Heart rate variability (HRV) is the variation in time between each heartbeat. While it is a measure of cardiac function—just like your heartbeat—HRV is actually controlled by your nervous system. Generally, when your body is under stress, the sympathetic branch of your nervous system initiates the “fight or flight” stress response which increases your heart rate. Alternatively, when the perceived threat is resolved, the parasympathetic branch of the nervous system returns you to a resting state, decreasing your heart rate.
Multiple studies have demonstrated that HRV is a measurable indicator of stress and stress adaptability as well as a proxy for nervous system health. A high HRV is a signal that your nervous system is healthy and able to quickly adapt to changes in your surroundings, whereas a low HRV is a signal that your body is struggling to readjust after periods of stress. As we’ve previously discussed, chronic stress can have negative effects on our immune system making us more susceptible to a variety of chronic diseases and immune dysfunction.
HRV rates naturally tend to drop as we age. The good news is that there are many ways in which you can increase your HRV. These include regular exercise, getting consistent, good quality sleep, and following a healthy diet timed in alignment with your circadian rhythm (e.g., eating within a compressed window). All of these activities can contribute to increasing your resilience and therefore your body’s ability to deal with stress.
If you are already following these recommendations and are still having difficulty managing the stress in your life, a proven technique you can try is HRV biofeedback. One simple way to practice this, is by performing breathing exercises while tracking your HRV in real time. Many HRV trackers like the EliteHRV offer this type of functionality.
One notch up from there, is to try a purpose-built wearable like the Lief. Unlike other wearables that measure HRV through your finger or wrist, the Lief consists of an ECG that you can wear on your chest to generate a direct measure of your HRV. The device alerts you when your HRV levels drop so that you are better able to identify your stress triggers and use breath biofeedback to get into a more relaxed state. The Lief is used in medical settings and may even be covered by your health insurance.