I've never had accelerated heart rate when sitting in front of computer monitor.

Several years ago I did go through a few weeks, where occasionally at night I had my heart racing very briefly, but I was under alot of work stress at the beginning at that time for a new job that some clear project deadlines. It was definitely stress-related since I lost some sleep at that time also.

Then it went away after I became familiar with the organization's needs, expectations and took control of certain situations at work where I could.

Need to step and think about some underlying stress?

By the way, I've had a physical checkup by doctor three times since that incident. No heart problems at all. Most recent check was a few weeks ago for a health research project.

How old is your computer monitor anyway?