I'm not saying the body battery number was inaccurate. I'm saying it had sleep times and wakeup times that had nothing to do with when I was even in bed.
Check your settings. On mine I need to tell it when I am supposed to be sleeping 11 - 8 that’s how it knows to track sleep. It’s show me sleeping every night at 11 even if I’m not. Garmin instinct fyi.