The Nightmare Affair by Mindee Arnett
Sixteen-year-old Dusty Everhart breaks into houses late at night, but not because she's a criminal. No, she's a Nightmare. Literally. Being the only Nightmare at Arkwell Academy, a boarding school for magickind, and living in the shadow of her mother's infamy, is hard enough. But when Dusty sneaks into Eli Booker's house, things get a whole lot more complicated. He's hot, which means sitting on his chest and invading his dreams couldn't get much more embarrassing. But it does. Eli is dreaming of a murder. Then Eli's dream comes true. Now Dusty has to follow the clues - both within Eli's dreams and out of them - to stop the killer before more people turn up dead. And before the killer learns what she's up to and marks her as the next target.