Your mouth and your nose both lead into your throat, and from there there is one airway to your lungs.
So for your lungs, it shouldn’t make any difference which of the two you use. Same air, same destination.
The only difference is that your nose adds something to that air along the way that your mouth can’t make.
What happens in your sinuses
Around your nose are cavities in your skull, above your eyebrows and behind your cheeks. The cells lining those cavities make a gas called nitric oxide all day long.
It is a tiny molecule made of one nitrogen atom and one oxygen atom, and it is one of the substances your body uses to widen and narrow its blood vessels.
When you breathe in through your nose, you pull that gas down with it. It ends up in the air in your lungs and there it opens the blood vessels around your alveoli a little wider. More blood then flows past the place where the oxygen is absorbed.
Along the way, it also mildly fights bacteria and viruses in the air you breathe in. Your nose therefore delivers cleaner air than it takes in.
What your mouth does not do
Breathing through your mouth delivers the same air to the same lungs, without that boost along the way.
And more is lost. Your nose warms the air to nearly body temperature and humidifies it, so your airways do not dry out. It filters dust and pollen out in the mucus and hairs. It also adds resistance, which makes you breathe more slowly and deeply than when the airway is wide open.
Your mouth does none of those four things. Cold, dry, unfiltered air goes straight through it, and you breathe faster and more shallowly.
Why it matters most at night
During the day, you mostly breathe through your nose without thinking about it. When you sleep, your muscles relax and your mouth opens as soon as your nose gets even slightly in the way, and how you lie down determines how quickly that happens.
Do the math. At rest, you breathe about thirteen times per minute, so in an eight-hour night you take six thousand breaths. That means six thousand times when it matters which route the air takes.
That is why you wake up with a dry mouth and a sticky throat. That same hour of breathing through your nose would have given your lungs moist, warm air with that gas added.
What you can do about it
Practice during the day. Once a day, walk for twenty minutes with your mouth closed, just to the supermarket or during a phone call. It feels awkward for the first few days and then it doesn’t anymore.
See whether your nose can handle it. A nose that already feels tight during the day gets completely blocked at night, and then you automatically switch back to your mouth.
Rinse your nose with salt water before bed if you are bothered by dust or pollen. That removes the irritation that makes the swelling worse than it needs to be.
And keep it open at night. One side of your nose is always partly blocked, so the margin is smaller than you think. Nasal strips pull your nostrils outward and keep your nasal passage open with a small splint. Mouth tape keeps your mouth closed, so your body keeps using your nose once your muscles relax.
This week’s habit
One walk a day with your mouth closed. Twenty minutes and nothing else changes in your day.
If you notice that you open your mouth halfway through, you are going too fast. Then walk a bit slower and you’ll see it works again right away.
After a week, pay attention to your throat when you wake up. That is the first place you will feel it.
Every Night 1% Better.
Guy Veeke
PS: If nose breathing works fine during the day and you still wake up with a dry mouth?
Then your mouth opens as soon as you fall asleep. The combination of nasal strips and mouth tape keeps your nose open and your mouth closed, exactly during the hours when you can’t do anything about it yourself.
