Oura Ring vs Fitbit vs Apple Watch: this clinical study makes an excellent case for smart rings

Oura Ring trumps Apple and Fitbit by coming tops in a clinical study

Features By Matt Evans published 12 October 2024

At TechRadar, I often find myself pitting wearables against each other. Next week, you’ll be able to read what happened when I took the Coros Vertix 2S, Garmin Fenix 8 and Oura Ring Gen 4 out on a 5k run at the same time. I performed a similar test when pitting the best smartwatches against Strava while running the 2024 London Marathon.

One aspect of health tracking I haven’t group-tested is sleep tracking. Fortunately, researchers from Harvard Medical School and Brigham and Women’s Hospital, Boston, have done the legwork for me by testing the Oura Ring Generation 3 against an Apple Watch Series 8 and Fitbit Sense 2, to see which one is the most accurate. To set a benchmark, the three devices were also tested against a gold-standard, medical-grade polysomnograph (a tool used to diagnose and measure sleep disorders).

Studying 35 participants, the results showed that all devices accurately detected sleeping and wakeful states. However, the Oura Ring was best at discriminating between sleep stages, matching the polysomnograph with about 80% accuracy.

Published in the journal Sensors, the researchers wrote: “The Oura ring was not different from PSG [the polysomnograph] in terms of wake, light sleep, deep sleep, or REM sleep estimation.

“The Fitbit overestimated light (18 min; p < 0.001) sleep and underestimated deep (15 min; p < 0.001) sleep. The Apple underestimated the duration of wake (7 min; p < 0.01) and deep (43 min; p < 0.001) sleep and overestimated light (45 min; p < 0.001) sleep.

“In adults with healthy sleep, all the devices were similar to PSG in the estimation of sleep duration, with the devices also showing moderate to substantial agreement with PSG-derived sleep stages.”

While all three devices were accurate when it came to tracking wakefulness and sleep, the Apple Watch was the least accurate at measuring sleep stages overall. It’s worth noting that this test was conducted before the release of the Vitals app on watchOS 11, which has changed the way Apple tracks sleep using an Apple Watch. The Fitbit Sense 2, on the other hand, hasn’t changed the way it tracks sleep, so we can expect this to still be accurate, as far as it goes.

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