how to figure out which one your body likes best.
AC: That’s after this quick break
SD: Welcome back! Okay, Annie, I have a confession to make before we get into the science of how we’re supposed to sleep: I am an extremely picky sleeper.
AC: How picky are we talking?
SD: I have a whole pillow situation.
AC: Okay.
SD: I sleep on my side. I have a pillow between my legs, obviously a pillow under my head, and then I sleep with another pillow on top of my head.
AC: Wait, on top of your head?
SD: Yes, like, like fully covering my head.
AC: Covering your head?
SD: Yes. In college, my roommate Emma would sometimes come into our room and think I wasn’t home because she literally could not see me in my bed.
AC: Sarah, why are you sleeping with a pillow covering your head?
SD: Yeah. Honestly, I don’t know.
I mean, I picked it up when I studied abroad in New Delhi, India, and it was just really loud at night, and I somehow got in the habit of sleeping with, I think at one point it was actually two pillows over my head.
AC: Two pillows? That sounds both claustrophobic and hot.
SD: Yeah, it kind of is. And then I would also play rain sounds on my phone, and the sound would travel through the pillows in this really weird way where it was suddenly, like, all around me, and it was like my own little rain sound cocoon thing.
AC: All right. That sounds kind of nice, as a fan of ambient noise while I sleep.
SD: Oh. And yeah, apparently my brain decided, “Great, this is how we sleep forever now,” because years later I still do it without rain sounds. So how do you sleep?
AC: I have to admit that I’m a flopper, like side to back, back to side, side to stomach.
I’m just… I’m all over the place. I do usually fall asleep on my side, in part because I still use my pregnancy pillow despite my youngest child being almost three. But it’s like a full-body pillow, and it stays cool, and I love it, and I miss it dearly when I’m traveling.
SD: Yeah, maybe we all need pregnancy pillows.
AC: Yes, absolutely. Okay, so between the two of us, who is sleeping better?
SD: Yeah, well, it’s a little complicated, and it’s not always a competition, Annie.
AC: Mm, fine.
SD: But let’s start with the position that I feel like gets the worst reputation, sleeping on your back.
AC: Yes, it does. I feel like I’m always hearing that sleeping on your back is not great for you, but I think part of that is just because it looks a little creepy.
SD: Oh, yeah, it definitely can be. But the answer is a little more complicated on whether it’s good for you or not. For our original Popular Science story on the best sleep position, writer Laura Kiniry talked to Dr. John Saito for the story, a sleep specialist and representative for the American Academy of Sleep Medicine.
So Dr. Saito says that if you’re on your back with a supportive pillow, it can actually help keep your neck and spine in a nice neutral position.
AC: Okay. Justice for back sleepers. I don’t love it, but I will support it.
SD: Fair enough. Yeah, Dr. Saito also recommends if you like sleeping on your back, try putting a pillow underneath your knees that can help support the natural curve of your spine.
AC: Another pillow.
SD: I’m telling you, pillows are doing a lot of work in this episode.
AC: Yes. So back sleeping is good?
SD: It can be.
AC: But not always.
SD: Yeah. There are some pretty important exceptions. One is sleep apnea. When you’re on your back, your tongue might fall toward the back of your throat, which can narrow or block your airway. So bad.
So if you have sleep apnea or you tend to snore, a different position may help keep that airway more open.
AC: Okay. So be sure you can breathe. Great advice always.
SD: Yeah. Very good advice. Dr. Saito actually has a really easy way to remember what you should be thinking about when you choose a sleep position, your ABCs.
AC: Airway…
SD: Yes, airway, breathing, circulation.
AC: Okay. I can remember that.
SD: But there is one group where the advice about back sleeping is much more straightforward, babies. Babies should be placed on their backs to sleep because it reduces the risk of sudden Infant Death Syndrome, or SIDS.
AC: Yes. If you have an infant or are ever tasked with putting a baby to bed, please take a moment to brush up on the American Academy of Pediatrics’ latest recommendations.
I am very glad that my kids are nearing the end of that stage.
SD: Yeah. It’s one of those examples where sleep position advice can be completely different depending on who you’re talking about because then you get to adults and the advice changes dramatically.
AC: And we haven’t even gotten to side sleeping yet.
SD: Which is where things get even weirder because it might actually matter which side you choose to sleep on.
AC: Oh, yes. I do know a little bit about this from pregnancy.
SD: Oh, interesting. Dr. Saito says the right side might be better for blood flow, but then the left side might have an interesting benefit for your brain.
AC: All right. So tell me, why does my brain care which side I sleep on?
SD: So while you sleep, your brain has this waste clearance system called the glymphatic system. Your brain cells are working all day, and that activity produces metabolic waste, basically leftover molecules and byproducts from the normal chemical processes happening inside your brain.
AC: So my brain is taking out its own trash while I sleep?
SD: Exactly. While you sleep, fluid moves through brain tissue and helps carry away some of those byproducts. But according to Dr. Saito, research suggests that sleeping on your left side may help that process.
AC: I appreciate that my brain is cleaning while I do absolutely nothing.
SD: It’s very considerate, right?
AC: Yes.
SD: And which side you choose to sleep on can matter for other reasons, too. Johns Hopkins’s sleep neurologist Rachel Salas says that if you deal with heartburn or acid reflux, sleeping on your right side can make it worse, while sleeping on your left may help.
AC: All right, so left side is winning?
SD: Yeah, but I wouldn’t order the trophy, you know, just yet.
For adults, lying on your right side might be better for your circulation, says Dr. Saito, as well as lowering the pressure on your heart. This is because your mediastinum, a flexible compartment located between the lungs, helps hold your heart in place.
AC: Ah, the right side’s back in it.
SD: And even how you sleep on your side can make a difference.
AC: Oh, boy.
SD: Don’t worry, we’re not ruling out pregnancy pillow just yet. But if you’re relatively straight, side sleeping can help keep your spine aligned.
If you curl up a little, that can sometimes help relieve lower back pain.
But if you curl up too tightly, you can compress your chest and diaphragm, which can make it harder to breathe.
And then there’s another part of side sleeping that is particularly relevant to both you and me: what you do with your legs.
AC: Pillow!
SD: Pillow! Dr. Saito recommends that side sleepers try putting a pillow between their knees, because it can help keep your head, neck, hips, and spine better aligned.
AC: So your elaborate pillow system is scientifically validated.
SD: At least, you know, one pillow in the system is. The two-pillow rain cocoon has yet to be evaluated.
AC: We’ll fund the study.
SD: And then there are stomach sleepers.
AC: I feel like stomach sleepers are the wild card here.
SD: They kind of are. Sleeping on your stomach can help keep your airway open, which is good, but it can also put more strain on your neck and spine.
So, win/lose, and Dr. Saito has a pillow trick for them too. A thin pillow underneath the hips can help.
AC: There truly is a pillow for every occasion.
SD: There really is.
AC: So is there a winner when it comes to sleep position?
SD: Side sleeping definitely has some advantages.
AC: Okay.
SD: But at the end of the day, sleep position isn’t one size fits all.
You’re looking for the position that lets you breathe easily, keeps your body supported, and this is important, is actually comfortable enough that you can sleep.
AC: Which feels obvious when you say it like that.
SD: Right? And if you don’t have pain or breathing problems and are sleeping comfortably, there isn’t really any reason to force yourself into some supposedly “perfect” sleep position.
Plus, we don’t stay perfectly still when we sleep anyway, as you know. Dr. Saito points out that nobody really sleeps like a log. We naturally move around during the night.
AC: Yes, floppers vindicated.
SD: Both of our sleep positions are backed by some real science. Huzzah.
AC: Yes. Thank goodness, because trying to control what position I’m in while unconscious feels like a very impossible task.
SD: And that actually brings us to the other part of sleep I want to talk about because we’ve spent this whole episode asking: Am I sleeping the right way? And now there are watches and rings and apps that will give you a score every morning telling you exactly how well or how badly you supposedly slept.
AC: Which sounds useful.
SD: It can be, but what happens when you start trying to get the perfect sleep score?
AC: Oh no.
SD: Yeah. Some people become so fixated on optimizing their sleep that the anxiety around sleeping starts making their sleep worse.
AC: So you can lose sleep worrying about whether you’re getting the right sleep?
SD: Exactly.
AC: That feels extremely human.
SD: It really does. So after the break, should you actually try a sleep tracker? What does a sleep score really mean? And when is it better to just stop looking at the data and go to bed?
AC: I suddenly feel very nervous about checking my phone tomorrow morning.
SD: Don’t check it.
We’ll be right back.
Welcome back. Okay, Annie, before the break we established that there’s no perfect way to position your body while you sleep.
AC: Right. Although I did learn that I apparently need more pillows.
SD: I mean, if you ask me, more pillows are always the answer. But there’s another way people are trying to perfect their sleep now: tracking it.
AC: Which I totally understand. You wake up, you look at your watch or your ring or your phone and immediately wanna know, how’d I do?
SD: Exactly. And more than a third of Americans have used some kind of electronic sleep tracker. But there’s a weird problem here. The more you obsess over getting perfect sleep, the harder it can actually be to sleep.
AC: Which seems unfair.
SD: I know. It really does. And there’s actually a name for this, orthosomnia.
Researchers first identified it in 2017 after noticing patients coming in anxious about what their sleep trackers were telling them, and that anxiety can become this vicious cycle. You see a bad sleep score, so the next night you get into bed thinking, “Okay, I have to sleep well tonight.”
AC: And then you’re lying there thinking, “Why am I still awake? I need eight hours.”
SD: Exactly, and now you’re stressed, which makes it even harder to fall asleep.
And here’s another reason not to panic over your sleep score: These devices are far from perfect. They’re pretty good at estimating things like when you’re asleep, when you’re awake, and your heart rate, but experts say some of those more detailed measurements, like exactly how much time you spend in different sleep stages, they aren’t nearly as reliable.
AC: So if my phone tells me I got terrible sleep, but I wake up feeling great?
SD: Trust yourself. Or at least don’t let a number convince you that you should feel terrible.
AC: Hmm.
SD: Sleep trackers can still be useful for spotting patterns over time, but experts say they should be used alongside the most old-fashioned sleep tracker of all: How do you actually feel?
AC: I like that sleep tracker, and it’s free.
SD: Completely free. As one of the experts in our story put it, sleep should be restful, not a competition.
AC: That is good advice. Stop trying to win at sleep.
SD: Exactly. Just go to sleep, preferably surrounded by at least two, three, four, five, six pillows.
AC: Naturally.
And that’s it for this episode. But don’t worry, we’ve got more episodes of Ask Us Anything live in our feed right now. Follow or subscribe to Ask Us Anything by Popular Science wherever you enjoy your podcasts. And if you like our show, leave a rating and a review.
SD: We care what you think. Our producer is Alan Haburchak, and this week’s episode was based on stories written for Popular Science by Julia Daye and Laura Kiniry.
AC: Thank you team, thank you pillows, and thank you everyone for listening.
SD: And one more time, if you want something you’ve always wondered about explained on a future episode, go to popsci.com/ask and click the “Ask Us” link.
AC: Keep the questions coming.
SD: Until next time, may your spine stay aligned.
AC: Your sleep score remain blissfully ignored.
SD: And your bed have exactly as many pillows as you need.
AC: Even if one of them is on your head.
SD: Especially if one of them is on your head.
AC: Good night.
SD: Sleep well.