Sleep tracker, sleep tracking sensors: our buying guide

Are sleep trackers effective at measuring sleep quality and duration throughout the night? How do devices, bracelets, and watches detect different sleep phases? Stick around, we answer all your questions about the different ways to monitor your sleep in this article!

Top Sleep Trackers at a Glance:

We'll give you all the details on these models a bit further down. But if you're in a hurry, here’s our selection:

What is a sleep tracker for?

First, let’s lay the basics: what exactly is a sleep tracker and what is it used for?

A sleep monitor is a device, gadget, or app that analyzes your sleep by recording multiple factors (heart rate, movements, breathing, for example). Tracking with these devices lets you learn more about sleep duration, quality, different sleep phases, and sleep habits.

In short, a sleep tracker allows you to analyze, among other things, sleep cycles, their sequence, the duration of light and deep sleep. If you think you might have sleep issues such as insomnia, difficulty falling asleep, or nighttime awakenings, it can give you a first indication.

There are several types: from smart bracelets to devices you install in your bed, as well as smart watches. You have a range of features for all budgets. But more on that later.

Features: real-time sleep monitoring, heart rate tracking

So, how does it work? It's simple: the sleep tracker measures various data that are then analyzed by an algorithm. Depending on the type of tracker, you’ll get more or fewer data points measured:

• ⏰ Bedtime and wake-up time, time spent lying down, sleep rhythm.
• ❤️ Heart rate: useful to know when you fall asleep and how your sleep phases progress.
• 😮💨 Breathing: like heart rate, helps track the progression of sleep cycles.
• 📊 Oxygen saturation: can alert you to possible sleep apnea or oxygenation issues.
• 🌡️ Body temperature: temperature is essential for rest. Measuring your body temperature allows the tracker to relate it to your sleep. (Check our full guide on ideal sleep temperature.)
• 🫨 Movements: if your tracker has an accelerometer, it can detect your movements in bed, their frequency, and count.

All collected data are analyzed and processed by algorithms (via a dedicated sleep app, for example) to provide insights on sleep duration, but also the different cycles: light sleep, deep sleep, REM sleep, nighttime awakenings, and the sequence of sleep cycles throughout the night.

Once all this info is collected over a significant period (several nights under normal conditions), you’ll get not only indications but also personalized tips for better sleep: the ideal sleep duration, recommended bedtimes and wake-up times… Basically, a customized sleep routine.

💡 Note: depending on the type of device, data accuracy and analysis may vary. Some measurements can be off, especially if you are lying quietly in bed; a poorly calibrated or low-precision tracker might think you’re taking your best nap ever. We recommend choosing a fairly advanced tracker for more reliable results.

Smartwatch, bracelet, or sleep sensor: which one to choose?

There are several types of sleep trackers to monitor your sleep:

• 🔗 Smart bracelets: you’ve probably heard of fitness bracelets like Fitbit or Xiaomi Mi Band, which mainly measure heart rate. Simple to use, these models are sufficient for basic tracking. However, if you want a detailed and reliable analysis, we recommend the Whoop bracelet, which we’ll discuss below.
• ⌚️ Smartwatches: a step up, like Apple Watch, Samsung Galaxy Watch, and other versatile devices that do more than just tell the time. By measuring your heart rate, oxygen saturation, and temperature, they provide fairly accurate sleep analysis. Results are accessible through a wide choice of dedicated apps.
• 💍 Sleep rings: even more advanced, these sensors measure the same signals as above, plus your movements. Comfortable and discreet, they offer reliable and precise sleep tracking.
• 🛏️ Bed sensors: placed under your pillow or mattress. These are specialized devices designed exclusively for sleep tracking and can even integrate directly with smart mattresses and pillows.
• 📡 External sensors: focus solely on environmental factors like noise (snoring, breathing, movements). They can be standalone devices for your nightstand or smartphone apps.

Of course, your choice depends on your needs, preferences, and budget. If you’re unsure which model to pick, we’ve prepared a carefully curated selection just below 👇

Best Sleep Trackers: Our Top 5

Still a bit lost? Don’t worry, here are five trackers we recommend for real-time sleep monitoring!

Oura Ring 4, from €399

If we could recommend only one sleep ring, this would be it! Discreet, comfortable, and powerful, this smart ring measures over 20 different metrics, such as:

• Resting heart rate
• Heart rate variability (HRV)
• Respiratory rate
• Blood oxygen level
• Body temperature
• Day and night movements and steps

With all these variables, the algorithm gives you a sleep score (and a readiness score) taking into account your bedtime and wake-up time, sleep rhythm, total sleep, REM, deep, and light sleep. You can view all reports and personalized advice in the dedicated app, available on Android and iOS.

But the Oura smart ring does more than that: it also tracks your activities, rest periods, and stress levels. In short, a complete tool with a holistic approach for daily well-being, though it comes at a price: from €329 (+ €5.99/month subscription, first month free).

RingConn (Gen 2), from €299

We also suggest an alternative smart ring: the RingConn Gen 2 and its Air version. Not tested by the team, but with interesting specs, it deserves a spot on our list.

The RingConn Gen 2 is a smart ring that tracks sleep, heart rate, and SpO₂, with the ability to detect certain signs of sleep apnea. Battery life is around 10–12 days, allowing continuous monitoring without constant recharging.

The Gen 2 Air version offers the same sleep, heart rate, and SpO₂ tracking features but without apnea detection. It’s lighter, slightly cheaper, yet still autonomous and subscription-free.

Whoop 5.0, from €319

Another team favorite! This is a highly comprehensive wristband, functioning both as an activity and sleep tracker. What makes it unique? It has no screen, but accurately measures several variables useful for understanding and optimizing your sleep:

• Heart rate
• HRV: heart rate variability
• Respiratory rate and O₂ saturation
• Skin temperature
• Sleep onset and duration
• Different sleep phases

Popular with athletes and celebrities, this device works like a wristband with a screen but with much greater precision and performance, while being discreet: all the benefits of a smartwatch without the drawbacks.

Charging is done via a separate mobile case. The goal is to wear the band continuously for precise tracking and personalized calibration.

Pricing is mostly subscription-based, as a band comes with each plan. Annual rate: from €319, with the first month free.

Fitbit Charge 6, €159.95

The Fitbit Charge 6 is a versatile wristband that tracks both activity and sleep. It automatically measures sleep duration and phases (light, deep, REM) and provides a sleep score in the Fitbit app to better understand your nighttime habits.

It also tracks heart rate and oxygen saturation (SpO₂) and offers various sport modes. Some advanced analyses are reserved for Fitbit Premium subscribers.

Compared to specialized models like the Whoop 4.0/5.0, the Charge 6 offers less precise tracking and is less recovery-focused, but remains a solid all-round choice for combining health, sleep, and activity tracking with good value for money.

Apple Watch SE 3, from €269

The other wearable we want to highlight is the famous Apple Watch. This smartwatch has become increasingly capable at tracking sleep and daily activity, while serving as a useful extension of your smartphone.

The Apple Watch SE 3 is the latest entry-level version, with integrated sleep tracking. It records sleep duration and phases and provides a sleep score summarizing your night in the Health app. This generation also includes wrist temperature detection and alerts for potential sleep apnea over time, enhancing overall health tracking.

The main point of interest is the sleep analysis, integrated with the iPhone Health app and other available apps. If you want a versatile but effective device, it’s worth checking out.

Price: starting at €269.

Withings Sleep Analyzer, from €149.95

This under-mattress sleep sensor is a tech marvel: it can detect sleep apnea episodes, measure cardiovascular health, breathing, movements, and even snoring. Upon waking, all results are analyzed in the free Withings app (iOS & Android).

A true alternative to medical devices, developed with sleep doctors at Béclère Hospital in Paris. Price: €149.95

EightSleep Pod 5, from €3,048

Here we are at the Rolls-Royce of sleep trackers: a smart mattress with automatic temperature control and integrated tracker with excellent performance and unmatched measurement accuracy.

It’s expensive (€3,048 for the older version, €5,448 for the ultra-premium latest version), but if you’re looking for the best sleep tracker, it had to be included.

Final Word: Sleep Trackers

What is a sleep sensor and what is it for?

A sleep sensor helps you understand the quality of your nights and identify potential issues. These devices measure sleep-related signals such as heart rate, breathing, movements, and oxygen saturation to provide actionable data every morning.

Are all sleep trackers equal?

No. Some trackers offer more precise measurements and detailed analyses than others. To get consistent and useful data, it’s best to choose a high-quality model that matches your goals (sleep tracking, sport, recovery, etc.).

Which tracker should I choose for sleep monitoring?

Before buying, define your priorities: do you want a device specialized in sleep, general health tracking, or a versatile model (activity + sleep)? Do you prefer a discreet ring, a wristband, or a mattress sensor? These criteria influence your choice of the most suitable model.

How do I know if my sleep is improving with a tracker?

To measure improvement, track trends and scores provided by your tracker over several weeks. Regular comparisons help identify changes in sleep duration, consistency, or quality.

Do I need to wear the tracker every night?

For consistent and comparable data, it’s recommended to wear your tracker every night. If you prefer not to wear anything, solutions like the Withings Sleep Analyzer (placed under the mattress) allow tracking without a wristband or ring.

Are tracker data reliable?

Reliability depends on the model. Smart rings (Oura, RingConn) and some specialized wristbands (Whoop) generally provide more accurate measurements than basic or all-in-one models.
Trackers remain consumer devices, not medical instruments. They help spot trends or anomalies but don’t replace medical advice. For persistent problems or serious sleep disorders, consult a doctor or sleep specialist.

Do I need a subscription to access sleep tracker data?

Some models require a subscription for advanced analytics or detailed reports (e.g., Whoop or some Oura Ring features). Others, like the Fitbit Charge 6 or Withings Sleep Analyzer, provide basic data without mandatory subscription.

Which are the best sleep trackers?

The team’s favorites, the ones we use daily: Oura Ring, Whoop, and the latest Apple Watches. If you have other recommendations to add to this list, feel free to share them in the comments!