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Apple Watch sleep data not syncing automatically to iPhone

My partner updated her phone from a 17 Pro Max to an 18 Pro Max recently. Pretty much all the glitches from that have been resolved except one - previously she could look at her sleep score on her phone as soon as she woke up, so it presumably synced from her Apple Watch as she slept.


Now it always says No Data at that time. By fiddling around through numerous menus etc on both the phone and watch I have discovered I can manually get it to sync two ways; by turning both watch and phone off then on again, or by unlocking the watch then hitting Sync Now under the Health app on the phone.


Both are on 27.0.1 , and they are paired via bluetooth. The phone is in airplane mode at night to prevent interruptions, but bluetooth is allowed under the airplane mode settings. This is how it was on the old phone too.


Can anyone suggest what can be done about this? While not terrible it is a nuisance every day!

1 reply

Hi there


Please try this


  1. On the iPhone, open the Watch app.
  2. Go to My Watch > General > Reset.
  3. Tap Reset Sync Data.
  4. Note: It will seem like nothing happened when you tap it because this process runs entirely in the background. Give it a few minutes to complete. 


2. Check the iCloud Health Sync Toggle

Sometimes the migration to a new iPhone breaks the secure data bridge between the watch, the phone, and iCloud. 

  1. Open the iPhone Settings app and tap your Apple Account (Name) at the top.
  2. Tap iCloud > See All (under "Saved to iCloud").
  3. Locate Health and toggle Sync this iPhone to OFF.
  4. Restart both the iPhone and the Apple Watch.
  5. Go back to the same setting and toggle Sync this iPhone back to ON.