Heart Rate Variability (HRV)

Heart Rate Variability (HRV) is a measurement of the variation in time between each successive heart beat. A person who is more relaxed may experience greater variability in their heart rate as it changes its pace organically, resulting in greater variation in time between each beat. This is a high heart rate variability, which is a good thing because it indicates relaxation and low stress. Contrast this a hypothetical person with low heart rate variability, meaning that the heart is beating at a consistent, droning pace – less variation between each beat – more like a metronome. This type of heart rate occurs when the fight-or-flight mechanism is activated, for example, which can be an indicator of stress.

Variation in heart rate is controlled by autonomic nervous system (ANS). The ANS automatically deals with necessary body functions that keep us alive, so that we do not have to do so consciously. Functions such as breathing, digestion, blood pressure, including the regulation of our heart rate.

The autonomic nervous system is further divided into two large components: the sympathetic nervous system and the parasympathetic nervous system. One of the mechanisms controlled by the sympathetic nervous system is the stress response, or the fight-or-flight mechanism which controls the release of stress hormones to stimulate the body and mind into activity when necessary.

It activates when we see something that causes a sense of fear or danger, which will be different for all people, flooding our body with adrenaline and cortisol so we can fight or flee at full capacity. Some might exhibit negligible stress response when they see a brown bear in the wild, while others might be flooded with adrenaline upon sight of a chihuahua due to debilitating fear of dogs. Remember that there is no objective definition for the parameters of fear. Fear is subjective, and in some sense, a choice. The parasympathetic nervous system will engage once the danger has passed, helping our body to relax again and return to ‘normal’.

All of this information from the autonomic nervous system is processed by a part of the brain called the hypothalamus. The ANS sends signals to the hypothalamus, which then instructs the body on what to do. Either stimulating it, relaxing it, or maintaining it’s state as is. As such the autonomic nervous system (and by inclusion within the array of functions and mechanism controlled by the ANS, heart rate variability) is influenced by a number of factors of environment and life.

Healthy diet will have a positive effect on the ANS, as will good sleep, healthy relationships, mental health, experiences we feel as positive and exciting, perspective and mood, as well as exercise. On the other hand, excess stress (or a lack of resilience to stress), toxic relationships, little to no exercise, and a poor diet will all negatively effect the ANS. These are some of the factors which determine HRV. Lower heart rate variability may indicate an unhealthy lifestyle. Factors like little stress (or a developed capacity to deal with stress constructively), positive, intimate, supportive, and loving relationships, daily exercise, and many more generally tend towards higher heart rate variability. This suggests greater health, relaxation, and a healthy lifestyle.

The potential of HRV as an indicator of health is one of its greatest benefits.

Heart Rate Variability (HRV) might indicate emotional resilience, resilience to stress, and behavioural flexibility. [1] HRV can non-intrusively provide a source of information, real-time feedback on the quality of our lifestyle. It can tell us if there are imbalances in our ANS, which then indicates that there are imbalances in our lives relating to the factors that we have been discussing. In this way HRV gives us powerful, actionable data to inform our choices towards better lifestyle decisions. Moreover, it can even indicate the quality of our emotions, thoughts, and feelings in our reaction to them based upon the effect they have on our mind and body as indicated by HRV.

HRV can be measured with an electrocardiogram analysis, performed by a doctor. Or else more accessibly by modern wrist watches that function as heart rate monitors, or a chest strap monitor, which is superior in accuracy to the wrist-heart-rate-monitor-watches. [1]

Resources

1. Heart rate variability: How it might indicate well-being. Harvard Publishing Staff. 1 Dec 2021. https://www.health.harvard.edu/blog/heart-rate-variability-new-way-track-well-2017112212789. Accessed 09 Jan 2022.