The Vagus Nerve
The Vagus Nerve is the 10th and longest of the 12 cranial nerves. The word “vagus” is derived from the latin word meaning “wandering” as it travels throughout the entire upper body and innervates multiple visceral organs en route. It is a nerve made up of 20% efferent fibers and 80% afferent fibers.
The vagus nerve serves as an important physical connection between the mind and the body and largely serves to maintain homeostasis. It is a major player in the autonomic system, helping modulate both the sympathetic and parasympathetic nervous system. During episodes of increased sympathetic output, or when the “fight or flight” response is activated, the vagus nerve activates to counteract the increased sympathetic output by both reducing sympathetic output and increasing parasympathetic activity. This vagus nerve response helps people recover from stress and anxiety, and helps people maintain a calm and relaxed state in stressful situations or to recover from stressful events.
However, many people have poorly functioning vagus nerves and are unable to recover from stressful or anxious situations. Often these people will experience a stressor that triggers the “fight or flight” response, and they can’t recover from it and they will either live in a constant state of severe stress, or they will experience a debilitating anxiety attack. Another common experience is seen in high-performing individuals living a fast-paced lifestyle with a million things to do. For these people, it is necessary to be in a sympathetic state throughout the day in order to complete each task, but this is a problem at night when it is time to slow down, recover, and fall asleep. Often these people cannot rest and recover because their minds are moving at light speed and they can’t get the rest they need.
Stimulating the vagus nerve using various manual tactics is an effective drug-free way to recover from stressful events, an anxiety attack, or to just physically slow everything down when it is time to rest and recover. There are a handful of ways to effectively stimulate the vagus nerve, such as slow-paced or prolonged exhalation breathing, cold water plunges, singing or humming, gargling, brushing your tongue, and a handful of others. However, these techniques take several minutes to activate the vagus nerve and are not always accessible or practical in common stressful situations.
One promising vagus nerve stimulation method is by using electrical energy waveforms. Neurons communicate with each other via electrical and chemical impulses, so applying artificial electrical energy to a nerve is an immediate way to activate a nerve and its connected neural pathway. Electrically stimulating the vagus nerve in and around the ear has been demonstrated in clinical research to both objectively and subjectively decrease the physical symptoms of anxiety and the “fight or flight” response. Because of its safety profile and ease of use, electrical vagus nerve stimulation devices provide the most effective and practical drug-free way to activate the body’s built in relaxation response and recover from stress and anxiety faster.
Vagus Nerve Stimulation and the Heart
One of the most common physical symptoms of an anxiety episode or “fight or flight” response is an elevated heart rate. The vagus nerve plays a major role in regulating heart rate, and studies have shown that electrically stimulating the vagus nerve can cause heart rate to significantly decrease (Badran et al., 2018).
Heart Rate Variability (HRV) is another physiological measurement that is correlated to anxiety and sympathetic states. Generally, people with high HRV levels can respond to stressors better and recover from sympathetic spikes faster. People with lower HRV levels tend to experience the effects of stress and anxiety more frequently and for longer periods of time.
In one vagus nerve stimulation study, treatment was able to increase the RMSSD component of HRV (indicative of increased parasympathetic activity) by 10.7% after a single 15-minute session, and 20% after two weeks of daily use (Bretherton et al., 2019). In another study, vagus nerve stimulation demonstrated a 17.5% reduction in the LF/HF component of HRV (indicative of decreased sympathetic activity) compared to just a 2.5% decrease in the placebo control group (Clancy et al., 2014).
Other studies have also reported significant increases in the RMSSD component of HRV when compared to a placebo group, indicating an immediate shift towards parasympathetic dominance (Borges et al., 2019; Yikloski et al., 2017). However, there are also studies that have reported no changes in HRV after short and long stimulation sessions (Gauthey et al., 2020).
Hoolest Product Design History
While no medical or wellness intervention for mental health is successful 100% of the time, it is clear that noninvasive vagus nerve stimulation techniques are capable of shifting people towards a parasympathetic state (“Rest and Digest). This is indicated by increases in the RMSSD component of HRV, an indicator of parasympathetic activity, and decreases in the LF/HF ratio component of HRV, an indicator of sympathetic activity. This suggests vagus nerve stimulation is a promising method to help people with anxiety or high-performing individuals who need rapid recovery from a sympathetic or “fight or flight” response.
At Hoolest, we spent two years designing, developing, testing, and validating a brand-new type of vagus nerve stimulation tool for any type of person living with increased sympathetic output. Our first goal was to create a dry electrode that didn’t have to be soaked in any messy gel or saline solution before use, and was also comfortable during treatment. So we created the VeRelief Electrode, a proprietary blend of dry materials that comfortably stimulates the vagus nerve, and any other peripheral nerve for that matter.
The next goal was to simplify the interface. We made it wireless, easy to hold in one hand, and implemented a design where the electrodes are always stored in the device so you don’t have to spend any time preparing the device before you use it. It stimulates the nerve at a region on the side of the neck called the Tympanomastoid Fissure, a region that contains both the auricular branch of the vagus nerve and the great auricular nerve (Kiyokawa, 2014). It is ready to be used within seconds so you can feel comfortable knowing you can quickly recover from a sympathetic spike anytime anywhere.
Hoolest Clinical Studies
In our first study, we tested a prototype with 47 healthy individuals (segmented from a population of 120 individuals). The device demonstrated a 19.3% increase in the RMSSD component of HRV (indicative of increased parasympathetic activity) and a 9.9% decrease in the placebo control group. We also demonstrated a significant decrease in heart rate (2.6%) after a single treatment session (Source).
In our second study, we tested the device with 18 competitive golfers with performance anxiety in a real-world golf environment. There were no changes in the RMSSD component of HRV, but there was a 4.6% decrease in heart rate in the active group and no change in heart rate in the placebo control group. Additionally, there was a 36% decrease in state-anxiety levels and an 8.8% increase in subjective feel in the active group after treatment, but only an 18% reduction in state-anxiety levels and 3.1% increase in subjective feel in the placebo control group (Source).
In our third study, we tested the device with 24 patients with self-diagnosed Post Traumatic Stress Disorder and Panic Disorder. The device demonstrated a 31% increase in the RMSSD component of HRV in the active group, and a 0% change in the placebo control group. Additionally, there was a 24% increase in HRV amplitude in the active group and a 7% decrease in HRV amplitude in the placebo control group. Heart rate was significantly reduced in the active group alone, and 100% of patients who received active treatment reported the treatment to be relaxing, where only 33% of those in the placebo control group reported the same (Source).
The results in our first three placebo-controlled clinical studies demonstrated similar results as past independent vagus nerve stimulation studies. It is clear that stimulating branches of the vagus nerve in and around the ear area can help people recover from elevated sympathetic nervous system activity via objective changes in Heart Rate and or HRV parameters, as well as improving how people feel via subjective levels of state-anxiety and relaxation.
However, much research still needs to be done to figure out what preexisting conditions must be present in order for auricular vagus nerve stimulation to have an effect on heart rate or heart rate variability. It does not have an effect on HR or HRV 100% of the time, and it depends on factors such as age, ethnicity, genetic factors, diet, fitness levels, time of day the measurement was taken, length of the measurement, environment the measurement is taken in, the device used to capture the measurement, and many other factors.
We also completed a case study with a single patient who used the device daily for 8 weeks. The patient was a 23-year-old male with PTSD and Panic Disorder due to a severely traumatic experience just a few years earlier. The patient used the device at least once per day everyday for 8 weeks and subjectively documented his experience by agreeing or disagreeing with the following statements.
“I feel better after using the device”
- Strongly Agree 63% of the time
- Agree 37% of the time
“The device decreases the severity of my symptoms”
- Agree 75% of the time
“I felt better having access to this device in case I have symptoms”
- Strongly agree 25% of the time
- Agree 75% of the time
“The device is easy to use.”
- Strongly agree 12.5% of the time
- Agree 75% of the time
- Strongly agree 37% of the time
- Agree 63% of the time
Patient Statement: “It has stopped some panic attacks from getting worse and [felt like] I was melting into my bed. Complete mental and physical relaxation.”
The VeRelief device is not intended to treat anxiety disorders like PTSD or Panic Disorder, but it is clear that those living with such disorders and mental health conditions can find value in being able to stimulate the vagus nerve on a daily basis.
The vagus nerve has been demonstrated in past research to be associated with sympathetic and parasympathetic output. Stimulating the vagus nerve has been shown to increase parasympathetic output or decrease sympathetic output after a single session. What this means is that it is an effective tool to help people calm down who are in a sympathetic state, and calm down quickly. It does not necessarily mean that people living with anxiety will feel better after auricular vagus nerve stimulation, such as those living in a state of constant worry or who have a tendency to ruminate on negative and intrusive thoughts, but rather people currently in a sympathetically dominant state like those who have trouble shutting their minds off at night or mentally recovering from an unwanted “fight or flight” response.
Effects of auricular vagus nerve stimulation also appear dependent on the task and setting during treatment. In an office setting when the person is doing nothing, HRV seems to increase more when compared to in a real-world setting or when a stressful task must be performed. Therefore, the best time and place for vagus nerve stimulation could be in a bedroom just before bed, in a hotel room after a long day of travel, or in any quiet and comfortable place.
Interested in implementing auricular vagus nerve stimulation into your daily routine? Check out our best product, the VeRelief Prime, and experience a brand new way to recover from a stress response!