I don't know about Carpal Tunnel, but a few years ago I was putting in some long hours and fell asleep in my chair. When I woke up both of my hands were numb like if you slept on your arm wrong.
The last two fingers of both hands STAYED NUMB. I decided to see the doctor about it. I explained the circumstances leading to the numbness. He said that having my elbows/forearms lay across the arm rests of my office chair while sleeping had pinched off my Ulnar Nerves and caused some damage.
I had to wear wrist braces so as to not continue stretching the nerves while they healed. I started using a Gel wrist pad for my mouse area. I also wore neoprene elbow braces "backwards" at bedtime to keep my arms straightened so to not be stretching the nerves.
It took almost a year for my fingers to quit going numb if my arms were bent for too long a period of time.
It was tough for me to think that just 5 hours of my arms laying DEAD WEIGHT across my arm rests could cause a year's worth of recovery time.
I now make sure that at least once every couple of hours I get up away from the keyboard and let my arms straighten out for awhile. I don't let my ELBOWS stay in contact with my arm rests either. I either hover them or shift my arms so that the underside of my forearm is on the rests.
The doctor said that the elbow and wrist joint are where the nerve is most vulnerable to damage from outside pressure. With that in mind I do my best to keep pressure off of those areas. I use to just recline back in my chair with my keyboard on my lap while resting my elbows on my arm rests to do my work. I also never used any pad on my desktop for my mouse area. I have since corrected those things.
Carpal Tunnel Syndrome Fact Sheet: National Institute of Neurological Disorders and Stroke (NINDS)
MedlinePlus Medical Encyclopedia: Ulnar nerve dysfunction
I also use the OLDER Windows Natural Keyboard. The keys are separated and more ergonomically correct. They quit making them and it took me about a year of searching on fleabay to get a good stock pile of working keyboards. (The Elite, Pro, and newer versions are just too cramped for me.)
http://en.wikipedia.org/wiki/Microsoft_Natural_keyboard
Sincerely,
MT