My 8 year old son said he saw a ghost that looks like a dragon with ears on the top of it's head?

It's probably that his mind is playing tricks, his imagination toying with him or possibly hallucinating via Sleep Paralysis. It happens with alot of little kids, but there's nothing to worry about.
I wasn't talking about the hallucinating part, not everyone experiences it, but it can be a possible answer to why he sees the ghost.