Apple Watch: Tracking Sleep And Heart Rate

The Apple Watch is a popular smartwatch with built-in sleep-tracking features. It can help you track your sleep and heart rate, displaying a graph of sleep stages and heart rate during the night. The watch uses green LED lights paired with light-sensitive photodiodes to detect the amount of blood flowing through your wrist at any given moment, which allows it to calculate your heart rate. To enable sleep tracking, you need to configure your Watch-specific sleep settings in the Watch app. You can also view your sleep data on your Apple Watch by opening the Sleep app and turning the Digital Crown.

Apple Watch sleep tracking accuracy

The Apple Watch can be used to track sleep and heart rate. However, there are concerns about the accuracy of the sleep-tracking feature.

To get the most accurate results when using the Apple Watch to track sleep, Apple recommends the following:

• Ensure the watch is charged to at least 30% before going to bed.
• Wear the watch for at least one hour while sleeping.
• Ensure the watch fits comfortably on the wrist. A loose watch may register too much movement during sleep.

According to a study that compared 37 devices to an EEG device, the Apple Watch is the best performer for sleep tracking. Another study that analysed 11 consumer sleep trackers (CSTs) found that the Apple Watch 8 showed substantial agreement with polysomnography, indicating its potential for sleep monitoring.

However, some users have reported discrepancies in the sleep data recorded by the Apple Watch compared to other devices or their own perception of sleep quality. For example, the Apple Watch may report lower deep sleep scores than other devices or algorithms. Additionally, the Apple Watch does not calculate resting heart rate while the user is sleeping, which may affect the accuracy of heart rate data.

It is important to note that no app or watch can accurately measure sleep stages, and they all rely on algorithms to make their best guesses. The accuracy of sleep tracking on the Apple Watch may vary depending on individual factors such as BMI, sleep efficiency, and apnea-hypopnea index.

Heart rate monitoring during sleep

The Apple Watch can monitor your heart rate while you sleep. This feature is available on the Apple Watch Series 4 and later, as well as all models of the Apple Watch Ultra. The watch uses green LED lights paired with light-sensitive photodiodes to detect the amount of blood flowing through your wrist at any given moment. When your heart beats, the blood flow in your wrist and the green light absorption is greater. By flashing its LED lights hundreds of times per second, the watch can calculate the number of heartbeats per minute.

To monitor your heart rate during sleep, make sure your Apple Watch is charged to at least 30% before bed and has Sleep Tracking enabled. When you first create a sleep schedule, you can set up general settings such as your sleep goal, bedtime and wake-up times, and wind-down time. You can also enable Sleep Focus, which limits distractions before you go to bed and protects your sleep after you're in bed.

After wearing your watch to bed, you can view your sleep data by opening the Health app on your iPhone or iPad. Tap "Browse" at the bottom of the screen, then tap Respiratory and Respiratory Rate to see your respiratory rate data. You can also view your recent sleep data on your Apple Watch by opening the Sleep app and turning the Digital Crown. This will show your Sleep Stages data, Time Asleep, and Sleep Duration for the last 14 days.

In addition to heart rate monitoring, the Apple Watch can also track changes in your nightly wrist temperature and respiratory rate while you sleep. This data can provide valuable insights into your overall health and sleep quality.

Setting up sleep tracking

Next, open the Apple Watch app on your iPhone and hit the Sleep tab. Toggle the slider for 'Track Sleep with Apple Watch' to turn on this setting. You can also turn on Charging Reminders to remind you to charge your watch before your wind-down time.

Now, set up your sleep schedule. This includes setting a sleep goal (how many hours of sleep you want to get), turning on Sleep Focus, and setting a wind-down time. Sleep Focus limits distractions before bedtime and protects your sleep after you're in bed by simplifying your Lock Screen and turning off notifications. You can also create multiple sleep schedules, such as one for weekdays and another for weekends.

Once you've set up your sleep schedule, it's time to wear your Apple Watch to bed. Make sure the watch fits comfortably on your wrist; if it's too loose, the accelerometer may register too much movement during your natural sleep. In the morning, you can check the Sleep app on your watch to see how much sleep you got, including the time spent in each sleep stage and your sleep average over the last 14 days.

Additionally, you can use third-party sleep-tracking apps on your Apple Watch, such as Pillow, which can record sound during the night and track power naps. These apps may offer more detailed insights into your sleep patterns.

Sleep tracking features

The Apple Watch has a built-in sleep tracker that can be used to monitor sleep trends and help you sleep better. To access the sleep tracking feature, look for a bed icon with a greenish-blue background on your Watch. When you open the Sleep app, scroll down to check or set your sleep schedule. The Apple Watch will track your sleep automatically even if you never open the app again.

On your iPhone, the sleep functions are part of the Health app. Open the Health app, tap Browse, then tap Sleep. From here, you can view data on recent nights of sleep, and set your sleep schedule for the future. At the bottom of this screen, you can edit your next sleep schedule or your full sleep schedule. This tells your phone when you’re planning on sleeping.

The Sleep app on your watch will show you the amount of sleep you got the night before, the time spent in each sleep stage, and your sleep average over the last 14 days. The app will also show you your heart rate during the night, your sleep trend, and monthly and yearly highlights showing whether you’re getting more or less sleep than in the past.

To get the most accurate results when wearing your watch to sleep, turn on Charging Reminders. On your iPhone, open the Watch app and tap the My Watch tab, then tap Sleep. Tap Charging Reminders to turn on a reminder on your Apple Watch to charge before your Wind Down time. If your watch battery dies, it won't track your sleep data. Make sure that you're wearing your Apple Watch at a comfortable fit. If your watch is too loose, the accelerometer might register too much movement during your natural sleep.

Sleep tracking with older Apple Watch models

Sleep tracking is available on all Apple Watch models, but the Apple Watch SE lacks the blood oxygen sensor used to enhance sleep tracking accuracy. Older Apple Watch models, such as the Series 8 or the first-gen Ultra, have a functioning blood oxygen sensor, which provides slightly better sleep tracking accuracy.

To track your sleep with an older Apple Watch model, you need to configure your Watch-specific sleep settings in the Watch app. First, ensure your Apple Watch is charged to at least 30% before bed, with Sleep Tracking enabled. Then, wear your Apple Watch to sleep for at least one hour. You can also set up Charging Reminders to remind you to charge your watch before your wind-down time.

To access your sleep data, open the Health app on your iPhone or iPad. Tap "Browse" at the bottom of the screen, then tap "Sleep". From here, you can view data on recent nights of sleep and set your sleep schedule. You can also tap "Show More Sleep Data" to view additional details, such as the time and percentage you spent awake or in REM, core, or deep sleep.

The Apple Watch's sleep-tracking function can display a graph of sleep stages, and it can also track your breathing rate as you sleep, providing greater insight into your overall health.

Frequently asked questions