Sleep is elusive.
Unless you’re participating in a sleep study, there’s no real way to know how you’ve slept other than conducting some personal inquiry. Do I feel tired today? When did I actually go to bed? It’s not exactly a foolproof system.
Consumer-grade sleep tracking devices promise an alternative. A slightly more definitive, “data-driven” way of knowing how long you slept, how well you slept, and even how long you spent in each sleep stage. Sleep tracking has become a bread-and-butter feature for wearable devices. Your new smartwatch can probably tell you how long you slept last night if you wear it to bed. That fitness band you use to track your runs? There’s a good chance it can give you some insight into your resting heart rate during last night’s slumber.
Sensors observing your movement, heart rate, blood oxygen levels, and even body temperature all come together to offer a consistent view (though not necessarily a medically accurate one) of what last night's sleep looked like. The quantified self applied to when you’re moving the least.
Now how useful that is to the average person will vary. Research suggests that tracking your sleep might actually be bad for some people in the long run. But the real question should be: What can you do (and what do these trackers and services do) with the information you collect? To put the benefits of sleep tracking to the test, I spent two weeks wearing smartwatches from Google and Apple, and a smart ring from Oura, in the hopes of gaining some insight into my sleep, and just what nighttime self-surveillance actually gets you.
The wearables
Sleep tracking devices are numerous, and there are several that don't even require you to wear anything at all, but the average person is most likely going to track their sleep for the first time through a device that offers tracking as just one of many features. With that in mind, here’s what I wore:
- The Apple Watch (I used the Series 7) has set the standard for what the modern smartwatch can do, offering a mix of simple apps, the ability to receive and act on notifications from your phone, and to monitor your health and fitness. Apple makes a point of its health and fitness features too, offering a dedicated subscription service called Fitness+ ($9.99 per month), a direct connection to the Health app in iOS, and several specific features (fall detection and arrhythmia detection, among others) for emergency health events.
- The Pixel Watch is Google’s first attempt at a flagship smartwatch to pair with its Pixel phones. It works just like the Apple Watch but with Google flavoring (including apps for popular Google services like Google Home and Google Maps) and the health-tracking expertise of Fitbit. Google acquired Fitbit in 2021, and the Pixel Watch, besides running the Fitbit app, ties directly into the Fitbit Premium ($9.99 per month) subscription service.
- Finally, the Oura Ring (I used the third generation) is a smart ring packed with sensors (motion, heart, and body temperature) and worn by celebrities and athletes alike. Oura is best connected to a paid membership account ($5.99 per month) to unlock all of its in-depth analysis features. But in exchange, you get a variety of ways to analyze your information, along with guided meditations and other interactive content.
All three of these trackers feel different and have distinct on-device and in-app experiences, but they can be best organized in terms of how hands-on or off they are with your sleep-tracking data.
Apple Watch: the most hands-off
If you’ve accidentally worn a normal wristwatch to bed, wearing an Apple Watch isn’t much different. I’m a fairly deep sleeper and had no issues falling asleep with my Apple Watch Series 7 on, and thanks to its reliable battery life, I almost always make it through a night’s sleep on a charge. I imagine the only real issues you’ll run into is if your band is uncomfortable or if you wear your smartwatch too loose or too tight on your wrist. Easy enough fixes on their own.
All of Apple’s sleep features are concentrated in the Health app on iOS, where you can set a sleep schedule, and view any information your Apple Watch tracked while you were asleep. The app itself doesn’t offer guidance around when you should go to bed or when your alarm should be set in the morning other than the usual recommendation of 7–9 hours of sleep for adults, but setting a schedule is helpful for establishing a routine. Apple automatically creates a “Sleep Focus” based on your set bedtime, which will automatically silence notifications on your iPhone and Apple Watch, dim their screens, and can be used to limit which apps you have access to once you’re supposed to be getting ready for bed.
The Sleep app on watchOS has broadly the same functionality as the sleep section in the iOS Health app. Your current bedtime and alarm are listed at the top (you can adjust your next night’s sleep inside the app); there’s a readout of how many hours you slept last night (with estimates as to when you went to bed and when you woke up); and on watchOS 9, a chart displaying your sleep stages, with breakdowns of how much total time you spent in each (Awake, REM, Core, and Deep).
The Health app on iOS has more or less the same information, with some more variations. Outside of the sleep highlights you can find on the main Health screen, the sleep section has an ongoing chart you can sort by day, week, month, or six-month intervals, the time you spent in bed and the time you spent asleep, a chart showing your sleep stages and highlights on specific data points, like your respiratory rate or heart rate while you slept.
Everything is presented clearly, frequently, and in plain language. If you don’t know how to read an accompanying chart or graph, there’s usually a simple sentence that spells things out. For example, it could read something like, “Your average breathing rate while asleep has been consistent during the last 14 days.” Apple’s sleep tracking shows how good the company is at design and how feature-packed the Apple Watch is in terms of sensors, but it really doesn’t give you any guidance on how to use the data you collected. It’s cautious and hands-off to a fault. Apple has been careful to call the Apple Watch's various health tracking features more of a guardian and not a replacement for a healthcare provider.
Pixel Watch: much more hands-on
For all its good looks, the Pixel Watch is in many ways just a Fitbit. So if you’ve used one of the company’s fitness trackers before, you might have a good idea of what to expect from Google’s smartwatch. Thanks to its small size and round shape, I found it very easy to wear to bed, and I imagine that would be even easier with the comfy Stretch Band. Depending on how much you used it throughout the day (tracking workouts for example) you might have to charge it before bed to make it through the night, however.
You can see elements of your sleep data in the Fitbit app for Android, the Sleep Tile in Wear OS 3, and the Fitbit app for Wear OS itself, but the most in-depth is your phone. Like on iOS, sleep data (your sleep score and hours slept) appears on the main screen in the Fitbit app, and you have to tap in to view more. Fitbit builds everything around a glanceable sleep score that’s determined based on contributors like how long you spent asleep, how long you spent in Deep and REM sleep, and how “restorative” your sleep was.
The sleep tile on the Pixel Watch offers a simple circular visual of how much you slept last night, along with the total number of hours. If you tap it, you’re taken to the Fitbit app on the Pixel Watch that offers a stripped-down version of the data you’ll find in the main Android app. Hours slept, your sleep score, a chart, breakdowns of your various sleep stages, and a weekly average. Basic but good for a quick look.
There are graphs and charts for all the information the Pixel Watch collects. Still, the best thing Fitbit (and, by extension, Google) does is offer explanations for why each statistic might matter to you and suggestions for programs available in your Fitbit Premium membership that could help you make a change if you want to. It immediately makes tracking your sleep actionable in a way Apple doesn’t. It’s not nearly as proactive as it could be — though monthly “Sleep Profile” updates are another step in the right direction — but it makes useful connections between the vast array of features and services Fitbit and Google offer. It's something possibly worth paying for.
Oura Ring: the perfect balance of in-depth but unobtrusive
The Oura Ring has a pretty immediate advantage over the Apple Watch and the Pixel Watch. It’s both smaller and looks like a normal piece of jewelry. Oura hides the sensors on the inside of the band to make it look as normal as possible; the recently released Oura Ring Horizon in October is finally a perfectly circular ring. Of the wearables I tried, the Oura Ring also had the longest battery life of the bunch — up to seven days on a single charge.
Because the Oura Ring doesn’t have a display (this is a good thing, it's worth saying), the entire sleep-tracking experience is concentrated in its companion app. The Oura app has a dedicated tab for sleep and the same reliance on a sleep score as the Pixel Watch to give you a glanceable look at how you’re doing on the main page.
The sleep tab has a chart detailing the mix of time you spent in various sleep stages over the last week, breakdowns of your total sleep, time in bed, sleep efficiency, and resting heart rate, along with a list of all the factors Oura takes into account to determine your sleep score. Further down, there’s detailed information on last night’s sleep, your breathing regularity, and average heart rate variability (HRV).
The best part is that much like the Fitbit app, Oura has a detailed explanation for why these stats might be important that’s just a tap away. Similarly, Oura doesn’t try to take control of how you sleep too aggressively, but it does nudge a fair bit more by default: suggesting an ideal bedtime after you wear it for a few days, recommending a guided meditation or audio story to listen to before you go to bed, and generally encouraging you to check in with yourself if your sleep score is dramatically different between days.
While there’s always more the Oura Ring could do, Oura seems to strike the right balance between being informative, but not necessarily overwhelming. The right amount of proactiveness if you’re interested in changing how you sleep.
Did sleep tracking help?
As fun as all these features are, they are only useful if they actually do the job they claim to do. Of all the three trackers I wore, reading through Fitbit’s explanations of sleep data and following Oura’s bedtime recommendation made me feel more refreshed and a bit more in touch with how I sleep. The problem is I could have reached a similar conclusion by following a consistent bedtime and going to bed a bit earlier — two things the Apple Watch nailed when Apple introduced sleep tracking with watchOS 7 in 2020.
My sleep problems are minor compared to many people, but I think this experience has generally revealed one thing to me: The accuracy of these devices aside, they seem to collect more information than they, or really any normal person, know what to do with. The more proactive suggestions are helpful, and I admittedly enjoy geeking out over the various stats a smartwatch or smart ring can help present, but I can’t say any of it is essential yet.
They seem to collect more information than they, or really any normal person, know what to do with.
After wearing two smartwatches and a smart ring for two weeks, I also began to wonder if there are some things we just shouldn’t know about ourselves at all. Is knowing more a net good? For the obsessive or easily fixated, probably not. Sleep tracking, like step tracking and calorie counting, forces you to mechanize yourself. You're a machine with points that can be tracked and outputs that can be tweaked. Some trackers and services approach this more humanely than others, but the page always shows the same thing. Lines that go up and down, scores that increase and decrease, short friendly paragraphs with suggestions of what you can do differently.
In the right hands, used with restraint, a sleep-tracking device could help you change a habit. They’ll certainly make you aware of yourself in a different way. But for now, you can rest easy with the knowledge that some good old determination might get you just as far in the pursuit of a good night’s sleep. Just don’t use your phone in bed!
THE FUTURE OF SLEEP reveals what science currently knows about what sleep is, why we need it, and if we can hack our own slumber. Read the rest of the stories here.
