First, let’s be clear that a higher heart rate variability (HRV) is protective for the heart and therefore good for us.
Health obsessives and gym rats alike have likely heard of heart rate variability (HRV), which measures the heart’s ability to change its beat and pulse rate to stimulate blood flow. But, what exactly is HRV?
What Is Heart Rate Variability (HRV) And Why Is It Important
Heart rate variability (HRV) is the beat-to-beat variation in time between the heart’s contractions, or how regular or irregular your heartbeats are.
The heart has a natural rhythm that dictates the ups and downs of your heart rate. A healthy heart is able to maintain this rhythm without any interference from other factors, like breathing, exercising, and illness.
High HRV is an indicator of our heart health, while low HRV is often seen as a predictor of poor health outcomes. To measure HRV, you take your heart rate repeatedly throughout a fixed time period, and then measure the average amount of time between each heartbeat.
HRV is a sensitive yardstick of cardiac autonomic function, and experts use HRV to classify the risk of heart attacks, strokes, and sudden cardiac deaths. Experts also associate high HRV with higher emotional well-being and a more regulated emotional response.
What Is The Range of Heart Rate Variability (HRV)?
HRV in healthy persons can range from less than 20 to more than 200 milliseconds. Sinus arrhythmia occurs when the heart is beating regularly but the variability between heartbeats is larger than 0.12 seconds.
A fairly accurate way that is handy enough to gauge the normal HRV range is to wear a fitness band that records the HRV in a controlled environment, such as sleep, and builds a baseline over a few weeks.
The Vagus Nerve And Heart Rate Variability (HRV)
A low HRV can be a sign of a low vagal tone.
The vagus nerve is the main nerve of the parasympathetic nervous system (Brodal, 2010). Vagal tone is a marker for parasympathetic activity, which indicates how well a person can relax after a stressful event.
People with a low vagal tone often find it difficult to recover from stress in their daily lives.
We interpret low parasympathetic activity as a low vagal tone and high parasympathetic activity as a high vagal tone.
A heart that beats at different rates throughout the day is a healthy and well-functioning heart. This changeable nature of heartbeats is called heart rate variability, or HRV. Those with higher HRV have better general physical health.
Studies show a link between gradual loss of heart rate variability and an increased risk of dying in patients with heart disease. Lower levels of HRV can also cause worry, rumination (overthinking), and anxiety.
Now, it is the vagus nerve that controls the heart rate variability (HRV). So, if we measure and index the HRV, we can find out the activity level of the vagus nerve, or the vagal tone.
A more complex or variable HRV shows the vagus is active, and the person is in a resilient and adaptable state. They are also less likely to die of cardiac causes. As this research shows, stimulating the vagus increases the complexity of HRV during sleep and decreases it when awake.
Takeaway — To live longer and healthier, keep your vagal tone and your HRV high.
Natural Pacemaker of Our Heart: SA Node
Our hearts have a built-in pacemaker, the natural pacemaker of the heart called the sinoatrial node (SAN or SA node). It instructs our hearts to beat a certain number of times each minute. There is a problem when our hearts beat faster or slower than at a pace that is fixed by the SA node.
Now, the vagus (or the wandering nerve) controls the SA node. It oversees the SA node so that it does its job of instructing the heart to maintain its pace.
If we cut the nerve connection between the vagus and the heart, our hearts would start racing at crazy speeds.
Even if we were merely catching a breeze on a hammock, our hearts would beat 100 times every minute.
And any heart that beats that fast throughout the day can wear out our organs, and ourselves, rather too soon.
So, having an intact vagus that is always alert keeps our resting heart rate controlled between 60 and 80 per minute.
When we actively stimulate the vagus, as we did by letting in a deep breath watching that Supermoon above, our hearts go into relaxation.
What Is Vagus Nerve Stimulation (VNS)?
Activation of the vagus is called vagus nerve stimulation (VNS).
Stimulating the vagus affects many important autonomic functions in the brain and in the body, including neurotransmitter levels, inflammation levels, and metabolism.
Vagus nerve stimulation (VNS) is a promising option for treatment-resistant anxiety disorders, including PTSD. Studies have shown that VNS therapy reduces anxiety in rats and improves scores on the Hamilton Anxiety Scale in patients suffering from treatment-resistant depression.
In hospitals and medical facilities, experts can stimulate the vagus nerve by:
- Surgical therapy
- Chemical method
- Electrical stimulation
1. Surgical: VNS is a surgical therapy for uncontrolled seizures, given by transmitting mild electrical pulses to the brain via the vagus nerve. In surgical VNS, surgeons implant a device called a vagus nerve stimulator under the chest skin. It stimulates the vagus by sending mild electric pulses.
The United States Food and Drug Administration (FDA) has already approved this device. It is used as a treatment option for those who have medically uncontrollable seizures, and hard-to-treat depression.
2. Chemical: Certain anti-psychotic drugs can also stimulate the vagus, called chemical VNS.
3. Electrical: In 2018, the FDA cleared a Noninvasive Vagus Nerve Stimulation (nVNS) device to treat cluster headaches and migraines. It is a portable, hand-held gadget that gives mild electrical stimulation to the vagus nerve. Research showed evidence of a reduction in pain from migraines and the frequency of cluster headaches.
Many social media influencers claim that “resetting the vagus nerve” through shoulder stretches and massages can help anyone overcome their anxiety and depression, improve their memory, and boost their success in life.
Can these maneuvers really cure your stress?
More importantly, is “Vagus Reset” safe to do on your own?
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Author Bio: Written and reviewed by Sandip Roy—a medical doctor, psychology writer, and happiness researcher. Founder and Chief Editor of The Happiness Blog. Writes on mental health, happiness, positive psychology, mindfulness, and philosophy (especially Stoicism).
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