Full sleep tracking as a shift worker not possible with Garmin

I am a shift worker and every day and every week is totally different. That's why I can't set a time table for sleep mode with my Fenix 7.

I used the following workaround: Set sleep time to 00:00 - 00:01 every day. When I go to bed I activate the sleep mode manually via hotkey.

I want to measure pulse ox while I'm sleeping. But that's not possible because Garmin measures this value 4h in the middle of my set sleep time. But my set sleep time is only 1min. So there is no pulse ox measurement with my workaround.

Can anyone give me an advice how I can fix this? It would be great if it is possible to deactivate the time table in total.