How to track sleep on Apple Watch, and what each metric means

To track sleep on Apple Watch, open the Health app on iPhone, set up Sleep (sleep goal, bedtime, wake time and Sleep Focus), turn on Track Sleep with Apple Watch, charge the watch to at least 30% before bed, and wear it snugly to sleep. In the morning, the Sleep app shows your sleep score, time in each stage and a 14-day average.

Below are the setup steps, what each metric means, and how accurate Apple Watch sleep tracking is according to Apple's own data and independent tests.

How do I set up sleep tracking on Apple Watch?

Set up sleep tracking from the Health app on iPhone. Tap Get Started under Set Up Sleep, choose a sleep goal, bedtime and wake time, and turn on Sleep Focus. Then turn on Track Sleep with Apple Watch. Apple also recommends Charging Reminders, at least 30% battery at bedtime, and at least one hour of sleep with the watch on.

Step	Where	What to do
1	Health app on iPhone	Tap Get Started under Set Up Sleep
2	Same flow	Set sleep goal, bedtime, wake time and Sleep Focus
3	Same flow, or Apple Watch app, My Watch, Sleep	Turn on Track Sleep with Apple Watch
4	Apple Watch app, My Watch, Sleep	Turn on Charging Reminders
5	Before bed	Charge to at least 30%
6	At night	Wear the watch snugly for at least 1 hour of sleep

Source: Apple Support, "Track your sleep on Apple Watch and use Sleep on iPhone".

Fit matters. Apple notes that a loose watch can register extra movement, which may look like wake time.

What sleep metrics does Apple Watch track?

Apple Watch tracks time asleep, time in each sleep stage (Awake, REM, Core and Deep), a 0 to 100 sleep score, sleeping respiratory rate and, on supported models, wrist temperature changes. The Vitals app compares overnight metrics with your typical range, and supported models can send sleep apnea notifications.

Metric	What it means	Where to see it
Time asleep	Total estimated sleep	Sleep app; Health, Browse, Sleep
Sleep stages	Time and percentage in Awake, REM, Core (light) and Deep	Sleep app; Health, Sleep
Sleep score	0 to 100 from duration (50 points), bedtime consistency (30) and interruptions (20)	Sleep app; Health, Sleep Score
Respiratory rate	Breaths per minute during sleep	Health, Browse, Respiratory
Wrist temperature	Nightly change from your baseline (Series 8 or later, any Ultra)	Health
Vitals	Overnight heart rate, respiratory rate, blood oxygen, wrist temperature and sleep duration vs your typical range	Vitals app; Health, Browse, Vitals
Sleep apnea notifications	Possible sleep apnea flagged from breathing disturbances over 30 days, on supported models	Health notifications

Sources: Apple Support and Apple Watch User Guide pages listed below.

Some notes on each:

• Sleep stages. Core is Apple's name for light sleep (stages N1 and N2). Read what core sleep is.
• Sleep score. Duration is worth half the score. The Apple Watch sleep score guide explains each part.
• Vitals. Apple says you need to wear the watch to sleep for 7 days to establish a typical range. Factors such as medications, elevation, alcohol and illness can push metrics outside that range.
• Wrist temperature. See Apple Watch wrist temperature for what nightly changes can and can not tell you.

How does Apple Watch track sleep?

Apple Watch estimates sleep stages from its accelerometer, which senses wrist movement and the subtle movements of breathing. Apple trained the algorithm on 1,171 nights of lab and home polysomnography and validated it on 299 separate nights. It sorts each 30-second window into Awake, REM, Core or Deep.

Polysomnography is the clinical standard. It records brain waves, eye movements, muscle activity, breathing and heart rhythm in a lab. The watch can not see brain waves, so it estimates stages from patterns that tend to go with them.

Is Apple Watch sleep tracking accurate?

Apple Watch is accurate at detecting that you are asleep and less accurate at detecting brief wake periods and specific stages. In Apple's validation, a median of 97.9% of true sleep was labeled sleep, but only 75.0% of true wake was labeled wake. An independent 2022 study found 88% agreement for sleep versus wake and 53% for specific stages.

Test	Sleep vs wake	Specific stages
Apple validation (299 nights)	Sleep sensitivity 97.9%, wake specificity 75.0% (medians)	Most common error: deep labeled as core
Miller et al. 2022 (Apple Watch Series 6, 53 adults, 1 night)	88% agreement	53% agreement

Sources: Apple (2025); Miller et al., Sensors, 2022.

What this means:

• Total sleep time is the most reliable number. It may run slightly high because some wake time is counted as sleep.
• Stage minutes are estimates. Use averages over 2 to 4 weeks.
• The 2022 study found similar limits for other wearables. All six devices tested needed improvement for stage detection.

Does Apple Watch track naps?

Apple's sleep tracking is built around your sleep schedule and Sleep Focus, so check whether daytime naps appear in the Health app before relying on them. If a nap is missing, your total sleep for that day will look shorter than it was.

How should I read my Apple Watch sleep data?

Start with total sleep and consistency, then look at stages. Adults need 7 or more hours of sleep per night, according to the AASM and Sleep Research Society. Check whether you hit that on most nights and whether your bedtime is steady, before worrying about deep or REM minutes.

A simple weekly review:

1. Average time asleep. Is it 7 hours or more?
2. Bedtime spread. Are most bedtimes within about 30 to 60 minutes of each other?
3. Sleep score trend. Is it stable or rising?
4. Stages. Compare this week's averages with last month's, not one night with another.
5. Vitals. Note any nights flagged outside your typical range, and what you did the day before.

For normal stage ranges, see how much deep sleep you need and how much REM sleep you should get.

When should I see a doctor about my sleep data?

Apple states that Apple Watch is not a medical device. See a doctor if you receive a sleep apnea notification, if you snore loudly or a partner notices pauses in breathing, if you feel very sleepy during the day despite enough sleep, or if your vitals are repeatedly outside your typical range and you feel unwell.

Apple notes that sleep apnea notifications are not intended for people already diagnosed with sleep apnea or for anyone under 18.

How Svanu adds to Apple Watch sleep tracking

Svanu reads the sleep your Apple Watch writes to Apple Health and computes its own 0 to 100 sleep score on your iPhone: duration 50%, stage quality 30% and bedtime consistency 20%. Its Sleep screen shows stages, sleep debt over recent nights and a suggested bedtime for tonight based on your median wake time and sleep need.

It also has an Apple Watch app, widgets and a Siri shortcut for sleep. If you use a non-Apple device that writes sleep to Apple Health, such as Garmin, Oura or Withings, the same score works with that data. No account is needed, and all scores are computed on the phone. See how the app works or the sleep score guide.

Related reading

• Sleep score: what it measures and what a good score is
• Apple Watch sleep score: how it works
• What is core sleep on Apple Watch?
• Sleep cycle alarm: does waking in light sleep work?