Heart Rate Variability is a Measure of Health

Quick Takes

• Heart rate variability (HRV) measures the variation in time between consecutive heartbeats and is a powerful indicator of your body's stress response and overall health.

• Higher HRV generally indicates better health, stress resilience, and cognitive function, while lower HRV is linked to increased stress, inflammation, and various health risks.

• HRV naturally declines with age, but various lifestyle practices can significantly improve it regardless of your starting point.

• Stress triggers sympathetic nervous system activation (fight-or-flight), while recovery requires parasympathetic activation (rest-and-digest) - HRV helps measure this balance.

• HRV correlates with cognitive function, disease outcomes, mental health, autoimmunity, cardiovascular health, and even survival rates in cancer patients.

• Just one alcoholic drink reduces HRV, with effects lasting 4-5 days for some people - making it one of the most impactful factors affecting your daily measurements.

• Sleep restriction negatively impacts HRV, and it takes about 3 full nights of quality sleep to recover from just a few nights of poor sleep.

Favorite Finds

I created a step-by-step workbook you can use to measure and improve your HRV.

Here are some of resources for those who don’t need the workbook.

Measuring HRV

• Wearable devices like WHOOP, Oura Ring, Garmin, and Apple Watch offer reliable HRV tracking for most people. Some complain they don’t record their heart rate properly, in that case they have to use a chest strap and record first morning HRV only. Keeping track of my Garmin Body Battery has been my favorite way to work on my HRV.

• The Heartmath Inner Balance Sensor ($155) provides specialized HRV biofeedback

• Most modern fitness trackers capture nighttime HRV measurements during sleep

Improving HRV

• Controlled Breathing: Practice 6 breaths per minute for at least 5 minutes daily (no need for special equipment)

• Meditation Apps: Headspace, Calm, and Insight Timer offer guided practices

• The Tapping Solution App: Uses emotional freedom technique to reduce cortisol by up to 70%

• Gratitude Journaling: Just 8 weeks has been shown to improve inflammatory markers

• Movement Practices: Yoga, Tai Chi, or dance, including dance video games can benefit cognition, mood, and stress as revealed by improvements in HRV.

• Yoga nidra is another powerful practice (I love the 25+ minute videos on YouTube) that improves HRV.

• In his recent podcast, Andy Galpin provides valuable tips and information that served as an inspiration for this newsletter.

Deep Dive

Understanding the Science of HRV

HRV emerges from the interplay between your sympathetic nervous system ("stress response") and parasympathetic nervous system ("relaxation response"). Heartbeats are regular but not perfectly regular. The variation in the intervals between pairs of heartbeats reflects your autonomic nervous system's flexibility and adaptability - essentially how well your body handles stress and recovers from it.

The research shows strong connections between HRV and overall health outcomes. HRV is correlated with cognition, predicts ulcerative colitis flare-ups, is associated with cardiovascular events and death, correlates with cancer survival, and even predicts recovery from depression.

This is because HRV starts as information from the vagus nerve: this nerve travels throughout the body gathering status information from each organ. It then sends that information to the brain, which integrates it with its understanding of the sense of safety it is sensing — from past events, and from its interpretation of present reality informed by past events.

This makes HRV much more than just another fitness metric - it's a window into your body's entire regulatory system. The brain regions responsible for autonomic nervous system regulation (prefrontal cortex, anterior cingulate gyrus, orbitofrontal cortex, and amygdala) are the same regions involved in emotional processing, decision-making, and higher cognitive functions.

Even more critically, this is a modifiable health risk. We have a multitude of practices that improve HRV. Most of these practices are reviewed in the book The Simple Science of Wellness.

Practical Approaches to Improving HRV

CONTROLLED BREATHING

Controlled breathing exercises have shown especially beneficial impact on heart rate variability (HRV). When a person is relaxed, not stressed, their heartbeats have more variation between them, which we call high HRV. That's what we want. When we are under a lot of stress, either psychological or physiological (based on some illness for example) HRV drops very low.

A recent study compared slow-paced breathing at 6 breaths per minute, with and without biofeedback. Subjects had the same benefit with or without feedback, but the ones who got feedback felt more positive after the experiment. This suggests we can get similar benefits without a biofeedback machine, though the positive feelings may make some people more likely to continue to practice.

A further experiment compared different durations of exhale (either longer than the inhale, equal, or shorter) and found that the impact on stress reduction was similar. In other words, anyone can try breathing at about 6 breaths per second, for at least 5 minutes in a row, without worrying too much whether they are doing it exactly right, and reap the benefits of paced breathing. This can be repeated once or twice each day. Benefits are far-reaching and include improvements in the autonomic nervous activity of the heart, decreased symptoms of stress, anxiety, and depression, enhanced cognitive performance, possible improvement in gas exchange in the lungs, possible improvement in brain systems involved in emotional regulation, reduction of pain in fibromyalgia, and reduction of cravings.

For optimal results, follow these guidelines from research (Bentley et al, 2023):

• Avoid "fast-only" breathwork (slow breaths are needed)

• Each episode of breathwork should last longer than 5 minutes

• Practice should be guided (for example online or in a group)

• Multiple sessions per week are needed

• A duration of minimum 4-8 weeks is needed to see good results

OTHER STRESS REDUCTION PRACTICES

Many other practices improve HRV over time, including Heartmath, gratitude journaling, meditation, yoga nidra, tapping, and more. The parts of the brain that get a workout from these practices also integrate information from the brain and body to send signals of “safety” to the heart, which emerge as high beat-to-beat variability.

EXERCISE and DIET

A Mediterranean diet has been found to improve HRV. In general, glucose peaks and troughs, long periods of fasting, and inadequate calories worsen HRV. The fasting-mimicking diet can sometimes result in a powerful and lasting improvement in HRV.

Regular exercise is critical to keeping HRV optimized over time. Slow stretching, resistance training with plenty of rest between sets, low intensity cardiovascular exercise all have demonstrable benefits. But high intensity interval training, when practiced in a well-balanced exercise regimen, may have the best benefits. In the end, HRV is a way that the brain tells the body that “all is well” — which is more likely to happen when we are fitter.

SLEEP

Last but actually most important, sleep that meets quantity, quality, consistency, and continuity (not too many interruptions, good efficiency) is both a cause and consequence of good HRV. We went into much detail in a previous newsletter!

REFERENCES

Bach D, Groesbeck G, Stapleton P, Sims R, Blickheuser K, Church D. Clinical EFT (Emotional Freedom Techniques) Improves Multiple Physiological Markers of Health. J Evid Based Integr Med. 2019

Bentley TGK, D'Andrea-Penna G, Rakic M, Arce N, LaFaille M, Berman R, Cooley K, Sprimont P. Breathing Practices for Stress and Anxiety Reduction: Conceptual Framework of Implementation Guidelines Based on a Systematic Review of the Published Literature. Brain Sci. 2023

Chang KM, Wu Chueh MT, Lai YJ. Meditation Practice Improves Short-Term Changes in Heart Rate Variability. Int J Environ Res Public Health. 2020

Cui L, Tao S, Yin HC, et al. Tai Chi Chuan Alters Brain Functional Network Plasticity and Promotes Cognitive Flexibility. Front Psychol. 2021;12:665419. Published 2021

Gao J, Skouras S, Leung HK, Wu BWY, Wu H, Chang C, Sik HH. Repetitive Religious Chanting Invokes Positive Emotional Schema to Counterbalance Fear: A Multi-Modal Functional and Structural MRI Study. Front Behav Neurosci. 2020

Kees Blase, Eric Vermetten, Paul Lehrer, and Richard Gevirtz Int. J. Environ. Res. Public Health 2021

Liu J, Xie H, Liu M, et al. The Effects of Tai Chi on Heart Rate Variability in Older Chinese Individuals with Depression. Int J Environ Res Public Health, 2018

Pascoe MC, Thompson DR, Jenkins ZM, Ski CF. Mindfulness mediates the physiological markers of stress: Systematic review and meta-analysis. J Psychiatr Res. 2017

Pizzoli SFM, Marzorati C, Gatti D, Monzani D, Mazzocco K, Pravettoni G. A meta-analysis on heart rate variability biofeedback and depressive symptoms. Sci Rep. 2021

Redwine LS, Henry BL, Pung MA, et al. Pilot Randomized Study of a Gratitude Journaling Intervention on Heart Rate Variability and Inflammatory Biomarkers in Patients With Stage B Heart Failure. Psychosom Med. 2016

Tinello D, Kliegel M, Zuber S. Does Heart Rate Variability Biofeedback Enhance Executive Functions Across the Lifespan? A Systematic Review. J Cogn Enhanc. 2022

Tyagi A, Cohen M. Yoga and heart rate variability: A comprehensive review of the literature. Int J Yoga. 2016

Yang H, Haack M, Dang R, Gautam S, Simpson NS, Mullington JM. Heart rate variability rebound following exposure to persistent and repetitive sleep restriction. Sleep. 2019

Yuda E, Ogasawara H, Yoshida Y, Hayano J. Exposure to blue light during lunch break: effects on autonomic arousal and behavioral alertness. J Physiol Anthropol. 2017

Zaccaro A, Piarulli A, Laurino M, Garbella E, Menicucci D, Neri B, Gemignani A. How Breath-Control Can Change Your Life: A Systematic Review on Psycho-Physiological Correlates of Slow Breathing. Front Hum Neurosci. 2018

Zou L, Sasaki JE, Wei GX, et al. Effects of Mind−Body Exercises (Tai Chi/Yoga) on Heart Rate Variability Parameters and Perceived Stress: A Systematic Review with Meta-Analysis of Randomized Controlled Trials. J Clin Med. 2018