FWIW, my insomnia (including nightmares, anxiety, etc) has dramatically lessened since my injury, but this has taken months. It has only been in the last couple of months (months 9 and 10 post-injury) that I've started sleeping much better, although I still have some insomnia (now around 2 to 2.5/10 compared to 4 to 8/10 in the days and weeks following my injury). In my case it was just a question of time - I've never been on any meds.