What Happens in Vagus?

In many ways the literal opposite of what happens in Vegas, the Vagus nerve is the general of our parasympathetic nervous system (PNS) which is often deemed our “rest and digest” system.  The PNS is the counterbalance to the sympathetic nervous system (SNS), or the “fight or flight” system.  While one’s duty is to calm us down, the other is designed to ramp us up in times of stress or threat.  The vagus nerve ‘wanders’ from its origin in the brainstem with branches to many organs including the heart, lungs, digestive tract, and genitourinary organs where it has a myriad of roles from digestion to heart rate to immune response.

Overactivation of the SNS is a concept which is not new to the modern, health conscious community.  Where historically, the SNS related surge in cortisol, blood sugar, blood pressure, and heart rate were adaptive in small, intermittent doses to allow our ancestors to evade a  pursuant  lion or other predator, these same physiologic responses follow SNS activation to stressors in modern life.  However, in most cases today, such a physiologic response is maladaptive as the work emails and filing taxes are not in fact life threatening.  Chronic stress, as has unfortunately become the norm for us, is associated with deranged metabolism and cortisol cycles and even heart disease and mortality. 

Enter the counterbalance, the PNS and its MVP - the vagus nerve.  While we do unintentionally and frequently activate our SNS, the PNS is all too often neglected.  But it doesn’t have to be!  Natural contemplative practices like breathwork, meditation, yoga, tai-chi, and forest bathing can have powerful and far reaching physiologic responses due to PNS activation.  These practices have a growing body of objective evidence demonstrating improvements in heart rate variability (HRV - overall marker for health), blood pressure, resting heart rate, respiratory rate, cortisol levels and psychological resilience.  Ice baths, though through slightly different but overlapping mechanisms than PNS activation alone, also demonstrate noteworthy improvements in metrics such as HRV and immune function.  

In addition to the above noted practices which have been effective for many cultures for 1,000’s of years, electrical stimulation of the vagus nerve has been gaining traction and FDA approvals treating varying types of disease.  Invasive implantable devices as well as non-invasive transcutaneous devices can provide electrical stimulation to the vagus nerve, and are approved in the treatment of refractory epilepsy, PTSD, depression, asthma, headaches and migraines, irritable bowel syndrome, and more.  Owing to the ubiquitous influence of the vagus nerve throughout the PNS and body, research is ongoing regarding more widespread application of electrical vagus nerve stimulation for things like COVID, stroke recovery, heart failure, tactical and performance enhancement, and opioid use disorders.

Whether natural remedies such as yoga and meditation or electrical vagus nerve stimulation are more your speed, don’t forget the vagus nerve!  In our hustling and bustling modern lives, our SNS is in constant overdrive, but the calm, the vagus, and the counterbalance are never more than just a deep breath away.