Thanks everybody for your suggestions but I think I finally found the solution!
Yesterday on AppStore I've found a brand new app called Alarm Clock Extreme. I gave it a try and today I woke up at 6a.m. as I planned!
It's marvelous! To turn off the alarm you have to scan a Qr Code. I put mine in bathroom so when I get up I was already in bathroom washing my face with cold water :P
You can find this app
here
I think it's the solution for oversleeping
