Best AnswerI guess that first "no" was to not getting any heart rate readings. That is the basic thing that zone minutes and sleep score and stages are based on. Although I would think you might still get some sleep detected based just on being still, without getting sleep stages or score. I don't know what would make heart rate tracking stop. you could try a restart - that should never hurt.
If you get a red X, keep holding in the side button until you get the Fitbit logo even if it takes much longer than the 10 seconds.
Best Answer