The Vagus nerve
Rest digest and restore: can we reset it ourselves?
There has been growing interest recently regarding the vagus nerve. It plays a vital role in our body’s rest, digestion and relaxation and therefore when not sending the right signals can make us not feel great.
The vagus nerves form a part of the parasympathetic autonomic nervous system. The autonomic nervous system is divided into the sympathetic and parasympathetic nervous systems. The sympathetic nervous system produces our fight-or-flight response to perceived threats. The parasympathetic is a counterbalance to our stress response - rest, digestion and relaxation. Hence the vagus nerve is so important to our body’s calming and restoring regulation system.
Your sympathetic nervous system is always activated, helping to control and manage our bodily systems, but stress brings our bodies into a heightened sympathetic state, preparing our bodies for action. It is healthy to increase action our sympathetic nervous system during exercise and short-term stress. But ongoing stimulation of the sympathetic nervous system is not healthy.
The sympathetic nervous system stimulation increases heart and breathing rates, slows down digestion and lowers the immune response. Unfortunately, a lot of us are stressed beyond what is needed, and we continue in this heightened sympathetic state, unable to regulate and return to our parasympathetic, more relaxed state.
Stimulation of the parasympathetic, and vagus nerves reduces heart rate, promotes healthy digestion and metabolism, increases blood flow to organs and reduces inflammation, balancing your nervous system.
The wandering Vagus nerve
Vagus means wandering in Latin. The name reflects the long pathway and extensive branching of our vagus nerves. The vagus nerves run down the neck and travels into the thoracic (chest) cavity, sending branches to the heart and lungs, then pass through the diaphragm to innervate nearly all the abdominal organs.
Vagus-nerve stimulation slows the heart rate but increases heart-rate variability. A lower heart rate indicates the heart is working efficiently. Higher heart rate variability suggests the body is more relaxed.
Interestingly, about 18 per cent of vagus nerve fibres carry information from organs back to our brain. This forms part of the bidirectional gut-brain axis. This can explain the "butterflies in your stomach" when you feel nervous, and why gastrointestinal problems can cause anxiety and depression.
The vasovagal response is an over-reaction of the vagus nerves to counterbalance a stress. This is when an excessive drop in blood pressure and heart rate causes a person to feel dizzy or faint. Many wearable devices measure heart rate and heart-rate variability and can be a useful way to monitor vagal tone.
Here are some tips on how to stimulate the vagus nerve and help you to relax and improve your health:
● Because of the way the nerve innervates the back of your throat, humming, chanting, gargling and singing all create a vibration that stimulates the nerve.
● Laughing (and socialising), for the same reason as above, but also, you can’t be really socially engaged without being in parasympathetic state (remember to be fully present in the situation).
● Diaphragmatic breathing stimulates the vagus nerve: take deep, slow and mindful breaths into your belly using your diaphragm, and try keep the exhalation longer than the inhalation to get full benefits.
● Cold immersion has been shown to increase vagus nerve tone, so ending your morning shower with 30s to a few minutes of cold-water immersion can be helpful. It is important to stay calm as you turn the water colder and move around. This trains your nervous system to stay calm under stress. If a cold shower is too much, you can just begin by immersing your face in cold water for short periods.
● Meditation and mindfulness.
● Massage, especially foot massage and back massage.
● Osteopaths are also trained in manual techniques to balance your autonomic nervous system - calming down the sympathetic and stimulating the parasympathetic. They are also trained in breathing techniques and can help guide you in developing strategies for self-care of your nervous system.
References:
Henley CE, Ivins D, Mills M, Wen FK, Benjamin BA. Osteopathic manipulative treatment and its relationship to autonomic nervous system activity as demonstrated by heart rate variability: a repeated measures study. Osteopath Med Prim Care. 2008 Jun 5;2:7. doi: 10.1186/1750-4732-2-7. PMID: 18534024; PMCID: PMC2442110.
Howland RH. Vagus Nerve Stimulation. Curr Behav Neurosci Rep. 2014 Jun;1(2):64-73. doi: 10.1007/s40473-014-0010-5. PMID: 24834378; PMCID: PMC4017164.
Breit S, Kupferberg A, Rogler G, Hasler G. Vagus Nerve as Modulator of the Brain-Gut Axis in Psychiatric and Inflammatory Disorders. Front Psychiatry. 2018 Mar 13;9:44. doi: 10.3389/fpsyt.2018.00044. PMID: 29593576; PMCID: PMC5859128.
Hammer N, Löffler S, Cakmak YO, Ondruschka B, Planitzer U, Schultz M, Winkler D, Weise D. Cervical vagus nerve morphometry and vascularity in the context of nerve stimulation - A cadaveric study. Sci Rep. 2018 May 22;8(1):7997. doi: 10.1038/s41598-018-26135-8. PMID: 29789596; PMCID: PMC5964190.
Further reading:
https://www.ncbi.nlm.nih.gov/books/NBK537171/
https://www.hopkinsmedicine.org/health/wellness-and-prevention/the-brain-gut-connection