As a staff writer on Wirecutter’s sleep team, I test gear related to living more comfortably and getting a better night’s sleep, including ergonomic seat cushions and body pillows.

To understand the various components and accuracy of sleep trackers, I consulted:

• Claire Varellas and Nikki Rothberg, from Apple’s PR team focused on health, and Kristin Holmes, VP of performance science at Whoop
• Oura representatives, including product manager Caroline Kryder and Dr. Rebecca Robbins, a member of Oura’s Medical Advisory Board and instructor of medicine at Harvard Medical School
• Seema Khosla, MD, the medical director at North Dakota Center for Sleep

I also read dozens of journal articles and peer-reviewed research ranging in topic from sleep anxiety and orthosomnia to consumer habits in relation to sleep technology.

Wearable sleep trackers are great for people who have a healthy curiosity about what happens when they sleep and want concrete guidance on how to improve their sleep. Whether you want to optimize your rest in order to maintain peak athletic performance throughout the day, or you just need a nudge to remind you to get off TikTok and into bed, a sleep tracker might help.

Sleep trackers typically log the time and duration of your sleep, how much time they see you spending in each sleep phase (such as REM or deep sleep), and how often you wake or move during the night.

Many such devices double as fitness trackers or smartwatches and also track movement and activity and a range of other metrics, including heart rate, heart-rate variability (HRV), body temperature, blood-oxygen rate, and menstrual cycles. An accompanying app delivers analyses of your sleep and activity levels, which they often frame as “scores,” along with recommendations for improvement.

If you’re only mildly curious about your sleep and don’t want to commit to an expensive device, start with a free or modestly priced sleep-tracking app. And if you struggle with sleep anxiety (that feeling like you have a 5 a.m. flight every morning), you may want to avoid sleep trackers altogether. A 2017 article in the Journal of Clinical Sleep Medicine suggests that sleep trackers may cause some people to self-diagnose or seek treatment for perceived sleep problems, encouraging “a perfectionistic quest for the ideal sleep in order to optimize daytime function.”

Seema Khosla, MD, advises understanding the different sleep stages before jumping into your data: “Each sleep stage has its own job,” she said. There’s no need to panic if you got only three hours of “deep sleep” before a job interview, for example.

Sleep trackers can be a helpful learning tool, but they don’t replace medical care. If you have insomnia, sleep apnea, orthosomnia, or any other kind of sleep-related disorder, see a medical professional. If your doctor says that using a sleep tracker is a good idea, go for it.

Furthermore, sleep-tracking wearables aren’t always precise: Many calculate sleep and other factors inaccurately due to their reliance on actigraphy, a technology that measures movement. For example, in our tests, one tracker assumed that a tester was sleeping when they were awake but lying still. For medically accurate sleep-tracking data, a polysomnography test is the best way to go.

With that in mind, we sought out wearables that had third-party validation studies; all of the options we recommend in this guide had validation studies that were easy to find online. Third-party validation studies offer a level of commitment to accuracy and transparency from the company behind a sleep tracker, even if they are funded by the brand itself.

For this guide, we focused on what would make a sleep tracker most worthwhile for both a health-tracking aficionado and a curious novice, namely comfort, accuracy, and ease of use and data comprehension. After identifying five popular sleep and fitness trackers, we convened a testing panel of five volunteers (men and women ranging in age from mid-20s to mid-40s) with different lifestyles and sleep styles, including sleep partners, people with children or pets, snorers, and light and heavy sleepers.

Each volunteer tested one or two sleep trackers for three nights each while using a separate heart-rate sensor as a control. Each tester kept a daily sleep log noting their activity the day prior, the quality of their sleep, and their energy levels upon waking.

Throughout our testing, we aimed to answer the following questions:

How well does the sleep tracker log sleep and health data?

Commercial sleep trackers aren’t medical devices, but a good sleep tracker should be able to accurately capture and assess how your heart rate, energy output, blood-oxygen level, body temperature, and other metrics affect—and dictate—the quality of your sleep. Each brand, for example, hyped up its device’s heart-rate monitoring capabilities, so we put the devices to the test by asking testers to wear a Polar H10 heart-rate sensor in conjunction with a sleep tracker each night. We compared the two data sets and disqualified any trackers that were completely off the map. We also asked testers to fill out a daily sleep journal with how they were feeling and their sleep and wake times to see if the app’s findings seemed accurate.

How well does it track activities?

Our testers wore their sleep trackers all day, not just at night, as activity closely informs rest and recovery. We noted when a tracker mistook cycling for a jog, for example.

Is the data easy to interpret?

Sleep trackers with useful, contextualized data made the top of our list. We gravitated toward wearables that not only provided the hard numbers but also gave a comprehensive summary of what those numbers meant.

Does it offer actionable, well-rounded advice?

We favored trackers that used data from the previous day’s activities and the previous night’s sleep to make recommendations. If we had hit the gym hard, say, we appreciated a gentle nudge to rest up. We also prioritized trackers that adapted guidance to the wearer’s actual habits.

Is it comfortable to wear?

We favored sleep trackers that looked discreet during the day and were lightweight and comfortable enough that we could forget we were wearing them while sleeping.

Does it offer useful extras?

We took note of trackers with apps that offered extra features such as guided meditations, breathing exercises, “bedtime stories,” daily sleep journals, and coaching.

What about data privacy?

We reached out to the companies behind the trackers to learn more about their privacy policies. We noted which companies allowed you to opt out of data sharing and how each company shared personal data internally.

Who it’s for: This model is ideal for people seeking a discreet, easy-to-use sleep tracker with lots of personalized advice.

How it works: The Oura Ring is a titanium, wedding-band-shaped device that shines infrared (red and green LED light) beams through your skin and uses sensors to measure your respiratory rate, heart rate, heart-rate variability (HRV), blood-oxygen levels, and body temperature. It uses those metrics to track your sleep, and an accelerometer logs your activity and movement. It then synthesizes the two chunks of data—your sleep versus your energy output—to give you three daily scores, Sleep, Activity, and Readiness.

Why we like it:

It measures sleep well. Our testers generally reported that the Oura Ring logged their sleep accurately in comparison with their journals. Oura’s validation studies suggest that the company has invested in improving the accuracy of its sleep tracking. In a 2021 validation study of the current, third-generation Oura Ring, the device agreed with a polysomnography test 79% of the time, up from just 66% in the company’s 2016 validation study. A 2024 study, conducted by independent researchers with funding from Oura, concluded that the Oura Ring “did not significantly differ from PSG for the measures time in bed, total sleep time, sleep onset latency, sleep period time, wake after sleep onset, time spent in light sleep, and time spent in deep sleep.”

It measures heart rate and heart-rate variability accurately. The Oura Ring’s infrared light beams, located on the interior of the ring, helped to accurately measure heart rate and HRV while our testers were active and during rest. When tested against a heart-rate sensor, the Oura Ring proved to be the most closely aligned of all the sleep-tracking devices we tried.

Oura’s own validation study (PDF) shows that its HRV measurements are 98.4% accurate when compared against an electrocardiogram. Oura’s device was one of the first wearable trackers to measure HRV, which indicates the regularity or irregularity of time between pulses. High HRV is generally good; it suggests that you’re relaxed and well. Low HRV, when your heart beats in sync with a metronome, may be associated with physical or emotional stress.

Anecdotally, we found that the Oura Ring picked up on low HRV during times of high stress or sickness. For instance, the Oura Ring correctly registered that I was experiencing more stress than usual during a family emergency. Another tester found that while she was under stress during travel that affected her sleep, the Oura Ring picked up on her lower HRV and encouraged her to prioritize rest and relaxation.

Its data is easy to read and digest, and its app is easy to navigate. Like many of the sleep trackers we tested, the Oura Ring throws a lot of data at you in the form of color-coded charts and graphs. But it does a good job of presenting the most important information first. One tester, who describes herself as tech-averse, appreciated that the Sleep score appeared front and center in the app. Tapping the Sleep score leads to helpful recommendations.

In addition to your Sleep score, Oura offers an Activity score, which reflects how much you’ve moved around during the day, and a Readiness score, which combines elements of your Sleep and Activity scores to calculate your readiness for the day. For further data, you have to go looking in the Reports tab, which can appear at first like “a lot of lines and numbers” but was also easy to get used to, said that same tester.

Its recommendations are personalized and easy to implement. Of all the trackers we tested, the Oura Ring offered the most useful behavioral directives. Most of the sleep trackers we tried gave our testers a sleep score and sporadic nudges to get up and walk or to go to bed earlier, but not much else. The Oura Ring, on the other hand, told our testers to rest immediately when it noticed a low-HRV trend and recommended a breathing exercise or meditation.

After a night of tossing and turning, one tester was greeted with “Hope you’re feeling better after only getting 4 hrs and 59 minutes of restless sleep,” along with guidance to get fresh air and avoid an afternoon nap.

Our testers also found that they weren’t shamed for having non-typical sleep patterns. For example, rather than continually pushing a night owl to go to bed by 10 p.m., the Oura app adapted to their sleep habits to determine realistic bedtime goals.

It’s stylish, lightweight, and comfortable. The Oura Ring looks and feels like a piece of jewelry. It comes in two styles (smooth or faceted) and multiple finishes (silver, black, matte black, gold, and rose gold), so it’s easier to coordinate with your clothing and accessories than most wristband-style trackers. Our testers found it the easiest and most comfortable to wear of the trackers we tested.

Flaws but not dealbreakers

Its activity tracking can be inaccurate. The Oura Ring struggles to categorize certain types of exercise. While our testers reported accurately measured intensity, as in steps walked or calories burned, it sometimes falsely logged a jog as cycling, for example. You can edit miscategorized activities in the app, but doing so can be a nuisance. (The Oura Ring integrates with Strava, a fitness-tracking app and social media platform, but it's not seamless: you have to be signed into the Strava app and select the activity you want to track.) If accurate workout tracking is important to you, consider our also-great pick, the Whoop 4.0, or the Fitbit Inspire 3.

It’s expensive and requires a monthly subscription. The Oura Ring costs $300 to $550 depending on the design and finish (the technology and features are the same in all models). And you have to sign up for a monthly subscription, for a total cost of about $72 per year, to access most of Oura’s data and recommendations.

And it’s easy to lose. Testers also found that the Oura Ring was much easier to lose track of than other wearables, as they were more likely to take it off throughout the day to wash their hands, do chores, or shower. The Oura app for iOS has a Find My Ring feature, which will show the last location that your Oura Ring connected to your phone. But keep in mind that that might not be where you left it.

Key specs

• Subscription cost: $72 per year
• HSA/FSA eligibility: Yes, for the purchase of the device. Subscription and extended warranty fees aren’t eligible.
• Battery life: up to seven days
• Water resistance: water resistant for up to 12 hours down to 330 feet
• Warranty: one year
• Privacy: Oura doesn’t share the personal information it collects from its app or device for advertising and marketing purposes, but it does share your data internally. If your data is shared internally, the company encrypts and anonymizes it. For details, read more about Oura’s privacy policy.

Who it’s for: This model is a good choice for people who want to track both sleep and workouts and don’t mind inputting a lot of data into the app.

How it works: This low-profile, screenless, woven wristband tracker uses photoplethysmography (PPG, used to detect blood-volume levels) and LEDs to shine a light on your skin. The Whoop device then translates the differences in light (absorption and reflection) into changes in blood flow, which is how it calculates heart rate and heart-rate variability. The Whoop strap also uses an accelerometer to track motion. The accelerometer, the PPG, and the Whoop device’s “trademarked algorithm” make it possible for the tracker to determine your sleep stages.

Why we like it:

It offers accurate sleep and heart-rate data. The Whoop 4.0’s heart-rate tracking closely aligned with the heart-rate sensor we used for comparison, though not quite as closely as the Oura Ring’s did.

Our testers reported that the Whoop 4.0 was accurate as a sleep tracker, as well. “I've tried nearly every fitness device,” said our most physically active tester. “Whoop has been the absolute best when it comes to sleep tracking.” Compared with other trackers, the Whoop device more frequently sensed the correct time our tester went to bed and woke up. That same tester noted that one morning, despite counting eight hours of sleep according to her clock, she still felt tired. The Whoop app confirmed that she was low on REM sleep and needed more recovery.

In a Whoop validation study, the device correctly captured the time spent in various stages 64% of the time, compared with a polysomnography test.

It offers in-depth activity and recovery tracking. The Whoop system tracks more fitness-related metrics than the Oura Ring does. Every morning, you receive a Recovery score, which aims to show how prepared you are to tackle another day or workout. Whoop asks you to input your exercise sessions, such as cycling or jogging, directly; it then measures the activity’s strain, via heart-rate detection, to make recommendations, often in painstaking detail. For example, the app might tell you that you were in “Zone 3” during a workout, meaning you had hit 70% to 80% of your maximum heart rate. Our testers said that data like this helped them learn, in real time, if they were making strides in their fitness or overdoing it.

It’s comfortable and versatile to wear. Our testers found that the lightweight, woven Whoop wristband was comfortable to wear all day and during sleep. (In fact, I often forgot to take it off before hopping in the shower.) Though it isn’t as inconspicuous as the Oura Ring, the Whoop strap blended in with outfits more easily than the bulkier Apple Watch Series 8. Some testers liked that they could wear it on their bicep during workouts, and it would still collect data.

Flaws but not dealbreakers

It’s labor intensive. The Whoop app nudges you, in the form of a popup, to fill out a daily journal before accessing your scores. (If you want to skip this step and see your scores right away, you can exit out of the journal.) The journal questions ask about daily habits such as alcohol or caffeine intake, as well as the type of activity you engaged in, like jogging or cycling. You can curate the questions to make them more specific to your habits and activities. Some of our testers found that the daily-journal questions kept them aware of their habits and helped the Whoop system deliver better analyses. But others found it onerous and preferred the Oura Ring’s more passive interface.

It isn’t particularly stylish. Even though the Whoop band comes in numerous colors and patterns, it looks more like an athletic band than a stylish accessory.

The interface can be intimidating. The Whoop app’s interface isn’t as approachable as those of the other sleep trackers we tested, and its language takes some getting used to. Its app focuses more on performance and recovery, rather than energy and rest, and is peppered with terms such as “stress,” “strain,” and “impact analysis,” so using it can feel more like having a personal trainer than an encouraging gym buddy.

It’s also more difficult to access guidance in the Whoop app than in the Oura app. For example, if your REM and deep sleep account for less than 35% of your total time in bed, the app suggests that you consult a Whoop Coach (powered by AI) to learn how to improve instead of offering suggestions freely.

It has the most expensive subscription plan. Whoop doesn’t charge for its wristband, but to use it, you have to sign up for a $239 annual subscription (or $399 for two years).

Key specs

• Subscription cost: $239 (one year), $399 (two years)
• HSA/FSA eligibility: Yes, for subscription fees and battery packs.
• Battery life: up to five days
• Water resistance: water resistant for up to two hours down to 32 feet of water
• Warranty: lifetime
• Privacy: Whoop never sells your personal data. All data captured in the device and app is encrypted. For details, read more about the Whoop privacy policy.

We'll be keeping an eye out for the Samsung Galaxy Ring, a sleep- and health-tracking wearable that was announced earlier this year, as well as the Ultrahuman Ring, a no-subscription device with a similar look to the Oura Ring.

If you primarily want to track your workouts but are also curious about your sleep: You might like the Fitbit Inspire 3, our top pick in our guide to the best fitness tracker. The wrist-worn Inspire 3 uses heart-rate sensors and motion detectors to track your activity and energy output. Though this touchscreen wearable offered the most accurate fitness tracking, our testers found its sleep tracking to be inaccurate. One of our testers also said that its recorded sleep time was inaccurate, as it often determined that he was asleep well before he had actually gone to bed.

Without a subscription, the Fitbit app provides only your total sleep time and your time spent in each sleep stage, which creates your Sleep score. The subscription gives you access to additional sleep data, such as your general restlessness (time spent tossing and turning) and your sleeping heart rate. Though these are good data points, they are relatively hidden in the Fitbit app in comparison with what you get from the Oura or Whoop app. Considering that the relatively similar Whoop system offers a more holistic view of how your activity and rest interact, we’ve concluded that it’s worth the $300 up-front cost in comparison with the Fitbit app.

For details about data handling, see Fitbit’s privacy policy.

Apple Watch Series 8: Our testers liked how intuitive the Apple Watch was to use and how seamlessly it interacted with other Apple devices. However, it proved uncomfortable to wear while our testers were sleeping, and it did not always accurately measure their time spent sleeping, according to our testers’ sleep journals. At $420, it doesn’t make sense as a purchase just for sleep tracking.

Garmin Watch Venu Sq 2: Our testers also found this Garmin watch uncomfortable to wear to bed. Plus, it sometimes struggled to determine the difference between rest and actual sleep; in one instance, it inaccurately told a tester that she was still asleep when she was actually lying in bed and on her phone.

This article was edited by Christina Colizza and Courtney Schley.