I have no idea why you want to do it, it's absolutely terrible! I'm 13 and you become terrified because you sense a dark presence around you. Anyways, if you really want to scare yourself, then here are a few ways. Make a really irregular sleep pattern schedule. For example, during the day, sleep for like 3-4 hours as a nap. Then, sleep for a little during the night (like 3-5 hours). If you keep this sleep schedule up, you will start to experience sleep paralysis. So um... Good luck?