Set up sleep tracking
- On iPhone, open the Health app and follow the prompts to set up Sleep. Choose a sleep goal, a bedtime and a wake time.
- Turn on Sleep Focus so your Lock Screen and Watch stay quiet at night.
- Make sure Track Sleep with Apple Watch is on.
- Wear your Watch to bed, snug enough that it doesn't slide around. Apple needs at least an hour of wear to record a night.
Battery tips
- Apple asks for at least 30% charge before bed with sleep tracking on.
- Top up while you get ready for bed, or during breakfast and a morning shower.
What Apple Watch records
- Sleep stages: time Awake and in REM, Core and Deep sleep.
- Heart rate through the night, and heart rate variability while you're still. See HRV explained.
- Respiratory rate while you sleep.
- Wrist temperature changes on Apple Watch Series 8, Ultra and later.
Recent versions of watchOS also show Apple's own sleep score, built from duration (50 points), bedtime consistency (30) and interruptions (20). It's a good start, and everything above is saved to Apple Health, where other apps can use it with your permission.
What it can't do
A watch estimates sleep from movement and heart rate. It isn't a sleep study, which measures brain activity in a lab. Research on consumer sleep trackers finds they're good at telling sleep from wake and less consistent at sleep stages, especially on disrupted nights. So read the stages as estimates, look at trends over weeks, and don't worry about one strange night.
What makes a sleep score useful
- Duration against your own need, not a fixed 8 hours. Adults are advised to get 7 or more hours, but the right amount varies between people, and after a hard day you may need more.
- Consistency. Going to bed and waking at similar times matters as much as the total.
- Interruptions and efficiency. Eight hours in bed with an hour awake isn't eight hours of sleep.
- Stages, compared with your usual. Because stage estimates are rough, comparing with your own recent nights is fairer than comparing with textbook percentages.
- A next step. A score is more useful when it tells you what to do tonight.
What to look for in a sleep app for Apple Watch
There are plenty of good options. These are the questions worth asking of any of them, including us:
- Where does my sleep data go? Is it worked out on your phone, or uploaded to someone's servers? Is an account required?
- Does it learn my sleep need, or apply the same target to everyone?
- Does it help with bedtime, not just report last night?
- Does it need extra hardware? If you already wear a Watch, you may not need a ring or band. See how Auralo compares with WHOOP, Oura and Bevel.
- What does it cost each year, and which features sit behind the subscription?
How Auralo scores your sleep
Auralo reads your nights from Apple Health and works everything out on your iPhone. The sleep score is weighted points:
| Part | Weight |
|---|---|
| Time asleep against your sleep need | 40% |
| Deep and REM share against your 30-night median | 20% |
| Efficiency (asleep ÷ in bed) | 15% |
| Consistency of bedtime and wake time over 7 nights | 15% |
| Interruptions of 5 minutes or more | 10% |
Your personal sleep need
Your need starts from a personal base: the median sleep on your last 60 nights that were followed by HRV at or above your usual. It needs 10 such nights and stays between 6.5 and 10 hours; until then Auralo uses 8 hours and says so. On top of that it adds up to 45 minutes after a hard day, and up to 45 minutes to pay back sleep debt. Debt builds when you sleep less than you need and fades over time.
The sleep coach
Each evening the sleep coach suggests a wind-down time, a bedtime and a wake time, and it learns from every night. It looks at what came before good mornings: your training, late workouts, caffeine and alcohol you log, travel and stress. To keep the plan realistic, tonight's bedtime moves at most 30 minutes from your usual. With fewer than 14 nights of data it uses a simpler plan and says it's still learning.
The smart alarm on Apple Watch can wake you a little before your latest wake time, when movement or heart rate suggests lighter sleep. Your sleep also feeds the recovery score. The sleep score, sleep coach and smart alarm are all free, with no account. See the privacy policy.
FAQ
Does Apple Watch track sleep automatically?
Once you've set up a sleep schedule in the Health app with Track Sleep with Apple Watch turned on, yes. Wear the Watch to bed for at least an hour, charged to 30% or more, and it records your sleep and stages.
How accurate are Apple Watch sleep stages?
Consumer trackers are good at telling sleep from wake, and less consistent at sleep stages. Treat Awake, REM, Core and Deep as estimates and look at trends over weeks rather than a single night.
How many hours of sleep do I need?
Sleep experts recommend 7 or more hours a night for adults, but the exact amount differs between people and from day to day. Auralo learns a personal sleep need from your own nights and adds time after hard days or when you owe sleep.
When should I charge my Apple Watch if I sleep in it?
Many people top it up while getting ready for bed or during breakfast and a morning shower. Apple asks for at least 30% charge before bed with sleep tracking on.
Is Auralo's sleep score free?
Yes. The sleep score, sleep coach and smart alarm are in the free app. Auralo+ adds longer history, programs and PDF reports.
Sleep better from launch day
Auralo will be free for iPhone and Apple Watch. Join the waitlist and we'll email you once, on launch day.
Sources
- Apple Support. Track your sleep on Apple Watch and use Sleep on iPhone.
- Apple Support. View your sleep score on Apple Watch.
- Watson NF et al. Recommended Amount of Sleep for a Healthy Adult: a joint consensus statement of the American Academy of Sleep Medicine and Sleep Research Society. Sleep, 2015.
- Chinoy ED et al. Performance of seven consumer sleep-tracking devices compared with polysomnography. Sleep, 2021.
Auralo gives wellness information, not medical advice. For medical concerns, contact a health professional.