QUESTION! Please answer it. I had 3 unsuccessful attempts using tehcniques described in the book. (I've read all of it). I am pro at waking up, not moving and not opening my eyes. But so far, I haven't even reached sp and I am wondering: why?

So, here goes the question:

Since I don't use an alarm clock and wake up myself I noticed that time I wake up is always the same, like 3 hours after going to sleep. In all of my attempts I haven't reached even SP. May the cause of this be only 3 hours of sleep I get, before trying all of these tchniques?