The wrist-worn devices generally don't measure the heart rate precisely enough to measure heart rate variability (HRV). Does the Ōura ring measure heart rate precisely enough to get quality HRV data?
I though some certifications are surely needed for a device like Ōura ring, as it is a kind of medical device. And it seems to be that they have validated the device.
The support community of Ōura claims the following:
The validation report (previously confidential) of the ŌURA ring is based on the measurements done with the Finnish Institute of Occupational Health. We are collaborating with several universities, research organisations and sleep clinics in the US and additional validation reports will be released once available.
So far we have validated our sleep staging algorithms against Polysomnography, Interbeat interval (IBI) data against ECG derived R-R intervals, temperature measurement against a body temperature logger used in professional measurements and activity measurements against indirect calorimeter. In all of these we have either reached or exceeded the expected performance levels.
According to the link in the original question IBI is equivalent with HRV so it has been tested by the Finnish Institute of Occupational Health which seems to be independent organisation that validated the features of the device.
Here is the report of the tests.
Alright, I guess I can't comment but I can write a separate answer.
I looked a bit into the answer by Bence and summarized some more details below.
Current links since his are out of date now:
Epoch by epoch comparison of the sleep stages determined by the ŌURA ring and manually scored based on Polysomnography. Sleep stages were classified into Wake, REM, Light and Deep by both methods. The ŌURA ring was worn on the nondominant hand. The ŌURA ring displays 65.3% agreement, Cohen’s kappa 0.449.
The results are improved if you combine light and deep into a non-REM group and results are worse if you wear it on your dominant hand.
Some caveats to consider:
- Low sample size (n=14)
- Funded directly by Ouraring (if you think this could bias the study)
Fourteen subjects volunteered to participate in this study. Eight full polysomnograph recordings (four female and four male) and six EOG only recordings (two female and four male) were made. The recording and subsequent analysis was carried out by the sleep laboratory of the Finnish Occupational Health Institute, Helsinki, Finland1), an independent research institute. The research was funded by Ouraring.