Follow-Up:
I have a much milder version of what you have, and it's known as sleep paralysis, as another writer has mentioned. It began for me about 30 years ago, when I was 20, during a period when I was working nights. That was a very difficult schedule to adjust to, as I never got any really good sleep. After quitting that job, I continued to have occasional episodes, but they have gradually diminished over the years. I have them rarely now, usually at tims when I am especially exhausted. When they first started, they were accompanied by very vivid hallucinations or dreams. Those went away, but what does remain is that feeling of threat, dread and panic. I think it's a normal response to not being able to move or make a noise. When it happens now, I try to relax as much as possible and know that it will pass in a short time. I realize that your episodes are much more frequent and intense, so my solutions may not be enough for you. I think the best thing to do is consult a doctor, maybe a neurologist. You can tell if you've found the right doctor if he immediately knows what you're talking about. Don't waste your time with a doctor who seems unfamiliar with this disorder. This response is two years after you posted your question, and I hope you have found answers in that time that has helped your son and your own peace of mind. I wouldn't have written, except that there has been so much harmful nonsense written to you.