In most cases, Oura’s proprietary algorithms do a good job in showing very accurate resting heart rate and heart rate variability (HRV) readings and trends in the Oura app.
The algorithms have been tested and verified against data measured from healthy adults. If you have a heart condition or other health issue that causes continuous or regular arrhythmia, or you’re on continuous medication that affects your cardiovascular system, the Oura app may not be able to show your full resting heart rate and HRV data. Instead, you may notice gaps in your heart rate and HRV graphs. In some cases, you might not see your heart rate and HRV data at all.
Note: the Oura ring is not a medical device, and cannot therefore be used to diagnose or monitor diseases or other health conditions.