Hey, it could be worse, you could have my rotating sleep cycle. I went to bed at... er... *looks at notes* 9 AM today and got up at, uh... 4 PM. It is 5:30 here now and I just had "breakfast", in sarcastic quotes. Tomorrow I'll do those except one hour later. And so on...
But anyway... might sound odd, but have you tried asking a doctor about this? Sleep stuff can sometimes be caused by, or at least influenced by, medical stuff (like chemicals in the brain or whatever) so maybe a doctor might have a bit of advice to help you change it.
I can make one suggestion though: Dont try to change it all at once. Ease into it. Sudden sleep cycle changes can be a shock to the system, and that aint gonna help anyone.