Vagal Tone: A Measurable Indicator of Nervous System Health

What is vagal tone?

Vagal tone is the ability of the ventral vagus nerve to regulate the heart beat. It is referred to in medical literature as “cardiac vagal tone.”

Vagal tone is measured by tracking heart-rate and breathing rate at the same time. The heart-rate speeds up a little when we breathe in, and slows down a little when we breathe out.

The bigger the difference between inhalation heart-rate and exhalation heart-rate, the higher our vagal tone is.

Higher vagal tone means that the body can return to a coherent state quickly after a stressful experience ends. Higher vagal tone does not mean a person will be less activated by stressful events, but that they will recover more easily after safety is restored.

People with low vagal tone do not recover as quickly after safety is restored. If you have low vagal tone, you may feel stuck in high or low activation for a long time after a stressful incident has ended, or even flip-flop between those two up and down states.

There is a common misconception in the popular understanding of vagal tone which assumes that vagal activity and vagal tone are the same thing. However, having low vagal tone does not mean our vagus nerve is under-active.

Staying stuck when you’re in a safe space is not necessarily due to faulty neuroception either. Your body may be getting all the safe signals from your environment and your vagus may be sending the correct signals to attempt to control your heart rate to get you back to feeling calm/safe.

So if the vagus is nerve is functioning correctly, why do some people have low vagal tone?

Because a fatty protective layer of insulation around the nerve (called myelination) is weak or almost non-existent. Without insulation, the electrical information in our nerves can’t always travel to its intended destination. Without insulation, the neural information from the vagus gets scattered around the body instead of going straight to the heart.

Low vagal tone is due to low myelination.

Low myelination resulting in low vagal tone is the most common physiological effect of developmental trauma or emotional neglect (ie. lack of co-regulation). Low vagal tone is associated with cardiovascular conditions, strokes, depression, diabetes, chronic fatigue syndrome, and inflammatory conditions.

All human infants are born with low myelination. If development is not interrupted, a healthy myelin sheath is formed by age 2 or 3. When an adult caregiver is in safe coherent state, the child’s mirror neurons detect and replicate that state. The more frequently the child is in this mirrored ventral vagus state, the healthier their myelin sheath will be.

Generally, industrialized nations do not allow sufficient parent-child bonding time for the development of healthy vagal tone. Low vagal tone is a “silent epidemic” that affects the majority of the population in industrialized countries.

If human development requires time spent with an adult who is in a coherent state, what are we to do if we didn’t have access to that in our childhood? If you did not get to form this neural protection in childhood (like me), there is good news!

Adults can build myelin (a process called remyelination) and improve their vagal tone through co-regulation just like babies do. Spending time in a mirrored ventral vagus state allows the body to form a stronger myelin sheath at any age. Depending on how much mirrored ventral vagus time you can spend each week, you may be able to see a major shift in vagal tone after a year or two. (Side note, physical tissue disorders and other genetic conditions such as EDS can make this process take longer.)

There’s an old phrase in neuroscience that says “neurons that fire together wire together.” The myelination of the vagus similarly depends on the activation of the vagus nerve via safe connection with another mammalian nervous system.

Stimulating the vagus nerve when we are alone can help us feel calm in the moment, but it will not change vagal tone over time. Our vagus nerve needs the safe/calm influence of human and/or animal nervous systems to change tone. Many experts are so focused on offering solutions that can be easily done alone that they neglect the bio-social aspects of vagus nerve tone.

The myelination process is one way nature proves that we need each other.

My personal experience with changing vagal tone

6 years ago, when I was diagnosed with complex PTSD, I had low vagal tone. It would take me days to recover from a stressful event. I would often have multiple panic attacks in the same day because I couldn’t calm down after the first one. I could not be left alone for any significant period of time, especially if it was unplanned.

When I learned about vagal tone and myelination in my research, I started something I called my Radical Self Love Plan. It involved weekly scheduled activities that were highly likely to involve mirrored ventral vagus activation. If I were an animal person, I would have gotten a dog, but alas, I can’t deal with the sensory aspects of owning a pet. I chose group ventral vagus activities which I enjoyed and had easy access to: partner dance, free form dance, singing with others, free classes at the community yoga center, cuddle parties. I was open with others about the fact that I intended to use these practices to heal developmental trauma, and I found even strangers in these spaces were kind and encouraging.

After 2 years of this (plus binaural beats, and other solo vagus stimulating activities), I noticed a clear difference in my vagal tone. Recovering from shutdowns and panic attacks took less time. For the first time in my life, I could feel my heart rate calm when I took the time to notice my safe surroundings. I began to be able to track my vagal tone by comparing my breath and heartbeat. There was a noticeable difference on the inhale and exhale that hadn’t existed before.

A few months ago, I was in a car accident and got whiplash, a major trigger for me with history of car related PTSD. Less than 3 hours later I was in a ventral vagus safe mode. I took a picture to commemorate that moment, because I was just amazed. I had expected to feel anxious for hours and then shutdown for a few days while my system adjusted to the shock. The shock was no less intense than before, but the way my body processed it was totally different.

If your vagal tone is low like mine was, I’m writing this to hopefully give you some hope.

Vagal tone is not fixed. It can change over time. There is no quick way to change vagal tone, but with consistent practice, healing this developmental trauma is possible.