Learn more about the heart rate variability (HRV) measurements taken by the Oura Ring.
What Is Heart Rate Variability?
How Oura Measures HRV
Interpreting Long-Term HRV
Interpreting Short-Term HRV
The Importance of HRV
When Does Oura Measure Heart Rate Variability?
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What Is Heart Rate Variability?
Heart rate variability (HRV) measures the variation in time (milliseconds) between your heartbeats. HRV provides a snapshot into how your body is balancing between the two branches of your autonomic nervous system: your sympathetic ("fight-or-flight") and parasympathetic ("rest-and-digest"). HRV indicates how well the body is responding to physiological stress, managing recovery, and maintaining overall health.
Normal HRV can range anywhere from below 20 to over 200 milliseconds, depending on various factors such as age, sex, physical fitness, and genetics. The HRV value provided by Oura falls within this same range. HRV is a highly individual measure and you should compare your own HRV only with your own trends.
As a general rule:
- High HRV (relative to your baseline) is associated with activation of your "rest-and-digest" branch, general physical fitness, and good recovery. Higher average nighttime HRV measurements have also been linked to better sleep quality and vice-versa.
- Low HRV (relative to your baseline) is associated with activation of your "fight-or-flight" branch, stress (both good and bad), illness, and overtraining.
How Oura Measures HRV
Oura calculates your nighttime HRV using the root mean square of the successive differences (rMSSD), a well-known HRV parameter that provides a reliable and accurate view of your autonomic nervous system’s activity. The average HRV you see is the mean of all five-minute samples taken while you sleep. Oura accounts for changes in your HRV every five minutes throughout the night, instead of just once at a single point during the night. This continuous tracking offers greater accuracy and gives you a more detailed view of how your body is responding to stress from the previous day—and how well it's preparing for the day ahead.
Oura provides you with the following heart rate variability metrics:
- Average HRV: Your average HRV captured over the entire night
- Max HRV: Your highest HRV value captured over the entire night
You can find HRV under readiness, sleep, or Trends. Tracking your HRV in the Trends view can help you see how well you've recovered over the past week and whether you should pay closer attention to any internal or external stressors.
Interpreting Long-Term HRV
HRV can't reduce stress or improve your cardiovascular fitness on its own, but it can offer insight into how your behavior, environment, and emotions are impacting your body. Measuring your HRV can be a great starting point for a healthier lifestyle—whether it's helping you manage stress better, adding more physical activity into your routine, or understanding how your diet affects your body's stress response.
Check out "What is HRV Balance" on The Pulse Blog for more information.
Interpreting Short-Term HRV
1. Interpret Your HRV
- Higher HRV values tend to occur during REM sleep.
- Lower HRV values tend to occur during deep sleep.
2. Interpret Your HRV Values (High & Low)
HRV levels that are high or slightly higher than your normal range tend to be signs of good recovery. A higher HRV may be the result of:
- A much-needed rest day
- A cool bedroom at night
- Participation in more mindful, low-to-moderate-intensity activities like hiking or yoga
- Engagement in mindfulness meditation
HRV levels that are lower than your normal range are signs of excessive strain on the body. Lower HRV may be the result of:
- Dehydration
- Consumption of alcohol
- A late night meal or workout
- Illness
- Acute and prolonged stress
- A hot bedroom at night
- Jet lag and inconsistent sleep patterns
- Overtraining
Note: naturally, after a hard workout, your HRV will likely decline. As you recover, your HRV should rebound. If it doesn't return to your baseline or takes an extended period of time to, this can be an indication that you're training too often or too hard.
A significantly higher HRV may indicate readiness for physical challenges or under-stimulation of the autonomic nervous system, whereas a significantly lower HRV might suggest excessive strain or poor recovery, potentially due to factors like stress, illness or other strain, dehydration, or overtraining. There is variation in HRV at different stages of the menstrual cycle.
The Importance of HRV
HRV reflects how the sympathetic and parasympathetic branches of your autonomic nervous system work together.
When both of these branches send signals to your heart, your heart rate naturally increases and decreases, resulting in variations between beats. Heart rate and HRV tend to be inversely connected. When your heart rate is slower, there's more time for variation between beats, leading to a higher HRV. On the other hand, a faster heart rate leaves less room for variation, usually resulting in a lower HRV.
Having variation between your heartbeats is a sign that your autonomic nervous system is balanced and capable of responding to different stimuli in a healthy way.
When Does Oura Measure Heart Rate Variability?
Oura measures HRV during sleep to avoid the daytime "noise" that can affect your data and make it harder to interpret. Heart rate and HRV are sensitive metrics that can easily change from simple activities like drinking water, getting up to use the bathroom, or watching an exciting TV show.
For Gen2 users: Certain unguided sessions will provide heart rate, HRV, and skin temperature snapshots upon completion. These sessions can be used at any time of the day.
For Gen3 and Oura Ring 4 members: Explore contains meditation sessions and stories, some of which will also measure your heart rate, HRV, and skin temperature.
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What is Heart Rate Variability?
