The Vagus Nerve, explained


The vagus nerve is the inner nerve centre leader, also known as the 10th cranial nerve or cranial nerve X. It’s the longest of the 12 paired cranial nerves in the body and has the most extensive distribution because it passes through the neck and chest into the abdomen. The vagus nerve controls the entire parasympathetic nervous system, our “rest-and-digest” or “feed and breed” activities.

Vagus nerve fast facts

  • There are two vagus nerves, one on each side of the body.
  • It starts in the brainstem’s medulla, travels down the side of the neck, into the chest, then down into the abdomen. It navigates many visceral organs on its journey, including the heart, lungs, oesophagus, pancreas, and intestines.
  • Its name is derived from the Latin ‘vagary’ which means wandering.

The Vagus nerves role in the body?

  • The vagus nerve is a two-way communicator; it transmits signals throughout the body and then sends them back to the brain.
  • It regulates the immune response, hunger hormones and food intake, anxiety levels, and Inflammation levels.
  • The gut uses the vagus nerve like a walkie-talkie reporting back to the brain how we are feeling, our gut feelings are genuine.
  • It triggers the parasympathetic nervous system responsible for calming organs after the stress response or ‘fight-or-flight’ adrenaline response to danger. This branch of the nervous system is not under conscious control.
  • It helps regulate heart rate function, speech, sweating, blood pressure, digestion, production of glucose, breathing and many other functions.

The vagus nerve and health

A well-functioning vagus nerve will improve brain-body communication, help in balancing homeostasis and regulating organs. Research has shown that the vagus nerves’ health may be the missing link in treating many chronic conditions, including inflammatory illnesses such as arthritis

Vagal Tone

Vagal tone refers to the nerve’s activity; research shows that a high vagal tone improves the body’s ability to regulate blood glucose levels, reset the immune system and turn off inflammation, reducing the likelihood of illnesses like diabetes, cardiovascular disease and stroke. In contrast, studies have linked persistent low vagal tone with chronic inflammation, damage to blood vessels and organs.

Signs and symptoms of low vagal tone

  • Indigestion.
  • Gastrointestinal bloating and IBS.
  • A hiatus hernia.
  • Loose stools.
  • Stress, fatigue and anxiety.
  • Shortness of breath and prolonged hiccups.
  • Migraine headaches.
  • Hypertension (high blood pressure)

Measuring vagal tone

When we inhale the heart rate slightly speeds and slow down when we inhale, the vagus nerve controls the heart rate via electrical impulses to the heart’s sinoatrial node. Doctors can measure the vagal tone and cardiac health, with the difference between the inhalation and the exhalation heart rates—the more significant the difference, the higher the vagal tone, which is better for health.

Causes of low vagal tone

  • Excessive alcohol consumption
  • Overeating spicy food
  • Poor sitting posture or “tech neck” (see the previous post here)
  • Overstimulation of the vagus nerve can cause shortness of breath and prolonged hiccups.
  • Stress, fatigue, and anxiety can inflame the nerve (it’s a vicious cycle).

Benefits of high vagal tone

  • Ability to relax more quickly after a stressful event
  • Less anxiety
  • Better blood sugar regulation
  • Decreased risk of stroke and cardiovascular disease
  • In most cases lowers blood pressure
  • Better digestion because of proper production of digestive enzymes
  • Fewer migraines
  • Less likely to experience mood disorders or depression.

Self-help to improve vagal tone

The vagus nerve modulates the connection between respiration and heart rate, which means mind-body practices such as guided breathing exercises can slow heart rate and lower blood pressure.

A 2016 study reported that slow abdominal breathing also called diaphragmatic breathing was the most effective self-practice to increase vagal tone and increase wellbeing. Participants in right study effectively managed prehypertension and improved their stress response whether that was ; fight, flight freeze or faint using this simple activity. Regular deep breathing is the wellness secret integral to many mind-body practices; somatic movement, mindfulness meditation, yoga, tai chi, Qi Gong, some Pilates (sadly not all–yet) Its also used in chanting, repetitive prayer, used in guided imagery and by some singers too.

How breathing helps, here’s the science bit

Any deep, slow diaphragmatic breathing stimulates the vagus nerve, which in turn, activates the parasympathetic nervous system, remember thats the “rest-and-digest” part, it signals the heart to slow down, which calms the nervous system. The vagus nerve connects all of this signalling and triggers the neurotransmitter acetylcholine to release, which tells the lungs to breathe, literally giving us the breath of life.

Breathing exercise for the vagus nerve

If you feel under pressure, are stressing about a deadline or about to blow a fuse, or need to relax a little, try this simple and easy breathing exercise.

  • Inhale for a count of 5
  • Hold that breath for a count of 3
  • Exhale for a count of 6 or 7
  • Pause (wait) for a count of 3
  • Repeat until you feel back in control.

Tip: Breath in through your nose, out through the mouth. Exhale quietly and gently through your mouth, letting out as much air as you can.

Note: The body’s internal alarm system which activates a stress response is triggered by fast and shallow breathing, making the body think it’s under attack, getting it ready to react with a fight, flight, freeze, or fainting response.

Coming next, more about the Vagal nerve and your health


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