• Heart rate variability (HRV) reflects the heart’s adaptability to different situations and provides insights into stress levels, as well as overall health and well-being.
  • HRV is linked to the autonomic nervous system, with higher HRV associated with rest-and-digest and lower HRV with stress or illness.
  • HRV is unique to each individual. Monitoring your HRV with the Oura App can help you determine what’s normal for you, and when something is off.

What is Heart Rate Variability (HRV)?

As popular as the metaphor may be, a healthy heart doesn’t beat as regularly as a metronome — in fact, it changes its rhythm with each beat. This constant variation in milliseconds between your heartbeats is known as your heart rate variability, or HRV.

Some situations increase variation (high HRV), while others cause the time intervals between beats to stay more constant (low HRV).

You may be unaware of these subtle variations, but they reflect your heart’s ability to respond to different situations. HRV can react to stress and/or illness before resting heart rate (RHR), which makes it one of your body’s most powerful signals — providing useful insights into your stress levels, recovery status, and general well-being.

Member Tip: Oura members can determine how your HRV is moving up or down over time by monitoring your HRV balance, which contributes to your Readiness Score. A good HRV score is a sign that your body can adapt to stress and recover from challenges.

READ MORE: How Accurate Are Oura’s Heart Rate & HRV Measurements?

Heart Rate Variability, Explained 

HRV is linked to your autonomic nervous system (ANS) and the balance between the parasympathetic nervous system (PNS or rest-and-digest branch) and the sympathetic nervous system (SNS or fight-or-flight branch). By balancing the two forces, the ANS helps you respond to daily stressors and regulate some of your body’s most important systems, including heart rate, respiration, and digestion.

HRV is the most effective way of estimating your ANS balance, as it directly impacts your heart’s activity.

Independently, your heart beats to its own rhythm thanks to a built-in pacemaker called the sinoatrial (SA) node. Your SA keeps your heart firing at around 100 beats per minute.

However, your ANS greatly influences how your heart beats. All the cells within your heart’s pacemaker have direct phone lines from both sides of your ANS. They give input, beat to beat, on a cellular level to your heart:

  • Your rest-and-digest tells your heart to slow down, making room for variability between beats (higher HRV)
  • Your fight-or-flight system tells your heart to speed up, limiting space for variability (lower HRV)

These two systems can be silent, active, or shouting over each other at any given time. That’s a lot of conversation, and it leads to a lot of variation.

As a rule of thumb:

  • Higher HRV is associated with rest-and-digest, general fitness, and good recovery
  • Lower HRV is associated with fight-or-flight responses, stress, illness, or overtraining
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Heart Rate Variability is Unique to You

“High” and “low” heart rate variability is relative for each person. HRV is a highly sensitive metric, which responds uniquely for everyone.

Some individuals have steady HRV scores, while others fluctuate considerably. HRV is an evolving tool, which means, at every HRV level, your personal scores and body status observations are especially important.

Each person’s HRV is unique, so compare your HRV to your own averages and avoid comparisons to others. It’s normal to see daily and seasonal fluctuations in your HRV.

Keep in mind that many factors impact your ANS and, therefore, your HRV.

Factors You Can’t Control

  • Genetic factors: Your genetic makeup plays a significant role in determining your baseline HRV. Variations in genes mean you have a unique autonomic nervous system, which leads to individual differences in HRV patterns. As a result, you may naturally have higher or lower HRV. While you can’t change your genetic predispositions, it can help you to understand your HRV baseline.
  • Age: HRV changes with age. Generally, HRV tends to decrease as you get older. This decline is attributed to various age-related changes in the autonomic nervous system and heart function. Nonetheless, even within specific age groups, individual differences in HRV exist. 
  • Hormone cycles: Hormone cycles, particularly in women, can influence HRV. Menstrual cycles and fluctuations in sex hormones like estrogen and progesterone can affect the autonomic nervous system and, consequently, HRV. Changes in HRV during different phases of the menstrual cycle are not uncommon.
  • Emotion: Positive emotions and relaxation have been shown to increase HRV, indicating a more flexible and adaptive autonomic nervous system. Conversely,  anxiety and stress can lower HRV, indicating a less resilient autonomic response.

    Member Tip: In Explore content in the Oura App, you can access guided and unguided meditation and mindfulness content to help promote emotional balance and improve HRV. 
  • Illness: Certain illnesses and health problems, like cardiovascular diseases, diabetes, high blood pressure, or respiratory disorders, can impact HRV. During illness, HRV may decrease due to the body’s response to physiological stress. 

READ MORE: HRV and Stress: What HRV Can Tell You About Your Mental Health

Factors You Can Control

  • Sleep routine: Your internal biological rhythms, such as circadian rhythm and sleep-wake cycle, can affect HRV. For example, a sleep-wake cycle that promotes adequate and restful sleep can result in better HRV, while sleep disturbances and sleep deprivation can lead to decreased HRV. The good news is that you can align your lifestyle with your body’s natural rhythm to enhance your sleep routine and, in turn, HRV.
Member Tip: You can find out your chronotype (whether you’re a morning or night person) in the Oura App using the Body Clock and Chronotype feature. This makes it easier to align your lifestyle with your body’s rhythm and fall into a better sleep routine.
  • Environmental factors: Environmental factors, such as air quality, temperature, and altitude, can influence HRV.
  • Medications and substances: Various medications and substances can influence the autonomic nervous system and, consequently, HRV. For instance, stimulants like caffeine or certain drugs may increase sympathetic activity and reduce HRV.
  • Lifestyle: Your lifestyle choices, including your physical activity, sleep quality, stress management, as well as hydration, and dietary habits, all contribute to your distinct HRV patterns. This means that you have some control over your HRV balance.
Member Story: Using the Oura App, Jussi L. noticed that alcohol consumption negatively affected his sleep quality and HRV. “When I had a glass of wine I’d fall asleep quickly, but the quality of my sleep was horrible, and my HRV plummeted.” The app then provided insights that enabled Jussi to adjust his diet and evening routine, leading to a better HRV. “When making all these changes, my Oura stats started to improve. My HRV soared to 60 for a period, which for my age is terrific, and now hovers around 40,” he adds.

RELATED: Using Oura To Understand Your Body

What is a Good Heart Rate Variability (HRV)?

A normal HRV for adults can range anywhere from below 20 to over 200 milliseconds.* The best way to determine your normal level is to use a wearable that measures your HRV in a controlled setting, like sleep, and establishes a baseline over a few weeks.

Curious how other Oura members’ HRV scores stack up? We took a look at our community data, and found a range of normal HRV scores across Oura members, revealing interesting trends across age and gender. Head to this blog to learn more about Oura members’ average HRV.

Heart Rate Variability Has Short and Long-Term Trends

Because HRV is so responsive, there are multiple touchpoints where it can provide insights. Helpful short- and long-term metrics to track include average daytime and nightly HRV, as well as HRV Balance and HRV over months.

Each metric provides different insights.

  • How your nightly average HRV compares to your baseline, and whether it trends up or down, can help you know how to approach your day  (e.g., prioritizing rest or facing a challenge).
  • Comparing your daytime check-ins to your general baseline can give you insight into how certain activities, like meditation or exercise, affect your system.
  • How your HRV trends over a few weeks, your HRV balance, can help you identify if you’re successfully rebounding from taxing days (e.g., training, illness, stress).
  • How your HRV changes over months can reveal how major lifestyle changes (e.g., a new job, becoming a parent) are impacting your health.

Heart Rate Variability Has Natural Highs and Lows

Some explanations of HRV oversimplify it by asserting that a high number is always good and a low one is always bad. It’s far more complex.

While high HRV is generally positive, there are situations where low HRV is necessary and even desirable. For example, during strenuous exercise, low heart rate variability is a reflection of your fight-or-flight system appropriately dominating to get your heart rate up for activity. Your HRV will rebound afterward, as your rest-and-digest system takes over to help you recover.

These fluctuations occur throughout the day, as different daily stressors continuously challenge your system. Simply being excited, or moving from the couch to the bathroom, can change your HRV at any given moment.

By measuring your HRV during the day, you’re capturing your body’s response to these fleeting changes. If you want to understand your chronic physiological state, the best time to measure HRV is while you sleep.

At night, your body is in a consistent state, without any confounding variables (e.g., food, social interactions, changing environment). Some wearables take the apples-to-apples approach when it comes to your measurements. They fail to caveat that daytime measurements might mask your underlying ANS balance.

Which Patterns Matter?

Monitoring your HRV can help you reach peak productivity, manage stress, and fine-tune your training regimen.

A single nightly HRV reading can provide insights, like:

  • A higher HRV score that reflects a rest day, cool bedroom, or “mindful” low/moderate intensity activities such as hiking or yoga
  • A lower HRV score that results from dehydration, alcohol, late meal or exercise, illness, a high-intensity workout, acute stress, or a hot bedroom

You may notice that your HRV varies greatly from day to day. If you’re looking for patterns, what matters is your HRV trend.

READ MORE: How To Increase Your HRV (Heart Rate Variability)

What Is HRV? Infographic

*This HRV range is based on data that includes independent academic studies as well as Oura’s proprietary data. Academic studies are typically restricted to smaller or less diverse populations and therefore may not be representative of the general population in isolation. Oura’s goal in providing this broader range is to reflect the largest and most representative dataset possible. While it may be more common for HRV averages to cluster around certain numbers (e.g., 50 ms), there are individuals whose averages may not appear as frequently in the population but still represent their personal normal (e.g., 18 ms). The most effective way to analyze HRV is to compare your values to your personal baseline.