Hi Nick,
Same boat here. Since the injury, it's like my brain has forgotten how to sleep. I can fall asleeep and alsdo wake up several time throughout the night.

I have been on nortriptyline , also tried Nyquil, herbal teas, and currently trying melatonin. So far it helps me fall asleep faster, but doesn't help me stay asleep. Even the Beta-Blocker I am on for Migraines, makes me very drowsy....but I can't seem to stay asleep.

I am not a caffeine person so that is not an issue, I have cut out Tv before bed, and still can't seem to sleep well. The doc is aware, but doesn't seemed overly concerned....so I can relate!

Someone mentioned hyper-arousal sleep disorder after injury? Check out this page in the tbi guide: http://www.tbiguide.com/sleepdisorders.html

Let us know if you find something that works for you.