TBI and Nightmares

I had a good day yesterday. Slept well and managed enough energy to go outside before noon. I went chicken egg hunting and put together a nice little grill. It took about two hours giving me a little satisfaction by accomplishing a lengthy task. I got the mail and took a walk. It doesn't sound like it but it was a good early afternoon. Encouraged, I got the wheelbarrow and got a load of the old wood from across the street. Stacked, I headed back to move some cinder blocks. One load of four was enough. Out of steam, I hung with the chickens and watched the birds come and go from the feeder. Done for the day.
It seems a little silly on just how little work it really was. By bedtime my body was sore and I was tired. I read a little and settled in. It sometimes takes an hour to fall asleep regardless of how tired I am.
Let the games begin.
Why do so many of us have nightmares? Experiencing a brain injury, why doesn't it produce dreams of beautiful islands and fun times? It's not nightmares about my injury. After nine, ten or twelve hours of sleep with a nightmare thrown in the new day feels like a bog. Slow, foggy and exhausted start. I woke up very sore and was reminded once again that I know about everything there is about physical therapy and strengthening that would help immensely. That would mean practice, commitment and a schedule. Can you think of anything that's more difficult?
Oh. The nightmares. Ain't got a clue. Hate them. Survivable but effectively disheartening because there is nobody I can give a hard time to for being rude.
See. I am being nice.....