Conscious breathing isn't something that comes naturally to us. While this skill is inborn, if often lies dormant. If you watch the way that babies breath, it is full belly and full body. As we grow older and our cortex develops, social cues come online and we start to dampen this full body breath. Our cultural ideal of a flat stomach cause many of us to suck in and tighten our bodies instead of relaxing into breath; girls and women are expected to hold back anger, boys and men are expected to withhold emotions of sadness and grief; contracting and drawing in the belly is often a fear response, conscious or unconscious. Reawakening full belly breathing allows you to tap into one of your body's strongest self healing mechanisms.
Most adults breathe predominantly into their chest. The average lung capacity for an adult human is six litres of air! However many of us take short, shallow, or irregular breaths, or even hold our breath. We often only use half of our lung capacity. By not using the full depth of our lungs, the small blood vessels are the bottom of the lungs don't get their fare share of oxygen and can contribute to feelings of shortness of breath or even feeling anxious. Shallow breathing causes an increase in one's heart rate, a spike in blood sugar and blood pressure, and can contribute to indigestion and insomnia. With a chronic sympathetic tone of the nervous system, your body releases the stress hormone cortisol, which causes platelets in the blood to become sticky, making people more prone to heart attack and stroke, as well as suppressing the immune system.
While all breathing involves the diaphragm, shallow chest breathing hobbles the diaphragm, limiting its full range of motion. Deeper belly breath encourages more movement of the diaphragm, facilitating fuller oxygen exchange which in turn slows the heart rate and stabilizes blood pressure. Conscious breathing can also reverse well established patterns of tension in the body, and can help to access a feeling of calm when presented with uncomfortable sensations and experiences. Taking a few deeper breaths will lower your blood pressure, help stabilize your blood sugars, and improve your digestion, immune system function, and generally give you a feeling of well being. The Vagus nerve runs through the diaphragm, and belly breathing helps to stimulate this very important nerve which innervates your major organs and is the main component of your parasympathetic nervous system. More on this amazing nerve later!
Our ancestors lived in a predominantly parasympathetic state, with occasional sympathetic response when needed such as as in hunting, traveling, or running from danger. With modernity this has been reversed, and now we spend more of our time in sympathetic arousal with occasional dips into our parasympathetic nervous system.
So, if you needed a reason to take a few deep breaths, there you go!