The Vagus Nerve: Considerations in Understanding the Trauma Response, Part I
Written by: Megan Begley, LCSW
What is the Vagus Nerve?
As trauma therapy has evolved, it has increasingly focused on understanding autonomic nervous system (ANS) functions, both as a way to appreciate how post-traumatic symptoms develop and as a foundation for teaching therapists and clients skills that induce a relaxation response. The ANS consists of the sympathetic nervous system response (fight, flight, or freeze) and the parasympathetic response (rest and digest), which is designed to kick in after danger or distress has passed.
The parasympathetic response is regulated to a great extent by the vagus nerve, or tenth cranial nerve. Known as ‘’the wandering nerve,’’ it has branches that weave down from the brain’s medulla through the neck, chest cavity, and abdomen on both sides of the body. Its three main branches respectively serve the neck/throat, the spine and ear, and the heart, lungs, and esophagus. As such, it links the central nervous system, and therefore distress or relaxation cues, to most of the body’s other physiological functions. In turn, significant internal processes such as digestion and the immune response are shaped by vagus nerve activity.
Developing insight into vagus nerve functioning not only illuminates the mind-body connection (primarily the ‘’gut-brain axis’’), but creates awareness about constructive steps you can take to counteract trauma responses or chronic stress.
The most basic vagus nerve construct for mental health is that of vagal tone. Vagal tone is a measure of the cardiac response to stress, or said differently, how quickly a person’s nervous system can be restored to calmness after sympathetic activation. Vagal tone is captured by monitoring a person’s heart rate-to-breathing pattern–known as respiratory sinus arrhythmia or RSA – during resting state and also during stress challenges. Vagal tone is said to be high if the baseline level of calm is restored relatively quickly.
If you find that it takes a long time to relax once you get anxious or stressed, that’s a likely indicator that you have low vagal tone, and could benefit from exercises and habits that stimulate the vagus nerve. The below list, although by no means comprehensive, offers some suggestions:
1) Deep and slow breathing – this refers to diaphragmatic breaths (vs. shallow breaths taken from the lungs) with exhalations that extend longer than inhalations. Try inhaling to a count of 4, holding for a count of 7, and exhaling to a count of 8 with an audible ‘’whoosh’’ sound.
2) Yoga – research supporting the biological efficacy of yoga is largely related to its impact on vagal tone, and the yogic tradition is replete with other concepts that are increasingly validated through the lens of vagus nerve functioning. Complex postures aren’t necessary, as the focus on intentional breathing described above is key; also, stretching increases vagal activity via pressure receptors buried beneath the skin’s surface.
Yin Yoga, which focuses on achieving deep stretches through relatively simple poses, is a good type to try if you’re a beginner, or you dislike fast-paced or athletic styles.
3) Massage – like stretching, the firm touch of massage (or bear hugs by loved ones) stimulates vagal activity via pressure receptors beneath the skin.
4) Cold exposure – while admittedly not for the faint of heart, taking a cold shower or finishing with a cold rinse activates the vagus nerve.
5) Singing, humming, chanting, gargling, and laughing – these activities stimulate the vagus nerve at the throat area in the neck. The meditative practice of ‘’Ohm-ing,’’ (or ‘’Aum-ing,’’ as sometimes spelled), is an intentional example of chanting.
6) Simple exercises specific to the vagus nerve – these brief, highly feasible exercises (such as holding your head to each side for thirty seconds) led by posture and movement therapist Sukie Baxter on YouTube may be the easiest place to start: https://www.youtube.com/watch?v=eFV0FfMc_uo
Note that actually improving your baseline vagal tone is a broader task than using vagus nerve stimulation to relax in the moment. An upcoming second blog post on Polyvagal Theory will illuminate why this is thought to be the case.