Carpal tunnel syndrome is caused by damage to the median nerve, which passes through a "tunnel" of bones and ligaments at the base of the hand. This happens when repeated motions, such as typing, causes the tunnel to swell, compressing the nerve. This can cause shooting pains, radiating up the arm. It's part of a family of ailments called repetitive stress injuries caused when body parts are used regularly beyond their capacity.
The delicate wrist can be protected against carpal tunnel by exercise. It's been observed that carpal tunnel was rarer in the days of manual typewriters, which required far greater force to operate than computer keyboards. This slowed down the rate of typing. Also manual typewriters, for those old enough to remember them, required frequent breaks from typing for carriage returns, inserting paper and for corrections.
Carpal tunnel symptoms can be reduced by splinting the wrist at night, according to a study published in the January 2005 issue of the Archives of Physical Medicine and Rehabilitation. The study was performed by researchers at the University of Michigan Health System and the VA Ann Arbor Healthcare System.