How to Stimulate the Vagus Nerve with Breathing Exercises
The vagus nerve is the body's main relaxation pathway. It controls heart rate, digestion, stress response and recovery.
You can stimulate it deliberately through slow, diaphragmatic breathing, specifically at a rate of around 5.5 to 6 breaths per minute. This activates the parasympathetic nervous system, releases acetylcholine (the body's calming neurotransmitter), and measurably improves heart rate variability (HRV).
This article explains what the vagus nerve is, how breathing stimulates it, and the specific exercises to use.
If you are like most people, you do not have an intimate anatomical knowledge of your nervous system. But you are probably familiar with your "fight or flight" response, the sympathetic nervous system, or SNS. The sweaty palmed, adrenaline-charged, gut-twisting physical stress reaction.
The SNS is the evolutionary mechanism that primes you to fight, run or freeze when danger strikes. It has its uses.
But when it activates too often, you can end up chronically stressed. Stress floods the body with hormones, shuts off important brain functions, and contributes to inflammation. It is a risk factor in 75 to 90% of human diseases.
Your stress response is part of your autonomic nervous system (ANS). This is the system that takes care of automatic functions like breathing rhythm, heart rate, digestion, and blood pressure.
To maintain a stable internal environment, the ANS has two branches. One to up-regulate, and one to down-regulate.
The sympathetic nervous system (SNS) up-regulates. The branch that balances it is the parasympathetic nervous system (PNS), the "rest and digest" response that counters "fight, flight and freeze."
Constant interplay between the two keeps the body in homeostasis. Stress can be simply defined as anything that disrupts that balance.
What Is the Vagus Nerve and Why Does It Matter?
The vagus nerve is one of 12 cranial nerves in the body. Cranial nerves arise directly from the brain. Think of them like postal routes, delivering information between body and brain.
How the Vagus Nerve Controls the Parasympathetic Nervous System
The vagus nerve is the tenth cranial nerve and the longest. It travels right down to the colon, connecting with all the major organs along the way.
Most of its nerve fibers carry information from the body back to the brain. The vagus nerve is the main driver of the PNS. It controls your "rest and digest" functions.
Crucially, you can stimulate it on purpose, whenever you want to. You can also measure the results using heart rate variability (HRV). The more consistently you do this, the better your health will be.
What Is Vagal Tone and How Does It Affect Your Health?
The term "vagal tone" describes how well the parasympathetic nervous system functions. Think of it like muscle tone. Is it strong and flexible, or weak and rigid?
When the "fight or flight" response is stuck in always-on mode, sympathetic activation is high and parasympathetic tone will be low.
Good vagal tone means your PNS is working and your body is in balance. Low vagal tone and chronic stress are closely linked.
How to Measure Vagal Tone Using Heart Rate Variability (HRV)
Vagal tone can be measured using heart rate variability (HRV). The heart does not beat like a metronome. It constantly slows and speeds up as it adjusts to conditions inside and outside the body.
These fluctuations in heart rate are called HRV. The more variability between beats, the more adaptable your body is.
When vagal tone is good, your heart rate changes as you breathe. It speeds up during inhalation and slows during exhalation. This is called respiratory sinus arrhythmia (RSA), the heart in synchronicity with the breath.
Scientists have reported a positive feedback loop between high vagal tone and wellbeing. The more you improve your vagal tone, the better your physical and mental health will be.
As with vagal tone, the higher your HRV, the healthier you are likely to be. Low HRV is linked with high levels of cortisol, the main stress hormone.
It is found in people who are older or unfit, and in many physical and mental illnesses including:
- Heart disease and stroke
- Cancer
- High blood pressure
- Alzheimer's and diabetes
- Depression, anxiety, panic disorder and PTSD
- Erectile dysfunction and sexual dysfunction
Low HRV is associated with early mortality. It can be passed on from mother to baby.
It can also occur in successful athletes who overtrain and sleep badly, and in otherwise healthy people who have dysfunctional breathing patterns.
Vagal tone in the heart is also closely linked to both breath and emotions, affecting interpersonal qualities such as empathy, emotional regulation and attachment.
HRV is easy to track and very possible to improve. This means you can improve your vagal tone, which means you can improve your health.
When vagal tone increases, it tends to improve long-term. Working to optimise your HRV will have an ongoing positive impact on your resilience, both physical and mental.
It is also a valuable measure for doctors because it allows them to quantify stress and susceptibility to stress-related illness based on physical parameters. In other words, it is not all in your head.
How Breathing Stimulates the Vagus Nerve
It is well established that slow breathing leads to relaxation. Yoga, meditation, and martial arts all share slow, controlled breathing practices for this reason.
During stress, breathing tends to speed up. Very fast breathing is the number one predictor of heart attacks in hospital patients.
Here is why slow breathing directly activates the vagus nerve:
- Slow nasal breathing engages the diaphragm, which is connected to the vagus nerve
- The diaphragm is also connected to the heart, so deep diaphragm movements effectively massage the heart from within
- Slower exhalations activate the PNS, the body's relaxation response, which is controlled by the vagus nerve
When you breathe out, the vagus nerve releases a neurotransmitter called acetylcholine. Acetylcholine causes blood vessels to dilate and slows the heart rate. It is also important for memory and cognition in the brain.
The vagus nerve is only active in this way during exhalation. This is why many yogic and functional breathing practices emphasize the out-breath. It is by breathing out slowly that we build vagal tone.
During slow breathing, carbon dioxide also builds up in the blood. CO2 makes the vagus nerve more sensitive, slows the pulse, and improves the blood-filling of the heart.
So both increased CO2 and extended exhalation are important signals. The good effects come during the slow exhalation, not when we "take a deep breath."
Vagus Nerve Breathing Exercises and Other Activation Methods
Direct vagus nerve stimulation is only possible using a small implanted electronic device, used for decades in conditions including epilepsy.
But there are many natural ways to stimulate the vagus nerve indirectly. Because the vagus nerve connects to so many parts of the body, it can be activated via several routes:
- Cold exposure
- Slow diaphragmatic breathing
- Vagus nerve massage
- Meditation
- Singing, laughing and humming
- Sex
Cold Exposure and the Vagus Nerve
Breathing expert Wim Hof suggests several ways to stimulate the vagus nerve. His method involves deliberate hyperventilation and exposure to cold.
Exposing your body to acute cold conditions, such as a cold shower or splashing cold water on your face, increases vagus nerve stimulation. As your body adjusts to the cold, sympathetic activity declines while parasympathetic activity increases.
It is true that submerging the face in cold water increases PNS activity. The vagus nerve is responsible for many movements of the mouth including chewing and swallowing.
According to behavioral neuroscientist Dr. Stephen Porges, we can change our mental state just by using the muscles in our face. Porges has published detailed research into the social functions of the vagus nerve. He says our interactions with others can increase vagal tone and calm the SNS.
Scientists have also shown babies with more expressive faces have higher vagal tone. The cosmetic treatment Botox, which minimises facial expression, works by preventing the release of acetylcholine.
Splashing cold water on the back of the neck can also activate the vagus nerve. One research paper suggests wetting the face and neck with cold water after exercise, which scientists think may balance the SNS and relieve stress on the heart.
However, research shows that full body cold water immersion can be dangerous. It can activate the SNS and PNS simultaneously, which can cause potentially fatal cardiac arrhythmia.
Vagal Breathing Techniques: How to Breathe to Activate the Vagus Nerve
The vagus nerve is closely connected with the breath. It releases relaxing acetylcholine during exhalation. Good vagal tone can be measured with HRV, which is linked to RSA, the heart and breath in sync. And you can improve HRV with slow diaphragmatic breathing.
Research across a wide variety of studies shows there is an optimum breathing rate for vagus nerve activation. At a breathing rate of between 4.5 and 6.5 breaths per minute, vagal tone improves.
Most research settles on 6 breaths a minute as ideal [1]. One study narrowed this down to 5.5 breaths per minute with an equal ratio of inhalation to exhalation.
Here is why this works. Breathing slower means you spend more time exhaling, so you spend more time in PNS dominance.
You secrete more acetylcholine. Your heart spends longer in its slow phase, giving it more time to fill with blood.
You activate the diaphragm, which is innervated by the vagus nerve. Air gets deeper into the lungs, giving more time to extract oxygen.
Carbon dioxide increases in the blood, dilating the blood vessels and improving circulation. Blood flow to the brain improves and has a calming effect.
Nitric oxide opens the blood vessels in the lungs. Conversely, low CO2 is known to trigger panic attacks.
You can read about the research into 6 breaths a minute in much more detail in Patrick McKeown's book, The Breathing Cure.
Meditation is another way to bring the body and mind into a calm state. Many forms of meditation involve conscious breathing. Scientists discovered that during transcendental meditation, breathing can slow almost to a stop.
When you bring your body to a calm state, the vagus nerve feeds this calm back to the brain, the SNS deactivates and vagal tone increases.
Singing, humming, and gargling can all activate the vagus nerve via the muscles in the back of the throat. Humming also creates powerful vibrations in the nasal cavity, boosting production of nasal nitric oxide (NO).
In one study, significantly more NO was found in the nose after strong humming. Scientists have also found a connection between vagal tone and chanting. The mantra om-mani-padme-hum and the Latin rosary prayer both reduce the breathing rate to 6 breaths per minute.
What Is the Link Between Sex and Vagus Nerve Massage?
In women, the vagus nerve directly connects to the cervix and uterus, which means penetrative sex massages the nerve.
The vagus nerve innervates the voice box and throat too. Scientists exploring involuntary vocal sounds during sex linked them with hyperventilation. Slow, deep vagal breathing may connect with the vagus nerve to enhance female orgasm.
How to Increase Vagal Tone with Breathing
You can influence your vagus nerve using the Oxygen Advantage breathing exercises. These focus on:
- Nasal breathing
- Light breathing
- Deep diaphragmatic breathing
- Slow breathing
A home HRV tracker used alongside breathing exercises can give direct feedback about your vagal tone. There is no ideal baseline reading. The key is to be able to change your HRV using the breathing exercises. Higher is not always better.
For a quality HRV device, look at products in the $300 range. The Lief Therapeutics wearable ECG, the Polar H10 Chest Strap with the Elite HRV app, BioStrap, Oura Ring, WHOOP Strap, and HeartMath Inner Balance or emWave2 are all reliable options.
If possible, work with a certified breathing instructor to understand what changes in HRV mean for you.
For instance, if your HRV is lower after intensive training, you may be at higher risk of injury the next day. If your HRV is consistently high, you may be experiencing overtraining syndrome. This information can be invaluable when adjusting your training load.
Vagus Nerve Breathing: What the Research Shows
We have covered the functions of the vagus nerve and looked at how to build vagal tone. Now it is time to answer some more specific questions about how it impacts your health.
What Is the History of Vagus Nerve Research?
The chemical messenger released by the vagus nerve was identified in 1913 by English chemist Arthur Ewins and pharmacologist Sir Henry Hallett Dale.
Then in 1921, Otto Loewi found that activation of the vagus nerve triggered it to secrete a substance he called Vagusstuff. Vagusstuff, which turned out to be acetylcholine, caused the heart rate to slow, simulating activation of the parasympathetic nervous system.
Loewi and Dale were jointly awarded the Nobel Prize in Physiology or Medicine in 1936 "for their discoveries relating to chemical transmission of nerve impulses."
What Is HRV Biofeedback and How Does It Help?
In the 1990s, research psychologist Paul Lehrer devised heart rate variability biofeedback (HRVB). The main idea was to slow down the breath to get beat-by-beat heart rate data. This allowed patients to maximize RSA, synchronising heart rate and breathing pattern.
HRVB reduces stress in otherwise healthy people [2] and can improve athletic performance [3].
It has been used to help conditions as wide-ranging as asthma, COPD, irritable bowel syndrome, fibromyalgia, hypertension, cardiac rehabilitation, chronic muscle pain, anxiety, depression, PTSD and insomnia.
The improvements in gas exchange from HRVB training can also reduce symptoms of respiratory diseases, relieve stress-induced hyperventilation, and restore balance in the autonomic nervous system [4].
Should You Exhale Longer Than You Inhale for Vagus Nerve Stimulation?
Traditions such as yoga teach slow, deep breathing with an emphasis on longer exhalations. When you understand that the vagus nerve is stimulated during exhalation, this makes perfect sense.
In Oxygen Advantage we often use a prolonged exhalation to down-regulate the nervous system.
Countless trials have found that 6 breaths a minute is optimal for a wide range of reasons. But these often compared very different breathing rates. One study examined rates within a much narrower range, 6 and 5.5 breaths a minute, and came up with more specific guidance.
Scientists tested different inhalation to exhalation ratios: 5:5 (equal) and 4:6 (longer exhalation). The expectation was that longer exhalations would provide greater relaxation and a bigger increase in HRV.
But the results showed that 5.5 breaths per minute with an equal ratio of inhalation to exhalation (5:5) increased HRV most significantly. It also improved blood pressure receptor function and enhanced vagus nerve activation most effectively [5].
Can Vagus Nerve Breathing Lower Blood Pressure?
The blood pressure receptors, known as the baroreflex, control blood pressure by managing flow. When blood pressure increases, the baroreflex slows the heart. When it decreases, the heart rate increases to raise levels back to normal.
Blood pressure also fluctuates constantly when you breathe, due to pressure changes in the chest.
When the breath-to-heart-rate ratio is optimised for blood gas exchange, the baroreflex is at its most efficient. You can use slow breathing to increase HRV via the vagus nerve, and an HRV tracking device to strengthen your baroreflex over time [3].
Baroreflex sensitivity is also linked to CO2 sensitivity. You can reduce your sensitivity to CO2 by increasing your BOLT score.
A BOLT score above 25 seconds indicates a functional baroreflex, a slower resting heart rate, and better vagal tone. You can learn how to measure your BOLT score in our step-by-step guide here.
The connection across all these systems is slow breathing at 6 breaths per minute. Slow breathing stimulates the baroreceptors, makes the heart rate more flexible, and awakens the reactivity of the vagus nerve.
It shifts the autonomic nervous system away from "fight or flight" toward an open, relaxed, and socially oriented state. Allowing you to thrive on a physical, mental, and social level.
Why Is Slow Breathing Difficult and How Do You Start?
Yes, it is normal to find slow breathing uncomfortable at first. Some people even find it stressful to bring attention to the breath.
There is a physical reason too. When you slow your breath, you breathe a lower volume of air per minute. This is likely to result in feelings of air hunger, especially if your sensitivity to blood CO2 is high.
If you want to begin a practice of 5.5 or 6 breaths per minute, slow your breath gradually. Start by breathing in for 3 seconds and out for 3 seconds.
If that feels too challenging, begin with 2 seconds. Anything slower than your normal breathing rate is a great start.
How Do You Know If You Have Stimulated Your Vagus Nerve?
When you practice the breathing exercises, listen to your body. If you start to feel stressed, if your mouth becomes dry, or if your hands feel cold, you are pushing too hard and activating your stress response.
As you stimulate the vagus nerve, you may start to feel slightly drowsy. You may also notice a slight increase in watery saliva in your mouth. Your hands will begin to feel warmer as blood vessels dilate and circulation improves.
Throughout the day, bring your attention to your breath. Breathe through your nose, slowly and low into the belly.
In a fast-paced world, slow breathing becomes an essential element of self-care. The choice is yours. Stay stressed, or take some time today to slow down and tap into your vagus nerve, improving your resilience and long-term health.
Breathe in, 2, 3, 4, 5, 6, out 2, 3, 4, 5, 6.
To learn more about the vagus nerve and HRV, check out our podcast with OA founder Patrick McKeown and HRV specialist Dr. Jay Wiles.
If you are interested in trying the OA method for yourself, why not try our online course, download the free OA Breathing App or find an Oxygen Advantage® instructor near you.
References
- Russo MA, Santarelli DM, O'Rourke D. The physiological effects of slow breathing in the healthy human. Breathe (Sheff). 2017;13(4):298-309.
- Vaschillo E, Lehrer P, Rishe N, Konstantinov M. Heart rate variability biofeedback as a method for assessing baroreflex function: a preliminary study of resonance in the cardiovascular system. Applied Psychophysiology and Biofeedback. 2002;27(1):1-27.
- Lehrer PM, Gevirtz R. Heart rate variability biofeedback: how and why does it work? Frontiers in Psychology. 2014;5:756.
- Lehrer P, et al. Voluntarily produced increases in heart rate variability modulate autonomic effects of endotoxin induced systemic inflammation: an exploratory study. Applied Psychophysiology and Biofeedback. 2010;35(4):303-315.
- Lin IM, Tai LY, Fan SY. Breathing at a rate of 5.5 breaths per minute with equal inhalation-to-exhalation ratio increases heart rate variability. International Journal of Psychophysiology. 2014;91(3):206-211.