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VeRelief and Heart Rate Variability – Hoolest Inc.
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VeRelief and Heart Rate Variability

Heart Rate Variability

Heart rate variability (HRV) is the variation in time between consecutive heartbeats. It is a measure of the beat-to-beat changes in heart rate, which reflects the influence of the autonomic nervous system on the heart. HRV is typically measured by analyzing the electrocardiogram (ECG) signal, which provides a precise measurement of the time between each heartbeat.

The autonomic nervous system, which controls the "fight or flight" response and the "rest and digest" response, influences the heart rate through its two branches, the sympathetic and parasympathetic nervous systems. The sympathetic nervous system increases heart rate, while the parasympathetic nervous system decreases it. Therefore, HRV is an indirect measure of the balance between these two branches of the autonomic nervous system.

A high HRV indicates that the autonomic nervous system is well balanced, and the heart can quickly adapt to changing demands, such as stress or exercise. On the other hand, a low HRV suggests that the autonomic nervous system is less adaptable, and the heart rate is less responsive to changes in demands. HRV has been linked to various health outcomes, including cardiovascular disease, diabetes, and mental health conditions. Therefore, HRV is a useful tool for assessing an individual's autonomic function and overall health status.


The Various Measurements of HRV

In general, there are two ways you can measure HRV and get an understanding of your health: long-term HRV and short-term HRV. The main difference between long-term and short-term HRV measurements is the duration of the recording period. Short-term HRV recordings typically last from a few minutes to a few hours, while long-term HRV recordings can last for several days, weeks, or even months.

Short-term HRV measurements are often used in research studies and clinical settings to assess the autonomic nervous system's response to specific stimuli, such as exercise or mental stress. Short-term HRV recordings are usually obtained using portable devices, such as heart rate monitors or electrocardiogram (ECG) machines, which can be worn by the individual during the recording period.

Long-term HRV measurements, on the other hand, provide a more comprehensive assessment of an individual's autonomic nervous system function over an extended period. Long-term HRV recordings can provide insights into the individual's overall health status and the impact of various lifestyle factors, such as diet, exercise, and stress, on the autonomic nervous system. Long-term HRV recordings are typically obtained using wearable devices that can continuously monitor HRV over an extended period.

Both short-term and long-term HRV measurements have their advantages and limitations, and the choice of method depends on the specific research or clinical application. Short-term HRV measurements are more suitable for assessing acute changes in autonomic nervous system function, while long-term HRV measurements provide a more comprehensive assessment of an individual's overall health status and autonomic nervous system function over an extended period.


Sympathetic and Parasympathetic Components of HRV


The components of HRV that represent sympathetic output (fight or flight) are the low-frequency (LF) and very-low-frequency (VLF) components.

The low-frequency component of HRV is related to both sympathetic and parasympathetic activity, but it is primarily influenced by sympathetic activity. The low-frequency component reflects the baroreflex-mediated regulation of blood pressure, which involves the interplay between the sympathetic and parasympathetic nervous systems. Therefore, a higher LF component indicates a greater influence of the sympathetic nervous system on heart rate variability.

The very-low-frequency component of HRV is also related to sympathetic activity and reflects the long-term fluctuations in the R-R intervals. The VLF component reflects the slow oscillations in the cardiovascular system, such as changes in blood pressure and hormonal fluctuations, which are primarily modulated by the sympathetic nervous system.

Therefore, both the LF and VLF components of HRV are considered good indicators of sympathetic activity, with higher values indicating greater sympathetic output. In contrast, low HRV values are indicative of decreased sympathetic activity and a greater parasympathetic influence on the heart.



The components of HRV that represent parasympathetic output are the high-frequency (HF) and the root mean square of successive differences (RMSSD).

The high-frequency component of HRV corresponds to respiratory sinus arrhythmia, which is the variation in heart rate due to the respiratory cycle. The parasympathetic nervous system influences this component by increasing heart rate during expiration and decreasing it during inspiration. Therefore, a higher HF component indicates greater parasympathetic activity.

The RMSSD component of HRV reflects the short-term fluctuations in the R-R intervals, which is influenced by parasympathetic activity. The parasympathetic nervous system influences this component by increasing the variability of the R-R intervals.

Therefore, both the HF and RMSSD components of HRV are considered good indicators of parasympathetic activity, with higher values indicating greater parasympathetic output. In contrast, low HRV values are indicative of decreased parasympathetic activity and a greater sympathetic influence on the heart.


The Best (Most Accurate) Way to Measure HRV

It is important to note that different HRV measurement methods may not always provide consistent results, and the choice of method should be carefully considered based on the specific research or clinical application. It is also important to ensure that the HRV measurement is performed and analyzed correctly to obtain accurate and reliable results.

For short-term HRV measurements, electrocardiogram (ECG) is the gold standard method for measuring HRV, as it provides accurate and precise measurements of the R-R intervals. ECG is commonly used in research studies and clinical settings to assess the autonomic nervous system's response to specific stimuli, such as exercise or mental stress. Photoplethysmography sensors such as the Camera HRV smartphone app are also excellent sensors for short term HRV measurements. 

For long-term HRV measurements, wearable devices that continuously monitor HRV over an extended period are the most convenient and non-invasive method. These devices typically use photoplethysmography (PPG) or accelerometer sensors to measure HRV and can be worn comfortably throughout the day and night.

Before choosing a sensor, it is extremely important to make sure the sensor being evaluated is capable of giving you the specific measurement you are looking for. If you are looking for short-term measurements of RMSSD or HF components of HRV to assess the impact of an intervention on parasympathetic activity, then sensors like an Apple Watch, Oura Ring, or Whoop band will not be the best choice. Something like Camera HRV or an ECG chest strap sensor will be the best choice. 

To evaluate the immediate impact of the VeRelief product on the RMSSD component of your HRV, we recommend using the Camera HRV app! 


Variables that Affect HRV Measurement Accuracy

When measuring short-term HRV, several variables can have a significant impact on the accuracy and reliability of the measurement. Some of the most important variables to consider are:

  • Recording duration: The duration of the recording period can affect the accuracy and reliability of short-term HRV measurements. Longer recording periods generally provide more accurate and reliable measurements of HRV, but shorter recording periods may be more practical in some situations.
  • Body position: The body position can affect HRV measurements, as changes in posture can influence the autonomic nervous system's activity. For example, HRV measurements obtained in a standing position are generally lower than those obtained in a supine position.
  • Breathing pattern: Breathing pattern can significantly affect HRV measurements. For accurate HRV measurements, it is important to maintain a consistent breathing pattern throughout the recording period.
  • Physical activity: Physical activity can affect HRV measurements, as it can increase sympathetic activity and decrease parasympathetic activity. Therefore, it is important to control for physical activity when measuring short-term HRV.
  • Medications: Some medications, such as beta-blockers and antidepressants, can affect HRV measurements. Therefore, it is important to consider the medications that the individual is taking when measuring HRV.
  • Age and gender: Age and gender can affect HRV measurements, with older individuals and women generally having lower resting HRV values than younger individuals and men.

Other variables that have an impact on HRV measurement accuracy include the time of day the measurement was taken, sleep quality the night before measurement, diet and nutrition, hydration, your current baseline HRV level, and the sensor being used to take the measurement. 

For accurate and consistent short-term HRV measurements, we recommend taking them in a sitting position and in a calm and generally low-stress environment. Breathe at a pace that is comfortable and keep your eyes open and focus on something while looking ahead. 


Auricular Vagus Nerve Stimulation and HRV

In an early study assessing the impact of auricular vagus nerve stimulation with an early version of VeRelief on patients with self-diagnosed Post Traumatic Stress Disorder and Panic Disorder, parasympathetic components of HRV were increased after a single 10-minute treatment. 

In this study, patients recorded a 5-minute HRV recording to establish a baseline. They then used the VeRelief research product for 10 minutes, followed by another 5-minute post-treatment HRV measurement. 

The results showed a 31% increase in the RMSSD component of HRV and no change in the placebo group, indicating the VeRelief product is capable of helping those living with PTSD or Panic Disorder shift out of fight or flight and into rest and digest. Another notable result is that total HRV amplitude, representative of nervous system balance and mental resilience, increased by 24% in the active group whereas it went down by 7% in the placebo group. 

Active Baseline

Active Post 10Min Stim

% Change

Placebo Baseline

Placebo Post Stim

% Change




































HRV Amplitude








Applying HRV to your Life

The data in the above table demonstrates that VeRelief can be an effective tool to help people recover from stress, anxiety episodes, and generally increase their resilience to stressors and their ability to recover from stressful situations more effectively.

But how can you start measuring your HRV so you know how healthy your nervous system is?

There are two consumer HRV sensors we recommend for monitoring short-term HRV as accurately and easily as possible. 

  • Camera HRV: Camera HRV is a smartphone app that uses the light and camera on your phone to monitor each heartbeat via the blood pulses from your fingertips. While it requires you to remain extremely still during the measurement, it can be used anywhere, gives you accurate RMSSD data, and is the most affordable HRV sensor on the market. 
  • Polar H10: The Polar H10 is a chest strap heart rate monitor that provides accurate HRV measurements. It is suitable for short-term HRV monitoring during exercise and other activities. The best app to use to monitor short-term HRV with Polar is HRV Logger.

HRV sensors to stay away from when monitoring short-term HRV include Apple Watch, Fitbit, Oura Ring, Whoop, and other wrist wearables because they are very prone to motion artifact and they use proprietary algorithms to calculate HRV, so they don’t give you a true measurement of your autonomic nervous system activity. 

The best application for short-term HRV is to assess the immediate impact of a treatment or intervention on your nervous system. For example, you can take a 1-2 minute measurement of your RMSSD levels using Camera HRV, stimulate your vagus nerve using the VeRelief device for 5-10 minutes while in a sitting position, and then take another 1-2 minute measurement after using the VeRelief. You’ll be able to see the immediate impact of auricular vagus nerve stimulation on your nervous system!

Being able to measure your HRV accurately and easily allows us to monitor how various items or habits impact our nervous system and our overall health. We can learn what has a positive impact on our nervous system and do more of that, and what has a negative effect on our nervous system and do less of that. 

HRV is a powerful metric but can be very complicated to measure correctly. Feel free to reach out to our support team at if you would like any assistance on measuring HRV! And be sure to check out the VeRelief device and see if it has an impact on your HRV levels!

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