Sympathetic System, Parasympathetic System
Self-regulation is not learned alone: it is built, often through contact with an adult able to pass on their own calm. When that is not the case, or when life demands too much of our vigilance for too long, the nervous system can get stuck in a state of alert. How, then, do yoga and Ayurveda help us shift between tension and release, between activation of the sympathetic system and the parasympathetic system?
Ayurveda and yoga are particularly well suited to calming not just the heart rate, but the nervous system as a whole: the two are interdependent. The goal is to bring body and mind back into a parasympathetic state, the state in which we regenerate, in which we breathe enough to recharge, stay calm, and keep a clear mind.
Almost every yoga technique contributes to this, though some are more powerful than others. Yoga does not only work on calm: it also trains the sympathetic system, because the two branches of the nervous system cannot be disconnected from one another. Some approaches, in both pranayama and asana, are more stimulating, energizing: they correspond to activation of the sympathetic system. Postures and breathing practices that balance the two systems bring about heart coherence. Calming practices correspond to activation of the parasympathetic system: for example, breathing patterns that lengthen the exhale, and quiet, passive seated or reclining postures, as in Yin Yoga or any forward fold.
The vagus nerve plays a central role here: it is the longest nerve of the parasympathetic system, the one that, once activated, brings the heart back to calm, dilates the blood vessels, and releases the muscles. And the good news is that we can activate it voluntarily, through breath alone: slowing the exhale, lengthening it a little more than the inhale, for a few minutes a day, is enough to send a clear signal to the whole body, that a return to safety and calm is possible. Like breathing itself, like chanting, or the touch of cold water on the face, it is a skill that is cultivated, breath by breath, within reach of anyone who has a nervous system, which is to say, everyone.