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While many American workers might believe that — and behave as though — they have too much work to do and too little time to get it done, there is evidence that American workers also have a lot of time to waste.

A recent study due to be published in the Journal of Applied Psychology found that in a sample of 2,100 workers across 29 different occupations more than three-quarters (78%) said they had time to kill at work. In everyone of the occupations at least 50% said they experienced idle time. The occupations surveyed included lawyers, managers, and soldiers.

The researchers calculated that those idle hours cost businesses $100 billion a year. That’s a lot of money that employers pay out for little more than a better Solitaire score, but as a percentage of total U.S. wage and salary income of around $7.2 trillion according to Yardeni Research, it pencils out to about 1.4% of income, less than 7 minutes in an eight-hour day.

The researchers tested the distinction between the leisure time that follows completion of a task and involuntary idle time. Given a stupendously boring task of copying sentences exactly, typos and all, with no internet access or telephone to use once finished, research subjects stretched out the task to fill the time they were allotted rather than finish quickly and then sit on their hands. This involuntary idle time is just as stressful to employees as being overworked according to the researchers.

The researchers called this the “deadtime” effect, a reflection of the better known “deadline” effect where employee productivity typically increases when there’s a time limit on getting the work done. Telling the research subjects they could surf the internet once the finished copying the sentences led to quicker, more accurate work and happier workers.

One of the researcher co-authors, Andrew Brodsky, said, “Managers should evaluate employees based on outcomes rather than hours spent working or seeming to work.”

Visit the Harvard Business School’s Working Knowledge website for a more on the research.