I tested the Sleeptracker few nights and I'm really able to learn my own sleep cycles. I found that the first 2 to 3 hours I slept better maybe it was my stage 3 "Delta Sleep". For the other period, the DATA REVIEW recorded quite often, roughly 10 to 20 minutes once. For the first day testing, I can't wake up by the Sleeptracker, maybe my setup was not correct. During the days of the testing, I mostly woke up before the actual alarm time that I have set and I really can wake up easily without any reluctant feeling although I did not have to go to work or school.