next time shes sleeping do the same thing, she'll get the message
Plenty of options there. Cutting their power is one, but that'll end up with charges. I prefer the idea of knocking on their door and asking politely........once.
After they fail to change, quietly set up your stereo to face their house/ flat/ etc and set the timer (use one that has multiple on/ off options) to go on for 10 mins at 0545, 0610, 0630, 0700. Then call a friend and sleep over at their place. You get a good night sleep and they get a **** morning when they're hung over and tired.
If that fails, break in to their place, throw grass seeds on their carpet and water heavily.
Train her. I had a neighbor who would play rave music very loudly. So when he did that, I would put my speakers against our shared wall and put my Tool "Anima" CD on and blast it. He would turn his off and so would I. He wasn't a quick learner, but he got it eventually