It is supposed to but it doesn't work well at all. I turn on continuous heart rate tracking before bed each night and it only tracked REM sleep once in the 5 nights I have had it and even then it only tracked it for 2 hours before switching to the motionless/light/restless stats. Any suggestions on how to fix this?
It was only giving me the restless/motionless/ light measurements but after the update a couple of days ago I have gotten 2 nights in a row with full sleep tracking. Maybe there was some type of bug that was causing it to not get good readings.