Sunday, April 28, 2024

How Accurate Is Apple Watch Sleep Tracker

Sleep Trackers And Battery Life:

How accurate is sleeping tracking on the Apple Watch

Ever since I got my Apple Watch, Ive started tracking my sleep using its built-in feature, but it wasnt long before the battery died before the end of the day. It didnt matter if I used the watch during the day, it still wore down throughout the evening, leaving me with no way to get all of my data synced to my iPhone.

All that activity means your Apple Watch is going to need a charge. And sleep tracking will drain the battery life the most because the wearable will have to work harder to monitor your vitals.

A common concern expressed by Apple Watch users is battery usage. The lithium-ion batteries in both the 38mm and 42mm models are rated to last for 18 hours. This is based on the goal of getting ~4 hour in bright conditions with heavy usage, up to ~6 in normal conditions, up to ~10 in dim conditions.

I charge my Apple Watch every night before going to bed. Sometimes I hit a nice streak and make it a couple weeks in a rowIll miss one day but then charge the next night. But Ive missed nights of charging plenty of times, too. When my Apple Watch has less than 50% battery, I charge it before bed, too.

Sleep Researchers Compare Sleep Trackers With Polysomnograms

I suspect many people would like to know how big the elephant in the room is, but we just dont own elephant measuring tools. And theres no authority that regulates sleep trackers to help us out.

However, there have been a handful of studies in recent years where sleep researchers have compared sleep trackers with polysomnograms, EEG or sleep diaries.

The problem, as I see it, is that manufacturers regularly release new models or update the firmware. So most available published research involves sleep trackers that are either older models or entire brands that have since discontinued .

Still, they are interesting to consider as there are some common findings that crop up more than once.

1. Portable EEG + Fitbit Versa

A study in 2019 particularly interested me as it involved one of my favorite wearables the Fitbit Versa .

20 people used the Versa for 14 nights, as well as a portable EEG. They found the Versa was similar to the EEG for total sleep time, time in bed and calculated sleep efficiency. However, it differed when it came to sleep stages, time to fall asleep and time of first waking. They concluded:

The consumer sleep tracker could be a useful tool for measuring sleep duration in longitudinal epidemiologic naturalistic studies albeit with some limitations in specificity.

2. Polysomnogram + Jawbone UP3

Even though the Jawbone UP3 is now discontinued, this 2017 study is interesting because 17 patients wore the UP3 while undergoing a polysomnogram in a sleep lab.

Monitor Ambient Skin Temperature

Your bodys core temperature fluctuates while you sleep. For example, non-rapid eye movement sleep episodes are accompanied by core and brain cooling.

As a result, sleep monitoring devices can keep tabs on your skin temperature much like a fever thermometer to detect changes in your sleep cycle and, in particular, sleep onset. Both the WHOOP Strap 4.0 and the Oura Ring can monitor skin temperature!

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Pod Pro By Eight Sleep

The only device that Ive found to be relatively accurate and reliable is the Pod Pro by Eight Sleep. Its a temperature-controlled smart mattress that has sensors built into its mattress cover. The company calls it the ActiveGrid, and Ive been using it to track my sleep for the past few years.

Based on the comparison data Ive collected, Eight Sleeps tracking capability is more or less in line with WHOOP.

You can learn more about the Pod Pro by Eight Sleep in this article.

If you want to give the Pod Pro a try, you can use the link below and get $150 off the purchase price.

As indicated above, there are several other non-wearable sleep tracking devices on the market but none that Id consider to be accurate.

Still, despite my skepticism and all the negative reviews Ive read of those devices, I ordered the Emfit QS to give it a try.

Activity And Workout Tracking

Apple Watch Series 5: Seven features it needs to be the ...

Both wearables do a good job of recognizing and tracking different types of physical activity. For example, the last time I walked from the security area of the Atlanta airport to Terminal F , my Apple Watch asked me if Id like to start tracking an indoor walk. Plus, it had already captured every step I had taken since I sped up my pace .

On another occasion, I swam a few laps in our previous homes community pool. The Apple Watch recognized that I was swimming and started tracking a workout while counting my laps.

WHOOP, on the other hand, detected I was doing manual labor when I built our first chicken coop early in 2021. Additionally, WHOOP automatically recognizes many of my functional workouts that last longer than 15 minutes.

The latter is key for both fitness bands to detect and log workouts the workouts have to be long enough and raise your heart rate above a certain threshold in order to be recognized. The exact threshold varies by device and the type of workout youre performing.

For example, WHOOP recognizes physical activity as a workout if your heart rate is elevated for longer than 15 minutes and the activity resulted in a metabolic strain score of 8 or above. .

Heres an overview table that compares the activity and workout tracking features of both devices side-by-side.

Apple Watch

So WHOOP can theoretically detect all 87 types of workouts it has in its database.

Fitness Goals: How the Apple Watch and WHOOP Strap Score Workouts

Calorie Tracking

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Signal Analysis And Algorithm

Besides the physical challenges of shining light through blood vessels and accurately capturing the reflection, its up to complex algorithms in the device to convert the signal into a more or less accurate heart rate reading.

One of the big issues at play is noise. For example, if the sensor doesnt have sufficiently tight contact with the skin, ambient light can interfere with the reflecting light from the LEDs, thus reducing the overall signal quality.

On the other end of the spectrum, a sensor that fits too tightly might restrict blood flow and thus also reduce signal quality. Either way, the resulting heart rate reading might be inaccurate.

Consequently, if the HR reading is inaccurate, the resulting sleep monitoring will be as well. In my experience, most standard straps that look like regular watch straps dont provide a good enough fit for the sensor to remain in constant contact with the skin.

Thats why I use the Sport Loop *with my Apple Watch and the ProKnit strap with my WHOOP*. Regardless of what brand or type of device you choose, make sure it comes with a good strap that can be easily adjusted for a perfect fit. Trust me, that makes all the difference!

The second influencing factor is the quality of the signal processing algorithm. Unfortunately, most brands dont share much information about their algorithm and the expertise of the engineers who designed it.

The Process: How I Evaluated The Devices

I first assembled a panel of experts, both clinicians and sleep researchers, to advise me. They were:

Michael Grandner, director of the Sleep and Health Research Program at the University of Arizona Molly Atwood, an assistant professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine Kelly Glazer Baron, a clinical psychologist and associate professor of public health at the University of Utah with specialty training in Behavioral Sleep Medicine Dimitri Gavriloff, a senior clinical psychologist and Clinical Course Tutor in Sleep Medicine at the Sleep and Circadian Neuroscience Institute, University of Oxford Massimiliano de Zambotti, a researcher in the Human Sleep Research program at SRI International

I read the directions and tried each device for at least a few days to make sure they were working properly and delivering data to their apps, including information that would allow the devices to understand my sleep patterns over time.

My expert advisers agreed that wearing the devices at the same time would yield the best data. It would allow me to compare my Day 3 sleep duration, for example, across several devices in a way that was as close as possible to an apples-to-apples manner. They added that there would likely be little chance of the devices interfering with each other.

In terms of duration, they agreed that a two-week evaluation would yield a reliable but manageable collection of data.

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What Are The Best Free Apple Watch Sleep Tracking Apps

The following are some of the best free apps you can try:


In-app purchases are included for a premium. The first thing you will notice about Pillow is how vibrant it looks. It also performs very well when it comes to working as a sleep tracker. It is free, but if you want to get the most out of it, you have to pay a monthly fee of $4.99 per month or $27.49 for an annual premium subscription.

It collects your data through a combination of actions, including sounds, your heart rate, and movement. The data is then presented through perfectly created, easy-to-read charts. You will not struggle to understand the graphs because they are apparent and detailed.

They focus more on your sleep stages than Auto sleep. The app tracks sleep through deep REM and light sleep, time in bed, and the time you go to sleep. Afterward, Pillow delivers a sleep quality score and tracks your heart rate overnight. If you pay a premium, you get access to the sleep lab to get more insights.


Sleep++ is one of the most popular Watch sleep apps on the App Store. Its most significant selling point is how simple it is to operate. Everything is free. It does not have paid subscriptions. This is convenient since you will not have to worry about paying for anything.

However, you can observe your nights sleep duration, sleep duration, and bedtime consistency score. One thing we love about the app is the long-term trend data, also nicely presented.

How Accurate Is The Apple Watchs Calorie Counter

Apple Watch 6 Accuracy (Sleep, Heart rate, Steps)

Speaking of accuracy Just how accurate is the Apple Watchs ability to count calories?

As far as smartwatches and other wearable devices go, the Apple Watch seems to be one of the most accurate.

It might not be 100% accurate all the time, but given how many biometrics it analyzes, you can get a pretty clear idea of just how many calories you are taking in and burning each day.

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How To Measure Rem Sleep With Apple Watch

Open the Sleep app on your Apple Watch. Scroll down to see the amount of sleep you got the night before and your sleep average over the last 14 days.

You asked, how does my watch know Im in REM sleep? Using a process called actigraphy, your tracker translates your wrist movements into sleep patterns. Brainwaves, eye movements, and breathing are also required to determine the difference between deep REM sleep and light sleep.

Beside above, can a watch measure REM sleep? It generally cant accurately measure REM sleep. But sleep-tracking apps for wearable devices like the Apple Watch or Fitbit primarily look at movement and heart rate to determine when you are asleep or awake which are generally not precise enough to measure the different sleep stages, Dr.

Also, how do you measure sleep on Applewatch? In the Watch app on your iPhone, tap the My Watch tab, then tap Sleep. Then tap Track Sleep with Apple Watch to turn on this setting. To get the most accurate results when wearing your watch to sleep: Turn on Charging Reminders.

Data You Won’t Want To Sleep On

Armeen Poor, MD, is a board-certified pulmonologist and intensivist. He specializes in pulmonary health, critical care, and sleep medicine.

Our editors independently research, test, and recommend the bestproducts, and articles are reviewed by healthcare professionals for medical accuracy. Youcan learn more about ourreview process here.We may receive commissions on purchases made from our chosen links.

If youre someone who reliably gets restful nights of sleep, then you may not fully realize how detrimental insomnia or disrupted sleep can be for your physical and mental health. And its not just a lack of sleep: poor sleep hygieneincluding not sticking to a sleep schedulecan also make us feel worse.

There are also situations where a person might think theyre sleeping well, but, following observation, find out that their sleep is disturbed regularly by everything from nightmares, temperature fluctuations, or conditions like sleep apnea. Whatever the cause, it can be helpful to be able to track your sleep to see what you get up to at night and what adjustments you can make to improve your overall sleep quality and potentially even your mental health.

To help make that task easier, we spoke with the experts to find the best sleep trackers on the market.

  • Can take a few hours for sleep data to show up on the app

  • Lacks actionable advice

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Apples Wind Down Is Better Than Its Sleep Tracking

Though Im not thrilled with the sleep tracking functionality, Apple did a nice job with a related set of watchOS 7 and iOS 14 features called Wind Down. Rather than just telling you how much you slept, Wind Down provides a holistic approach to weaning you off your phone at night, softly encouraging you to settle down before a full Do Not Disturb regime kicks in.

If you prefer to use apps to relax, you can create iOS shortcuts specific to settling down, such as turning on a music playlist or podcast, opening an app for reading or journaling, or accessing apps for yoga and meditation. These shortcuts will appear on the iPhones Lock Screen so youre reminded to use them, and you can also initiate a watchOS Wind Down sleep mode that begins however many minutes you prefer before your scheduled bedtime.

These kinds of features may seem simple to implement, but theyre actually thoughtful, OS-level integrations that show how sleep tracking functionality could become part of a larger sleep management experience for some users. I might want to keep using Wind Down even in the absence of sleep tracking.

Why Trust Verywell Mind

5 Best Sleep Tracker Apps Apple Watch

As a seasoned health writer and editor with a special focus on mental health and well-being, Elizabeth Yuko understands how powerful stress-relieving activities can be for many peopleas well as the fact that theyre not one-size-fits-all. With decades of first-hand experience dealing with anxiety, depression, and post-traumatic stress disorder, shes always on the lookout for new products, techniques, and services that can help people cope with stress and other mental health challenges.

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How Sleep Cycles Work

To understand sleep-tracking data, I delved into how sleep works. There are three main stages: Light sleep, deep sleep and REM sleep .

The deep sleep stage is beneficial for physical restoration, like muscle reparation and metabolism recovery, researchers said. REM sleep, the stage in which we dream, helps in repairing our psychological and emotional networks.

On average, a person completes a sleep cycle, which includes each of the three main stages, every 90 minutes. To get a good nights sleep, you need to complete four or five cycles. Thats partly because the cycles are not the same throughout the night: The early cycles have more deep sleep, whereas the later ones have more REM sleep.

But our sleep-tracking tech? It generally cant accurately measure REM sleep.

In sleep-tracking labs, the gold-standard scientific equipment typically includes sensors that are connected to someones face and neck to measure eye and brain activity, among other variables.

But sleep-tracking apps for wearable devices like the Apple Watch or Fitbit primarily look at movement and heart rate to determine when you are asleep or awake which are generally not precise enough to measure the different sleep stages, Dr. Vallat said. Without a good look at REM sleep, those apps may give an incomplete picture of sleep quality.

Which Sleep Tracker Is Best Study Reveals The Wearables That Are Most Accurate

MORGANTOWN, W. Va. Just a few decades ago, it would have been impossible to track your sleep quality on a minute-by-minute basis. Of course, just like so many other areas of life, technology has changed all that. Wearable sleep tracking devices, such as the Apple Watch or Fitbit, are quite common nowadays. However, researchers from West Virginia University report some of these devices are much better at their job than others.

Joshua Hagen, director of the Human Performance Innovation Center at the WVU Rockefeller Neuroscience Institute, says he was motivated to conduct this research because there hadnt been a proper third-party assessment of sleep tracker quality across various brands. He and his team set out to test the efficiency of eight commercially available sleep trackers.

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Apple’s Not Planning To Use Your Sleep Data

Companies like Fitbit have used anonymized user data for years to study demographic sleep patterns and improve observations on sleep, but Apple doesn’t plan to do that. Instead, Apple has been building its machine learning models from data collected through internal studies.

“And that takes a long time. So we’ve been working on this for a while,” Lynch says. “We treat the data that’s being collected on a user’s device with a high level of sensitivity around privacy. Apple is not seeing your sleep data.”

Like other sensitive information collected by Apple devices, stats about your sleep stay on your device. You control where it’s shared, like with third-party apps connected to HealthKit, and Apple doesn’t collect the information.

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