Have you any idea what his nightmares are all about?

Does he sleep thru the night when he's with you?

The nightmares are the first thing I would want to address...and in doing so not pushing the issue of where he sleeps. If he sleeps better with you, then let it be for the time being. I know it's a sacrifice, but it will be only temporary though it seems like an eternity right now. It seems like it would be very self-defeating to force him to sleep in his room with these other issues he's having. You probably need to take some baby steps in working towards the end result of a peaceful sleeper in his own room. Be careful not to label him a terrible sleeper. He's got some issues right now, but they don't have to be permanent.

I had sleep problems as a child...no, I still have sleep problems. But as a child, I remember feeling very insecure because I was alone and I had poor eyesight so everything was scarier to me. Plus there were real people issues that brought more insecurity into my life that exacerbated my sleep problems. I often would lie awake in fear from bedtime (abt 9pm) until I feel asleep from exhaustion about midnight or 1am. Then there was that terrible night while at my older friend's house I watched "part" of The Shining. I had nightmares for 3 yrs!

So, I feel your son's pain....and yours too.

Is he really haveing nightmares or has he learned that screaming "nightmare" get him into mommys bed?  That would be the first thing I'd figure out.

My son had nightmares, and we cut out food (sugery food mostly) 2 hours before bed.  This helped great deal.  He is 12 now and will turn down treats offered before bed, just to make sure he is not going to have bad dreams.'

Sleeping problems are hard to break,  you have to be loving but firm about it and keep it up.  If you think even for a min you will give in to his scream and crying...then dont even bother to start. It's heart breaking I know!

 You'll have to pick a parenting tool you want to try, be it suppernanny's bedtime, or a book you like, We did "solve your childs sleep problems" with our first...stuck to it and it worked with in a week.

   Oh and the best thing we did with our 4 kids was keep them in thier crib until they were 3, that helps a-lot! If he is not still in one, Go back to a crib if you can.

Best of luck.

Michelle