This was my problem Sunday morning. I say morning because I didn't get off of work until 3am. But I had that same effect. Lying in many different positions, trying different stimuli or lack of stimuli and whenever I actually fell asleep, I always thought "Alright! I'm asleep!" and wake up. Get mad at myself for waking me up and repeat the rest of the 6 hours I tried to sleep. Probably had 2 hours of actual sleep.