It was probably just a dream. I mean, nightmare.
In Chris Priestley’s Freeze for Barrington Stoke, he tells the story of four teenagers (are they even that? Perhaps Y7, Y8?) who have had bad dreams the night before. Except they can’t remember what they were about. Maybe they had the same dream?

At school a supply teacher has come to talk about writing creepy stories. And suddenly the ideas seem to just flow, and all four of them agree to talk to the class about their particular, creepy ideas. And what about the strange girl who turns up late?
Maya, the main character, seems to really freak out during each reading, but no one else does.
Scary snowmen, scary ice, scary corpses from the nearby cemetery, and … You get the idea.
And then the four finally realise they did have the same bad dream, and they need to wake up! And, yeah…
(Very Scary Illustrations by Chris.)