The Power of Breath in the Sauna: How to Breathe for Better Sessions

Come back to your breath. What an invitation.

It seems simple enough. Air in, carrying oxygen, job done! But breathing is a whole physiological phenomenon of wow, more than oxygen in. Understanding how it works is the way to get the most from your breath, in the sauna and everywhere else

So let's get curious about how to breathe in a sauna.

The Carbon Dioxide Plot Twist

We have two entry points for getting air into the body, the nose and the mouth. It might seem logical that more air means more oxygen. So open the mouth, fill the lungs, get as much in as we can. Surely more is better.

Not quite. There's a fine balance to breathing, and that balance isn't really controlled by oxygen at all. It's controlled by carbon dioxide (CO₂).

Most people think of CO₂ as a waste gas. We breathe it out, so we assume the goal is to get rid of it. But it's what we retain, what stays in the blood, that lets us function the way we do. CO₂ is what allows oxygen to leave your blood and reach your muscles and your brain (this is the Bohr effect, and it's anything but boring). It keeps your airways and blood vessels relaxed and open. And your brain keeps a very close eye on it.

So much of this comes down to volume, the sheer amount of air you move in and out. Sensors in your brainstem and major arteries are constantly reading the CO₂ in your blood and adjusting your breathing to keep it in a narrow range. Breathe big and fast and you blow off more CO₂ than you need. This means your blood vessels narrow, including those to your brain, your airways tighten, and your nerves get a little more jumpy [Laffey 2002]. That's the light-headed, tingly, racing heart, can't-get-a-full-breath feeling, and it feels a lot like stress. The well-meaning advice to "take a big breath" can work against us if we don't consider the physiology.

The big breath belongs to stress. When a threat shows up, breathing gets faster and bigger to get us ready to fight or flee. That's ideal if a big hairy mammoth is chasing you a few thousand years ago. You'd flee (hopefully not fight), find a rock to hide behind, and once you were safe your breathing would settle and your CO₂ would come back up.

Fast forward to life now and we have mammoth-sized stress with no rock to hide behind. The stress doesn't switch off, so the big breathing doesn't either, and the body adapts to running on less CO₂. In one Australian study, people with asthma averaged CO₂ of 35, compared with 41 in people without asthma [Bowler 1998]. The stress keeps the breathing big, and the feelings of big breathing keep the stress going. We've adapted to cope, not to thrive.

Studies show that four weeks of breathing training focused on gently raising CO₂ levels, guided by a CO₂ monitor, is linked with a significant drop in panic symptom severity in people with panic disorder [Meuret 2008]. Why? Over-breathing lowers CO₂, and low CO₂ feeds the physical sensations of panic. How? By learning to breathe a little less, not a little more.

We Were Built to Breathe Through the Nose

Ever heard the breathing instruction "in through your nose, out through your mouth"? Where did that come from? It didn't come from your physiology.

We were designed to breathe through the nose, in and out, all the time. The mouth can be called on to help in times of trouble, but it was never meant to be a regular thing.

Somewhere across the centuries that drifted. The way we live changed: chronic stress, diet, sitting all day! We've adapted, and a lot of those adaptations haven't been in our favour in the long term.

We breathe around twenty thousand times a day, so any habit runs deep, and these days many of us mouth breathe without ever noticing. We lose the slow, warm, filtered, balanced breath the nose was built to give us.

And the nose gives back. Studies show that breathing only through the nose for five minutes at rest is linked with lower diastolic blood pressure and a greater rest and digest (parasympathetic) influence on heart rate, compared with breathing only through the mouth [Watso 2023].

Your sinuses produce nitric oxide in high concentrations [Lundberg 1995], and breathing through your nose brings that air in with every breath. Nitric oxide helps open the airways and blood vessels. It sounds counterintuitive, but in my clinical experience, a stuffy nose will often clear the more you gently breathe through it.

For some people, nose breathing isn't possible right now. It may be  temporary, a cold or some congestion, or something being looked into, like a deviated septum. If that's you, it's okay. Come back to the same two ideas: keep it easy, and manage the volume. Breathe gently and quietly through the mouth in an even, regular rhythm rather than big, forceful gulps. Where you can, bring a little awareness to the nose, because gently using it is often what helps clear it in the first place.

Your Diaphragm and the Volume Dial

When you breathe through your nose, the air has a smaller space to travel through, so you draw it in a little more deliberately. That gentle resistance calls your diaphragm into play, your main breathing muscle and the one we are built to use.

The nose does a second job here too. That same narrow path also keeps your volume in check, so you take in what you need and no more. 

Breathe through your mouth and you tend to breathe high in the chest, fast and shallow, leaning on muscles that were never really designed for the job. Smaller muscles around the neck and upper chest get recruited to help out, and when they're working overtime, that can feed into neck tension and discomfort. It's not that you're doing anything wrong, it's just not the setup that serves you best. Breathe through your nose and the body naturally organises itself around the diaphragm. One simple change, and a whole chain of things falls back into place.

Deep Isn't the Same as Big

A quick word on deep breathing, because depth and volume are not the same thing.

We fill our lungs well by using the diaphragm, so the breath expands your lower ribs a full 360 degrees: front, back and sides. That is the depth and breadth you're after. Filling your lungs shouldn't feel like a gulp, more like a sip. And despite what "fill your lungs" suggests, the breath lives low, down around your lower ribs where the base of the lungs sits and your diaphragm does its work.

We're also often told to breathe deep into the belly. My understanding is that "deep" caught on because it was better than shallow chest breathing. As it's been taught in different forms, the line between how we're built to breathe and using the breath to create a particular state has blurred.

Breathing into the belly can create a different experience, but it doesn't use your diaphragm the way it's designed to, with that full 360-degree rib expansion. Combine it with big mouth breaths and it can shift you away from rest and digest (parasympathetic) and towards a more stressed state. That's okay if it's your intention, stressing the system on your own terms. It's not okay if you think that's how you're meant to breathe all the time.

Easy Breathing

Always easy.

We're never chasing the feeling of not having enough air. As you bring more awareness to your breathing, it should always feel comfortable. Easy in through the nose, easy out through the nose. If nose breathing feels restrictive, do it only for short periods, or move to easy, quiet breathing through the mouth.

Think of it as a Goldilocks breath. Not too big, not too small, just right for you. At its best it is barely noticeable, quiet and light, the way a sleeping baby breathes. If you can hear yourself, or see your chest lifting and heaving, that is your gentle cue to soften.

Easy.

Why the Sauna Is the Ideal Place to Practise Breathing

This is where the heat comes in.

A sauna isn't only a hot room. It's one of the few spaces left where you sit still, with nothing to do, and turn your attention inward. Paying attention to what's happening inside your own body has a name, interoception, and it's something we barely get to practise in modern life.

Those quiet, focused minutes are exactly when we get to notice the things we can start to change. Breath is right at the top of that list, because it's one of the only parts of your physiology you can consciously steer. Studies show that slow breathing, under 10 breaths a minute, is linked with a shift towards rest and digest activity and better emotional regulation [Zaccaro 2018]. The way you breathe in the heat is a direct line to your nervous system.

You feel it the moment the sauna gets hot. The temperature climbs, your heart picks up, and there's a pull to open your mouth and breathe big. That's the instinct to fight the heat. But if you can stay with an easy, comfortable breath through your nose, you're sending your body a completely different message. You're telling it the heat is here and you are safe. You stay in the recover and adapt state, and the heat gets to do its work on you instead of becoming something to endure.

The same holds if you finish in the ice. The cold will beg you to gasp, and the most useful thing you can do is keep breathing easily through your nose. That is where the real practice lives.

How to Breathe in a Sauna: Where to Start

The good news is that breathing habits can be retrained. Studies show that physiotherapy breathing retraining, done either at home with a guided program or face to face with a physiotherapist, is linked with better asthma-related quality of life twelve months later [Bruton 2018]. As a physio, here's how I'd begin.

Notice, first. Through the day, just check in. In the shower, walking the dog, getting into the car. Where's your breath? Nose or mouth? Easy or effortful? No need to change anything yet, just notice.

Then gently shift to the nose. When it feels comfortable, let the breath move in and out through your nose. Keep it easy. If you like, time yourself the first few times and see how long it stays comfortable before you feel the urge to open your mouth.

Build it slowly. Do a little, rest, then come back to it. Over days and weeks, comfortable nose breathing stretches out and becomes your default again. The only question you ever need to ask is: is this comfortable? If it is, you're doing it right.

Bring it into the sauna. Settle in, sitting or lying, with an open, easy posture that gives your diaphragm room to work. Breathe gently in and out through your nose, keeping it low and quiet, down around your lower ribs. When the heat builds and the urge to gulp arrives, that's your moment to stay with a calm, easy breath. If you need to open your mouth, do. If you still feel short of air, step out. Never push into air hunger.

What About Wim Hof and Breathwork?

You've probably seen the big, powerful breathing methods: Wim Hof style breathing, breath of fire, and all of that. I think of those as special effects breathing. They're techniques designed to push you into a particular state, sometimes euphoria or something like it, and they absolutely have their place. I'm not saying they aren't valid or useful, because they are. But they need focused training, with the right understanding and someone to guide you, and they aren't for everyone. They also aren't how we're built to breathe day to day, and they're not the foundation.

The "foundation" is regulated, easy nose breathing all day long. Working with your breath, in partnership with your body, can give you similar if not better results without stressing the system. Get that working for you first, and when you do explore the special effects breathing, you'll get far more from it and always have a baseline to come home to.

Your Breath in the Sauna

For most of us, getting the most from our breath comes down to understanding, awareness, and breathing the way we are designed to. Easy and comfortable. In and out through the nose. Letting your diaphragm and your body run the way they were built to.

The sauna gives you the stillness to feel it, and the heat gives you something real to stay calm against. Put the two together and it stops being a hot room you sit in and becomes somewhere you can genuinely look after yourself.

Wondering if it will make a difference for you? Give it a go. Be your own research project, and listen to your body.

Breathe easy, sit with the heat and enjoy the benefits.

If you're thinking about bringing the sauna home, explore our traditional saunas.

Frequently Asked Questions

How should you breathe in a sauna?

Easy, quiet breathing in and out through your nose, low around your lower ribs. Keep the volume modest rather than taking big breaths. If you need to open your mouth, do, and if you still feel short of air, step out.

Should you breathe through your nose or your mouth in a sauna?

Through your nose, where it's comfortable. Nose breathing draws on your diaphragm and keeps your breathing volume in check, and breathing only through the nose at rest is linked with lower diastolic blood pressure and more rest and digest activity [Watso 2023]. If your nose is blocked, breathe gently and quietly through your mouth instead.

Why do I feel short of breath in the sauna?

As the heat builds, your heart rate rises and there's a pull to breathe big. Big, fast breathing blows off CO₂, which can leave you light-headed and tingly and make it feel harder to get a full breath [Laffey 2002]. Soften back to an easy nose breath. If you still feel short of air, dizzy or unwell, step out and cool down. Good airflow matters too, see our guide to sauna ventilation.

Can you do Wim Hof breathing in a sauna?

Powerful breathing techniques like Wim Hof style breathing are designed to push you into a particular state, and they're best learned with training and someone to guide you. Big, fast breathing lowers CO₂ and can leave you light-headed, and the heat adds to that, so the sauna isn't the place to try them for the first time. Easy nose breathing is the foundation.

How should you breathe in an ice bath after the sauna?

The cold will make you want to gasp. Keep coming back to easy breathing through your nose, as calmly as you can. If you can't settle your breathing, get out. Thinking about adding cold at home? Have a look at our ice bath.

Can you really retrain the way you breathe?

Yes. Physiotherapy breathing retraining is linked with better asthma-related quality of life twelve months later [Bruton 2018], and breathing training that gently raises CO₂ is linked with a significant drop in panic symptoms [Meuret 2008]. Start small, keep it comfortable, and build it over days and weeks.

Want to Go Deeper?

If this has sparked your curiosity (welcome to the rabbit hole), here's where I'd point you.

Breath by James Nestor, a brilliant, very readable journey through why how we breathe matters so much.

Tess Graham, the breathing physiotherapist I trained with. Her BreatheAbility books and online program are a great place to start retraining your everyday breathing: breatheability.com.

I also unpacked a lot of this with Dr Jodi Richardson on the Well, hello anxiety podcast. Listen to the episode here.

And if you love the ritual side of sauna, read What Is Aufguss? The Sauna Ritual Explained.

Glossary

Bohr effect: how carbon dioxide helps your blood release oxygen to the muscles and brain that need it.

Nitric oxide: a gas made in your sinuses that helps open airways and blood vessels.

Interoception: your sense of what's happening inside your body, like your heartbeat, breath and temperature.

Parasympathetic (rest and digest): the part of your nervous system that calms, restores and recovers.

Sympathetic (fight or flight): the part of your nervous system that gears you up to respond to a threat.

Air hunger: the uncomfortable feeling of not getting enough air. A sign to ease off.

References

Bowler SD, Green A, Mitchell CA. Buteyko breathing techniques in asthma: a blinded randomised controlled trial. Medical Journal of Australia. 1998;169(11-12):575-578. MJA

Bruton A, Lee A, Yardley L, et al. Physiotherapy breathing retraining for asthma: a randomised controlled trial. Lancet Respiratory Medicine. 2018;6(1):19-28. PubMed 29248433

Laffey JG, Kavanagh BP. Hypocapnia. New England Journal of Medicine. 2002;347(1):43-53. doi:10.1056/NEJMra012457

Lundberg JO, Farkas-Szallasi T, Weitzberg E, et al. High nitric oxide production in human paranasal sinuses. Nature Medicine. 1995;1(4):370-373. doi:10.1038/nm0495-370

Meuret AE, Wilhelm FH, Ritz T, Roth WT. Feedback of end-tidal pCO2 as a therapeutic approach for panic disorder. Journal of Psychiatric Research. 2008;42(7):560-568. PubMed 17681544

Watso JC, Cuba JN, Boutwell SL, et al. Acute nasal breathing lowers diastolic blood pressure and increases parasympathetic contributions to heart rate variability in young adults. American Journal of Physiology: Regulatory, Integrative and Comparative Physiology. 2023;325(6):R797-R808. doi:10.1152/ajpregu.00148.2023

Zaccaro A, Piarulli A, Laurino M, et al. How breath-control can change your life: a systematic review on psycho-physiological correlates of slow breathing. Frontiers in Human Neuroscience. 2018;12:353. doi:10.3389/fnhum.2018.00353

Eva brings her physiotherapy and breath background to Peak Sauna Ice. This is general wellbeing information, not medical advice. If you have a respiratory or heart condition, check with your GP before sauna or cold exposure.