This has happend always when i try to enter sp/wbtb

I went to sleep around 8pm, woke up at 3:40, Went to the bathroom and then went back to bed, i started to relax all my muscles and tried to stay conscious. Then i entered sp, i felt all the vibrations, and i started to see a face, but then slowly the sp started to loose its power, and then eventually i was wide awake and not in a dream. This has always happend to me when i try to enter sp, Was it because i fell asleep while i was relaxing and i woke up in sp?