Oura Ring 2 Teardown | Hacker News Reader

Oura Ring 2 Teardown

ifixit.com

123 pointszdw71 comments

I saw a talk on consumer wearables in sleep at the Sleep Trends conference this spring. There was a great presentation comparing consumer sleep trackers, and how their advertised reporting of "accuracy" can be misleading.

If you do a thought experiment: let's say I make a "sleep tracker" that is just a piece of plastic, no sensor, and write an algorithm that always presumes the wearer is in stage N2 sleep. Since we spend around 50% of our night in N2 sleep, this algorithm would start with a fairly high baseline accuracy of 50%.

Sensitivity and specificity are much better measurements of accuracy, because they measure the false positive and false negative rates. A comparison of Oura against a medical polysomnogram showed that while it's very good at detecting sleep, it's very bad at detecting not sleep:

From https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6095823/: "ŌURA ring had a 96% sensitivity to detect sleep, and agreement of 65%, 51%, and 61%, in detecting “light sleep” (N1+N2), “deep sleep” (N3),and REM sleep, respectively. Specificity in detecting wake was 48%"

The current state of the art in sleep measurement really requires some sort of EEG measurement beyond just PPG and HR, what Oura uses. The Dreem headband is a good example (https://dreem.com/), but it's definitely more cumbersome than a ring. It's tailored more like a medical service for insomnia than for the average consumer interested in quantified self.

I own a Dreem V2 headband and though it's more cumbersome than a ring, it's really not a problem. It takes me less than a minute to put it on and activate it each night and though it's a little uncomfortable at first, I got used to it quite quickly.

I disagree that it's "more like a medical service for insomnia". The app does have some of your standard CBT stuff in it if you choose to use it but there's also a lot for people without major sleep problems as well. For example there's a sleep schedule function that will give you bedtime reminders and automatically wake you in the morning when you're in a light stage of sleep.

As far as data, I'd say that's one of the major focuses of the app. "Sleep reports" (weekly summaries of your sleep habits) are made very prominent in the main screen of the app and contain reasonably comprehensive but very approachable pieces of data.

As for accuracy, I've compared various products of various kinds such as under bed, apps and wristbands (though not Oura) and found basically everything but Dreem to be pretty garbage at doing anything more than detecting that I'm laying in a bed. I'm not convinced it's possible to detect that I'm awake but lazily delaying leaving the bed with anything but an EEG.

What's the point after discovering what helps you sleep? I found out I don't sleep well when there's any extra light, and after that there's little benefit from my sleep tracker, except it's also a fitness tracker that I don't think is cumbersome to keep on.

What does the data do for you now? I have a day's worth and then I don't care much after, history isn't very usable or actionable.

If your sleep is absolutely perfect and you never have any issues with energy or anything like that, there probably isn't a point for you.

My sleep isn't perfect. I don't have insomnia but I'm terrible at keeping a sleep schedule on my own, I can have trouble falling asleep or I can be woken early for various reasons. The data helps me quantify these problems and act on them.

For example I can see that I was bad at adhering to my sleep schedule and try harder. If I didn't have this data I wouldn't know that there was a problem or how bad it was. If I had trouble falling asleep or woke early, I can check the app and see how much sleep I actually got and have an idea of what my energy levels through the coming day are going to be like.

My sleep isn't perfect either but if you feel fine you probably slept enough and if you didn't, you won't. I use a sleep tracker but it's not very useful except for that day.

The issue to me is that you never seem to fix your issues from sleep. Did you solve the problems?

Garmin acquired FirstBeat Analytics less than two weeks ago [1]. According to DC Rainmaker, "They power the vast majority of Garmin’s fitness and outdoor training-focused algorithms" but they are also used by other manufacturers. The Garmin's Sleep Stage tracking, powered by FirstBeat Analytics [2], use higher power red LEDs at night. I wonder if OURA uses a separate technique, maybe even transmissive PPG.

[1] https://www.dcrainmaker.com/2020/06/garmin-acquires-firstbea...

[2] https://assets.firstbeat.com/firstbeat/uploads/2019/11/First...

The red LEDs on Garmin watches are used for SpO2 (Pulse Oximeter) tracking, not sleep tracking. They are also generally regarded as terrible[1].

[1] https://www.dcrainmaker.com/2018/06/garmin-fenix5-plus-5s-5x...

I was conflating two useful sleep tracking metrics, SpO2 and Sleep Stages, my bad. You are correct, Garmin’s sleep tracking does not require the red LED SpO2 to estimate sleep stages. Since the sleep stage algorithm is Machine Learning derived, it is plausible that SpO2 data could improve sleep stage predictions but that is speculation.

I skimmed through the Fenix review you linked to and I didn’t see anything like your “generally regarded as terrible” claim. From the conclusion:

> ...adding in Pulse Oximetry support and the ClimbPro bits, to differentiate themselves in a way not seen before. There’s no question this feature is targeted directly at the high-altitude folks that historically would have gone Suunto.

Pulse Oximetry in continuous trackers is relatively new and the extra battery consumption may indeed turn out to be an unacceptable trade-off. The Oura was used by the NBA to predict COVID-19 infection. I assumed, therefore, that SpO2 was tracked. It is a useful metric and I find the possibility of having it in a finger ring form factor intriguing.

>It's tailored more like a medical service for insomnia than for the average consumer interested in quantified self.

There used to be a EEG headband aimed at the quantified self group (cost $100 or $150) but they went out of business. Probably because for that group a fitbit like tracker was good enough. So I'm guessing the medical side and higher price point is seen as a better business model.

The Zeo headband fits this description?

Last time this came up I mentioned the Dreem headband which is still actively produced.

The post I replied to mentioned Dreem but they're at a $500 price point from what I can tell which is beyond the usual non-medical need consumer.

A long-time HN user here and I’m stoked to see our product on the HN front page

Note: If you are interested in working at Oura, we are hiring SW Engineers both in Helsinki, Finland and San Francisco.

Current open positions can be found on https://ouraring.com/careers and new positions are opening in a few weeks.

Congrats on getting your product ripped apart on video ;)

Ultra-low power indeed: I often get 6+ days of use before having to recharge. I’ve been very happy with mine; the sleep tracking seems quite consistent with my subjective experience, and the activity/exercise detection matches closely with the data from my Apple Watch.

I love the aura ring. AFAIK it is clearly the best non-intrusive sleep tracker and I would recommend it to anyone for sleep tracking. But in my experience the activity tracking is horrible because the ring achieves low power consumption by being off most of the time. I would suggest using a different device for daytime activity tracking.

Serious question - what is sleep tracking useful for? While I can see the benefit of tracing activity, I have no idea why would I want to track my sleep. I fall asleep, I wake up, what is there to track? Or rather, even if it tells me that I had a period of less/more movement during the night, what kind of actionable information can you possibly get out of it?

So many ways it's useful.

Wether you have trouble sleeping or not, it allows you to measure what "good" and "bad" is for you.

If I have alcohol before I sleep and don't use a sleep tracker, I generally assume I have a bad nights sleep. But my interpretation is all anecdotal. A sleep tracker can tell me though that I get up X more times when I have alcohol, I sleep Y less hours in each stage, I have a higher heart rate by Z much, have a lower heart rate variability, etc.

And you may think "so what?" We'll, that's the whole point. Now you know...not just "kind of know" that alcohol is bad for you.

It allows you to confirm what you think may be true, but can't prove.

Do you really need it to prove that drinking alcohol, especially before bed is bad for you? This is a well known medical fact. I don't see the point...

I'm building some unobtrusive alerting with mine (they have a public API). I'm bipolar, and less sleep is often correlated with a hypomanic episode. My oura helps me track my overall sleep and see patterns over time.

It also shows when I woke up in the middle of the night, which isn't always obvious to me when I fall back asleep soon after, but definitely impacts my sleep quality.

If you wake up happy, energised in a consistent manner then there isn't much to get out of sleep data. But a lot of people don't sleep consistent times with consistent results and not knowing why that happens leaves you with little control on how to improve your sleeping.

Without proper sleep, life loses a lot of its value.

This may sound obvious but I find the main benefit is that when I have data on my sleep I find myself being more intentional about my sleep patterns. Because I can see the results of an intervention to, say, go to sleep earlier, I feel like I have more control over my sleep patterns.

For myself the sleep duration tracking is the most useful data generated from sleep tracking.

It allowed me to identify food intolerances that had a significant impact on my sleep.

I am struggling with a similar problem (food, and gas in particular, affecting my sleep) and was wondering if you'd be willing to share more about your experience.

Sorry for such a late reply. For me the two biggest culprits are sulfites (increased sleep disturbances) and fructose (reduced deep sleep and more chaotic cycles).

What's weird about the fructose is I don't have the symptoms associated with such an intolerance; namely gas. Good news is that there is an enzyme (Fructaid) that helps mitigate it for me, so I don't have to completely cut it from my diet.

In the US, sulfites can be sneaky. Labels are required to list them if directly added to a product, but not for sulfite-containing ingredients sourced from a third-party. So the raisins in that trail mix very likely contain sulfites.

Very cool, mind sharing some? Others may have the same.

Sorry for the late reply. For me it was Fructose and Sulfites. See my above comment for more details.

> I fall asleep, I wake up, what is there to track?

Oh man, I remember those days. Enjoy them while you have them.

I used it to see what causes good and bad sleep. It's mostly useless after that.

Yep. It's useless for activity tracking.

It thought I was sedentary while I was doing a spin workout.

They still don't have a way to manually start activity tracking via an app.

It's not useless for activity tracking. It _may_ be useless for spin workouts though.

I've worn it with a gear fit and phone based trackers at the same time and the deltas are negligible in my experience.

You can tag a ‘workout’, right? Start time, duration, and level of intensity.

I have an Apple Watch that I wear overnight and have a sleep tracking app. Have you compared your ring to your watch to see if they report similar results? I have been considering the ring for HRV tracking (the Apple Watch only tracks HRV at random times when you are still, whereas the ring apparently tracks continuously) but also wondered if the sleep tracking is superior. Thoughts?

I started wearing an Oura ring about 10 days ago, and I’ve continued wearing my Apple Watch at night to compare the data collected by the ring and a couple of apps I use (AutoSleep and Pillow). Feel free to send along any specific questions (email is on my profile) about how they compare.

It's worth to know that the watch also tracks HRV whenever you use the Breathe app, so if you want to get consistent HRV readings the easiest way is to use Breathe once a day (for example right when you wake up).

So it basically consumes 3-4 mAh a day? That's crazy little.

Would you recommend it? I've looked at them a few times & have been close to buying one a few times.

I'd totally recommend if you want to form a healthy sleeping habit. It helped me understand my body a lot and put me in the right direction in terms of having quality sleep. The activity tracker in my opinion is good and a bonus but not as important as sleep tracking

I've had mine for about 6 months now and would recommend it to anyone who is interested in sleep tracking.

As others have said, watches and other devices are better for generic activity tracking, but the Oura ring is just so easy to wear to bed. No worrying about battery life or sweaty wrists.

The readiness and sleep scores the ring gives me are pretty much on point every time and make it easy to quantify your sleep to actual numbers you can compare with other data.

Before buying one I tried to make research about its effectiveness and there are some very alarming reports, coming, of all places, from the research published by the same company. So this isn't even biased...

    “From EBE analysis, ŌURA ring had a 96% sensitivity to detect sleep, and agreement of 65%, 51%, and 61%, in detecting “light sleep” (N1), “deep sleep” (N2 + N3), and REM sleep, respectively. Specificity in detecting wake was 48%.”

    Specificity in detecting wake was 48%! If this was a medical test, it would never be approved by FDA.

    A specificity of 48% means that there is a 48% chance that someone is awake when the device says they are asleep.

    That is horrible.

This is very surprising and alarming. As the author later goes on to describe, this has real implications and possible negative effects, this is not just a benign error here and there. Users are apparently supposed to use the Oura data to change or at least adjust and improve their sleep habits, and of course if they will do it based on faulty information, the adjustments themselves are going to be faulty and it can lead to worse or sub-optimal sleep!

Apparently you can still use Oura to track heart rate and HRV, but their own proprietary markers like “readiness” are probably based on all of their data including sleep, so they are not going be that accurate either.

This matches my experience having received one Nov 2018 (and returning it a few weeks later). It was constantly getting my actual sleep times wrong, more often than not marking me as being asleep while watching tv in the evening.

After contacting support, their solution was an upcoming update to their app where I'd be able to edit the data so that I could override the app whenever I knew it was wrong. Which completely invalidates the primary reason to own this product. I mean, if I knew when I was asleep, why would I need a ring to track it?!

So given that it couldn't properly track sleep, doesn't track activity (by design), the only other purpose in my mind was to track HRV. And count me as skeptical of the accuracy of that data as well.

Also worth noting that the ring itself is not designed by Oura but by another company: https://haltian.com/reference/oura-ring/

Further, even though Oura is a private company, its financial information is public (as is any Finnish company's): https://www.finder.fi/Tuotekehitys+tutkimus-+ja+suunnittelup...

This is incorrect, the Oura ring 2 has been mostly designed by in-house team, not Haltian. They have been involved in the process though.

Thanks for the correction! I don't know the details on the second iteration (assumed same applies as with the first gen), so I assume you have better information.

Just did the Tour du Mont Blanc (8 days of mountain hiking) with the oura 2 in plane mode. It recorded everything.

I misplaced it in the washing machine twice and it still works as brand new.

Besides the proprietary aspect of the platform and false positive reporting sleeping while not, I have only good things to say about mine.

Nifty little device.

If you have an oaura ring you can participate in a USCF study that is trying to determine if it can help predict COVID: https://ouraring.com/ucsf-tempredict-study

I think the idea is similar to what the NBA is doing: monitor doctors and nurses with the ring to try to detect COVID. But they are trying to properly study the idea.

I am impressed with my ring after having had it for about a year. The battery life seems to be as good as ever. The only concern I have is that I often have to wear it on a different finger. My hands are less bloated, which I credit partly to having been more active since I’ve had it.

From my experience the last thing you need for good sleep is a tracker. I’d try to fix sleep hygiene first and adapt a strict sleep schedule you do every day.

Some people (myself included) fix (sleep) hygiene problems by first closely watching and diagnosing them.

Your comment would sound silly if it said "last thing you need for good code is a debugger, I'd try to add a linter first". Or "last thing you need to maintain a good weight is a scale, I'd try to eat better first".

Neither are exclusive, and the former helps the latter if you use it well.

There are multiple things under the "sleep hygiene" umbrella, Oura lets me quantify my experiments.

Do I sleep better when it's colder, how about different pillows, blankets? What does alcohol do to my sleep? etc.

With the ring I've got actual data to back up a general feeling of did I sleep well/badly.

Yeah this seems like a solution in search of a problem. I don't see how it's worth the price. Reading the comments in this thread gives me an interesting view into why people choose them.

> The Oura Ring came out in May 2019

Wait, what? I got mine in Feb 2019. Did they re-release it or something?

Oura ring 2 launched in Dec 2017 and shipments started in April 2018.

That’s a long time since new launch. Have they refined it since 2018?

Gen 2

I'm pretty sure mine is gen 2 as well.

Didn't know what this ring was. Is it better than binary sleep/wake tracking? Here's the closest thing to a study on this thing I found: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6095823/ :-/

There are a few others, some of them by in-house science team

https://iopscience.iop.org/article/10.1088/1361-6579/ab840a

https://www.researchgate.net/publication/335764849_Following...

It's a great device.

If there is a primary flaw, it's that it can't be resized. If you are sufficiently motivated to become more active, the ring becomes too loose over time.

Not the worst problem, but it ends up in caught in the drain more than I'd like.

I wonder if it's currently technically feasible to make a version with swappable batteries while maintaining the same form factor, functionality and other properties the product has as-is.

I know a lot of other products could have better serviceability and repairability if one were to sacrifice form factor, dimensions or aesthetics, but for a product like this it doesn't seem obvious to me how one would go about that, but it'd be very interesting to speculate on.

Not really no, the whole package is encased in a completely waterproof way.

Any kind of swappability would require connections, which in turn would compromise the IP rating.

What's the reason that you can't use this ring for exercise? It feels like such an obvious feature to include so there must be some technical reason?

It achieves low power consumption by being off most of the time. That works out just fine for sleep because sleep phases take a long time to change and to verify that you need to take multiple samples over long time periods. But to accurately track movement characteristics you need to be always on.

The instructions it came with tell you not to wear it while using dumbbells or barbells. As for cardio, I guess it's ok. Mine tends to say I took 20% more steps per day than reported by the pedometer app on my phone. I have no clue which one is more accurate though.

Guessing the extremely tiny battery has something to do with it. It's a bit like how Apple Watch's battery life tanks when you use it for exercising and I don't think the Apple Watch gives the most accurate/highest resolution readings.

I would assume that to achieve a 7 day battery life they only take rare measurements of your heart rate, which makes it unfit for the kind of high resolution heart rate tracking people are used to from fitness watches. They also mention that any sport which has a significant level of hand involvement might disturb the reading.

They do still track general intensity of activity though, which for general health is probably a more relevant metric than exact heart rate.

Night-time PPG measurement of Oura ring IS high-resolution. PPG is measured only when you are still enough.

Activity tracking is based on accelerometer data.

The Oura only measures heart rate in five-minute intervals [1] while sleeping. A workout set/running interval could easily be completed within five minutes, making the measurement useless.

I've had many instances where my Oura failed to track heart rate while I was asleep, if the ring rotates, slides to a thinner part of my finger, or I am moving a little too much.

[1]https://ouraring.com/heart-rate-while-sleeping

Indeed, the automatic HR measurement powers the heart rate sensor array only when the accelerometer reports that the ring is stationary, i.e. the user is likely sleeping. This also makes sense because hand movements tank the accuracy of the sensors anyway. With manual measurements, you can still only get useful data if you're using it to measure during meditation or rest.

Anyone else prefer the text + pictures teardown format over the video teardowns they've been doing recently?

Would it be possible to have this device charged kinetically, or via body heat, or ambient wifi?

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