Sleeping Problem!!!!!!

Habit is really a scary thing.... Once you are used to something, someone or a situation..... you are dead.... You'll be tied to it... Its so hard to change one's habit... My case now is...... I CAN"T SLEEP THE TIME I WANT TO SLEEP!!!!!! I tend to sleep quite late before I started my "changing" plan... now I'm trying to sleep early (as it is part of the healthy lifestyle) but I can't.... haiz.... Even though I made myself to be tired so that I can sleep early but my eyes just won't close...until the time I used to sleep before.... It seems like they got their own will...What to do??? Anyone got any idea??? TEACH ME!!!!!!