What do i do if I can't sleep and I have to wake up in a few hours?

Guys, I'm dying here! Last night I went to sleep at midnight. I had to wake up at 600AM, which would have been on the brink of just enough sleep. Then, I woke up at 400AM and couldn't go back to sleep, it wasn't that I had to go to the bathroom, I tried that, and it wasn't loud or anything in the neighborhood. I had to wake up at 600AM to go to an appointment before work, and it was horrible because I knew I had to wake up, and I'm looking at the clock like-if I fall asleep now, I'll oversleep, since I only had an hour left by then. I'm afraid if this happens again, I won't know what to do...like duh go to sleep even earlier might be a quick answer, but what do you think?