This review [1] compared the results of 6 sleep trackers with sleeping laboratorium measurements. It concludes that the trackers were able to track the lenght o

This review [1] compared the results of 6 sleep trackers with sleeping laboratorium measurements. It concludes that the trackers were able to track the lenght of the sleep quite accurately. OTOH all trackers displayed large errors in measuring the type of sleep e.g. deep sleep, light sleep & REM. They conclude that sleep trackers are good for creating awareness of your sleepquota. [1] https://www.heise.de/ct/ausgabe/2015-25-Schlaftracker-vs-Schlaflabor-2910003.html https://www.heise.de/ct/ausgabe/2015-25-Schlaftracker-vs-Sch...