Lately, there has been a lot of interest in the Vagus nerve and its calming effects on the body. The Vagus is a cranial nerve that is associated with the parasympathetic nervous system (PNS). The parasympathetic nervous system slows the heart rate, dilates the blood vessels, rests the body, conserves energy, and allows food to digest more easily.
There are medical devices now being sold that directly stimulate the Vagus nerve, which paradoxically has a sedation-type effect on the body. In yoga practice, however, there are many tools that can naturally hack into the function of the Vagus nerve and increase the calming of the nervous system, overall.
Here is a short list:
1. Slow, deep breathes with long, slow exhales. Have both the inhales and exhales come from the nose and not the mouth. This directly stimulates the Vagus nerve. Pranayama practice helps develop this action.
2. Draw bones into their joints and hug muscles onto their bones. This action calms the nervous system and allows muscles to stretch farther and more safely. Technically, these actions reduce the firing of spinal reflexes that otherwise protect the tendons and muscles from abrupt contraction. Golgi Tendon Organs and Muscle Spindles are the names of two of the reflex receptors.
3. Engage the Bandhas. The primary bandhas along the spine correspond with the parasympathetic nervous system. Mula bandha engagement corresponds with the sacral plexus, the lower aspect of the PNS. Working together, the Jalandhara and Uddiyana bandhas engage the thoracic spine, and important location of the PNS.
4. Cover the body with weighted props or blankets for Savasana. This has a swaddling-type effect that calms the nervous system and stimulates tissue healing. Weighting the body is also valuable in restorative and rehabilitative yoga postures to unleash Savasana's greatest effect. Blankets or bolsters placed over the top of the thighs is especially calming.
5. Similarly, place an eye pillow over the eyes. This puts sight traction on the occular muscles that will stimulate the Vagus nerve to lower the heart rate. This is called the Oculocardiac reflex.
6. Using props can calm the nervous system. When a body part becomes suspended, such as the knees being elevated away from the floor while sitting or the head "hanging in mid air" in Upavistha Konasana, the stress response can be triggered. Contact with a prop can reduce the reaction.