Vagal Tone: What It Is, How It Impacts Our Health, & How To Improve It
"The vagus nerve is like a magic wand we can use to influence how we feel and how our body responds to stress."
—Dr. Arielle Schwartz
“Vagal tone” sounds like ominous sci-fi lingo but it’s something that plays a huge role in our health. Vagal tone refers to the balance of activity between the parasympathetic and sympathetic nervous systems through the vagus nerve. This balance in the vagus nerve plays a vital role in regulating a wide range of bodily functions, including heart rate, digestion, and immune response.
In recent years, there has been growing interest in the vagus nerve as a potential target for therapeutic interventions. Studies have shown that stimulating the vagus nerve can have a number of beneficial effects, including reducing stress, improving mood, and boosting the immune system.
Let’s dive into what vagal tone is and how it impacts our health.
What Is Vagal Tone?
The vagus nerve, also known as the tenth cranial nerve or CN X, is a critical component of the autonomic nervous system, playing a multifaceted role in regulating various physiological functions within the human body. Vagal tone, which is a measure of the vagus nerve's activity, is an important indicator of the nerve's health and functionality. As the longest cranial nerve, the vagus nerve originates in the medulla oblongata of the brainstem and extends through the neck and chest, branching out extensively to innervate multiple organs and tissues (hence, “vagus” which is Latin for “wandering”).
The vagus nerve conveys vital sensory and motor information between the brain and several organs, including the heart, lungs, digestive tract, and various glands. It serves as a vital communication highway, connecting the brainstem to the rest of the body and facilitating bi-directional neural signaling.
The afferent fibers of the vagus nerve transmit sensory information from organs such as the heart, lungs, and gastrointestinal tract back to the brainstem, enabling the brain to monitor physiological parameters and maintain internal equilibrium. About 90% of the fibers of the vagus nerve are afferent.
The efferent fibers of the vagus nerve extend from the brainstem to innervate target organs, providing motor output that regulates bodily functions. Notably, the vagus nerve influences heart rate through its connection to the sinoatrial node, known as the "pacemaker" of the heart, and it also innervates the smooth muscles of the digestive tract, contributing to peristalsis and digestive secretions. About 10% of the fibers of the vagus nerve are efferent.
The vagus nerve and the Hypothalamic-Pituitary-Adrenal (HPA) axis are interconnected through complex bidirectional communication, influencing each other's activity and function, thus playing essential roles in the body's stress response and autonomic nervous system regulation.
What Does The Vagus Nerve Do?
The vagus nerve, a prominent player in the autonomic nervous system, bestows an array of profound benefits to the human body. This cranial nerve, also known as CN X, showcases remarkable clinical significance in regulating physiological processes, mental health, and overall well-being. Let us delve into the vagus nerve's clinical intricacies and unveil its exceptional advantages.
Autonomic Regulation
At the heart of the autonomic nervous system, the vagus nerve takes center stage in orchestrating the parasympathetic division. This division stands as the champion of the body's rest and digest response, counterbalancing the sympathetic division's fight-or-flight mechanism. Through its extensive neural connections, the vagus nerve exerts profound control over vital functions, including heart rate, respiratory rate, gastrointestinal motility, and glandular secretions. By steering the body into a state of relaxation and equilibrium, the vagus nerve fosters optimal physiological functioning.
Cardiac Effects And Cardiovascular Health
Among its myriad of contributions, the vagus nerve plays a pivotal role in influencing heart rate and rhythm. It communicates with the sinoatrial node, the cardiac pacemaker, to regulate the heart's rhythm and maintain appropriate heart rate variability. Vagal tone holds remarkable clinical importance, as higher vagal tone is associated with improved cardiovascular health and decreased risk of cardiac events. Through its cardioprotective effects, the vagus nerve is a guardian of heart health, promoting longevity and resilience against cardiovascular disorders.
Gastrointestinal Harmony And Digestive Well-being
The vagus nerve extends its influence to the gastrointestinal tract, spearheading digestive processes crucial for nutrient assimilation and energy balance. By innervating the smooth muscles of the digestive system, it oversees peristalsis, which propels food along the digestive tract, and regulates secretions that facilitate the breakdown and absorption of nutrients. This intricate neural control enhances gastrointestinal harmony, aiding in digestive efficiency and mitigating gastrointestinal disturbances. Moreover, the vagus nerve's involvement in the gut-brain axis establishes a crucial link between the gut and mental health, shaping the emerging field of psychogastroenterology.
Mental Health And Emotional Equilibrium
Beyond its impact on physiological functions, the vagus nerve casts its benevolent influence on mental health and emotional equilibrium. Through its parasympathetic modulation, the vagus nerve fosters a sense of calm and relaxation, contributing to stress reduction and resilience against psychological distress. Enhanced vagal tone has been associated with improved mood, reduced anxiety, and better coping mechanisms in the face of challenges. Moreover, the vagus nerve's interactions with the limbic system and prefrontal cortex play a vital role in emotional regulation, establishing a profound link between vagal health and mental well-being.
Anti-Inflammatory And Immunomodulatory Effects
In the realm of immunity, the vagus nerve emerges as a masterful conductor of anti-inflammatory processes. It possesses the ability to dampen excessive immune responses and inflammation through the cholinergic anti-inflammatory pathway. By releasing acetylcholine, a neurotransmitter with anti-inflammatory properties, the vagus nerve exerts regulatory control over immune reactions, potentially offering therapeutic avenues for managing inflammatory disorders.
Ways The Vagus Nerve Can Be Damaged
Here are some of the causes of vagus nerve damage:
Trauma: The vagus nerve can be damaged by a blow to the head, neck, or chest.
Tumors: Tumors that grow in the neck or chest can press on the vagus nerve and cause damage.
Infections: Infections, such as Lyme disease or meningitis, can also damage the vagus nerve.
Autoimmune diseases: Autoimmune diseases, such as Guillain-Barre syndrome, can attack the vagus nerve and cause damage.
Medications: Some medications, such as chemotherapy drugs, can damage the vagus nerve.
Symptoms Of Damage To The Vagus Nerve
Damage to the vagus nerve can cause a variety of symptoms, depending on the area of the nerve that is affected. Some common symptoms of vagus nerve damage include:
Heart problems: Heart rate irregularities, such as bradycardia (slow heart rate) or tachycardia (fast heart rate), and fainting (a.k.a.
Vasovagal syncope)
Digestive problems: Constipation, diarrhea, bloating, nausea, and vomiting
Respiratory problems: Shortness of breath, difficulty swallowing, and hoarseness
Speech problems: Difficulty speaking or a change in voice quality
Taste problems: Loss of taste or a change in taste perception
Pain: Pain in the face, neck, chest, or abdomen
Heart problems: The vagus nerve plays a role in regulating heart rate and rhythm. Damage to the vagus nerve can cause heart rate irregularities, such as bradycardia (slow heart rate) or tachycardia (fast heart rate). In some cases, vagus nerve damage can even lead to fainting.
Impairments of various reflexes associated with the vagus nerve:
The gag reflex: This reflex is triggered when something touches the back of the throat. It causes the back of the tongue to rise and the vocal cords to close, which can lead to gagging or vomiting.
The cough reflex: This reflex is triggered when something irritates the airways. It causes the diaphragm and other muscles in the chest to contract, which forces air out of the lungs.
The baroreflex: This reflex is triggered by changes in blood pressure. It causes the vagus nerve to send signals to the heart, which can slow down the heart rate or increase the heart rate.
The Bezold-Jarisch reflex: This reflex is triggered by pain or other stressors. It causes the vagus nerve to send signals to the heart, which can slow down the heart rate and lower blood pressure.
Factors Influencing Vagus Nerve Function
The optimal functioning of the vagus nerve, a cornerstone of the autonomic nervous system, is influenced by a multitude of clinical factors that bear significant implications for overall health and well-being. Understanding these critical determinants sheds light on the complex interplay that governs vagal activity and its potential impact on various physiological processes. In this clinical exploration, we unravel the key factors that sway vagus nerve function and their relevance in shaping health outcomes.
Stress: Chronic stress can lead to reduced vagal tone, disrupting the balance between sympathetic and parasympathetic nervous systems and affecting cardiac regulation, digestion, and mental health.
Chronic Illness: Chronic diseases like cardiovascular disease, diabetes, and autoimmune disorders may impact vagal activity, potentially contributing to disease pathophysiology and persistent inflammation.
The Gut-Brain Connection: Bidirectional signaling between the gut and brain, facilitated by the vagus nerve, influences physical and mental health. Altered gut microbiota may affect vagal function and contribute to gastrointestinal and mood disorders.
Breathing: Techniques like deep breathing can positively influence vagal tone, promoting relaxation and parasympathetic activity.
Physical Activity/Overtraining: Regular exercise has been linked to improved vagal function, enhancing cardiovascular and autonomic regulation while overtraining has been linked to vagal tone impairments.
Sleep Quality: Adequate sleep is essential for optimal vagus nerve activity, supporting mental and physiological balance.
Social Connections: Positive social interactions and strong social support have been associated with increased vagal tone and emotional well-being.
Inflammation: Vagal pathways play a role in regulating immune responses, suggesting the potential for vagal-based anti-inflammatory therapies.
Neurological Disorders: Conditions like epilepsy and migraine have been linked to vagal disturbances, emphasizing the nerve's relevance in neurological health.
Low Acetylcholine: Acetylcholine is a neurotransmitter that plays a crucial role in the communication between nerve cells and is involved in various physiological processes, including muscle contraction, memory, and the autonomic nervous system regulation. No surprise, it's the main neurotransmitter of the vagus nerve. Low acetylcholine symptoms include poor concentration, reading comprehension, difficulty following directions, and neuromuscular fatigue.
Techniques To Improve Vagal Tone
Breathwork: This is one of the most effective ways to stimulate the vagus nerve. When you breathe deeply, you are activating the parasympathetic nervous system, which is responsible for calming the body and mind. Control of the breath cannot be overstated and it has been shown to improve a number of areas of health from decision-making to pain management to managing anxiety. Breathwork is a simple and easy way to improve vagal tone.
Cold exposure: Exposing yourself to cold temperatures can also help to stimulate the vagus nerve. Research has shown that even simply applying cold to the neck increases HRV while decreasing heart rate. This is because cold temperatures activate the sympathetic nervous system, which in turn activates the vagus nerve. Cold exposure can be done by taking a cold shower, swimming in cold water, or simply spending time in a cold environment.
Exercise: Exercise is another great way to improve vagal tone. When you exercise, your heart rate increases, which sends a signal to the vagus nerve to slow down the heart rate. Exercise also releases endorphins, which have mood-boosting effects.
Probiotics: Probiotics are live bacteria that are similar to the bacteria that naturally occur in the gut. Probiotics have been shown to improve vagal tone, and they can be taken as supplements or found in fermented foods such as yogurt, kefir, kombucha, kimchi, and sauerkraut.
Laughter: Laughter is a great way to reduce stress and improve vagal tone. When you laugh, your heart rate and breathing rate increase, which sends a signal to the vagus nerve to slow down the heart rate. Laughter also releases endorphins, which have mood-boosting effects.
Singing, humming, and chanting: These activities all involve using the vocal cords, which are innervated by the vagus nerve. Singing, humming, and chanting can help to stimulate the vagus nerve and improve vagal tone. Dr. Julia Bartrop recommends this way of chanting:
“Hold the vowel (o) part of the ‘OM’ for 5 seconds then continue into the consonant (m) part for the next 10 seconds. Continue chanting for 10 minutes. Conclude with some deep breathing and end
with gratitude.
Massage: Massage is another great way to improve vagal tone. Massage can help to relax the body and mind, and it can also stimulate the vagus nerve.
Nutrition: A healthy diet that includes plenty of fruits, vegetables, and grass-fed whole foods can help to improve vagal tone while avoiding inflammatory foods and ingredients like seed oils. Good nutritional tactics include:
Taking care of your microbiome and eating fermented foods
Eating anti-inflammatories foods such as turmeric, leafy greens, fruits.
Getting enough fiber, at least 30 g per day.
Get enough acetylcholine. Acetylcholine is made from choline, which we get from diet, mostly animal-based foods (pasture-raised egg yolks, grass-fed meats, chicken) and spinach.
Sleep: Sleep is essential for overall health and well-being, and it is also important for vagal tone. When you do not get enough sleep, your body produces more stress hormones, which can damage the vagus nerve.
Manage stress: Stress can have a negative impact on vagal tone. There are many different ways to manage stress, such as exercise, meditation, and yoga. Find what works best for you and make it a part of your daily routine.
Spend Time In Nature: Research have shown that spending time in nature can help to improve vagal tone. This is likely due to the fact that nature is calming and relaxing, which can help to activate the parasympathetic nervous system. You can spend time in nature by going for walks in the park, hiking in the woods, or simply sitting in your backyard and enjoying the fresh air. One systematic review found that time in nature decreased perceived levels of stress in 5 our ot 6 studies and physiological stress in all of the 7 studies that they looked at.
Meditation: Meditation is another great way to improve vagal tone. Meditation involves focusing your attention on the present moment, which can help to calm the mind and body. There are many different types of meditation, so you can find one that works best for you.
Vagus Nerve Stimulator: The FDA has approved the use of vagal nerve stimulators for treating depression, epilepsy, and stroke recovery.
How Do You Measure Your Vagal Tone?
Measuring or testing the vagus nerve directly is a complex and invasive procedure typically reserved for clinical research or specific medical conditions, however, certain indirect methods can provide insights into vagal tone, which reflects the activity of the vagus nerve. The easiest way to get an approximation of vagal tone is through heart rate variability (HRV).
HRV is a widely used and accessible measure to estimate vagal tone. It assesses the variation in time intervals between successive heartbeats, reflecting the balance between sympathetic and parasympathetic nervous system activity. It's generally thought that high HRV suggests a strong vagal tone, while low HRV may indicate vagal dysfunction. Since vagal tone is so difficult to measure directly, measuring this correlation is difficult and has been shown to be more closely related to this parasympathetic "modulation" rather than "tone." Until there is a better way to measure this, I suggest the use of HRV, especially if you suspect you have dysfunction of the vagus nerve or if you have incurred a recent acute injury (brain injury, stroke, spinal cord injury, hospitalization, PTSD, etc.).
To learn more about HRV, read How To Improve Your HRV Score: 8 Ways According To Science and What is Heart Rate Variability (HRV) & 12 Things It Can Tell You.
Another more blunt way to assess the general state of your vocal tone is to look inside your mouth. Look in the back of your mouth and determine if your uvula (the hanging ball) is in the middle and if the arches and palate of the throat is symmetrical. Look here at different points of the day such as low-stress moments (after meditation, a bath, when going to bed) vs. high-stress ones (after a hard workout, stressful situations, etc.). Your vagus nerve is also linked to your voice. A monotone voice may indicate poor vagal tone.
What I Do
I've long been a proponent of HRV. While I have bouts of time when I use it (particularly when race training), this biofeedback has taught me what improves my HRV, and theoretically my vagal tone, such as drinking less and further away from bedtime, getting enough protein but not eating too much at meals, and taking cold showers. Read here for more of my lessons learned.
While I tend to optimize the low-hanging fruit: exercise, mental health, and sleep (most nights), I put some effort into the higher-hanging (?) fruit such as humming, gargling, and breathwork. I usually do these in the car during commutes but I'll incorporate them in activities with the kids and during walks as well (humming along to a song, for example).
Over the past few years, I've also taken steps to address specific challenges, such as my naturally monotone voice and limited lung capacity which may have a connection to my vagal tone.
Conclusion
The vagus nerve is a complex and important nerve that plays a vital role in many aspects of our health. It is involved in regulating heart rate, digestion, immune function, and even mental health. There are a number of things that can affect vagal tone, including stress, chronic illness, and gut health. However, there are also a number of things that we can do to improve vagal tone, such as deep breathing, yoga, and spending time in nature.
By understanding the vagus nerve and how it works, we can take steps to improve our overall health and well-being.
Here are some key takeaways from the article:
The vagus nerve is the longest cranial nerve in the body.
It has a wide range of functions, including regulating heart rate, digestion, immune function, and mental health.
Vagal tone is a measure of the activity of the vagus nerve.
Higher vagal tone is associated with better health outcomes.
There are a number of things that can affect vagal tone, including stress, chronic illness, and gut health.
There are also a number of things that we can do to improve vagal tone, such as deep breathing, yoga, and spending time in nature.
I hope this conclusion helps to summarize the key points of the article and leaves you with some actionable steps that you can take to improve your vagal tone.
Fun fact: The reason you get butterflies in your stomach.
When a person experiences strong emotions like nervousness or excitement, the brain's limbic system, which is responsible for processing emotions, sends signals to the autonomic nervous system, including the vagus nerve. These emotional signals can lead to vagal activation, affecting a variety of organs, including the stomach.
The vagus nerve innervates the stomach and gastrointestinal tract, influencing gut motility and digestive functions, and when we’re “emotionally aroused (excited, nervous, etc.) then this can lead to the sensation of "butterflies."
Related:
