Your skepticism is justified. Oura publish their data, and to quote them:

>Oura ring was 96% accurate in detecting sleep compared to polysomnography, 48% accurate in detecting wakefulness, 65% agreement in detecting “light sleep,” 51% agreement in detecting “deep sleep” and 61% agreement in detecting REM

So it's basically wrong with sleep categorization about half the time.

oura ring hardware is horribly limited in terms of precision. let it not be a barrier to invest in a good wrist/arm/head band

Many have already pointed that there have been studies to measure the accuracy of sleep analysis by wearables. They aren't that great. If you have a concern, you should definitely seek out a polysomnograph, and wearables should not be a replacement for that. However, you can't get a polysomnograph every night, and wearables are probably the best option for regular analysis. Just because they're not that great doesn't mean they're useless, and doesn't mean they won't improve.

they can be

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8120339/

Most devices (Fatigue Science Readiband, Fitbit Alta HR, EarlySense Live, ResMed S+, SleepScore Max) performed as well as or better than actigraphy on sleep/wake performance measures, while the Garmin devices performed worse.

"Performance of seven consumer sleep-tracking devices compared with polysomnography" Sleep. 2021 May PMC8120339

Seems to accurately analyze them. Conclusion "Device sleep stage assessments were inconsistent."

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8120339/

This research was funded by the Office of Naval Research, Code 34. (see also Disclosure Statement)

From the study: "Most devices (Fatigue Science Readiband, Fitbit Alta HR, EarlySense Live, ResMed S+, SleepScore Max) performed as well as or better than actigraphy on sleep/wake performance measures".

Great news.

The Garmin one is discontinued.

Also, is there a more "layman readable" version of this paper/report?

The Garmin watches have been replaced by newer versions with upgraded sensors. Garmin's tracking isn't perfect, but each version has made small improvements.

Yes, the study evaluates the accuracy, and the results are not good!

Garmin publishes their accuracy data: https://www.garmin.com/en-US/blog/health/garmin-health-annou...