The breath plays a key role in your health in part because the vagus nerve extends into the smooth muscle of the lungs and heart. The nerves connecting to the heart and lungs have both sympathetic and parasympathetic functions. The sympathetic nervous system is associated with quick, intense breaths into the upper lungs, a condition often referred to as over-breathing or hyperventilation. During times of stress, your nervous system initiates the release of cortisol via the hypothalamic-pituitary-adrenal axis (HPA-axis) to mobilize your self-protective defenses through an increase in heart rate and respiration. When this continues overtime, rapid upper chest breathing leads to over-breathing or hyperventilation which is associated with panic attacks and anxiety.

While changes in breathing happen automatically in response to stress, we also have the ability to alter our physiology through conscious, mindful changes in our breath rate. Long, slow exhalations engage the vagal break and the parasympathetic relaxation response slows down your heart rate.

The health of the autonomic nervous system is measured through vagal tone and vagal efficiency. Vagal tone is measured by changes in heart rate in relationship to the breath. The heart rate typically increases on each inhalation which reflects a subtle engagement of the sympathetic nervous system and decreases during each exhalation as the parasympathetic nervous system re-engages. The relationship between your breath and these changes in heart rate is referred to as heart rate variability (HRV). Having higher vagal tone means that you have greater variability between the number of heartbeats on the inhalation as compared to the number of heartbeats measured on the exhalation. Simply put, vagal tone is measured by your ability to move between stress and relaxation efficiently and easily. You can think of this as the physiological basis for resilience which allows you to flexibly respond to inevitable challenges of life.

This practice involves creating an even length of your inhalation and your exhalation with diaphragmatic or “belly” breathing. I encourage you to study the effect that a simple practice has on your body and mind. 

• Find a comfortable place to sit where you feel supported and at ease. Begin by simply noticing your breath. Notice the length of your inhalations and exhalations. Notice the transitions between the inhales and exhales. Notice if you are feeling any physical, emotional, or mental distress or tension. 
• I recommend bringing one or both hands over your navel and focusing each inhale into your lower lungs by expanding this area like a balloon and exhaling as your draw your navel back toward your spine.
• When you are ready, begin to create a measured length of your breath with a count of four on each inhale and a count of four on each exhale. You can easily tailor this breath to meet your needs by increasing or decreasing your count.
• When you feel complete, take the time to notice any observations about yourself during this breathing practice.