Why isn’t my Apple Watch Series 7 reading Blood Oxygen while I sleep?

For weeks now my AW S7 doesn’t read my Blood Oxygen levels at night or during sleep. I don’t know why. I recently installed 11.4 but the issue remains, even after multiple restarts.

I filed a feedback report 2 weeks ago but obviously nothing came of it. In general it reads it maybe twice a day.

What am I supposed to do? It worked fine previously.


Interestingly it appears to read it shortly after I wake up which I find curious because in the app itself it says it can make a measurement when you don’t move and your wrist is up, which are both far less the case at that time.


Thank you.


[Re-Titled by Moderator]

Apple Watch Series 7, watchOS 11

Posted on Apr 5, 2025 1:45 PM

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Posted on Apr 12, 2025 10:02 AM

Solved it!


Just checked the settings in Health and noticed (remembered) that I had turned BO2 readings off for Theater mode.

I have an automation that turns on Theater mode whenever the Sleep focus is on, because in Theater mode the Watch defaults to a red flashlight instead of white.

I turned background measurements on for Theater mode and think it’s going to work now.

Now I’m waiting to be annoyed by it when I’m actually in a theater but that’s on me, just like this entire thread 🙃

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Question marked as ⚠️ Top-ranking reply

Apr 12, 2025 10:02 AM in response to Mr. Unko

Solved it!


Just checked the settings in Health and noticed (remembered) that I had turned BO2 readings off for Theater mode.

I have an automation that turns on Theater mode whenever the Sleep focus is on, because in Theater mode the Watch defaults to a red flashlight instead of white.

I turned background measurements on for Theater mode and think it’s going to work now.

Now I’m waiting to be annoyed by it when I’m actually in a theater but that’s on me, just like this entire thread 🙃

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Apr 12, 2025 5:00 AM in response to Mr. Unko

There has been a new revelation:

it DOES read BO2 levels when I sleep, IF I‘m still sleeping after 8am…

So it basically just refuses to work before 7/8 am. Whyyyyyyyyyyy?

I‘m willing to give any and all information to resolve this issue but filing a feedback report doesn’t lead anywhere.

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Why isn’t my Apple Watch Series 7 reading Blood Oxygen while I sleep?

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