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The ultimate guide to heart rate variability (HRV): The key to understanding your health

November 2nd, 2023,

10 min read

The ultimate guide to heart rate variability (HRV): The key to understanding your healthfeatured image

Breathing exercises are a great way to improve your cardiovascular health. With practice, you will be able to improve your heart rate variability (HRV). But what exactly is HRV and why do you need to improve this? In this article, we will tell you all about heart rate variability (HRV). This article aims to explain:

  • How to measure HRV
  • Parasympathetic and sympathetic nervous systems
  • Good, regular, and low HRV ranges
  • Effects of aging and sleep on HRV
  • Variations in your HRV
  • Practical tips on improving HRV
  • How breathwork improves HRV
  • Various HRV measuring devices
  • FAQ

What is heart rate variability?

Our heart does not beat to a fixed, regular rhythm like a metronome. The rhythm of a healthy heart is rather irregular, with the intervals between successive heartbeats constantly varying. This variation between heartbeats is normal, it’s even considered healthy. This is called heart rate variability, or HRV for short.

When your heartbeats vary more over time, and your HRV is thus higher, it's considered a sign of a healthy heart and a flexible nervous system. If the variation is low, it could indicate stress, fatigue, or other health issues. In simple words, HRV helps us understand how well your heart and body can adapt to different situations.

There are different ways of measuring HRV (time-domain, frequency-domain analysis...). Some formulas lead to HRV expressed in milliseconds, while others are expressed on a scale from 0 to 20. At moonbird, we use the difference between HR max and HR min to calculate HRV. Based on our calculations, HRV typically varies between 0 and 20, with higher being better.

The autonomic nervous system consists of two branches: the sympathetic and the parasympathetic nervous system. Think of the sympathetic and parasympathetic nervous systems as the gas pedal and brake pedal of your body. The sympathetic system revs you up when you're facing challenges, while the parasympathetic system calms you down and helps you rest.

These systems also affect how your heart beats. When you're stressed or active, the gas pedal (sympathetic system) makes your heart beat more regularly. When you're relaxed, the brake pedal (parasympathetic system) makes your heart beat less regularly.

Measuring these changes in your heartbeats, your HRV tells us how your body is handling stress and recovery. When your HRV is higher, it usually means your body is in good shape. So, understanding these systems helps us see how your heart and body are doing in different situations. It's like having a window into how well your engine runs and how you cope with the ups and downs of life.

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In situations where stress is high, such as facing a demanding work deadline or feeling anxious, your HRV might drop. Intense exercise and lack of sleep can also temporarily lower HRV.

Practices like deep breathing, meditation, and relaxation techniques tend to increase HRV by activating the calming parasympathetic system. Engaging in light exercises, experiencing joy and laughter, and moments of genuine happiness can also lead to higher HRV levels.

You should note that HRV can vary from person to person and can be influenced by a range of factors.

Good, normal, and low HRV ranges

The average heart rate variability stands at 15 bpm. At 25 years old, it rises to 17, but by 35, it drops to 14, at 45, it decreases to 12, and at 55, it drops to 11. These findings predominantly come from individuals who prioritize their health, often athletes, looking to perform better at whatever they do. These numbers are just to give you an idea.

Rather than fixating on comparisons to established norms, it's far more useful to monitor your own heart rate variability trends. If you're dedicated to improving your overall health and fitness, you should expect your heart rate variability to gradually increase over time. Conversely, a declining trend in HRV may indicate overtraining or engagement in unhealthy habits, such as poor nutrition or sleep.

While the chart illustrates the technical definition of "normal HRV", determining what "good heart rate variability" is a far more difficult question and should be studied for each person separately. Therefore, you can see that the average line extends to a wider range.

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HRV as you age

As you grow older, your HRV tends to decrease. This means that the variation in time between your heartbeats becomes less pronounced.

Several factors contribute to this decrease. Changes in cardiovascular health, reduced physical activity, accumulated stressors throughout life, unhealthy lifestyle habits, and the presence of age-related health conditions can all impact your HRV. These factors collectively affect the autonomic nervous system's regulation of heart rate and contribute to the observed reduction in HRV as you age.

Keep in mind that individual differences play a role, and some older individuals may maintain higher HRV levels due to healthy lifestyles, while others may experience more significant declines. Monitoring changes in HRV over time can provide insights into how your body responds to aging.

HRV when you sleep

Your HRV experiences shifts while you sleep. During sleep, your body progresses through three different stages - light sleep, deep sleep, and rapid eye movement (REM) sleep. Each stage is associated with unique HRV patterns:

  • Light sleep: Your HRV tends to lessen when you relax and fall asleep. This could be due to the increased influence of the parasympathetic nervous system, which promotes relaxation.
  • Deep sleep: HRV often continues to decrease during deep sleep. This stage prioritizes physical recovery and relaxation, leading to reduced HRV.
  • REM sleep: Your HRV frequently rises and becomes more variable during REM sleep. This might be linked to heightened sympathetic nervous system activity, reflecting intense brain engagement and potential heart rate shifts.

Factors like sleep quality, disorders, and individual disparities can affect HRV during sleep. Conditions such as sleep apnea can disrupt regular HRV patterns, causing irregularities.

If you monitor your HRV during sleep you can gain insights into your sleep quality and autonomic nervous system function. A consistent sleep routine, addressing sleep-related concerns, and practicing relaxation techniques like deep breathing exercises before going to bed can help maintain a balanced HRV during sleep.

Why your HRV might be low

A low heart rate variability could occur due to various reasons. Your HRV reflects the flexibility of your autonomic nervous system, which controls your vital functions. When your HRV is low, it might indicate challenges in switching between stress and relaxation responses. This can be caused by factors like chronic stress, inadequate sleep, unhealthy lifestyle choices, lack of physical activity, or underlying health conditions such as high blood pressure, cardiovascular issues, diabetes, anxiety, or depression. Additionally, age-related changes and genetic predispositions can also contribute to lower HRV. Identifying the cause requires careful consideration of your overall health, habits, and potential medical conditions.

How to improve your HRV


Improving your heart rate variability (HRV) through physical activity involves adopting a holistic approach that encompasses various aspects of your well-being. You can enhance your HRV by focusing on your physical health with the following:

  • Regular exercise: Engage in consistent physical activity, including both aerobic exercises (like walking, jogging, or cycling) and strength training. Aim for a balanced routine that challenges your cardiovascular system and promotes muscle strength.
  • Healthy diet: Consume a nutritious diet rich in fruits, vegetables, whole grains, lean proteins, and healthy fats. Avoid excessive sugar, processed foods, and unhealthy fats since they immediately impact cardiovascular health.
  • Adequate hydration: Stay well-hydrated throughout the day. Proper hydration supports optimal bodily functions, including cardiovascular health.
  • Quality sleep: Prioritize getting enough high-quality sleep each night. Maintain a regular sleep schedule and create a comfortable sleep environment to support your body's recovery. Slept badly for a night? You will see your HRV plummeting the next day!
  • Moderate alcohol and caffeine: Consume alcohol and caffeine in moderation, as excessive intake can negatively affect your autonomic nervous system and HRV. Drank some glasses of wine yesterday? Your HRV will most likely decrease today.
  • Tobacco and substance use: If you smoke or use other substances, consider quitting or reducing your consumption. These habits can impact your cardiovascular health and HRV.


Boosting your HRV through your mental well-being means making good choices and following routines that help you feel better emotionally and become stronger. You can do this with:

  • Stress management: Relaxation techniques such as breathing exercises or meditation are one of the easiest ways to increase HRV, reduce stress, and promote a balanced autonomic nervous system.
  • Healthy routines: Establish consistent daily routines that include regular exercise, quality sleep, and time for relaxation. A structured routine can contribute to better mental and physical health.
  • Social connections: Prioritize meaningful social interactions and maintain supportive relationships. Engaging with friends and loved ones can reduce stress and enhance HRV.
  • Positive mindset: Cultivate a positive and optimistic outlook on life. Practice gratitude, focus on your strengths, and challenge negative thought patterns.
  • Creative expression: Engage in creative activities that bring you joy, such as art, music, writing, or gardening. Expressing yourself creatively can boost your mood and overall well-being.
  • Prioritize rest: Ensure you get adequate rest and allow yourself time for relaxation. Set aside moments in your day for activities that bring you peace and calmness.
  • Seek support: If you're struggling with your mental health, don't hesitate to seek professional help. A therapist or counselor can provide guidance and strategies to manage stress and emotions effectively.
  • Be kind to yourself: Treat yourself with kindness and self-compassion. Avoid self-criticism and engage in self-care to give yourself some peace of mind.

Remember that improving your HRV through mental health practices is a journey that requires patience and consistent effort. Small, intentional changes in your daily life can contribute to enhanced emotional well-being and, consequently, better HRV.

Biofeedback training

Improving your HRV through biofeedback training involves a process where you learn to become more aware of your body's internal processes and use this awareness to positively influence your HRV. You can do it with:

  • Monitoring: Start by using biofeedback devices or apps that measure and show your HR and HRV. These tools provide real-time data about your heart rate and HRV, helping you understand your body's responses whilst practicing HRV-improving activities.
  • Deep breathing techniques: Slow, deep breaths can activate your body's relaxation response and stimulate the parasympathetic nervous system, which is associated with higher HRV.
  • Visual, auditory, or tactile tools: Some biofeedback tools use visual, auditory, or tactile tools (like moonbird) to guide your breathing, whilst showing your HR and HRV. Sync your breath with these tools to help regulate your heart rate and improve HRV.

Biofeedback training empowers you to have more control over your body's responses, which can lead to improved HRV. This takes time and practice. Consistency and mindfulness play a significant role in achieving positive outcomes. Aim for daily sessions of biofeedback training to gradually improve your HRV over time. As you become more skilled, you can challenge yourself with more advanced techniques. For example, you can work on maintaining higher HRV levels during stress-inducing situations.


Breathwork, like slow, deep breathing, helps your HRV by calming your body's "rest and digest" system, reducing stress, and promoting relaxation. When you control your breath and exhale longer than you inhale, it creates a rhythmic heart rate pattern called RSA, which is good for HRV. Breathwork also boosts vagal tone, which is linked to better HRV and heart health.

By paying attention to your breath, you become more aware of how your body works and can improve your HRV. It also reduces stress, which is good for your HRV. Plus, proper breathwork gives your cells more oxygen and improves blood flow, helping your heart work well and your HRV. Lastly, breathwork makes you feel calm and mindful, which has a positive effect on your HRV. To make your HRV better, practice breathwork daily, choose a technique you like, and gradually increase how long you do it. You can also combine it with activities like meditation or yoga for even better results.

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HRV measuring devices

How is HRV measured?

Your HRV can be measured in both a medical and a non-medical setting. In a medical setting, HRV is often measured using electrocardiography (ECG ). An ECG is made by placing electrodes on the chest and limbs to record the electrical signals produced by the heart. These signals are then processed to analyze the time intervals between successive heartbeats. In that way, your HRV is calculated.

In non-medical settings, HRV can be measured using consumer wearable devices like heart rate monitors, smartwatches, or fitness trackers. These devices use optical sensors that detect blood flow beneath the skin, allowing them to calculate heart rate and heart rate variability. Some of these devices use photoplethysmography (PPG) to measure changes in blood volume, which is then used to derive HRV data. For instance, the moonbird device relies on a PPG sensor for the measurement. Although not medical-grade, several studies show that PPG measurements are very accurate.

Both medical and non-medical methods often involve collecting data over a specific period, which can range from a few minutes to longer durations. The collected data is then processed using various algorithms to calculate different HRV parameters, such as time domain, frequency domain, or nonlinear domain parameters.

Which tools can you use to measure your HRV?

There are several tools and devices you can use to measure your HRV. Some of these tools are medical-grade, while others are consumer-grade and suitable for personal use. Here are some options:

  • ECG devices: Medical-grade electrocardiography (ECG or EKG) devices are the most accurate way to measure HRV. These may require a visit to a healthcare professional and involve placing electrodes on your chest and limbs.
  • Wearables: Many fitness trackers, smartwatches, and heart rate monitors like Apple Watch, Fitbit, Garmin, Oura ring & WHOOP have HRV measurement capabilities. These devices typically use optical sensors to detect changes in blood volume under the skin and can provide convenient HRV data.
  • Mobile apps: Numerous mobile apps are available for both iOS and Android platforms that use your smartphone's camera and flashlight to measure HRV. These apps often utilize photoplethysmography (PPG) technology.
  • HRV monitors: Specialized HRV monitors are designed specifically for tracking heart rate variability. These devices may offer more accurate measurements compared to some consumer wearables.
  • Chest straps: Some chest strap heart rate monitors, commonly used by athletes and fitness enthusiasts like the Polar ones, can also measure HRV.
  • Biofeedback devices: Biofeedback devices are designed to help you learn to control your body's physiological functions, your breathing for example. Some biofeedback devices can measure HRV and provide real-time feedback to help you manage stress and relaxation. For instance, moonbird is a tactile breathing coach that guides you to a calm breathing pace. You simply have to follow its relaxing breathing pace. The device measures your HRV and you can see the statistics in moonbird’s app.

When deciding on a device for HRV measurement, take into account aspects like precision, user-friendliness, compatibility with your devices, and the particular functions you would like to use. Remember, many of them will use (slightly) different algorithms to calculate HRV. Therefore it is important when checking for HRV improvements over time, to stick to the same tool to compare your results.


What is a good heart rate variability?

A healthy HRV reflects a balanced autonomic nervous system, linked to improved cardiovascular health, stress resilience, and overall well-being. But what's considered "good" can vary based on factors like age, fitness, and health.

Can heart rate variability be too high?

Higher HRV is usually good, showing a balanced nervous system and good health. Very high HRV can be a concern, but it's rare and usually related to medical conditions or extreme situations.

Can you improve heart rate variability?

To boost HRV and overall health, maintain exercise, practice relaxation, sleep well, eat balanced, limit alcohol and caffeine, spend time with loved ones, try relaxation and biofeedback, do HRV-specific exercises, prioritize mental well-being, and avoid excessive workout intensity. Small changes add up to positive effects.

How to calculate heart rate variability?

HRV is determined by analyzing the time intervals between heartbeats, known as RR intervals. Common methods are time-domain and frequency-domain analysis, with apps automating calculations. Some devices, like moonbird, offer real-time HRV. For medical accuracy, consult a healthcare or HRV specialist.

Understanding and harnessing your heart rate variability can unlock profound insights into your health and well-being. As we've seen in this article, HRV serves as a dynamic window into the intricate interplay between your autonomic nervous system, stress responses, and overall cardiovascular health.

By recognizing the significance of HRV's variations in time between heartbeats, we gain a valuable tool for assessing the adaptability and resilience of our bodies. Whether through specialized devices, biofeedback training, or intentional breathwork, the ability to influence and improve HRV emerges as a powerful means of enhancing both physical and mental well-being.

Want to raise and control your HRV with a useful tool? Moonbird is just the device you need to measure your HRV and relax in no time through guided breathing exercises! It is a tactile breathing coach that you can take with you, wherever you go. Download the app with various guided breathing exercises and live biofeedback.

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