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The best sleep trackers 2021: sleep longer and more deeply

The best sleep trackers
The best sleep trackers 2021 (Image credit: Andrey Popov / Shutterstock)

We've tested the best sleep trackers available today, putting each one through its paces over the course of several nights to find out which one gives you the most insight into your sleep, and can help you feel more rested in the morning.

A sleep tracker can offer a surprising wealth of data that can help you improve your sleep hygiene and avoid restless nights tossing back and forth. 

Many fitness trackers and smartwatches offer sleep tracking as standard, measuring your heart rate at night to show how long you spent in each stage of sleep (deep, REM and light) plus any periods awake. Some can also monitor blood oxygen saturation (SpO2), which can reveal whether you might be suffering from breathing disturbances that are interrupting your sleep and leaving you feeling groggy in the morning.

Fitbit is now testing a new feature for the Fitbit Sense and Fitbit Versa 3 that will detect snoring and ambient noise as well, which should help give you a fuller picture of what's happening at night.

The best sleep tracker: Withings Sleep Analyzer

Withings Sleep Analyzer (Image credit: Withings Sleep Analyzer)

1. Withings Sleep Analyzer

The best sleep tracker all-round

Reasons to buy
+Lots of data+Affordable+No wearables necessary
Reasons to avoid
-Requires electrical outlet

The Withings Sleep Analyzer is a pad you can slip under your mattress to keep a track of your sleep quality without having to wear anything on your wrist.

It means you can just jump into bed and you don't have to worry about putting on an extra sleep tracker, and if you do own a fitness tracker or smartwatch you can rest assured that it will be possible to charge it while you doze.

The Withings Sleep will monitor lots of stats too, including your sleep phases, your heart rate, the amount of time you've been snoring and the duration of your sleep.

If you just want to crawl into bed and have all of your sleep quality recorded and ready for you to digest in an easy to use app, the Withings Sleep is the perfect sleep tracker for you.

Read our full Withings Sleep Analyzer review

The best sleep tracker: Polar Vantage V2

Polar Vantage V2 (Image credit: Polar)

2. Polar Vantage V2

The best sleep tracker for athletes

Reasons to buy
+Great recovery insights+Lightweight and comfortable
Reasons to avoid
-Expensive-Laggy touchscreen

The Polar Vantage V2 is a multi-sports GPS watch built for keen runners, cyclists and swimmers. As anyone who's engaged in tough training knows, recovery is one of the most important parts of improving your performance, and the Vantage V2 has two sleep tracker tools to help you optimize it: Recovery Pro and Nightly Recharge.

Recovery Pro takes into account sleep quality, as well as your long term training load, mental stress levels, and the results of subjective questions, and suggests ways to tweak your training plan to get the right balance between training and recovery.

Nightly Recharge uses a combination of ANS (autonomic nervous system) and sleep quality data, ANS charge looks at how well your nervous system calmed down during the first hour of sleep, based on heart rate, heart rate variability, and breathing rate. These two scores are compared to your baseline, and the Polar Vantage V2 will use the resulting information to give you personalized recommendations on exercise, sleep, and regulating your energy levels.

If you're serious about your performance, it's a fantastic sleep tracker for helping you achieve the right balance of work and rest.

Read our full Polar Vantage V2 review

The best sleep tracker: Muse S

Muse S (Image credit: Muse)

3. Muse S

The best sleep tracker for relaxation

Reasons to buy
+Excellent mindfulness tools+Rich sleep tracking data
Reasons to avoid
-App is battery-intensive-Takes some getting used to

The Muse S is a soft headband that monitors brain activity through your skin, as well as tracking movement, heart rate, and skin temperature. It uses that cocktail of data to help guide you through meditation sessions during the day, and to provide detailed sleep tracking at night.

The band sits comfortably around your head, with the central pod in the middle of your forehead, and is an interesting option for anyone who struggles wearing a watch at night. It connects to the Muse app on your phone via Bluetooth, and eases you off to sleep with gentle soundscapes or spoken-word 'journeys' (essentially gentle bedtime stories to help you relax).

Once you're settled down, the Muse S will monitor your sleep, including restlessness and which side you sleep on. In the morning, all the information is ready to review in the app, which gives you an extremely detailed breakdown of your nocturnal activity and wellbeing.

What we enjoyed most about the Muse S was its meditation training, but it's also an excellent sleep tracker and a good option if you want to incorporate mindfulness into your daily routine.

Read our full Muse S review

The best sleep tracker: Fitbit Sense

Fitbit Sense (Image credit: Fitbit)

4. Fitbit Sense

The best sleep tracker for cutting stress

Reasons to buy
+Detailed mood and stress logging+Super comfortable+Encourages healthier habits
Reasons to avoid
-Some tools require Fitbit Premium

All the best Fitbits offer sleep tracking, monitoring your heart rate variability throughout the night to determine how long you spend in light, deep and REM sleep, but the Fitbit Sense is also packed with mindfulness tools that will help you measure your stress levels and keep them under control.

It also measures blood oxygen saturation during the night, helping you spot signs of sleep apnea, which can leave you feeling shattered in the morning. If it detects a potential problem, the Fitbit app can generate a report that you can share with your doctor to start a conversation. Skin temperature is measured overnight as well, so you can spot variations over time.

It's also the most comfortable smartwatch we've ever tried thanks to its super soft silicone Infinity Band, which has no hard pieces against your skin.

During the day, you'll benefit from a rich set of activity tracking profiles with on-board GPS, guided breathing tutorials, an ECG sensor, and on-demand stress checks.

Read our full Fitbit Sense review

The best sleep tracker: Philips SmartSleep Deep Sleep Headband

Philips SmartSleep Deep Sleep Headband (Image credit: Philips)

5. Philips SmartSleep Deep Sleep Headband

The best sleep tracker for deeper sleep

Reasons to buy
+Soft, ergonomic design
Reasons to avoid
-Expensive-Self-adhesive sensors

Another forehead-mounted sleep tracker, the Philips SmartSleep Deep Sleep Headband is designed specifically for people who typically find themselves sleeping for less than six hours, and get poor quality sleep.

It's larger than the Muse S, but is entirely self-contained, with no detachable control unit. Attach the two self-adhesive sensors before settling down, and the band will monitor your sleep stages and movement. It's specifically intended to extend REM sleep, and uses quiet audio tones (not loud enough to wake you) when it detects that you've entered this stage to prolong it.

It's not a medical device, and isn't intended to treat medically diagnosed insomnia, but the Deep Sleep Headband is certainly worth a shot if you've been struggling to get enough good quality rest lately.

The best sleep trackers of the future

If you have a Google Home system, you might also be interested in pre-ordering the new Google Nest Hub 2, which will have sleep-tracking built in. There'll be no camera watching you doze; instead, the device will use ambient light and temperature sensors, together with its microphone, to monitor your breathing and movement overnight

In the morning, you'll be able to see how changes in the room affected your sleep, and ask questions like 'Did I snore last night?'. We'll be putting these features to the test as soon as possible.

Cat Ellis

Cat is the fitness and wellbeing editor at TechRadar. She's a trained run leader, and enjoys nothing more than lacing up and hitting the pavement. If you have a story about fitness trackers, treadmills, running shoes, e-bikes, or any other fitness tech, drop her a line!