Oura Ring 5 Scientific Review (1 Month Of Data)
In a Nutshell
Oura Ring 5 delivers exceptional nighttime heart rate and HRV tracking that matches ECG chest straps, but sleep stage accuracy dropped to second-tier performance (70% average sensitivity) versus Ring 4's first-tier results, with REM detection at only 57% agreement against EEG reference. Exercise heart rate tracking remains weak—correlations of 0.91 for spinning, 0.95 for running, and 0.72 for outdoor cycling—making it unsuitable for activities with rapid heart rate changes or significant hand involvement. The smaller form factor improves comfort, but users needing reliable sleep staging or exercise HR should consider alternatives like the Ring 4, Whoop, Fitbit, or a chest strap.
These notes were generated by AI and may contain inaccuracies.
The smaller form factor of the Aura Ring 5 has grown on the reviewer over the course of more than a month of testing. While the reviewer personally has no problem wearing larger smart rings, the smaller design offers improved comfort compared to substantially larger devices like the Ultra Human Ring Pro. The smaller design is noted as not being the most interesting discovery from systematic testing.
The reviewer is getting worse sleep stage tracking results from the Aura Ring 5 compared to the Aura Ring 4. This finding is based on all data collected across more than a month of testing, making it difficult to dismiss as simple day-to-day variation. The reviewer discussed these findings with Aura, and according to the company, their internal testing doesn't show any meaningful difference in sleep stage tracking performance between the Ring 5 and Ring 4. The reviewer cannot explain why their results appear worse, as they are wearing it on the same finger as before. A second Aura Ring is being tested on the right index finger, but data from the left ring finger is the focus of this analysis.
Nighttime heart rate and heart rate variability measurements from the Aura Ring are described as absolutely stellar, remaining the best in the business based on testing. Exercise heart rate tracking appears to be improving but is still not where the reviewer would want it to be, particularly for activities involving rapid changes in heart rate or significant hand involvement.
The reviewer is a post-doctoral scientist specializing in biological data analysis. This is not yet the final complete review of the Aura Ring 5, as additional testing is planned using a second ring and testing on a second person. The results presented are described as the most comprehensive presentation of Aura Ring 5 data in any single video, using all data collected over more than a month rather than selecting representative examples.
Heart rate tracking during the night shows super good agreement between reference measurements and Aura Ring 5 measurements. The reviewer's heart rate ranged between 35 and roughly 58 BPM during testing nights. The Aura Ring 5 was able to pick up on differences of even 2-3 BPM in this narrow range. Individual night comparisons show the reference (red) and Aura Ring (blue-green) overlapping very well, with both devices picking up the same heart rate patterns including drops and stabilizations. The Elite HRV detected some spikes where the reviewer was out of bed, but the Aura Ring appears to average out or filter these moments.
Heart rate variability (HRV) measurements showed the Aura Ring performing amazingly well. The reviewer's HRV varied between 20 and roughly 130, and the Aura Ring was able to pick up on most of this variation. While HRV measurements are noisier than heart rate measurements, the results are described as better than most devices and possibly among the best results the reviewer has ever seen. The blue line follows closely along the black reference line. HRV is calculated as an average over 15 minutes (600-900 seconds), which is consistent with the approach used for all devices tested.
The reviewer trusts the Aura Ring's nighttime heart rate and heart rate variability metrics fully, stating they are likely very close to measurements taken by an ECG chest strap, which is the gold standard. In the app, heart rate and HRV metrics are displayed, with the reviewer noting that their heart rate was relatively stable and already quite low during one particular night.
Sleep stage tracking results are described as confusing and surprising. The reference device is the Zmax EEG headband, described as a silver scientific standard for sleep stage studies. Deep sleep agreement is very good at 81%, meaning 81% of what the reference identified as deep sleep was also tracked as deep sleep by the ring. Light sleep agreement is 72%. REM sleep shows the weakest performance at 57% agreement, with REM sleep being confused with both light sleep and awake time more frequently than expected.
In specific example nights, deep sleep detection mostly agrees with the reference, with the Aura Ring sometimes detecting a bit of extra deep sleep. For REM sleep, the ring detected very little REM sleep in some nights, missing multiple segments that the reference detected. The ring detected REM sleep partially as awake time and partially as light sleep. Some nights show good REM sleep agreement, though with some REM sleep predicted as light sleep or awake time. The exact position of sleep cycles appears correct, even when stage classification has issues.
The Aura Ring 5 ranks in the second tier for sleep stage tracking, no longer in the first tier where the Ring 4 was previously. Top devices (first tier) include the Aura Ring 4, Whoop strap, Eight Sleep Pod, Fitbit, Google Pixel Watch, and Apple Watch. Second tier devices include newer Amazfit devices, some newer Garmin models, and Galaxy watches from 2025. Third tier includes Polar devices, some older Garmin models, and newer Huawei models. Fourth tier (lowest) includes the Y band, Coral devices, and some older Huawei models.
For the absolute best sleep stage tracking, the reviewer recommends the Aura Ring 4 (which will be retested), Fitbit devices including the $100 Fitbit Air, Whoop strap, Apple Watch, and Eight Sleep Pod. The Eight Sleep Pod is described as the favorite sleep improvement device despite being the most expensive, as it can cool and heat each side of the bed independently, which helps with temperature regulation issues during sleep.
The reviewer has been having some trouble sleeping, which may cause the ring to detect awake time more quickly, potentially explaining the confusion with REM sleep. Cohen's kappa, another sleep stage metric, shows the same average between Ring 4 and Ring 5. The reviewer prefers average sensitivity because Cohen's kappa doesn't weigh each sleep stage equally. Aura indicated they want to publish their sleep stage tracking testing in a scientific journal and will share results once accepted.
The sleep score is calculated by taking the average sensitivity over the three sleep stages, which is 70 for the Aura Ring 5, giving it a sleep stage rating of good but not great. The reviewer hopes results will improve with more testing and that the ring might learn from the user over time.
For spinning/indoor cycling, the correlation is 0.91, which is quite okay but not perfect. Many points fall below the reference line (too low heart rate detected) and some above (too high heart rate). Individual sessions show the ring struggling particularly in the beginning of sessions, possibly due to body heating up and increased blood flow to fingers causing swelling and tighter fit. Performance improves near the end of sessions.
Running shows better results with a correlation of 0.95. Most points are on or close to the reference line, with minor deviations. Some cadence lock issues occur where the ring detects running frequency instead of heart rate. Overall, running performance is described as quite okay since running involves the least finger involvement compared to other activities.
Outdoor biking shows the weakest performance with a correlation of only 0.72. The ring most often detects too low heart rate and sometimes too high. The ring fails to pick up on major heart rate changes, going through an average heart rate and missing variations. Road bike rides perform better than city bike rides, where traffic light stops create more drastic heart rate changes. The ring misses all details in heart rate during biking sessions.
For indoor cycling, the Aura Ring performs better than only 13% of other devices tested. For outdoor cycling, it performs better than only 19% of other devices. For running, it performs better than 50% of devices tested. The heart rate score is calculated as the average correlation over the three cardio exercises (running, biking, spinning), giving the Aura Ring a score of 86, which translates to a heart rate rating of okay.
The performance in running and indoor cycling drives the current assessment. For biking, the recommendation is not to use an Aura ring but instead to use an external heart rate monitor either on the biceps or preferably a chest strap. Aura is improving with this generation, but the ring is not quite there yet as a dedicated heart rate monitor. It can potentially be recommended for running only.
After more than a month of testing, the overall impression of the Aura Ring 5 is somewhat mixed. The smaller form factor has grown on the tester, and the added comfort of a more compact design is appreciated, particularly when comparing it to a larger ring such as the Ultra Human Ring Pro. The nighttime heart rate and heart rate variability measurements are genuinely really good, and Aura continues to set the standard here for nighttime heart rate and HRV. The Aura Ring 5 delivers some of the best results seen from consumer wearables.
Exercise heart rate tracking is moving slightly in the right direction but is not really there yet. Performance can be acceptable under relatively straightforward conditions, but it is still not consistently reliable enough across different types of exercises, especially when the hand is involved somehow, creating pressure on the ring and rapid heart rate changes. If highly accurate exercise tracking is the priority, the recommendation remains to use a good heart rate chest strap or another device that has been properly validated for the specific type of exercise.
The big surprise is the sleep stage tracking. Across this data set, the Aura Ring 5 performed worse than previous testing of the Aura Ring 4, even though Aura states their internal testing does not show a meaningful difference between the two generations. The cause of this discrepancy is not known, and stronger conclusions than the data supports are not drawn. Results are real but representative of one ring tested on one body.
This is not the final complete review. Plans include repeating at least part of the testing with a second ring to determine whether the current unit could be influencing the results, and also using a different finger. If possible, data from a second person would help establish whether the sleep stage tracking results are reproducible or simply reflect something specific to the ring, physiology, or finger. This analysis includes every usable measurement collected over more than a month.
While there are still questions to answer, this video provides one of the most comprehensive data-driven assessments of the Aura Ring 5 currently available in a single place. The preliminary conclusion is that the Aura Ring remains exceptional at measuring heart rate and heart rate variability during the night, and the new smaller design can also offer a meaningful improvement in terms of comfort. Exercise heart rate tracking still needs work, and the unexpectedly weaker sleep stage tracking results require further investigation.
The goal is not to simply tell whether a device is personally liked. The goal is to show the data, explain what it does and does not allow concluding, and help decide whether any device like the Aura Ring is suitable for individual needs.
If deciding to get an Aura ring, an Ultra Human ring, an Amazfit watch, a Fitbit Air, a Whoop strap, or the Eight Sleep Pod as a favorite sleep improvement device, different affiliate links are available in the description below that support the wallet and the channel. There is also a general Amazon affiliate link that does not cost anything extra to use, but clicking that link before making Amazon purchases supports the channel even when buying items like toilet paper or coffee beans. Videos on the Fitbit Air and the Eight Sleep Pod are recommended for viewers watching this video on the Aura Ring 5.
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