Fitbit does not attempt to track sleep stages w/o HR monitoring; it's just Awake, Restless or Asleep. Yes with nothing but accelerometer data stillness can be m

Fitbit does not attempt to track sleep stages w/o HR monitoring; it's just Awake, Restless or Asleep. Yes with nothing but accelerometer data stillness can be mistaken for Asleep, but I think you're misremembering when you say "deep sleep".