HRV and the Vagus Nerve - Hanu HRV
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HRV and the Vagus Nerve

If you struggle to calm your anxiety or suffer from chronic daily bouts of stress, your vagal tone may be hindered. Your vagal tone is representative of the health and activity of the most crucial nerve branches in the body – the vagus nerves. 

Toning your vagus nerve can help improve your mental and physical health profoundly. What’s better is that heart rate variability readings can help you get valuable insights into how activated your vagus nerve is at any given moment. While heart rate variability is not a direct measurement of vagal tone per se, it can offer insights into how activated or deactivated the nerve is under certain situations and circumstances.

“By developing an understanding of the workings of your vagus nerve, you may find it possible to work with your nervous system rather than feel trapped when it works against you.” — Dr. Arielle Schwartz, Clinical Psychologist.

What is the Vagus Nerve? 

The vagus nerve is the 10th cranial nerve that begins in the lower back part of the brain. This nerve cluster is arguably the most essential branch of nerves in the body.

In Latin, “vagus” actually means wandering. This description is very fitting, as the vagus nerve is the longest cranial nerve that wanders down from the brain into the spinal cord. It runs from the brain stem down to the colon and powers many unconscious processes. These processes include digestion, breathing, and the unconscious functioning of many of your internal organs. The vagus nerve innervates (connects) to all major organ systems, including the lungs and heart. 

It’s worth paying attention to the “tone” of your vagus nerve. Vagal tone is an internal biological process that represents vagal nerve activity. Increasing your vagal tone activates the parasympathetic nervous system, which is responsible for calming the body after a stressor. Having a higher vagal tone means your body better adapts to stress and training adaptation through the activation of the vagus nerve. This adaptation leads to enhanced stress resiliency and an ability to calm your sympathetic nervous system (fight or flight system) when activated.

Vagal Tone Quote

The Importance of Vagal Tone and HRV 

The vagus nerve triggers the parasympathetic nervous system, which is the part of your autonomic nervous system that helps you calm down and rest. It counteracts the systems in your body that are activated when you feel stressed. Think adrenaline, increased heart rate – the classic mechanisms of sympathetic arousal. 

When you activate the parasympathetic nervous system via the vagus, this process is mediated by a neurochemical called acetylcholine. Acetylcholine is responsible for reducing nerve firing and can slow the system down (i.e., lowered HR, decreased respiration rate, etc.).

A healthy, functioning autonomic nervous system is about having the ability to prime the body for any stressor that it may encounter while also triggering the appropriate activation at any given time. Also, a faulty nervous system can occur through an inability to turn off this “fight or flight mode,” so having the ability to deactivate the stress response is also vital in identifying a healthy vagal tone. Measuring heart rate variability can help you identify your body’s ability to maintain autonomic regulation, as a higher variability speaks to a healthy vagal tone. 

If you know how to do so, the vagus nerve can function as a magic button you can press to improve your body’s ability to manage stress healthily. 

The vagus nerve controls heartbeat activity, so heart rate variability and vagal tone go hand in hand. Having a healthy “vagal tone” means having an adaptive, resilient, and normally functioning autonomic nervous system and cardiovascular system. A healthy vagal tone can be identified when the sympathetic and parasympathetic nervous systems perform their respective jobs to keep the body ready for action while still relaxing, resting, and healing when needed. 

Vasovagal Syncope

One example that illustrates the profound relationship between heart rate variability and the vagus nerve is a condition known as vasovagal syncope. 

Vasovagal syncope is a condition that results from the misfiring of vagal nerves responsible for diverting blood to the brain and managing heart rate. These misfires can cause your blood vessels to open and your heartbeat to slow down simultaneously. The result is blood pooling in your legs and a drop in blood pressure, preventing enough blood from reaching the brain. If this perfect storm occurs, you can briefly lose consciousness. This condition is prevalent in children and young adults. 

Vagal Tone and Mental Health

In 2010, researchers discovered a positive relationship between a good vagal tone, positive emotions, and good physical health. This relationship tells us that the more you increase your vagal tone, the more your physical and mental health will improve. Looking a little deeper, we can infer that having an excellent vagal tone is your body telling you that you are keeping a good relationship with stress in your life. 

Gut Brain Axis

The Role of the Gut-Brain Axis

Another critical aspect of the vagus nerve is that it forms a link between the gut and the brain, playing a role in what scientists call the gut-brain axis. Experts have been studying the gut-brain axis to look for connections between stress and conditions such as arthritis and depression. 

Studies have shown that conditions that interrupt the gut-brain axis, such as irritable bowel syndrome and inflammatory bowel disease, lead to inflammation. This inflammation is detrimental to gastrointestinal and autonomic nervous system function. Since HRV readings inform us of the health of these aspects of the nervous system, HRV, the vagus nerve, and gut health are inextricably linked.

Can Vagal Tone Be Measured?

Your vagal tone can be measured by tracking and analyzing your heart rate, breathing rate, and heart rate variability (HRV) altogether. Your vagal tone is typically higher when your heart rate variability (HRV) is high. 

If your vagal tone is suppressed, don’t worry – you can take steps to increase it by stimulating your vagus nerve. Increasing your vagal tone will allow you to respond more effectively to life’s emotional and physiological demands and maintain a healthy, balanced lifestyle. 

So how can you achieve a healthier vagal tone and autonomic balance?

Here are a few tips:

How to Increase Vagal Tone 


Engaging in conscious breathwork exercises is a great way to trigger the vagus nerve and improve vagal tone. The theory here is to use breathing to consciously develop a deeper connection between your mind and your body. When doing breathwork, don’t focus on sensory inputs, such as sound, light, and other distractions, and instead focus on simply being still. 

While doing breathwork, you can slowly begin to do a “body scan” that will help you feel how your body is doing and give you the ability to do a self-check-in. Research tells us that even engaging in just a few minutes of this centering breathwork benefits the health of the parasympathetic nervous system and your vagal tone

We recommend closing your eyes and silently focusing your attention on your breaths. If a thought comes up, notice it and return to your breath. As you do it more, you can slowly scan throughout your body to check in with yourself and get out of your mind for a few minutes. 

This exercise is perfect for increasing emotional control and improving your mental well-being. Using a Hanu device to measure HRV is a great way to look into how these exercises are helping you to cultivate a healthier vagal tone. 

Intermittent Fasting

As we learned earlier, there is an undeniable connection between heart rate variability, the vagus nerve, and your gut health. One of the best things you can do for your gut health is to engage in intermittent fasting. 

Intermittent fasting is a mild form of fasting that gives your digestive system a break from time to time. It has been shown to reduce inflammation, improve immune health, and improve vagal tone. Digestion is a parasympathetic activity. Giving your body a break from digestion will provide more energy for recovery and rejuvenation.

The simplest way to engage in intermittent fasting is to abstain from eating for a few hours before bed or skip breakfast first thing in the morning. Either of these scenarios creates about a 12-14 hour fasting window that can provide incredible benefits to your health and overall wellbeing

Circadian Rhythm

Get Into a Rhythm

Your circadian rhythm, which is your body’s natural time clock, is another thing that you can use to tone your vagus nerve. Staying on a regular schedule and engaging in activities such as light exposure and a regular sleeping schedule reinforce these patterns in your body. 

These schedules and activities promote healthy cortisol levels and sleeping patterns. We recommend getting in at least 20 minutes of sunlight first thing in the morning and watching the sunset to help reinforce these natural patterns in your body and tone your vagus nerve to be more balanced. 

Get the Right Amount of Exercise 

When improving vagal tone, the key is to optimize the interaction between the heart and the nervous system. Not training enough AND overtraining can work against you, injuring your immune system and throwing off your vagal tone. You should aim for a sweet spot when you train, where you are challenging yourself, learning about your limits, and listening to your body’s signals. You can use Hanu’s HRV data to understand how well your body responds to your training plan and whether or not you need to find more balance in your workout routine. 

Vagus Nerve Stimulation 

Experts believe the vagus nerve might form a link between depression, metabolic disease, and heart disease, as we have explored. Researchers say that a technique known as vagal nerve stimulation (VNS) can potentially help with various health issues, including multiple sclerosis, Alzheimer’s disease, headaches, rheumatoid arthritis, and even anxiety and stress disorders. 

Vagus nerve stimulation involves using a device that stimulates the vagus nerve through targeted electrical impulses. In traditional vagus nerve stimulation, a device is surgically implanted under the skin on your chest, and a wire is threaded under your skin connecting the device to the left vagus nerve. When activated, the device sends electrical signals along the left vagus nerve to your brainstem, directing signals to specific areas in your brain. The right vagus nerve isn’t used because it presents dangers to the health and activity of the heart. 

While this is a more invasive and less natural approach than the other points on this list, recently, there have been more noninvasive vagus nerve stimulation methods that don’t require surgical implantation. These devices have been approved in Europe to treat epilepsy, depression, and pain. The Food and Drug Administration recently approved a noninvasive device that stimulates the vagus nerve to treat cluster headaches in the United States.

The FDA has also approved vagus nerve stimulation to treat depression in people who have treatment-resistant depression, those who haven’t improved after trying four or more medications, and those whose doctors recommend continuing standard depression treatments and vagus nerve stimulation.

Eat Omega-3 Fatty Acids 

Researchers have also discovered that omega-3 fatty acids can increase vagal tone and heart rate variability. Studies have shown that they reduce heart rate and increase heart rate variability, likely stimulating the vagus nerve. So be sure to eat plenty of foods rich in Omega 3’s, such as salmon, oysters, flax seeds, chia seeds, and walnuts.

Cold and Hot Therapy

Cold and Heat Exposure 

Exposing your body to stressors such as an ice bath or a sauna can help to trigger your body’s adaptogenic response system and improve your vagal tone. Studies have shown that purposeful exposure to these stressors can help to decrease depression symptoms, reduce the risk of cardiovascular disease, trigger cardiac-vagal activation, and increase heart rate variability.   

Control Your Vagal Tone, Improve Your Health

You don’t have to be controlled by your body and mind. Understanding the role of the vagus nerve and HRV gives you the power to gain control over your health and well-being on a much deeper level. By stimulating the vagus nerve, you can send a message to your body that it’s time to relax and de-stress, leading to long-term improvements in mood, well-being, and resilience. 

If you are looking for a comprehensive system that can assist you in your efforts to enhance your vagal tone, Hanu is your all-in-one tool. Using a biofeedback device that provides heart rate variability data can give you a candid look at how well your stress response system is functioning and the state of your vagal tone.

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