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topicnews · October 13, 2024

According to a study, there is a clear winner

According to a study, there is a clear winner


Three smart trackers against a medical gold standard. (RioPatuca Images – Adobe Stock)
Three smart trackers against a medical gold standard. (RioPatuca Images – Adobe Stock)

Intelligent trackers have long since become an integral part of our everyday lives. Be it to count steps, measure heart rate or monitor our sleep.

A new study from Harvard Medical School and Brigham and Women’s Hospital in Boston has now examined three more precise trackers and pitted them against a polysomnograph (PSG for short) (via Techradar).

The goal: How accurate are the three trackers in comparison?

What is a Polysomnograph?? A polysomnograph is a medical device that records various parameters such as brain activity, heart rate, respiratory movements, oxygen saturation, eye movements and muscle activity during sleep to analyze sleep and diagnose sleep disorders.

The study

The above study examined the accuracy of the three sleep trackers compared to the PSG. Thirty-five healthy adults aged 20 to 50 years without sleep disorders were monitored overnight in a clinical setting.

All participants wore the Oura Ring for one nightthe Fitbit and the Apple Watch and were monitored simultaneously with the PSG.

Even if the number of participants of 35 people is not necessarily representative, it still gives an excellent insight into the potential of many sleep trackers.

Oura Ring 3 emerges victorious

The results show that all devices had high sensitivity (≥95%) in detecting sleep vs. wake state. However, the ability to differentiate between different sleep stages (light, deep, and REM sleep) varied.

The Oura Ring is now in its fourth generation.
The Oura Ring is now in its fourth generation.





The Oura Ring is now in its fourth generation.

The Oura Ring showed the best match with PSG herewhile Fitbit and Apple Watch had weaknesses, particularly when it came to detecting deep sleep.

  • »The Fitbit overestimated light sleep (18 min; p\, according to the study.

The Oura Ring is no different from PSG in terms of awake, light sleep, deep sleep, or REM sleep estimates.

What does “p” say? If the p-value is less than about 0.001, you can be fairly certain that the result is not due to chance. The probability of this is less than 0.1 percent. This means that the null hypothesis that there is no effect or difference can be practically ruled out. A p-value of less than 0.001 also indicates that it is very unlikely that the result can be explained by chance.

It’s also important to note that Fitbit is included in two of the 35 participants This study did not record data and Apple did not record data on six of the 35 participants in this study. According to the study, all three devices charged, synced and initialized correctly. The Oura Ring recorded sleep for all participants.

These cases of data loss were taken into account in the analysis, but no specific measures to repeat the process were described.

By the way, colleague Vera has already spent a night in the sleep laboratory:

Sleep tracker versus sleep laboratory – How accurate are Apple Watch and Co.?
Sleep tracker versus sleep laboratory – How accurate are Apple Watch and Co.?


Start video


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Sleep tracker versus sleep laboratory – How accurate are Apple Watch and Co.?

New models are now on the market

The Oura Ring 3, the Apple Watch 8 and the Fitbit Sense 2 were used in the study. However, new models and software updates have now been added that potentially improve the algorithm for recognizing sleep phases.

For example, the Apple Watch 8 was used with watchOS 10. The update to watchOS 11 adds the Vital app, which has changed the way Apple records sleep using an Apple Watch.

It might also be interesting to take a look at the current Pixel Watch 3, which measures sleep based on Fitbit devices and has probably improved in terms of the measurement data.

Conclusion of the study

The study comes to the conclusion that the devices are quite reliable distinguish between sleep and wakefulness, but the accuracy in detecting specific sleep phases could be improved.

This accuracy is particularly important so that users receive accurate information and do not stress themselves unnecessarily, overestimate the results or, in the worst case, even become ill.

The results also highlight the importance of evolving sleep monitoring technologies to meet users’ needs.

Not all smart rings are reliable at measuring sleep

A ring’s measurements are potentially more reliable than those of a smartwatchAt least it was about the oxygen saturation of the blood (SpO2). The blood circulation is simply better in the finger than in the forearm. In addition, the smartwatch will slip if it is not tight enough.

Other factors also play an important role in the measurement, such as the sampling rate of the device.

Even if the Oura Ring emerges as the clear winner (at least in this study), this does not have to apply to all smart rings. In our experience with the Galaxy Ring (test report follows), sleep data detection is unreliable compared to smartwatches and bracelets like Whoop.

We generally recommend the English-language YouTube channel The Quantified Scientist if you are looking for a sleep and fitness tracker. Rob worked intensively on evaluating the various trackers and comparing them with medical devices.

Do you wear a ring, bracelet or smartwatch to monitor your sleep? What are your experiences? Write them in the comments below!

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