I slept on the floor of my parents bedroom until an absurd age because I thought my room was haunted. The event that finally broke me was one night I was sleeping on their floor (because company protects you from ghosts obviously) when I heard the noise of their bedroom door opening. I open my eyes to see a dozen or so pairs of feet entering the room silently, as nit to wake anyone else up. I tried to sit up to see what was going on, only to find myself unable to move. I looked above me and there was a figure, clad in a black suit holding me down.
That alone would have scared most people but what paralyzed m with fear was his face. Or rather, a lack of face. It was blank, as if someone had stole it. All that was left was a mouth, a ragged oval that sucked at the air and stole my breath. I glanced down at the figures standing at my feet to see that they too had no faces. They knelt down and held me to the floor as one put on a pair of gloves. They were going to take my face. They had theirs stolen and wanted mine to replace it. I would become one of them.
I saw my mother's hand, hanging over the bed, just out of reach. I tried to move, to wake her. Maybe if I got to her in time, she and my father could escape. They could take my sister and get out before the faceless men came for them. But the men held me down as the gloved man placed a knife to my temple. He made a small incision and slipped his finger inside, pulling at the skin and tearing my face away. I struggled to warn my mother but I couldn't move, couldn't breathe, vision fading as my face was torn away.
I awoke to find my parents standing over me, lights on, dog going bonkers and my sister standing in the doorway. Apparently, I had started shrieking in my sleep and they couldn't wake me, before my heart finally gave out. My mother, who was trained in CPR, had to revive me as my heart had stopped beating out of sheer terror. After this incident, we went to the hospital where it was discovered that I suffer from pretty severe sleep paralysis. That, coupled with a birth defect that makes my heart weak, had nearly killed me.
Don't believe what they tell you kids, you dreams can hurt you.
Tl;dr Sleep paralysis made me think my house was haunted for most of my young life when finally a very severe episode managed to stop my (already weakened) heart.