How do I fix my sleeping body clock?

alright so i've been frustrated. every night i've been going to bed at like 3:30 and stuff. but the past two nights ive been getting to bed at like 2. ive been waking up at like 12 or 1 and I dont like it. Ive even set my alarm to get up early so I can fix this, but i've just been sooo tired. gaaah idk what to do! I hate sleeping the day away! help!