Oddly, this came up briefly with my T today. Mostly because I'd gotten lots of sleep last night but don't generally sleep that well, and it's reflected by my FitBit tracking. (T said he doesn't wear his at night, and the app keeps telling him that he should.) I tend to get lots of light sleep, a fair amount of REM sleep, and not much deep sleep. And have lots of awake periods, but I know I'm actually awake during them (in fact, sometimes it thinks I'm asleep when I'm actually awake...)

One thing that could help you is that it says "awake/restless," so it could just be that you're moving around a lot in your sleep (possibly while dreaming?), but not actually awake. Mine does not track heart rate during sleep (FitBit Charge 2, I think?)

I know there are some newer, fancier models of FitBit, so maybe check into those?

Or, if you're concerned that, say, you're getting up and doing things, maybe you could set something up to record yourself while you're asleep? Just audio might be sufficient.