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. 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, the specific exercises to use, and how to build a consistent practice at your own pace.

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 (SNS), the sweaty-palmed, adrenaline-charged 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), 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 fibres 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, and in turn 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.

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 emphasise 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 forced deep breath.

Vagus Nerve Breathing Exercise: How to Start

The most effective way to activate the vagus nerve through breathing is to slow your breathing rate gradually and consistently over time. Research shows that slower breathing rates, particularly in the range of 5.5 to 6 breaths per minute, produce measurable improvements in HRV and vagal tone [1,5]. But this is a research finding, not a starting prescription. Individual progression and consistency matter far more than hitting a specific number immediately.

The goal is to begin where you are and reduce gradually.

If your baseline breathing rate is 18 breaths per minute, working toward 14 or 16 over several weeks is meaningful progress. If your baseline is 12, working toward 10 or 11 is the right focus. Even slowing by 1 to 2 breaths per minute, practised consistently, builds vagal tone over time.

Step-by-Step Vagus Nerve Breathing Exercise

This exercise uses nasal breathing with a focus on slow, diaphragmatic exhalation. Use it daily for 10 to 20 minutes.

1. Sit upright or lie down in a comfortable position. Close your mouth and breathe only through your nose throughout.
2. Place one hand on your belly. As you inhale, feel your belly rise. As you exhale, feel it fall. This confirms you are breathing from the diaphragm, not the upper chest.
3. Begin by breathing in for 4 seconds and out for 4 seconds. This is your starting point. If 4 seconds feels too challenging at first, start with 3 seconds. Anything slower than your normal breathing rate is a valid and effective starting point.
4. Focus on the exhalation. The vagus nerve releases acetylcholine during the out-breath, so make the exhale slow, complete and unhurried.
5. Over the following days and weeks, extend gradually. Move from 4:4 to 5:5, then to 5:6 or 6:6, only when each step feels comfortable and natural. There is no benefit to forcing a rate that creates tension or anxiety.
6. As you practise, notice the signs that the vagus nerve is activating: a slight feeling of drowsiness, increased watery saliva in your mouth, and warm hands as blood vessels dilate and circulation improves. If your mouth becomes dry or your hands feel cold, you are pushing too hard. Ease back.

Practise this exercise daily. Consistency over weeks and months is what builds lasting vagal tone and improved HRV. The Oxygen Advantage app includes a guided breath pacer to support this practice.

Other Methods of Vagal Activation

Because the vagus nerve connects to so many parts of the body, it can be activated via several routes beyond breathing. These can complement a breathing practice but are not substitutes for it.

Singing, humming and social connection

Singing, humming and gargling 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. In one study, significantly more nitric oxide 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 around 6 breaths per minute, which may explain part of their calming effect.

According to behavioural neuroscientist Dr. Stephen Porges, our interactions with other people can increase vagal tone and calm the sympathetic nervous system. Positive social connection is a direct input to the vagus nerve.

Meditation

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.

Sexual activity and the vagus nerve

In women, the vagus nerve directly connects to the cervix and uterus, and research suggests this pathway plays a role in sexual response. Scientists exploring involuntary vocal sounds during sex linked them with changes in breathing rate. Slow, deep vagal breathing may connect with the vagus nerve in this context. This is an area of ongoing research rather than a primary activation strategy, but it illustrates the breadth of systems the vagus nerve touches.

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 at your own pace, progressively reduced over time

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. If your HRV is lower after intensive training, you may be at higher risk of injury the next day. If your HRV is consistently elevated, it may indicate 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. Here is a closer look at the science behind specific questions.

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, allowing patients to maximise 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 sense.

In Oxygen Advantage we often use a prolonged exhalation to down-regulate the nervous system. Research consistently shows that slower breathing produces measurable HRV improvements. One study examined rates within a narrow range, comparing 6 and 5.5 breaths a minute, with different inhalation to exhalation ratios: 5:5 (equal) and 4:6 (longer exhalation).

The expectation was that longer exhalations would provide greater relaxation. But the results showed that breathing at 5.5 breaths per minute with an equal inhalation to exhalation ratio (5:5) increased HRV most significantly. It also improved blood pressure receptor function and enhanced vagus nerve activation most effectively [5]. This suggests that consistency of rhythm and pacing may matter as much as exhalation length.

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.

The connection across all these systems is slow, nasal, diaphragmatic breathing practised consistently. It 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.

How Do You Know If You Have Stimulated Your Vagus Nerve?

When you practise 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. Ease back to a slower rate that feels genuinely comfortable.

As you stimulate the vagus nerve, you may start to feel slightly drowsy. You may notice a slight increase in watery saliva in your mouth. Your hands will begin to feel warmer as blood vessels dilate and circulation improves. These are signs the PNS is activating.

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.

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Activate Your Vagus Nerve with Oxygen Advantage

To learn more about the vagus nerve and HRV, listen to 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 breathing course, download the free OA Breathing App, or find an Oxygen Advantage instructor near you.

You can read about the research into breathing rate and HRV in much more detail in Patrick McKeown's book, The Breathing Cure.

References

1. Russo MA, Santarelli DM, O'Rourke D. The physiological effects of slow breathing in the healthy human. Breathe (Sheff). 2017;13(4):298-309.
2. 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.
3. Lehrer PM, Gevirtz R. Heart rate variability biofeedback: how and why does it work? Frontiers in Psychology. 2014;5:756.
4. 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.
5. 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.