I would be curious to know if your son has ever experienced hypnogogic hallucinations? These are hallucinations not related to psychosis but related to the stages of sleep and is part of a REM sleep disorder.
I had them quite bad when I was a child and teenager, I saw all sorts of things, figures, monsters, people in my bedroom. I thought I was either psychotic or I was being visited by some sort of supernatural beings. I was seeing a psychologist at the age of 14 for various issues and I told her about the visions and that I only got them at night, either when just falling asleep or upon waking up. She told me about hypnogogic hallucinations and it was a great relief to me.