I've found the app recommended by wirecutter https://thewirecutter.com/reviews/best-sleep-tracking-app/ https://thewirecutter.com/reviews/best-sleep-tracking-a

I've found the app recommended by wirecutter https://thewirecutter.com/reviews/best-sleep-tracking-app/ https://thewirecutter.com/reviews/best-sleep-tracking-app/ Quite accurate, at least for time to sleep, and time asleep. I think the REM, NREM etc is mostly noise, if you are getting 8+ hours a night every night (super hard to do!) the quality of sleep should be fine. The best thing is to set a "go to bed" alarm, for night owls like me its so easy to say you go to bed "around 10" when in fact it can be much later.