The vagus nerve is the longest cranial nerve in the body and is responsible for controlling many of the body's involuntary functions. It is involved in the regulation of heart rate, digestion, and other autonomic functions. It also plays a role in the regulation of emotions, and is involved in the control of facial expressions.
The Vagus nerve cannot be activated directly. It can be stimulated through activities such as deep breathing, yoga, meditation, and massage. Other activities such as singing, humming, and gargling can also stimulate the Vagus nerve.
So practicing yoga and meditation can help calm your nervous system through the stimulation of the Vagus Nerve.