There definitely needs to be a solution, something like this doesn't seem acceptable in 2022/2023. This is also something that affects more watches than the fenix 7. 

Personally, I get sleep overridden anywhere from 4 - 10 times per month. Really makes looking back at historical details (sleep score.etc) and using other linked functionalities difficult.

I've similar issue, but it's with long "nap", copied from my other thread:

Shinatesu said:

Today I got a mess up sleep (I know), like I sleep from 6PM to around 1AM, and then wake up for some night stuffs and come back to sleep from 3AM to 6AM. And now my Fenix 7s think that I'm only sleep for 3 hours from 3AM, so the score is terrible. It completely forgot my full 7 hours sleep right before that.

So, apparently, if you do sleep for 12 hours straight, but you accidentally awake few hours between the sleep session. Then you still don't sleep enough according to advanced sleep monitoring algorithm of flagship Garmin devices.

Make sure you also highlight and send a PM to “Garmin - Chris” as he said in the sticky post in begining of this thread so that he get aware of the issue. Garmin seems to react on the number of persons report an issue according to the philosophy that if more people reported the more severe it must be and vice versa

“…replacing your prior night's sleep, please highlight my name and send me a Private Message. Thank you!”

Garmin - Chris FYI

Running on SW 13.14 (beta) but I have not seen any updates to sleep algorithm in release notes. However I discovered that on the watch in settings located at “notifications & alerts” => “system alerts” there is a menu named “jet lag adviser” which had items like sleep and naps to turn on or off. I turned off the whole thing (status == off) and after that I have for many days now not had any issues with daytime sleep. Can anyone that has a lot of problems with daytime sleep try this out and see if it helps or if this is just a lucky coincidence due to a little bit higher pulse than before when awake due to less training. Good to know if this is what cause the problem or not.

I wear a Whoop continuously as well as my Garmin Fenix  7. Night’s sleep is similar on both devices however the Whoop correctly records sleeps as naps if they occur outside of your normal sleep/ wake cycle ( which is not fixed by time). Naps are deducted from the sleep time required during the next sleep cycle.

I agree that sleep monitoring is not as good as it could be on the Fenix, but it was not amongst the primary reasons for which I bought the watch. I hope that progress will be made on this front, but until then…nothing is perfect.

Sleep was neither the primary reason why I bought the Epix 2. (same SW as Fenix 7) but the training readiness together with race widget was the reason I bought it and those features got destroyed by fake sleeping replacing the good night’s sleep 

With that said it seems that some improvements have been done on sleep algorithm lately since I have not get any fake naps replace my nights sleep for a while now. Looks promising 

Garmin - Chris Some more updates on the topic. I have not had any fake sleep replacing my nights sleep for almost a month now so there seems that some improvement have been done to algorithm lately; I am currently running SW 13.14.

With that said my watch started to detect sleep already at 20:00 yesterday until 6:00 in morning today when woke up. However watched some movie in Sofa and did not went to bed until 23:40. Watch registered 20-06 as sleep with some awaken periods. The good part however was that it did not replace any sleep and that it was possible to edit the sleep times in the GC App that synchronized back to watch and also updated sleep and training readiness on watch. Really good that that you could repair yourself now if sleep was not correct. Much happier now.