While trying to find out why I wake so damned early, typically 5am, I stumbled across this site which is more informative than many others.

http://sleepdisorders.about.com/od/h...Awakenings.htm

I think I may be suffering from Advanced Sleep Phase Syndrome! So will try the tips given here:

http://www.sleephealthfoundation.org...rder-aspd.html

Maybe of use to others with MTBI 'sleep distubance'.