Set your morning, then settle in.
Choose the latest time you need to be up on your phone or Watch. On the phone, adjust the time and confirm it. Your preferred early wake window and bedtime planning target live in Settings, so you don't need to set them each night.
The app suggests a bedtime using a reference model and, when enough usable records are available, estimates from your recent nights. Treat it as a planning guide, not a promise about exactly when you will fall asleep.
On your Watch, tap Start tonight and check that the monitoring screen appears before you settle in. Keep your Watch charged and worn for the session.
First-night checklist ↗Your Watch follows the changes.
The current app uses wrist movement and heart-rate measurements to estimate awake, light, deep and REM stages. This happens locally on the Watch.
These are software estimates. They can be incomplete or wrong; a quiet wrist is not proof that you are asleep. The report separates unknown periods and available data from estimated stages.
What about other measurements?
With permission, the app can read available heart-rate variability, heartbeat series, breathing rate, blood oxygen and sleeping wrist temperature records. These supplement your review; they are not all continuous inputs to the current live staging rules. Availability depends on your device, permissions and recorded samples.
A window for a gentle nudge.
Choose an early wake window if you want your Watch to look for a suitable moment before your latest wake time. The decision uses recent local stage estimates. It does not wait for an AI response.
Prefer a fixed time? Choose No early wake in your wake preferences. The monitoring session then aims to remind you at the time you selected.
What if it doesn't find a suitable moment?
The app has a deadline fallback that attempts to wake you at your latest time. Its early-wake rules consider recent light or awake estimates and also include a REM condition near the end of the window. This is not a guarantee of the sleep stage you will wake from.
For an important morning, keep a separate backup alarm. A powered-off Watch, an interrupted session or other device conditions can prevent an app reminder.
See the night. Add your perspective.
When the Watch record reaches your phone, open Sleep to see estimated time asleep, stage changes, waking and trends across nights. Add how you felt on waking, with an optional note.
If you grant access to Health sleep records, those records can be compared with the app's estimates. They remain distinct sources. A record labelled “unspecified” is not automatically labelled light or deep.
Missing data is part of the picture. A partial night or a short nap may give you less information than a complete recording.
Help with missing or different records ↗Explore what your records might mean.
Request a weekly review or ask the assistant about your nights. It uses the summaries provided with your request; chat also sends the messages you choose to type.
AI explanations can be mistaken. Use them to explore your records, not as a diagnosis or as a guarantee about the next night. AI features require a configured, available service and an internet connection.
Read the AI data explanation ↗