I'm not a real avid computer person, at the most I spend one or two hours, broken up through the day, at a keyboard. The symptoms of numbness, tingling and pain in the area you describe sound like carpal tunnel syndrome. The carpal tunnel is a narrow passageway between the bone and ligament in the wrist. The median nerve runs through this passageway. Pressure from an inflamed tendon can irritate this nerve and cause the symptoms you describe.
Symptoms often are most bothersome at night.
The cause is associated with repetitive motion but can also be caused by being overweight, a cyst on the tendon, rheumatoid arthritis, pregnancy and other conditions. Prevention requires taking frequent breaks when doing repetitive activities such as tennis, needlework,or playing piano. Especially avoid repetitive hand motions with a bent wrist. Gently warm up your hands before starting a repetitive task, and do wrist circles and stretch your fingers and wrists. You can take an anti-inflammatory medication, such as aspirin or ibuprofen, to help the inflammation.