I don't know how much it would help, but are you seeing a therapist about the nightmares? Maybe they could help you get to the bottom of what's causing them and, in the process, also help you find ways to cope. In the meantime, have you tried reading before bed, or meditating? You could also put on a sound machine to help you sleep. But those are my suggestions, at least -- it's really different for everyone what helps them sleep.

I hope this helps, at least.