Depends what types of sleep you want to track. Simply if you're sleeping or not? Oura is studied to be relatively accurate at determining if you're asleep or n

Depends what types of sleep you want to track. Simply if you're sleeping or not? Oura is studied to be relatively accurate at determining if you're asleep or not. What stage of sleep you're at, and if you're at REM? They all seem to fail this. In all cases, apps (phone/watchOS) are pretty much universally bad. Hardware like Beddit doesn't seem to pass the test either [0]. Oura has some OK results for basic tracking but it isn't great either [1]. This source talks about Oura more comprehensively [2]. Fitbit Ultra seems to be OK at sensitivity [3]. There's an interesting test from an undergrad researcher at Brown University from 2017 too [4]. There's a couple of other studies and also studies interpreting other studies you can find on the topic. The short version is that it depends what you're after. If you're happy with just knowing whether you're asleep or awake Oura and Fitbit seem to be the best the market has to offer with reasonable accuracy. Oura has some results with OK estimations of deep sleep, but nothing I would rely on for accuracy. If you have the money there's some FDA approved products that are pretty expensive. I must say it's slightly amusing that we're fear-mongering over self-aware superintelligent AI taking over the world while we can't even reasonably replicate polysomnography on a consumer device. [0]: https://www.ncbi.nlm.nih.gov/pubmed/30853052 https://www.ncbi.nlm.nih.gov/pubmed/30853052 [1]: https://www.ncbi.nlm.nih.gov/pubmed/28323455 https://www.ncbi.nlm.nih.gov/pubmed/28323455 [2]: https://nutritionalrevolution.org/2019/07/20/why-the-oura-ring-sucks-for-tracking-sleep-and-might-be-harming-your-health/ https://nutritionalrevolution.org/2019/07/20/why-the-oura-ri... [3]: https://academic.oup.com/sleep/article/38/8/1323/2417994 https://academic.oup.com/sleep/article/38/8/1323/2417994 [4]: http://sleep.cs.brown.edu/comparison/ http://sleep.cs.brown.edu/comparison/