Vagus nerve activation, nervous system regulation and health
How increasing vagus nerve activation and improving vagal tone can provide health benefits
Nervous system regulation is a pretty hot topic in the health and wellness field at the moment. But how do the responses our nervous system has affect our health and how can we improve it?
Today I'll be talking about the parasympathetic and sympathetic nervous system and what the research shows around the benefits of increased parasympathetic/vagal nerve activation as well as some practical ways we can increase vagal tone/vagal dominance.
Nervous system regulation is a pretty hot topic in the health and wellness field at the moment. But how do the responses our nervous system has affect our health and what can we do to do improve its potential health benefits?
Today I'll be talking about the parasympathetic and sympathetic nervous system and what the research shows around the benefits of increased parasympathetic/vagal nerve activity as well as some practical ways we can increase vagal tone/vagal dominance.
Breaking down the main parts of the nervous system
In our body we have the central nervous system (CNS), which includes the brain and spinal cord, and the peripheral nervous system, containing all other nerves that branch off from the central nervous system around the rest of the body. Signals are sent from the peripheral nerves around the body to the CNS and brain and vice versa.
The Autonomic nervous system
The autonomic nervous system is part of the peripheral nervous system and controls involuntary functions of the body like breathing, heart rate, blood pressure, digestion and body temperature. These functions are usually subconscious but some of these can be consciously influenced like our breathing rate and heart rate through increased parasympathetic activation.
We have three main parts of our autonomic nervous system. The sympathetic nervous system, parasympathetic nervous system and the enteric nervous system.
The Sympathetic nervous system
The Sympathetic nervous system (SNS) is known for its ability to cause the “fight, flight or freeze” response. This causes increased blood pressure, heart rate, respiration rate, stimulates energy availability, and reduces activity of non-essential bodily functions like digestion.
The SNS is involved in breathing where, during inhalation, it helps to dilate airways so that we can get a good amount of oxygen. The SNS has a role in regulating our immune system and can up or down-regulate inflammation.
The Parasympathetic nervous system
The Parasympathetic nervous system (PNS) acts in opposite ways, it is known for its “rest and digest” processes. With the ability to lower heart rate, blood pressure, breathing rate, and increase digestion processes.
The SNS and PNS are always active, and they can work together or separately to control different physiological responses around the body.
The Enteric nervous system
The enteric nervous system (ENS) can function separately to the rest of the nervous system. It is primarily responsible for regulating digestion and often gets signals from the SNS and PNS as well as sending signals through these systems. The ENS is a group of nerve cells spread out along the entire gastrointestinal tract and controls digestion responses through muscle contraction and relaxation, secretion and absorption, and blood flow of the gut, also with the ability to influence immune system responses with the aim to support the overall balance and health of the gut.
Autonomic dysfunction
Autonomic dysfunction is when the autonomic nervous system doesn’t operate as it's meant to. An imbalance or overactivity of part of the autonomic nervous system can cause negative health effects. For example, if the sympathetic nervous system is overactive or the parasympathetic nervous system is underactive. It has been shown to be involved in autoimmune disorders including rheumatoid arthritis and diabetes. This suggests that managing the function of the autonomic nervous system and vagus nerve may help improve inflammatory conditions as well as provide other health benefits.
The Parasympathetic nervous system and its role in health
The Vagus nerve
The vagus nerve is the main component of the parasympathetic nervous system making up around 75% of the PNS. It is the main message receiver and sender of the PNS and has influence over a large range of functions throughout the body. The vagus nerve has a role in immune response, controlling mood, heart rate and digestion, as well as regulating food intake, satiety and energy balance. Its non-optimal functioning has been associated with the development of psychiatric disorders like depression and anxiety, as well as obesity, and stress-induced inflammatory diseases.
The vagus nerve is one of the connectors between the gastrointestinal tract and the brain, sending information about the organs to the brain to help with overall body functioning. Parasympathetic fibres stimulate salivation and fibres connected to the enteric nervous system then stimulate gut activity.
Vagal tone
Vagal tone is a term used to describe vagus nerve activity, higher vagal tone means more activity of the PNS compared to the SNS, which is beneficial for health and overall wellbeing.
Having higher vagal tone generally means the body better regulates functions like heart rate, digestion, and stress responses. People with higher vagal tone have generally been shown to have better emotional regulation, cardiovascular health, lower inflammation and it has shown positive impacts on stress, mental health and conditions like inflammatory bowel disease (IBD).
Vagal dominance
Vagal dominance is a term used when the vagus nerve/PNS is more active than the SNS. Long term practice of techniques designed to stimulate the vagus nerve and result in increased vagal dominance can shift the body from being SNS to PNS dominant.
Heart rate variability
Heart rate variability (HRV) is a measure of the time between each heartbeat. This reflects vagal tone and is used to show general health, physical fitness, reactivity and how we recover from high stress levels. Higher heart rate variability is related to lower stress, better health and disease outcomes. Having good vagal tone and HRV have been shown to reduce the risk of cardiovascular disease, hypertension and chance of inflammation.
There is an inverse relationship between HRV and inflammation and cardiovascular disease risk, meaning the lower the heart rate variability the higher inflammation and cardiovascular disease risk.
Benefits of increased vagal tone
Reduced inflammation
The PNS has a role in immune system functioning and inflammatory processes. With the PNS influencing immune system activity, and the immune system also being shown to influence PNS activity. Stimulation of the vagus nerve has been shown to suppress inflammation in the body through this relationship.
Improvements in mental health
Increased vagal tone has been shown to reduce the likelihood of mental health disorders including depression and anxiety and it has been shown to improve positive emotions in people with depression. With regular practice of methods that increase vagal tone helping to improve symptom severity in people with depression and anxiety.
Increased vagal tone has also been shown to improve cognitive function in areas including memory formation and recall.
Inflammatory bowel disease (IBD)
Relaxation related methods to increase vagus nerve activity and improve vagal tone have been shown to benefit people with IBD, reducing pain and anxiety, and improving quality of life.
Chronic pain
Regular practices to improve vagal tone have also been shown to improve chronic pain.
Stress and immune function
Stress has been shown to influence immune function. Acute, short-lasting stress, lowers immune function and chronic stress increases the immune response. This relationship is reflected in autoimmune disease, where it has been shown that stress can worsen autoimmune symptoms. A component of this is SNS and PNS imbalance, where in chronic stress situations, the SNS is overactive, reducing vagal tone and HRV.
Supporting digestion
When in the PNS “rest and digest” state our bodies are better able to digest food. Increasing rate of digestion and improving nutrient absorption, potentially reduce gut symptoms like bloating, and making it easier to tell when we are hungry and full.
How to stimulate the vagus nerve, improve vagal tone and spend more time in a parasympathetic state
Electrical stimulation can be used to stimulate the vagus nerve but there are also natural ways to do this ourselves. Meditation, hypnosis, acupuncture, breathing exercises and mind body exercises like yoga and Thai chi help us stimulate the vagus nerve. These practices have been shown to increase vagal tone and HRV shifting us to a more vagal dominant state.
Meditation and yoga
Meditation and yoga have been shown to have benefits on mental health, cognitive performance and physical health. Because they often involve breathing techniques, generally slow breathing with long exhales, these practices stimulate the vagus nerve, likely being a component of the health benefits gained.
Yoga, meditation, and Thai chi have been shown to have beneficial effects on the immune system. Reduction in inflammatory markers like C-reactive protein and pro-inflammatory cytokines have been shown. With research also showing benefit of these practices for cognition, through executive functioning and working memory, showing the potential to help with age-related cognitive decline.
Singing
Singing, humming and using your voice stimulates the vagus nerve because it is connected to the muscles in the back of the throat and the vocal cords. We can often reach a more relaxed state after singing whether in the shower, the car, with people, or anywhere else.
Cold exposure
Cold showers, ice baths, dunking your face in cold water, all have similar effects. Short term cold exposure can stimulate the vagus nerve, reduce stress and lower heart rate. Cold exposure often causes an initial fight or flight SNS response, after a short time the body relaxes and shifts into a more relaxed PNS state.
Keeping active
Physical inactivity has also been linked to issues with parasympathetic nervous system function which is also common in people with chronic pain conditions. Keeping active has many health benefits including supporting vagus nerve activity.
Breathing
Activity of the vagus nerve can be modulated/influenced by relaxation-based practices, especially those that focus on the breath. With SNS activity increasing during inhalation and the vagus nerve/PNS increasing during exhalation and slow breathing cycles.
Slow breaths signal a state of relaxation to the body. Paying attention to the breath, slowing it down, taking deep diaphragmatic/belly breaths and having a longer exhale than inhale helps to promote vagus nerve activity and improve vagal dominance. This can reduce stress, slow the heart rate, improve heart rate variability and blood pressure. As we practice this more, increased awareness occurs, and we can influence our body to do this more often and more automatically.
By choosing actions that are associated with relaxation like slow breathing, yoga, and meditation, messages are sent from the vagus nerve through the CNS to the brain that the body is in a low threat situation and it is safe to relax. The brain then sends messages through CNS to the vagus nerve and the rest of the body influencing more activation of the rest and digest state. These actions help influence long term changes in vagal tone, shifting to a more vagal dominant state.
Increasing activation of the vagus nerve, improving vagal tone and vagal dominance, can have a wide range of benefits to our health and wellbeing. Improving our cardiovascular health, reducing heart rate and blood pressure, improving cognition and mental health, reducing stress and chronic stress, promoting a state of rest, recovery, and relaxation, improving digestion, immune function and reducing symptoms of inflammatory conditions.
Incorporating some of these practices, even just beginning simply with 5 minutes of intentional breathing each day, can have a great effect on feelings of wellbeing, lowering stress and improving mental health among the many other health benefits.
