Breathing: Why the Nose Knows Best

When you own your breath, nobody can steal your peace.

       — Anonymous

Why do we use nostril breathing instead of mouth breathing? In a nutshell, our noses are made for breathing and our mouths are designed for eating.

  • Our nostrils are much smaller than our mouths. There is 50% more resistance to air flow when we breathe through our noses compared to our mouths. This increased resistance stresses our diaphragm and lungs in a healthy way, helping to maintain elasticity and improve overall lung volume. If we slow our breathing down, our parasympathetic nervous system engages and we enter a state of deeper relaxation where the stress hormone cortisol is decreased. Longer exhalations also provide more time for oxygen uptake. Additionally, if we exhale too much carbon dioxide too quickly, our blood pH levels become imbalanced and our bodies decrease oxygen intake as a result (too high of a percentage of oxygen in our bodies is actually toxic). Our bodies are always striving towards homeostasis, a level of balance. Decreasing carbon dioxide does not mean a rise in oxygen, it actually can decrease it!
  • Our nasal cavities provide around 90% of our own personal air conditioning. They also recover 1/3 of the heat and moisture that is exhaled. Outside air is warmed up as it passes through the nasal passages, providing a humidifying effect. Diffusion, the process in which oxygen and carbon dioxide are exchanged, only takes place in the presence of water. That extra humidity from our nasal passages helps to ensure that there is enough water present for our bodies to properly process releasing carbon dioxide and absorbing oxygen.
  • Our sense of smell is a large part of the breathing process that is often overlooked. Obviously we smell with our noses and not with our mouths. Our smell influences many automatic responses throughout our bodies (olfactory bulbs send information to the hypothalamus). Our nasal cavities contain receptors that detect any chemicals present in the air we breathe. If any chemicals are present, our bodies respond immediately by triggering the release of nitric oxide to kill incoming bacteria. If we breathe through our mouths all the time, we disregard our first line of defense against pollutants.
  • Our nostrils are constantly changing which side is more open than the other. This is called nasal vasoconstriction. Throughout the day our breathing switches between being predominantly through the right and left nostril. Each nostril is innervated by five cranial nerves on the opposite hemisphere of the brain. Thus, breathing through the right nostril stimulates the left hemisphere of the brain and breathing through the left nostril stimulates the right hemisphere of the brain. Brain asymmetry increases overall cognitive efficiency. In yoga we attribute the right nostril as yang, ha, and the sun. The left nostril is yin, tha, and the moon. Imagine the symbol of a yin-yang. There is a degree of overlap of yin and yang in the smaller circles. Similarly there are periods of time when transitioning from one nostril to the other where both nostrils are equally open.
  • Deep abdominal breathing also improves our blood circulation. Deep abdominal breathing causes a change in the shape of both the abdominal and thoracic cavities. When we exhale deeply from our abdomen, there is lower pressure in our abdomen than in our lower body. This causes the venous blood (blood without any more oxygen) from the feet and legs to flow up towards the abdomen. As we inhale deeply, the compression of the abdomen causes the venous blood to flow towards the lower pressure of the chest, flowing back to the heart. This cycle is repeated with each inhalation and exhalation, drawing the blood up from the lower body and back to the heart more efficiently. Once the blood reaches the right side of the heart, it is pumped to the lungs to pick up more oxygen before returning to the left side of the heart and being sent out to the rest of the body.

When it comes to breathing, our nose knows best.  

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