People with PTSD may also view going to sleep as a loss of control. The lack of awareness and control that comes with sleeping may be frightening for a person with PTSD, thereby further intensifying arousal and interfering with sleep. Finally, the sleep problems connected with PTSD may lead to a problematic cycle. Because of a lack of sleep during the night, a person may sleep more during the day, leading to greater difficulties falling asleep at night. (Source- about.com)
But you already knew that, didn't you?
I actually don't have a problem sleeping during the day. I am generally active enough, have a busy enough schedule, and drink enough coffee that I stay awake during the day. It's not that I can't sleep at night, it's that I don't want to.
I don't often have dreams if I sleep less than six or so hours a night, because I am not asleep long enough that my mind can really dream. I know, mostly subconsciously and a little consciously, that if I stay up too late I'll never get to REM sleep. So I disassociate-- my mind shuts down, stops paying attention to anything that's not going to kill me-- and I find whatever excuses I can to not go to bed. My internal systems are very good at ignoring what time it is.
When I do dream, my dreams are often disturbing representations of events that haven't actually happened-- you'd think that I would dream specifically about my childhood trauma, but I don't. Sometimes I dream that I'm back in the service again. Sometimes I dream and don't remember anything, but still wake up feeling very disturbed and out of sorts. And, sometimes, my mind makes up new trauma for me to live out in my dreams. Those are the worst, I think-- it's bad enough that I have the original versions to deal with, now I have sequels.
I'm going to try to treat the sequels as real from now on-- apply what I've learned about dealing with the PTSD from the original events, to the new (, made up, in my dreams only) events. And I'm going to continue to remind myself, as I do every morning after I've had these f'ed up dreams, that I'm still here and whatever happened in the dream stayed there.