What Does Your HRV Actually Tell You? The 101 On This Buzzy Health Metric

Thanks to technology, we have smartwatches, wristbands, and other wearable devices that help us monitor our health. And one of their metrics that may be new to you is your heart rate variability, or HRV.

HRV is a method for assessing changes in the cardiac cycle1. Simply put, HRV “refers to the time between heartbeats,” explains Bradley Serwer, MD, FACC, a board-certified interventional cardiologist and the Chief Medical Officer of CardioSolution. “While most people have a relatively regular heart rate, there is always some variability in the time between individual beats.”

As for how your heart rate variability works, the autonomic nervous system, or ANS, controls your heart rate2 and, ultimately, your HRV. The ANS comprises the sympathetic (“fight or flight”) and parasympathetic (“rest and digest”) responses.

“When the autonomic nervous system is in balance, there tends to be a higher variability in time between heartbeats,” said Serwer. “When the autonomic nervous system is out of balance either due to increased stress (physiologic or psychological), illness or autonomic dysfunction, the variability between heart rates decreases.”

“Heart rate variability can be measured using a standard electrocardiogram, ECG, or photoplethysmography (PPG) as seen on many smartwatches, smartphones, and fitness trackers,” said Serwer. Many people use an Apple Watch, Fitbit, chest strap, or other fitness tracker to monitor their HRV and overall heart health.

Monitoring your HRV may detect early warning signs of cardiac problems. According to a 2019 study, a low HRV was a strong predictor of myocardial ischemia, which occurs when blood flow is partially or completely blocked due to plaque buildup.

Measuring your HRV is a noninvasive way to notify you of any imbalances in your autonomic nervous system. In fact, according to a 2020 study, HRV was a valid indicator of autonomic nervous system disturbance (ANSD)5 in patients with tetanus.

Use fitness trackers to your advantage: As mentioned, an easy way to monitor your HRV is with a fitness tracker like an Apple Watch or a Fitbit, which can give users a daily fitness score. “This fitness score can be positively affected by regular aerobic exercise, lack of stress, healthy diet and may be negatively affected by sedentary lifestyles, high-stress levels or illness,” said Serwer.

Prioritize mental health: Given that stress contributes to a low HRV, ensuring you’re taking care of your mental health is essential. Some ways to incorporate self-care into your routine are engaging in mindfulness practices, talking to loved ones, taking supplements for stress, and seeking therapy if needed.

Your heart rate variability provides a snapshot of how your nervous system is functioning—and if your HRV is low, it could be a sign that you need to spend more time prioritizing sleep, stress management, and other factors like exercise and diet.