Very Difficult to wake up early in the morning

I am a damn and deep sleeper , if i started sleeping no one can wake me up. So i leave this as  an action item to my father, he used to call me every morning and make sure  i woke up. This  is a daily routine job of him . Today morning i was in a big dream, that time  i got a wake up call from my father . After answering the call, i asked him why he called me on a holiday, he said that today was Friday, not Saturday, then only i realized it was a working day.
        I need to get rid of this activity of my dad calls me on every  morning to wake up me. I tried many , but nothing actually workouts. Some day before sleeping, i will say to myself need to wake up @ -- : .. am, but some time i  woke up at the proper time, that i prayed last night, but most of the times, it was not working out.

Y waking up early is so difficult ?