What is Vagal Tone?

Mary McMahon
Mary McMahon

Vagal tone is the degree of activity occurring within the parasympathetic nervous system, resulting in changes to the heart rate and other key functions. The vagus nerve, among many other things, inhibits the heart beat to keep the organ beating within a safe range. When the vagal tone increases or decreases, a patient will experience changes in heart rate, and these can sometimes become dangerous or even fatal.

Changes in the vagal tone correspond with changes in heart rate.
Changes in the vagal tone correspond with changes in heart rate.

When activity increases, patients experience bradycardia, where the heart slows down, because the inhibitory effect of the vagus nerve is stronger. Patients with decreased tone will develop tachycardia, a fast heart rate, because the nerve is not acting to suppress activity within the heart. This can be the result of a temporary situation, or a long term health problem. Sometimes, changes are not necessarily a sign of disease. Athletes, for example, have a higher vagal tone, and as a result will have a slow resting heart rate.

Medical tests can be run to discern any disorder involving the vagus nerve.
Medical tests can be run to discern any disorder involving the vagus nerve.

The vagus nerve experiences reflex reactions in response to certain physical stimuli, like being dashed with cold water or tensing the abdomen. Its goal is to keep the body in a state of homeostasis, where all internal systems are stable and running at a reasonable speed for the conditions. In response to some stimuli, vagal activity can decrease, allowing the heart to speed up. This may increase the flow of blood, facilitating the flight or fight response.

A diagram showing the vagus nerve.
A diagram showing the vagus nerve.

Medical professionals can use a variety of techniques to examine the level of influence being exerted by a patient's parasympathetic nervous system. This can include listening to the heart and running tests with various stimuli to see how the patient responds. If a patient appears to have a disorder involving the vagus nerve, the healthcare professional can look into possible causes and discuss treatment options with the patient. Some patients may be prone to issues like fainting because of changes vagal tone or the intensity of responses to stimuli.

After confirming a disorder of the vagus nerve, the doctor will discuss treatment options with the patient.
After confirming a disorder of the vagus nerve, the doctor will discuss treatment options with the patient.

Researchers also believe the vagus nerve can provide important information about stress levels. Fluctuations in tone may indicate rising or falling levels of stress, including chronic stress, where people's bodies may be stuck in a permanent state of heightened awareness. Understanding stress is important for treating conditions like post traumatic stress disorder and can help medical practitioners explore possible methods for treatment and management, including using medications and psychotherapy to help patients reduce stress levels and stay healthy.

Psychotherapy may be recommended in order to help patients learn to reduce stress.
Psychotherapy may be recommended in order to help patients learn to reduce stress.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


Is there a cure?


A friend of mine who works with children with autism told me about some recent research. The study seemed to indicate that massaging an autistic child can improve social interaction, facial expression, and sounds.

The vagal nerve starts in the brain, then to the heart, the gut, ears and mouth - that's amazing.

They don't know for sure if this is true for infants, but for people who have low vagal tone also have high levels of cortisol hormone and lower levels of dopamine and serotonin in their brains.

Research is still being done to show how much massage sessions on autistic children can help them.


Stress is being found to be a big factor in many health situations. The heart is definitely affected by stress, both on a temporary basis and chronically.

Some people, including myself, are "hot reactors." Our systems are on high alert when a real upsetting situation is happening, or a perceived danger causes a "fight or flight" reaction. Heart rate and blood pressure goes up.

The vagal tone decreases when this stimulation of the parasympathetic nervous system is going on.

Chronic stress can also affect the vagal tone of the heart in a more complex way. Many of us need to find ways to decrease stressful reactions of our bodies.


My mother’s physician uses a process called vagal nerve stimulation to treat her severe depression. It sends electrical impulses to her brain that help improve her symptoms. Her doctor tried this treatment because her medication did not help her at all.

The vagus nerve is actually two nerves on either side of the body. Each one runs from the abdomen up to the brainstem through the chest and neck.

Her doctor implanted a pulse generator into her chest. He connected the left vagus nerve in her neck to the pulse generator by running a wire under her skin. The generator sends electrical impulses through the nerve to her brain.

The electrical signals affect her brain’s mood center. She really does seem to be in a better mood after a treatment.


My sister’s doctor performed an ECG on her after she complained of chest pain and heart palpitations. He had seen in his initial exam that her heart rate was very rapid.

He determined that she had tachycardia. Her heart abnormality caused it to emit rapid electrical signals. Before trying any medications or surgery, he recommended something called vagal maneuvers.

Whenever she experienced a fast heartbeat, she was supposed to do one of these maneuvers to affect her vagus nerve. The various actions included placing an icepack on her face, coughing, or pushing as though she were about to defecate.

These vagal maneuvers actually worked for her. If they had not, she likely would have had to take medication.


When my brother was 34, he developed bradycardia when his vagal tone increased. His heart slowed to under 60 beats per minute. Because of this, his brain was not getting the oxygen it needed.

He frequently had spells of near-fainting. He felt dizzy, weak, and tired most of the time, and he had trouble catching his breath. When he started to get chest pains, his wife made him go to his doctor.

While trying to determine the cause of his bradycardia, his doctor found that he had an electrolyte imbalance. Since electrolytes are required for the conduction of electrical impulses, this imbalance caused his vagal tone to increase.


My vagal tone had decreased in response to my chronic state of stress. My heart rate and blood pressure were higher than they should have been, and I knew my health was declining.

I worked in a stressful environment. I constantly had multiple deadlines to meet, and most of the work was being given directly to me, rather than divided among the workers. I knew I had to get out of there to save my heart as well as my mind.

I left as soon as I found a less stressful job. I have noticed in the three months since I quit that I am almost calm, and that is a sensation I haven’t felt in the six years since I started my old job. My vagal tone has increased, and my pulse and blood pressure are now normal.

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