Sleep trackers compared: rings, watches, apps and bed sensors

A sleep tracker is a device or app that estimates when you fell asleep, when you woke and how settled your night was. The main types are smart rings, watches and fitness bands, phone apps, under-mattress or bedside sensors, and EEG headbands. Most are good at sleep timing and total sleep, and much weaker at splitting the night into stages.

Below: each type compared side by side, what the research says about accuracy, and how to choose.

What does a sleep tracker actually measure?

None of them sees sleep directly. Sleep is defined by brain activity, which is why the clinical test, polysomnography, records brain waves overnight in a sleep lab. A consumer tracker records simpler signals and an algorithm turns them into a best guess:

• Movement: long periods of stillness suggest sleep.
• Heart rate and HRV: optical sensors in rings, watches and bands read your pulse. Heart rhythm changes between sleep stages, which gives the algorithm more to work with than movement alone.
• Breathing and movement from outside the body: picked up by under-mattress pads and bedside sensors.
• Sound: many phone apps listen for movement and snoring.
• Brain waves: EEG headbands read them through forehead sensors, the closest a home device gets to a sleep lab.

So the light, deep and REM figures in your app are estimates, not measurements. Our guide to sleep stages explained covers what each stage does.

Sleep trackers compared by type

This compares types, not brands. Models within each type differ, so use it to narrow the field first.

Type	What it measures	Comfort	Battery and charging	Typical cost model	Main limitation
Smart ring	Movement, heart rate and HRV; many add blood oxygen, some add skin temperature	Light, and nothing on the wrist, but it must be the right size	Varies by brand; check the stated days per charge	One-off price, though some brands add a membership	A loose fit weakens the signal; can get in the way when lifting
Watch or fitness band	Movement and heart rate, often HRV and blood oxygen	Some people find a watch bulky in bed	Varies widely by model; check it covers several nights	One-off for most; WHOOP is sold as a membership that includes the band	Tends to count quiet time awake as sleep
Phone app	Movement and sound, with the phone on or beside the bed	Nothing to wear	Your phone stays by the bed all night	Often a free version with a paid upgrade	Accuracy varied widely between apps in testing
Under-mattress or bedside sensor	Movement and breathing, sometimes heart rate and snoring	Nothing to wear	Usually plugs in at the wall	One-off price; check for app fees	Tended to overestimate time taken to fall asleep in one study; stays at home when you travel
EEG headband	Brain waves through forehead sensors	A band on your head all night, which some people cannot sleep in	Needs charging between nights	One-off price; check for app fees	Comfort, fewer models to choose from, and still an estimate

The cost model matters as much as the price. At the time of writing (October 2026), Oura's own site lists UK membership at £5.99 a month or £69.99 a year, and says that without it the ring and app still work but the insights and data you get are much more limited. WHOOP's UK membership page lists plans at £169, £229 and £349 a year, each including the device. Our breakdown of a smart ring with no subscription over two years runs the full numbers.

How accurate are sleep trackers?

Good at sleep timing and total sleep

In a 2022 validation study by Miller and colleagues, 53 healthy adults spent a night in a sleep lab wearing six devices at once: Apple, Garmin and Polar watches, an Oura ring, a WHOOP band and a Somfit forehead device. Against polysomnography, they agreed on sleep versus wake 86% to 89% of the time, and the authors judged all six valid for the timing and duration of sleep.

Weaker at sleep stages and time awake

Agreement on the exact stage (light, deep, REM or awake) was only 50% to 65%, and the authors said all six needed improvement on stages. Most of a night in bed is sleep, so a device can score well overall just by calling most of it sleep. The harder test is spotting time awake.

A 2023 study of 11 consumer sleep trackers in 75 people in Korea tested watches, a ring, bedside and under-mattress devices and phone apps. Wearables generally overestimated sleep by scoring wake as sleep, while bedside and under-mattress devices tended to overestimate how long people took to fall asleep. Stage accuracy varied widely. The app that did best was made by the company several authors work for, which the paper declares.

A 2024 review for the Sleep Research Society by de Zambotti and colleagues found that consumer devices now outperform traditional research wristbands (actigraphy), but clear limits remain: wake scored as sleep, poor tracking of naps, signal errors, and uncertain performance where skin colour or obesity affects the sensors.

EEG headbands come closest on stages

In a 2020 study of the Dreem headband in 25 people at a sleep centre, the headband's automatic staging matched expert scorers 83.5% of the time, close to the 86.4% average agreement of the human scorers themselves. Most of the authors worked for its maker. The trade-off is sleeping in a headband every night.

What this means for you

1. Trust bedtime, wake time and total sleep the most.
2. Treat minutes of deep or REM sleep as rough estimates. One night with little deep sleep is not proof of a problem.
3. Watch averages over a week or two, not single nights.
4. Stick to one device. Every brand calculates its sleep score differently, so two trackers will rarely agree.
5. Check the numbers against how you feel during the day.

Which sleep tracker suits which sleeper?

• You want sleep and recovery data but dislike a watch in bed: a sleep ring. It sits on your finger rather than your wrist and weighs a few grams, so it is easy to forget in bed. Get the size right, because a loose ring gives weaker readings.
• You already own a smartwatch or band: try its sleep tracking for a few weeks first.
• You hate wearing anything in bed: an under-mattress or bedside sensor, which stays at home when you travel.
• You are curious and on a tight budget: a sleep tracker app. Focus on bedtime, wake time and total sleep.
• You want the most detailed stage data: an EEG headband, if you can sleep in one.
• You train hard and want to know when to back off: a ring or band that tracks overnight heart rate and HRV.
• You already worry a lot about your sleep: think twice. Sleep doctors have described orthosomnia, a perfectionist chase for ideal sleep driven by tracker data, in patients who sought treatment for problems they had diagnosed from their trackers. If checking your score makes nights worse, look weekly or stop.

How to choose a sleep tracker: seven questions to ask

1. What do I want it to tell me? Sleep length, readiness to train and snoring are different jobs.
2. Will I use it every night? Comfort beats features.
3. What will it cost over two years? Add any membership to the price.
4. What happens if I stop paying? Check the brand's own site.
5. When will I charge it? Topping up while you shower avoids gaps.
6. Does it work with my phone? Check the iOS and Android versions.
7. What are the returns, sizing and warranty terms? These matter most for rings.

Is there a good sleep tracker without a subscription?

Yes. Many trackers of every type are sold outright with nothing to pay afterwards. Read the brand's own pricing page for the words "membership" or "subscription" and what happens if you do not pay.

PulseRing Pro has no subscription: every metric is included in the one-off £89 price for as long as you own it. It does not read skin temperature, it does not track your cycle, and it does not detect sleep apnoea or any other condition.

A tracker tells you what happened. The useful part is what you change

Data on its own does not improve sleep. Use it to test one change at a time:

1. Track a week or two of your normal routine.
2. Change one thing, such as a fixed wake time, an earlier last coffee or a darker bedroom.
3. After at least a week, compare averages, not single nights.
4. Keep what helps, then test the next change.

If you wake with a dry mouth, our guide on how to stop mouth breathing at night sets out what to try, in order. The Sleep Reset System puts the tracker and the tools for these tests in one box: PulseRing Pro, the Peak Blackout contoured sleep mask, Peak Mouth Tape and Peak Airflow nasal strips. Mouth tape is a wellness habit, not a treatment, and it is not for anyone with a blocked nose, breathing problems or suspected sleep apnoea.

When to see a doctor rather than buy a tracker

A tracker cannot rule a sleep disorder in or out, and a normal score does not mean you are fine if you feel unwell. NHS guidance (UK advice; elsewhere, ask your own doctor) says to see a GP if:

• your breathing stops and starts while you sleep, you make gasping, snorting or choking noises, or you always feel very tired during the day, which can be signs of sleep apnoea
• changing your sleeping habits has not helped, you have had trouble sleeping for months, or poor sleep is making it hard to cope with daily life, which the NHS lists under insomnia

The NHS also suggests asking someone to watch you sleep and bringing them to the appointment. And do not drive if you feel sleepy.

Frequently asked questions

How accurate are sleep trackers?

They are good at sleep timing and total sleep and weaker at stages. In a 2022 lab study, six popular wearables agreed with polysomnography on sleep versus wake 86% to 89% of the time, but on the exact stage only 50% to 65% of the time. Treat deep and REM figures as estimates and watch weekly averages.

What is the best sleep tracker without a subscription?

There is no single best one, because it depends on whether you want a ring, a watch, an app or a sensor under the mattress. Many trackers are sold outright with no ongoing fee. Check each brand's own pricing page for a membership and what happens without it. PulseRing Pro has no subscription, with every metric included in the one-off £89 price.

Is a sleep ring better than a watch for tracking sleep?

Neither type is better at sleep tracking in general. In a 2022 lab study comparing watches, a ring, a band and a forehead device, all were valid for sleep timing and duration and all needed improvement on stages. Choose on comfort: some people find a watch bulky in bed and prefer a ring, while others dislike anything on their fingers.

Do sleep tracker apps work without a wearable?

Yes, many phone apps estimate sleep using movement and sound with the phone on or beside the bed. They are the cheapest way to start. In a 2023 study of 11 trackers, phone apps varied widely: one scored best on sleep stages, while another was heavily biased towards scoring deep sleep. Use an app mainly for bedtime, wake time and total sleep.

Can a sleep tracker detect sleep apnoea?

A consumer sleep tracker cannot diagnose sleep apnoea. Only a sleep test arranged by a doctor can do that. PulseRing Pro does not detect sleep apnoea or any other condition. If your breathing stops and starts at night, you gasp or choke in your sleep, you snore loudly or you always feel very tired in the day, see your GP or doctor.

What is the best budget sleep tracker?

The cheapest option is a free phone app or the sleep tracking on a watch or band you already own, so try that for a few weeks first. If you then want overnight heart rate and HRV without a watch, look at a ring with no subscription, and compare two-year costs including any membership.

This article is for general information and is not medical advice. PulseRing Pro is a wellness device, not a medical device, and does not diagnose or treat any condition. If you are worried about your health, speak to your GP or a qualified clinician.