Natalie: Well, if you want my recommendation and since we are on the topic of horror movies. Cannibal Holocaust is my pick. Don't want to give away too much about the movie, but it so hyper-realistic, that the film makers had to testify in the court about it being just a movie and none of the scenes actually being real. I'm not sure if you're going to find a copy of it. So just watch it online if you can.
Oh good @Suleman, the less sleep you get, the better the horror movie jejeje.
Let me then recommend one I like a lot, but it´s not quite a horror flick, it´s more like a cross of a comedy and horror. It´s a movie from Spain called "El día de la bestia" - "The Day of the Beast." You can probably find it with English subtitles; it´s worth watching :)