Yeah I've had it twice but really only remember the first one. So I fell asleep shortly after finishing writing an essay. I was very tired and fell asleep pretty fast. An important detail about how I fell asleep was that I fell asleep on my back, with my arms and legs straight. This wasn't a regular thing by any means but I didn't think much of it. At the time, before I drifted into my dream, I remember feeling like my legs started to disappear. The Dream: So, this was a long time ago. I don't remember that many details but I'll give it a go. I was walking my dog at night. My dad usually does this but he wasn't home yet so I decided to take her out. I remember there being a "fog" type substance that only allowed me to see about 20 ft ahead or behind me. As I began walking home. The thought slipped into my head that, "maybe something can see me through this fog". It was a subtle thought but one that freaked me out and made me head home quickly. As I approached my front door I remember feeling very anxious. Like I had to get inside quickly or someone or something would get me. My mom finally opened the door and a rushed down to my room (my room is in the furnished basement of my house). However, I didn't pay any attention to my mother at all. Now that I think about it. She didn't look like my mother at all. It was around this point in my sleep that I heard a terrible noise outside my door. I slowly began regaining conscious and I heard a subtle but discreat knock. Followed by another one. I closed my eyes and hoped I was still dreaming. When my eyes were shut, my door creaked open. I opened my eyes again. Still lying on my back. I could make out a tall, dark shadowy figure standing at the foot of my bed. I just stared at him for minutes. He slowly cocked his head and started to lean over me. Pulling out a knife from his coat. I wanted so badly to turn on my lamp next to me. It only occured to me that I could move or speak at all while this was going on. I don't remember how it ended but I know I fell back asleep. This 4 minutes was easily the scariest moment of my life.