Pranayama (breathing exercises) exude vast brain and body benefits through stimulating parasympathetic nervous activity and increasing vagal tone.
Our body’s Autonomic Nervous System (ANS) helps us to regulate stress and threat responses, and branches off into two main categories: the Sympathetic Nervous System (SNS) and Parasympathetic Nervous System (PNS). The SNS responds to threatening environments by increasing metabolic activities and facilitating energy mobilization (“fight or flight”), while the PNS responds to social engagement & safe environments (“rest and digest”).
Prolonged and consistent activation of the SNS is associated with a plethora of mental illnesses such as major depression, epilepsy, and post-traumatic stress disorder – while its opposition, the PNS, helps to maintain optimal homeostasis.
The PNS is composed of five sets of vagus nerves projecting information to and from different areas of the body (ie. abdominal viscera, pharynx, larynx, lungs, heart, trachea, external sensory receptors, etc) and the Central Nervous System (CNS; brain and spinal cord). Therefore, there lies a bidirectional influence between emotional states/ cognitive thought processes and their somatic/ bodily expressions with vagus nerves bridging the comunication. In other words, the body listens to the brain, but the brain listens to the body as well.
So where does yoga come into play?
In one word: breath.
“The fact that breathing is the only autonomic function that can easily be voluntarily controlled provides a portal through which specific selected breathing patterns can be used to send messages to through PNS, SNS, and interoceptive systems to affect how the brain perceives, interprets, and responds to stress or threat.
Because breathing is vital to survival, information from the respiratory system must be noticed and attended to immediately.” ~ Streeter, Gerbarg, Saper, Ciraulo, & Brown (2012)
This not only means that breathing exercises can tell the brain that it can chill out and veer into a more safe allostatic state, but that this communication is extremely rapid.
Different types of breathing exercises have been shown to increase PNS activity. For example, ujjayi breath (resistance breathing involving laryngeal contracture and partial closure of the glottis) increases intrathroracic pressure, baroreceptor stimulation, respiratory sinus arrhythmia, and heart rate variability, while using breath holds with ujjayi multiplies PNS effects. In addition, chanting om (resistance breathing while contracting the vocal cords) increases vagal tone and physiological relaxation.
Therefore yogic breathing can be a powerful tool in preventing and combating a number of chronic illnesses involving hyperactive SNS activity by defeating allostatic load. And furthermore, it’s simple, accessible, and effective!
Streeter, C., Gerbarg, F., Saper, R., Ciraulo, D., Brown, R. (2012). Effects of yoga on the autonomic nervous system, gamma-aminobutryic-acid, and allostasis in epilepsy, depression, and post-traumatic stress disorder. Medical hypotheses, 78 (5), 571-579.