Why You Should Practice Breathing Through Your Nose (And Not Your Mouth)

Written by Reid Winick, DDS

We all remember Mom telling us to chew our food slowly. Why? Because it promotes proper digestion by allowing the digestive enzymes in the saliva to start breaking down your food at the beginning of the digestive cycle. Similarly, proper breathing can also affect our biology.

Bikram yoga promotes nasal breathing during the majority of its postures (24 of 26 poses). For instance, the first posture (Standing Deep Breathing/pranayama) and the last posture (Blowing in Firm Pose/Kapalbhati in Vajrasana) incorporate both nasal and mouth breathing for several reasons.

Standing "Deep Breathing" helps prevent respiratory problems such as bronchitis, emphysema and shortness of breath. "Blowing in Firm Pose" improves digestion and circulation, and increases the elasticity of the lungs with every forceful exhale (this is the same theory behind the spirometers that are used in hospitals for post-op patients). This posture also strengthens the abdominal organs and increases circulation to them.

Everything we do affects our biology, be it eating, exercising, sleeping … or breathing.

So what’s the big deal about breathing through your nose and not your mouth? Nasal breathing is an extremely important part of your 90-minute Bikram yoga session. Basically, it comes down to how our breathing affects the carbon dioxide (CO2) levels in our lungs and blood. It has very little to do with oxygen levels.

Proper carbon dioxide levels, which regulate the healthy narrow pH range of the blood, allow for the adequate release of oxygen to our tissues and our brain. Many of us, throughout our lives, have been given the vague impression that CO2 is bad for us. Quite the contrary — without CO2 we wouldn’t get the oxygen we need. Proper CO2 levels are what trigger our red blood cells to release the oxygen they carry.

Most of the CO2 that we use actually does not come from the atmosphere; our own bodies manufacture it as a byproduct of natural bodily processes. Therefore, if we aren’t breathing correctly, then we’re also not producing the proper levels of CO2 in our bodies that we critically need.

Consider, as an example, a can of soda. We’ve all enjoyed a nice cold soda on a hot day; it’s full of sparkle and life and fizz. We’ve all also experienced what happens when you leave an open can out for a while. You come back and the drink is now flat; it’s lost its fizz.

What’s in a can of soda? Water, salts, sugars, coloring … and CO2 (hence the term “carbonated beverage”). Interestingly, blood contains the same main ingredients ... water, salts, sugars, coloring (from the hemoglobin in our red blood cells) and, again, CO2. What would happen if our blood lost its fizz?

So how does all this work?

The lungs store CO2. If carbon dioxide levels fall below a certain level of pressure, we start to experience imbalances, which turn themselves into symptoms. The brain is set to trigger breathing through the diaphragm as long as there is adequate carbon dioxide levels in the lungs. You will achieve and maintain the proper level of carbon dioxide as long as you breathe functionally.

Functional adult breathing is 8-10 breaths per minute at rest, in and out through the nose, not through the mouth, driven by the diaphragm, not by the upper chest. Most importantly of all, breathing should be silent. If breathing can be heard, it’s not functional.

Why nasal breathing?

Because noses are made for breathing!

They have a four-stage filtration system:

  1. The hair filters out the particles in the air
  2. The mucous has an enzyme that kills viruses and bacteria
  3. The turbinates and sinuses warm and condition the air and produce
  4. Nitric oxide (improves lung function)

Before the air enters the lungs it goes over the final two filters; the adenoids and the tonsils.

This system is important since the lungs are very sensitive and therefore respond better to air that has gone through these four filtration stages of the nose, rather than through the mouth.

Close your mouth!

In a person who breathes heavily through an open mouth, we will see three immediate problems:

  1. Lower CO2 levels in the lungs
  2. Lower CO2 concentration in the blood
  3. Restricted O2 flow to the brain and other tissues

Why is this a problem?

Low CO2 levels cause blood pH to rise toward its alkaline limit and an alert is sent to the brain.

The brain stops the diaphragm from working, in order to halt breathing and allow CO2 levels to rise again.

The moment the blood pH is restored and O2 flows again, the brain tells the diaphragm to start to move and the next breath is allowed.

The Downside of Poor Breathing

In order to maintain the proper level of carbon dioxide in the lungs, and thus a healthy blood pH range, we need to control the rate and depth by which we breathe. This is done using the diaphragm. If we don't use the diaphragm as the primary muscle of breathing, we will have problems maintaining the correct carbon dioxide level within our lungs.

When we breathe through our mouths, we start to use our upper chest to breathe and don’t use the diaphragm correctly. This poor breathing cycle upsets our body chemistry and causes the CO2 to decrease to a dysfunctional level in our lungs. This will trigger the brain to halt the diaphragm from working until the carbon dioxide level in our lungs is restored to a healthy level.

This is done by preventing the expulsion of too much carbon dioxide during mouth breathing. Because of this, we may get a tight feeling in our chest or have trouble breathing. By directly controlling our diaphragm, the brain tries to limit the amount of CO2 that we lose.

Tube Tension

In an effort to decrease CO2 expulsion, the brain will also automatically narrow the tubes in our body. Tubes? Think about it … we are “totally tubular!”

Nothing happens in the body that doesn’t involve a tube of some sort … digestion, respiration, circulation.

From the largest tubes like our intestines and esophagus down to the smallest ones such as the veins and capillaries, our brain will constrict these in an effort to increase our CO2 levels back up into the proper range. Mouth breathing affects much more than just our CO2 and oxygen levels; it impacts everything from digestion and the flow of blood and lymph to even our mood and cognition.

Breathing through your nose can assist you in obtaining an easier and better outcome during your Bikram yoga session. Breathe correctly, restore balance to your body and you can change the way you feel.

So … close your mouth, open your nose and breathe in health!

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