Before buying one I tried to make research about its effectiveness and there are some very alarming reports, coming, of all places, from the research published by the same company. So this isn't even biased...
“From EBE analysis, ŌURA ring had a 96% sensitivity to detect sleep, and agreement of 65%, 51%, and 61%, in detecting “light sleep” (N1), “deep sleep” (N2 + N3), and REM sleep, respectively. Specificity in detecting wake was 48%.”
Specificity in detecting wake was 48%! If this was a medical test, it would never be approved by FDA.
A specificity of 48% means that there is a 48% chance that someone is awake when the device says they are asleep.
That is horrible.
This is very surprising and alarming. As the author later goes on to describe, this has real implications and possible negative effects, this is not just a benign error here and there. Users are apparently supposed to use the Oura data to change or at least adjust and improve their sleep habits, and of course if they will do it based on faulty information, the adjustments themselves are going to be faulty and it can lead to worse or sub-optimal sleep!
Apparently you can still use Oura to track heart rate and HRV, but their own proprietary markers like “readiness” are probably based on all of their data including sleep, so they are not going be that accurate either.
This matches my experience having received one Nov 2018 (and returning it a few weeks later). It was constantly getting my actual sleep times wrong, more often than not marking me as being asleep while watching tv in the evening.
After contacting support, their solution was an upcoming update to their app where I'd be able to edit the data so that I could override the app whenever I knew it was wrong. Which completely invalidates the primary reason to own this product. I mean, if I knew when I was asleep, why would I need a ring to track it?!
So given that it couldn't properly track sleep, doesn't track activity (by design), the only other purpose in my mind was to track HRV. And count me as skeptical of the accuracy of that data as well.
Apparently you can still use Oura to track heart rate and HRV, but their own proprietary markers like “readiness” are probably based on all of their data including sleep, so they are not going be that accurate either.