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What are best sleep trackers and are they really accurate?
Sleep is an elusive bedfellow nowadays: With a third of adults in the US not getting enough sleep, it's no wonder we have an entire corner of the market reserved for products dedicated to it. In my personal experience, when I considered lack of sleep could be one of the biggest causes of daily stress, I took the leap and got a sleep tracker.
Wearing a sleep tracker to bed was eye-opening; day in and day out, I was able to see in black and white why I'm so tired every single day. My sleep information showed me I wasn't getting enough sleep, plain and simple. And having the data available on my phone each morning motivated me each night to make better choices to improve my sleep hygiene.
Choosing the right sleep tracker for you, however, can be a challenge. We explore the most popular options as well as some you may have not heard about, to help you choose the best sleep tracker for you or your loved one.
Also: How to sleep better with the Apple Watch
- Sleep cycle tracking
- All the features of a smartwatch
- No subscription to track sleep
- Must be paired with iPhone
- Shorter battery life than other wearables
Tech specs: Up to 18hr battery life | Sleep cycles | Wi-Fi, bluetooth, GPS, and/or cellular options | 41mm and 45mm models | IP6X dust and water resistant | Blood oxygen, body temperature sensor, EKG, irregular heart rate alerts | iOS only
Notoriously popular among both smartwatch and Apple fans, the newest Apple Watch also comes with WatchOS 9 from the get-go, though older compatible versions can also get it with an update. and the Apple Watch Ultra also tracks sleep.
The Apple Watch now tracks how long you spend in bed and asleep, as well as sleep stages, like REM, core (light) sleep, and deep sleep. This data is available as soon as you wake up, and, if you enjoy an Apple ecosystem, can be paired seamlessly with your iPhone's focus, to switch when it detects you're awake.
According to ZDNET's own Christina Darby, "The Apple Watch became just as much of a nighttime accessory as my retainer. I loved having insight into the one thing I wasn't used to tracking -- my sleep".
Read the review: Apple Watch 8 is a sleeper hit, even if it doesn't match Samsung's sensors
- Long battery life
- Free six months Fitbit Premium with purchase
- Inexpensive
- Paid membership required to unlock all health features
- Limited functionality
Tech specs: Up to 10 days battery life | Sleep cycles | Bluetooth | 39.4 x 18.54 x 11.7mm | Up to 50m water resistant | Blood oxygen, skin temperature sensor, high/low heart rate alerts | iOS and Android compatible
One of the most popular wearable devices also used as a sleep tracker on the market is the Fitbit. These fitness trackers use machine learning algorithms to put together the user's data collected during the night and determine a sleep quality score, as well as sleep cycles.
With different styles at different price ranges, there is one Fitbit for all: from the most affordable and simple one in the Inspire 3 to the smartwatch Fitbit Sense 2.
A medical study on the accuracy of wearables to track sleep concluded that, while Fitbit models with sleep staging did show a promising performance "for consumers to obtain gross estimates of sleep parameters and time spent in sleep stages, they are of limited specificity and are not a substitute for PSG".
Read the review: The Fitbit Inspire 3 is a low wrist, high reward tracker at $99
- No wearables
- Also tracks heart rate
- Consistent data
- Tracks snoring
- Not water-resistant
- Only tracks breathing and heart rate
Tech specs: Plug-in | Sleep cycles | Wi-Fi | 24" x 7" x 0.19" | Not water-resistant | Breathing and heart rate | iOS and Android
The Withings Sleep tracking pad is a slim device that goes under the mattress and tracks sleep cycles, breathing and heart rate, has snore detection, and puts the data together to give you an overall sleep score at the end of the night, much like the Fitbit.
These pads are popular among sleep tracking enthusiasts and could even help users detect sleep disorders like sleep apnea.
- Comprehensive sleep data
- Sleep and recovery scores
- Expensive
- No fitness tracking
Tech specs: 2.5 days battery life | Sleep cycles | 1.5" x1.5" x 0.45" | Splash-proof | Blood oxygen, breathing and heart rate | iOS and Android compatible
There's all kinds of sleep-tracking wearables available for sale, from smartwatches to meditation headbands. But the Biostrap EVO wearable health monitor collects data while you sleep to determine your sleep stages and your overnight recovery levels. It provides users with comprehensive data that shows the quality of sleep they're getting.
Biostrap, the manufacturer of this sleep tracker, provides healthcare professionals and organizations with different devices for remote physiological monitoring of patients and as part of clinical research.
- Focused on sleep data
- Good battery life
- Sleek design
- No screen
- Paid membership required for all the features
- No step or calories tracking
Tech specs: Up to 5 days battery life | Sleep cycles | Bluetooth | 1.5" x1.5" x 0.45" | IP68 water resistant | Blood oxygen, skin temperature sensor, heart rate | iOS and Android compatible
There are a lot of wearables on the market right now, and one that tends to slip through the cracks is the underrated Whoop 4.0, especially as it compares to the Apple Watch.
The Whoop 4.0 is a no-nonsense fitness tracker that doesn't have a screen, simply built to be worn and track fitness and sleep data. It's an uncomplicated device, something you wear on your screen with a band, which is really all you see.
As a fitness tracker, the Whoop 4.0 tracks strain, "defined as the measure of your cardiovascular load, scored on a scale of 0 to 21" on our review. This measure helps you see how your body performed during workouts and what kind of recovery it will need.
Read the review: Screenless wearable helps you avoid injuries, track sleep details
- Nothing to wear
- Wakeup light
- Doubles as bedside clock with smart alarm
- Has specific placement requirements to track accurately
- Paid membership to unlock all features
Tech specs: Plug-in | Sleep cycles | 5.2" x 6.7" x 1.45" | Wi-fi | Measures movement and breathing rate | iOS and Android compatible | Room temperature sensor, clock
The Halo Rise is a smart bedside sleep tracker that doubles as a wake-up light and smart alarm. This means that it gradually adjusts the built-in light to slowly wake you up, simulating the gradual brightening of the sunrise.
The smart alarm feature senses when you're in a light sleep stage to wake you up, much like some Fitbits do.
With no wearables involved, the Halo Rise sits on your bedside table, looking a lot like a makeup ring light, sensing your body movements and breathing rate to determine when you fall asleep and your sleep stages. The jury is still out on non-contact bio-motion sensing devices, but some studies have found that they can be relatively accurate, with most common errors being at failing to detect waking up after sleep onset.
- Generally comfortable enough to sleep in
- Guided and unguided meditation
- Paid subscription to unlock all benefits
- Can be uncomfortable in some positions
The Muse S meditation headband not only tracks your sleep but helps you fall asleep through guided and unguided meditation. While you start the night with some relaxing meditations, the device will track your sleep as you drift away, making it a dual-purpose wearable.
Meditation is a practice that can add many health benefits to your life, like lowered blood pressure and less stress and anxiety, according to different studies.
This also has the added benefit of sensing when you're waking up in the middle of the night, to quickly play more audio to try and lull you back to sleep.
Read the review: I slept with a meditation headband, Here's why you should, too
- Sleek, easy to blend in with regular jewelry
- Long battery life
- Paid membership required to unlock all features
Tech specs: Up to 7 days battery life | Sleep cycles | Bluetooth | 7.9mm wide, 2.55mm thick | Up to 100m water resistant | Blood oxygen, skin temperature sensor, heart rate monitoring | iOS and Android compatible
Another wearable device is the Oura Ring which, unlike other more popular trackers, is worn on a finger rather than the wrist. Oura claims to accurately track sleep cycles, total sleep time, resting heart rate and heart rate variability, movement, putting them all together to give you a sleep score.
When compared to polysomnography, the Oura ring proves to be 96% accurate in detecting sleep, and 65% accurate in detecting light sleep, 51% for deep sleep, and 61% for REM sleep.
According to ZDNET's Matthew Miller, a new sleep tracking algorithm "will provide even more accuracy that we already see with the Oura Ring" in future updates.
Read the review: Oura Ring 3 review: Unobtrusive 24/7 health tracking with more to come in 2022
What is the best sleep tracker?
The best sleep tracker overall is the Apple Watch Series 8. Data has the power to alter our state of mind and what we do about our habits. And, though it's important to be aware of the things we may be unknowingly doing that may have a negative effect on our health, being able to trust the accuracy of the data is key.
This is why the Apple Watch's sleep tracking abilities make it stand out from the rest. It combines all the data it gathers from you each night to give you its best approximations of your sleep quality and cycles; with the bonus of being an Apple smartwatch and all the features that come with that.
But a simpler option like a Fitbit, for example, may be more suitable for those not interested in all the bells and whistles of the Apple Watch.
| Sleep tracker | ZDNET's take | Price | Battery life | Sleep cycles | iOS & Android | Subscription offered? |
| Apple Watch Series 8 | Best overall | $430 | 18 hours | ✔ | iOS only | No |
| Fitbit Inspire 3 | Best for a budget | $100 | 10 days | ✔ | ✔ | Yes |
| Withings Sleep Pad | Best under-mattress tracker | $130 | Plugged in | ✔ | ✔ | No |
| Biostrap EVO | Best for data fans | $319 | 2.5 days | ✔ | ✔ | No |
| Whoop 4.0 | Best alternative to Fitbit and Apple | $300 | 5 days | ✔ | ✔ | Yes |
| Halo Rise | Best bedside option | $140 | Plugged in | ✔ | ✔ | Yes |
| Muse S | Best headband tracker | $350 | 10 hours | ✔ | ✔ | Yes |
| Oura Ring | Best for 24/7 monitoring | $299 | 7 days | ✔ | ✔ | Yes |
Which is the right sleep tracker for you?
This will vary from person to person and according to individual preferences. Personally, I wasn't always one to wear a fitness or sleep tracker, I've used some forms of them for my kids. You can thank the obsessive in my OCD for buying a couple different trackers when they were babies.
Though the ones I got for them didn't track sleep cycles, just time asleep, heart rate, and blood oxygen levels; I do enjoy wearing my Fitbit Inspire 2 and Apple Watch to bed each night to see the data each morning.
As a previous Fossil-WearOS-fan briefly turned Apple-Watch-user turned Fitbit-wearer, I have to say I really enjoy the simplicity of the Fitbit Inspire 2, but, most of all, I enjoy the sleep stages breakdown. Maybe it's that OCD again, but give me some data to obsess over and I'll buy into whatever you're selling.
With a Fitbit and other devices like the Withings mat, you get a snapshot of what your sleep cycles looked like in nights past: how long you were asleep and awake, as well as how long you likely spent in each of the different sleep stages and how long your sleep cycles were. After that, it's all a matter of preference: wristband, headband, mattress pad, etc.
| Choose this sleep tracker... | If you want... |
| Apple Watch Series 8 | An accurate sleep tracker plus smartwatch that fits seamlessly into your Apple ecosystem |
| Fitbit Inspire 3 | Long battery life with effective sleep tracking algorithms |
| Withings Sleep Pad | An under-the-mattress solution that doesn't interfere with your sleep |
| Biostrap EVO | Compehensive data results in your phone or tablet each morning |
| Whoop 4.0 | No frills, just sleep and fitness data with no screens or notifications |
| Halo Rise | A no-contact bedside tracker with bonus wakeup light and smart alarm |
| Muse S | A sleep headband complete with meditation |
| Oura Ring | A 24/7 device that you won't even remember you're wearing |
How did we choose these sleep trackers?
Poor sleep quality could mean an increased risk of dementia, obesity, cardiovascular disease, depression, and even certain types of cancer. The potential of avoiding these ailments is motivating enough to get anyone to track their sleep in hopes of identifying problem areas and fixing them.
The craving for health information is constant nowadays. We want to know how many calories and macros are in our daily diets, what our heart rate and blood oxygen level is, and how much sleep and the quality of it has become part of that.
With health and tech companies creating new sleep devices, aids, and trackers, it's no wonder the market is flooded with them. Choosing the best sleep trackers involves some of my personal experience with them, along with thorough research and exhaustively reading different sleep studies on these devices.
What are sleep cycles?
A sleep cycle is comprised of three or four different stages: awake, light sleep, deep sleep, and rapid eye movement, or REM. On a typical night, when you first go to bed and fall asleep, you'll enter either light or deep sleep, likely one after the other, and then move to REM sleep.
This cycle will last about 1.5 hours, then repeat itself in intervals closer to two hours, maybe with a few awake minutes in between, but always ending with REM sleep. As the night progresses, you'll likely experience less time in deep sleep, while the REM stages will become longer.
A regular night of sleep should be about 50% light sleep, 20% REM sleep, 20% deep sleep, and maybe 10% awake.
Are sleep trackers really accurate?
The go-to study to analyze sleep has long been polysomnography, which analyzes a person's oxygen level, heart rate and breathing, eye and leg movements, simultaneously with an electroencephalogram, or EEG while they sleep. The latter is the one where they stick 14 electrodes to you that detect the electrical activity in your brain, your heart rate, and muscle movement.
An EEG can be used to study your brainwaves as you navigate through different stages and cycles in your sleep. A wearable smartwatch or fitness tracker on your wrist, however, is far from your brain.
The most popular wearables like the Fitbit, Apple Watch, Garmin watch, Galaxy Watch, etc, use a combination of tracking heart rate and heart rate variability (HRV), movement, breaths per minute, and, on occasion, skin temperature. The ones that track sleep cycles then use an algorithm to make an educated guess on what your sleep cycles look like, based on your body's response.
A 2017 study compared polysomnography with the performance of a Fitbit Charge 2 in 35 adults and found that the Fitbit detected sleep onset with a 96% accuracy, but overshot time spent asleep by 9 minutes.
With regards to sleep cycle and stages detection, the study revealed the Fitbit detected light sleep with an 81% accuracy, deep sleep with only a 49% accuracy, and REM sleep with a 74% accuracy.
A newer study published in April of 2022 compared the performance of the Fitbit Alta HR with the results of an EEG both worn simultaneously by 40 college athletes while sleeping. This work found that the Fitbit is a useful tool for athletes' sleep management as it resulted in satisfactory concurrence with the EEG in tracking sleep onset, time spent asleep, and sleep cycles.
While not 100% accurate, the Fitbit was found to have a strong correlation in total sleep time and between the percentage of deep sleep in between sleep onset and initial REM sleep.
Which sleep trackers are more accurate: wearables or no-contact?
Wearable sleep tracking devices have the advantage of combining data collected by several sensors at once to determine aspects like sleep cycles. They typically gather a combination of heart rate, movement, breathing rate, skin temperature, and comparisons with resting heart rate.
No-contact sleep trackers, however, like the Halo Rise, rely on sensing movement, so it monitors your breathing and body movements, as well as environmental factors like light, temperature, and noise levels.
Though these all individually tout to be the most accurate, we can't say for sure unless both types are compared with polysomnography, which is the gold standard for sleep tracking.
Are there alternative sleep trackers worth considering?
With so many sleep trackers available, there are a lot of good alternatives worth considering. Here are our top picks of alternative sleep trackers:
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