I know a lot of people observe this. Including myself. For some weeks now I sleep very few hours and when come back after school I go for a little sleep. The thing is tht tht I must leave for training @ 6 PM. And I have never overslept, meaning I wake up from a deep sleep exactly 10min before 6!? How can my body tell when it is time to wake up for me. I have did it sereral times when I had no alarm clock at the moment, before going to sleep I just say in my thoughts for several times tht I will wakr up in time to leave for school. I have done this when going to sleep @ 11PM and 3AM and results are the same! I wake up in time. Several times I have woken up at +- 15min the time I ordered for myself to wake up. How does our brain know the right time? During sleep! I know tht it is active during sleep, but not all times, it shuts down several times a night - what we call "deep" sleep. well not completely shuts down, but stops thinking. I duno, just thought it to be interesting and maybe you know where the timer is storedPlease Register or Log in to view the hidden image! Cheers!