Sleep Stages not working on Apple Watch series 10? How do I get it to work.

I've set it all up as instructed, and I am getting length of time I slept but no sleep stages data. I've tried everything including restarting both my phone and watch. My watch is only 2 days old. I'm extremely disappointed because I ditched my Fitbit and bought this Apple Watch for this very reason. Is there some special, obscure trick I'm missing? Or did I just buy a dud?