Waking Up Unintentionally

For some reason for about a week now, I've been waking up at 5-6:00 in the morning... Because of this when I try to go back to sleep I usually have an unintentional failed WILD or I just can't go back to sleep... My normal scheduled sleep pattern is 11:30-7:30 on a school day. And this waking up is really annoying because strangely at about 1-3:00 in the afternoon everyday I get VERY tired and start falling asleep which leads to more failed stuff... What's going on and what can I do about it?

EDIT: I can also remember this happening to me a few years ago (As well as my friend) except the time was different and my sleep schedule was different.

Had this too, woke up everynight at 5:00 - 5:15.
Still happens to me sometimes but what somehow solved it for me was sleeping at 11:00 so I could sleep 7 hours instead of the usual 6 hours. I'm afraid that doesn't really help your situation.