Sleep score has changed for the worse since iOS upgrade

My initial reaction to your post was to write: "You're Dreaming".

...but that is obviously the reverse of what is being reported.

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There was notification is the upgrade for iOS 26.2 that suggested sleep scoring had changed.

But detecting less REM sleep has not been reported here.

It is not likely to be a software error -- you may in fact be dreaming less these last few nights. By fiddling with the Health app on your phone, you can compare current to Average REM amounts over time, weekly, monthly, or 6 month-ly.

I've had a similar trend in my sleep tracking since the upgrade to 26.2, my sleep tracking has devolved to "No Data" since the upgrade. I've upgraded, rebooted, unpaired, re-paired, still "No Data". I've talked with tech (can't remember what level) before recently, and she had no answers to the "No Data" problem. It's possible that my sleep has actually deteriorated to the point of "No Data", but wouldn't the watch track a low score...even "0" rather than "No Data "? "No Data" implies to me that the watch is not tracking. What do you think?

I have the similar issue on my Ultra 2 since watchOS 26

Sitting and reading the newspaper on my iPad after breakfast is seen as a nap, as well as getting to bed early in the evening, just because I'm sitting in front of the computer streaming content, without hardly moving in my chair.

Or checking the time on my watch in the night, turning around after that and falling asleep right away is counted as being awake for 20-60min.

watchOS 26.2 showed some improvements for two nights and then continued to give false readings.

My 3rd party sleep tracking, which uses the same data from the Health App, is showing more realistic results.

All effected users should all let Apple know about this issue by using the Feedback link, I have already submitted mine.

Feedback - Apple Watch - Apple

My REM sleep does not appear remarkably different from before, and I have never seen the "no data" report.

This leads me to believe there is some OTHER factor in play than the version of iOS or watch OS.

My sleep scores after 26.2 have dropped precipitously and I am no longer using the Apple Watch to track my sleep. I was told on ChatGPT that they changed the tracking protocol to be more conservative. It mistakenly rates some sleep as awake. I initially started tracking my sleep to see if I was getting 7-8 hours sleep even though I was occasionally awake for a while most nights. With 26.2 my sleep dropped to 4-5 hours per night and my awake time increased to 2.5 to 4.5 hours per night. I don't need to aggravation of this so I am ceasing to use the watch to track sleep. I have seen sleep improvement the first two nights without the watch on my wrist. It seems to me giving people worse ratings and tracking might not be the best way to be people to use your watch.

I think part of the problem is that more people struggle with their sleep than Apple seems to be aware of, and the fact that they would tinker with people's health by rolling out an imperfect sleep tracker is insensitive to say the least. Many, myself included, perhaps rely on sleep scores more than we should, especially if they prove to be...unreliable.

Readers--

if this were a pervasive issue, the forums would be swamped -- completely overwhelmed with users complaining about it. That is not the case.

My watch reported more deep sleep last night than it has ever reported. As far as I can tell, this feature on MY setup is working great, which suggests there is not a pervasive issue with this version of the software itself.

When you have a complaint that SEEMS to be a software version issue, but others are NOT having such problems, the issue most likely lies elsewhere.

That is why I posted my watch model, in hopes of other posting theirs and possibly finding some other correlation, such as the problem following a particular model watch. My band is a fabric band with velcro closure.

It seems to me the "weak link" in recording correct sleep data is having the band adequately tight to get good readings, but not so tight as to wake you up..

it would seem prudent at this point to start calling Apple Support, and see if they have anything clever to say, collected from other callers or from some internal documents we are not privy to.

Official Apple Support

Did you also update WatchOS to 26.2?

I find watch upgrades difficult because it requires the Watch be on the charger and charged at least 40 percent AND the phone be nearby the whole time.

I wear an Apple Watch series 10 (GPS) 46 mm on my left wrist.

I do have a sleep focus set for 10PM to 9 AM daily.

No issues.

I have noticed less REM but the biggest issue is reporting that I’m have been awake while I’ve actually been asleep and my deep sleep periods have completely disappeared.

I updated the iphone prior to updating the watch. My watch is never at 40% battery level unless I am using it in a sports event.