When a person is relaxed, a healthy heart’s beating rate shows remarkable variation in the time interval between heartbeats. By calculating this variation i.e. your heart rate variability (HRV) while you sleep, Oura can help you better understand your body’s reactions and your readiness to perform.
How does Oura calculate your HRV?
Oura calculates your night-time HRV from the rMSSD, a well-known HRV parameter that provides a good view on your Autonomic Nervous System activity. The HRV reading you see in the readiness view is the average of all the 5-minute samples measured while you sleep.
The HRV value given by Oura can range from anywhere below 20 to over 100. Defining a normal range is tricky: your own minimum and maximum values depend on several factors, such as your age, hormones, circadian rhythm, lifestyle and overall health. Because of this it’s best to compare your numbers to your own baseline values.
Because your HRV is measured throughout the night, the reading Oura gives will most likely differ from a reading you get when measuring your HRV for a few minutes just after waking up, or during the day, when there are lots of other internal and external factors that can affect the measurements.
What can your HRV tell you?
HRV is a good indicator of your recovery status. Typically when a person is under physical or mental stress, parasympathetic activity decreases and sympathetic activity increases. As a result, heart rate increases and HRV decreases. Sometimes HRV reacts earlier than heart rate, which makes it a particularly sensitive measurement.
High HRV is typically a sign of general health and fitness, whereas lowered HRV can be a sign of stress or overtraining. HRV also tends to decrease with age. Exercise is one of the best ways to increase HRV and reduce stress. Exercise, like lots of other things, is dose dependent: too much can lead to overtraining and negative health consequences. Strenuous exercise may lower HRV for one night but increases future HRV levels.
For more insights, check out the following articles in the Oura blog:
What Is Heart Rate Variability And What Can You Learn From it.
How to Measure Heart Rate Variability?