Breathing is one of the most essential aspects of good health, yet almost no one thinks about it? Perhaps because it is so fundamental and goes unnoticed.

There is a new body of research that shows that all of the breathing disorders, from asthma to tuberculosis, from emphysema to interstitial lung diseases, have been linked with an overactive immune system. The immune system is not only system to benefit from proper breathing. The brain benefits as well. Research from Japan shows that during relaxed abdominal breathing, brain waves also show a pattern of relaxation. Finally, heart rate variability (HRV) has been studied extensively. Poor HRV has been linked with increased mortality after heart attack, and has also been shown to be linked with depression, anger, and anxiety. Research has found that proper breathing can improve HRV and reduce immune activation.

The bottom line: when we consciously and mindfully focus on our breathing, a rhythmic pattern of healthy heart rate variability and healthy immune function result. And that mean a longer and healthier life[2].
Three Types of Breathing
As Dr. Liponis [2] describes, there are three types of breathing:

1. Clavicular breathing — A breath that comes from high up in the shoulders and collarbones
2. Chest breathing — A breath that comes from the centers of the chest
3. Abdominal breathing — A breath that comes from the abdomen

The fist breathing pattern uses the collarbone (i.e. the clavicle) to help move air. You see it most often in people who are feeling panicked, or who truly are struggling for breath, as those with emphysema often do. Clavicular breathing is the most abnormal form of breathing. It occurs with serious breathing impairment or during extreme stress--such as in a panic attack.

The second breathing pattern is the most common kind. Your chest and lungs will be expanding, but the expansion is restricted by tension and tightness in the muscles around the abdomen and ribs. This causes the chest to expand mainly upward, with less airflow and more rapid respiration.

The third kind of breath comes from the abdomen and uses diaphragm. When the diaphragm contracts, your lungs expand, pulling air in through your mouth like bellows. When you breathe from your abdomen, your belly will expand and move out with each inhalation. Your chest will rise slightly, but not nearly as much as with chest breathing; your abdomen is doing all the moving.

Doing abdominal breathing, you can activate vagus nerve and trigger a relaxation response. The relaxation response, which is the opposite of the stress response, is necessary for your body to heal, repair, and renew.

What's Vagus Nerve?
Your body's levels of stress hormones are regulated by the autonomic nervous system (ANS) [3]. The ANS has two components that balance each other, the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS).

* The SNS turns up your nervous system. It helps us handle what we perceive to be emergencies and is in charge of the flight-or-fight response.
* The PNS turns down the nervous system and helps us to be calm. It promotes relaxation, rest, sleep, and drowsiness by slowing our heart rate, slowing our breathing, constricts the pupils of our eyes, increases the production of saliva in our mouth, and so forth.

The vagus nerve is the nerve that comes from the brain and controls the parasympathetic nervous system, which controls your relaxation response. And this nervous system uses the neurotransmitterr, acetylcholine. If your brain cannot communicate with your diaphragm via the release of acetylcholine from the vagus nerve (for example, impaired by botulinum toxin), then you will stop breathing and die[6].

Acetylcholine is responsible for learning and memory. It is also calming and relaxing, which is used by vagus nerve to send messages of peace and relaxation throughout your body. New research has found that acetylcholine is a major brake on inflammation in the body[4]. In other words, stimulating your vagus nerve sends acetylcholine throughout your body, not only relaxing you but also turning down the fires of inflammation which is related to the negative effects from stress[1].

Exciting new research has also linked the vagus nerve to improved neurogenesis, increased BDNF output (brain-derived neurotrophic factor is like super fertilizer for your brain cells) and repair of brain tissue, and to actual regeneration throughout the body. For example, Theise et al[5] have found that stems cells are directly connected to the vagus nerve. Activating the vagus nerve can stimulate stem cells to produce new cells and repair and rebuild your own organs.

There are many ways to activate the vagus nerve and turn on the relaxation response. When you take a deep breath and relax and expand your diaphragm, your vagus system is stimulated, you instantly turn on the parasympathetic nervous system, your cortisol levels are reduced, and your brain heals.

How to Activate the Vagus Nerve on Your Own
To practice deep breathing, inhale through your nose and exhale through your mouth. Remember to[3]:

* Breathe more slowly.
* Breathe more deeply, from the belly.
* Exhale longer than you inhale.

You can proceed as follows: take a breath into your belly (i.e. expanding your diaphragm) to the count of five, pause for a second, then breathe out slowly through a small hole in your mouth. While at rest most people take about 10 to 14 breaths per minute[3]. Ideally, reduce your breathing to 5 to 7 times per minute. Exhaling through your mouth instead of nose makes your breathing a conscious process, not a subconscious one.
As you do this, your muscles will relax, dropping your worries and anxieties. The oxygen supply to your body's cells increases and this helps produce endorphins, the body's feel-good hormones. Tibetan monks have been practicing this to modulate the effects of stress for decades. They don't practice these ancient techniques to improve their memory, fight depression, lower blood pressure, or heart rate, or boost their immune systems, although all of those happen.
Reference(s)

1. Sloan, R. P., et al. 2007. RR interval variability is inversely related to inflammatory markers: The CARDIA study. Mol Med 13 (3-4):178-84.
2. "Ultra-Longevity" by Mark Liponis, MD
3. "Prime-Time Health" by William Sears, M.D. with Martha Sears, RN
4. Pavlov, V.A., and K.J. Tracey. 2005. The cholinergic anti-inflammatory pathway. Brain Behav Immun 19 (6):493-99.
5. Theise, N.D., and R. Harris. 2006. Postmodern biology:(adult) (stem) cells are plastic, stochastic, complex, and uncertain. Handb Exp Pharmacol (174):389-408.
6. Your Brain on Food by Gary L. Wenk