The Vagus Nerve

The Vagus. The Control Tower

The purpose of this article is to show the importance of being aware of the silent interactions of mind and body; how they can cause ill health if they get out of control and how it is possible to get control over the involuntary subconscious inner management systems.

It is hard to say that any organ of the body is more important than another but there are some of which we are very aware and know how to take care of them to protect our health. The circulatory, respiratory and the digestive systems are  functions of our bodies about which we all are reasonably conversant.

When it comes to the brain, many people will be less well informed. It may seem that there is little we can do to access or control the mind  in the way in which we can manage breathing or the digestive system or maintain the health of the heart and circulation. The vagus nerve is a point of access.

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How the brain communicates.

The brain communicates to the rest of the body by two nerve routes. It also communicates chemically by hormones.

The two nerve routes are the spinal column and a series of large nerves called the Cranial Nerves. The twelve cranial nerves are in the main involved directly with functions above and including the neck: sight, eye movement, hearing, swallowing, taste etc.

One of the twelve, the tenth is by far the longest, passing down through the neck to reach almost all the organs of the body. This is the Vagus Nerve. There are two – left and right – but the function is talked about as if there were only one.

Major nerves carry messages both from the brain and information back to the brain. 80% of the vagus fibres carry information from all the organs which it serves back to the brain. Can we use this as an access route to the subconscious?

The Autonomic nervous System.

There are two components to nerve control of the body: Voluntary, through which we can command actions such as walking, running etc.

There is also the involuntary or Autonomic nervous system, ANS, which manages all essential functions in a subconscious way. Heart, blood pressure, digestion breathing all carry on while we go about our normal life.

Defence is also managed by the ANS. A fright, jumping away from an oncoming car or pulling away from a hot object all happen often before awareness of the danger. They are immediate and involuntary reflex actions.

The ANS has two functions one is the fright or fight or stress, section. The other, which is the job of the Vagus Nerve,  is the relax, recover and digest, control.

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If we think for a moment of what is required in a fight or flight situation:

A profound change is required from the normal resting state of the body. this is the stress reaction and stressed state of the body systems.

  • Energy is required so insulin is stopped to allow increased blood sugar
  • More oxygen is necessary so the lungs work harder
  • Heart rate increases to carry the oxygen and nourishment
  • Glycogen is released from storage in the liver to increase energy supplies
  • Changes occur in the blood to enable quick clotting in case of injury
  • Blood is diverted from skin and the intestines to muscles
  • The inflammatory process is altered in case of injury also
  • Non-essential functions such as reproduction are shut down
  • Digestion is a non-essential function at this time
  • If one has to escape, it will be helpful for stomach, bowels and bladder to be empty.
  • Mental function is altered to enable subconscious management of the situation.

This list is not complete but it can be seen what stress is doing to the body. It is essential for reaction and safety in an emergency but must be resolved. If it is not, the route to illness is obvious. Each point in the list above can be associated with illnesses.

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The role of the vagus nerve is to return functions to normal or resting state.

The actions of the vagus nerve:

  • Reduce heart rate
  • Reduce blood pressure by restoring circulation to the skin and digestive system
  • Relax breathing
  • Restart digestion and blood sugar management
  • And to restore all other functions in the list above.
  • Enable the mind to return to normal function.


Before I discuss what we can do with this knowledge we should look at what recent research is revealing about the role of the vagus in the digestive tract. It has been known for some time that stimulation of the vagus is helpful in severe depression (as well as in epilepsy).

This is achieved by the release of serotonin. Serotonin is a chemical which enables transmission of nerve impulses across nerve junctions called a neurotransmitter. It also seems to double as a hormone in that it is released into the blood to enable some of its functions. It is produced in the brain to a limited extent.

Serotonin plays a role in  mood and social behaviour, appetite, digestion, obesity, sleep, memory and sexual desire and function. Antidepressant drugs called SSRIs work by keeping high levels of serotonin in circulation. Prozac is such a drug.

The vagus and intestinal bacterial flora.

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The intriguing areas of research involve the production of serotonin in the intestines and the role of bacteria which normally live in the gut. 90% of serotonin is made in the intestines. Bacteria have a role in the manufacture of 60% of this.

There is evidence of communication from the brain to these bacteria through the vagus nerve to stimulate or control this production.

There is yet to be understood connection between this bacterial presence, serotonin produced by it and the stimulation of memory by messages sent to the brain via the vagus. Defensive warnings about dangerous food for example. (Reference link at bottom of page)

Vagal function can therefore be enhanced by dietary and bacterial management. For example, antibiotics may change the bacterial balance in the intestine which can be  restored by probiotics.

So what can we learn from this.

The vagus has the opposite effect to all the functions listed above for the stress reaction. Chronic stress causes disease; some say up to 75% of all illnesses.

Relaxation techniques, breathing control and meditation enable us to access the vagal nerve fibres which return to the brain and stimulate it power to relax and reverse all the potentially ill effects of stress.

Joe Sullivan. Author of The Mind Diet:

Reference link click here Influence of Tryptophan and Serotonin on Mood and Cognition with a Possible Role of the Gut-Brain Axis