Nasal breathing: what your nose really does, and how to switch without gadgets

What your nose has been shown to do

Your nose is a small air conditioner. It warms the air you breathe in to nearly body temperature, humidifies it, and filters out particles and some gases.¹ To do that, it’s twisty inside, and that comes at a price: breathing through your nose takes a bit more effort than breathing through your mouth.² So a slightly restricted feeling at first is normal.

1. Air flows in through your nose, often cool and dry.
2. On its way through the nasal cavity, it’s warmed to nearly body temperature and humidified.
3. Larger particles get caught in your nose.
4. A gas called nitric oxide joins in from your sinuses. With nasal breathing, it travels along into your lungs.

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What’s overblown

“18% more oxygen.” The figure comes from a small 1996 study of six patients on mechanical ventilation who were fed air from their own noses. In healthy people, only a value measured through the skin went up, by 10 percent in 6 of 8 people.^{3, 4} A review by breathing and exercise scientists finds little evidence that such effects carry over to healthy people.⁵ What is true: your sinuses produce nitric oxide, and it reaches your lungs when you breathe through your nose.^{6, 3} A measurable benefit for healthy people hasn’t been shown. More in Does deep breathing give you more oxygen?

A different face from nasal breathing. In children, mouth breathing is linked to differences in how the jaw and face develop. Those studies look back in time, though, and the children mostly had enlarged tonsils or breathing pauses during sleep.⁷ For adults, I found no study showing that mouth breathing changes the facial skeleton, and none showing that nasal breathing or “mewing” reshapes it.

Better athletic performance. Not shown for healthy people.⁵ As effort increases, most people switch to breathing through mouth and nose on their own. In one lab study, 20 of 30 healthy adults did, on average at about 105 watts.⁸ That’s normal, not a mistake.

Why only one nostril is often clear

Usually more air flows through one nostril than the other, and they take turns. In one measurement, this nasal cycle lasted about two hours while awake and longer during sleep. Lying on your side, the upper nostril was usually the clearer one.⁹ So if one side is blocked right now, rolling onto the other side may help.

How to make the switch

How adults can best stop mouth breathing has barely been studied. Only a few basics are backed by evidence; the rest is experience:

1. Check your nose first. Common reasons for mouth breathing include allergies, enlarged tonsils, and a deviated septum.¹⁰ If your nose is always blocked, get it checked instead of forcing yourself to breathe through it.
2. Start during calm moments in the day, like reading or working at a screen. A sticky note or a reminder helps you notice. That’s experience, not a study.
3. Breathe small and calm instead of deep. That comes from Buteyko practice and hasn’t been studied in healthy people, but many find it more comfortable than big breaths through the nose.
4. Don’t force it during exercise. Nasal breathing usually works at an easy pace; when it gets harder, let your mouth help.
5. Nights come last. I don’t recommend mouth tape; the reasons are in Is mouth taping safe?

And at night? In a small study of ten healthy adults, the mouth became more acidic when they had to breathe through it during sleep.¹¹ Whether that harms teeth over time wasn’t measured.

Common questions

Is nasal breathing better than mouth breathing?

What’s shown: your nose warms, humidifies, and filters the air.¹ Bigger health claims for healthy people haven’t been shown.⁵

Do I get more oxygen through my nose?

That hasn’t been shown for healthy people. The often-quoted 18 percent comes from measurements in six patients on ventilators.^{3, 4}

Why am I only breathing through one nostril?

That’s the normal nasal cycle: the sides take turns, about every two hours while you’re awake.⁹

Nasal breathing feels restricted. Is that normal?

A bit more resistance than mouth breathing is normal.² If your nose is always blocked, or blocked on one side, get it checked.

Can mewing change my face?

I found no study showing that. The link between mouth breathing and jaw development concerns children, mostly with enlarged tonsils.⁷

How do I breathe through my nose when it’s blocked?

That’s covered in the article on the Nasal Clear exercise.