I thought of another one as well. I always shared a bunk bed with a sibling right up until we moved to a big old house when I was 11. Sometimes I would get up in the night to pee. Actually now that I think of it sometimes I wouldn't get out of bed to pee just because it was so scary. I was a bedwetter
In the dim light that would be available through the bedroom window at night my brother's face would be a blurred mass of shadows. And I would see his face transform into a monster right before my eyes. Wolfman, Frankenstein, Count Dracula - or quite often alien, bizarre faces that made no sense except that I could see them very clearly. You name a distressing shape of any sort of fearful beast and I would see his face actually crawl into that configuration. The closer I peered up at him in the dark, the worse the details would be. Sometimes I could actually see a shifting of eyes or a mouth quiver - freaked the sh*t out of me. I draw closer and my brother's face would reappear. Draw back, and monster would drift back, reforming over his features and appear as solid as ever. I tell you, it was hard to get close enough to see my brother again, and very hard to climb back into the bottom bunk. I would lie in bed, knowing that above me was this transformed monster that was supposed to be my brother but wasn't, and it was waiting for me to fall asleep before doing whatever monsters do to little kids when they fall asleep. The tricks that low-level light play on someone with a vivid imagination like mine can sometimes be a real bitch.