Laughter Yoga and Parasympathetic Nervous System (PNS)
Many physiological and psychological mechanisms in the body are regulated by two autonomic systems of the body – one is the sympathetic nervous system (SNS), which stimulates the stress arousing system – also known as ‘fight and flight’ response and helps us to deal with any life threatening situations. The other is the parasympathetic nervous system (PNS), which stimulates the relaxation response and is also known as the ‘rest and digest’ response.
The most important cranial nerve which activates PNS is the vagus nerve, which carries sensory information between the brain stem and other vital organs including the heart and lungs. When this nerve is active (high vagal tone), it slows down the heart rate and the lungs breathe more deeply to promote a state of calm.
We do not require the PNS to be active all the time; it is only when some situations demand alertness, does it become active. However, our sympathetic system nowadays is working overtime due to too much stress. The vagus nerve is the key agent which activates PNS hence reducing the negative effects of stress on our body and mind.
Here is some important information about the vagus nerve, which you must know. According to researcher Van der Kolk 80 percent of the fibres of the vagus nerve run from body to brain and 20 percent the other way round. This means that we can easily activate the parasympathetic system by stimulating this nerve by the movement of the diaphragm. Deep abdominal breathing, belly laughing and chanting can activate the vagus nerve easily.
If you inhale quickly and exhale slowly, it will trigger the PNS and reduce the blood pressure and stress response. We follow the same thing in Laughter Yoga, where we encourage people to laugh longer so as to activate the diaphragm, hence the PNS. This works very well for anxiety, depression and hypertension. It also promotes optimism, emotional control and pain management.