Once when I was working for Corporate America, my supervisor happened to catch me playing solitaire on my computer. I froze mid-mouse-click, a deer in the proverbial headlights.

After staring at me coldly for several agonizing seconds as my heart sank through the floor, he melted into playful laughter.

"I'm kidding!" he blurted out. "Oh, you should have seen your face! But listen... seriously... you really need a better game than that. Here, try this one."

He commandeered my keyboard and surfed over to a shareware site, cheerfully extolling the merits of the new game while I could do nothing but stare in silent fascination.

There isn't any punch line here. It's a true story. He was dead serious about downloading the game package for me, and he was right about it being a good one. I played it avidly for years.

But there is a lesson in his actions: understanding the all-too-human needs of your direct reports is critical to good management.

The need for occasional breaks from repetitive tasks is an inescapable fact of human nature. Everyone needs them. But all too often we fail to take them when we need to. Afraid to look inefficient or less-than-dedicated or just plain lazy, many employees choose to stay at their post--be it a computer, a loading dock, or a cash register--rather than take the breaks they need to stay fresh and productive all day long.

Worse still, many corporate policies actually demand that people make this unfortunate choice, considerably undermining the effectiveness of their own workforce.

It may seem "natural" to expect higher productivity to come with more work time, but this simplistic formula ignores a profound truth: the human mind can only do the same thing for so long before it starts to shut down.

This natural drop off in repetitive ability can manifest in a thousand different ways, from mental symptoms such as stress, irritation and loss of focus to physical symptoms such as muscle stiffness and fatigue. I personally experience the need for breaks as a rising sensation of "squidginess." When I'm no longer functioning at optimum capacity, I can feel the difference, both mentally and physically. I sum these symptoms up by saying I feel "squidgy," but the word represents an entire group of sensations all bundled together for convenience.

Mentally I start to have a harder time focusing. My mind begins to wander and I have trouble keeping track of where I am in the larger work plan. I begin to miss details and to forget one or two of the six or seven next steps that I usually keep in my head.

Physically I find that I begin to squirm and fidget at my desk. I start to notice physical discomforts--eye fatigue, muscle stiffness, and general restlessness. I start to stretch, to rub my eyes, to scratch at imaginary itches, and to shift position frequently. I find myself thinking about getting up for another cup of tea or coffee or maybe getting a snack.

What I've learned is that I don't really need a snack or a caffeine boost; these are just excuses my mind is creating to try to get me to take the break I so desperately need.

Lest anyone should think that I suffer from ADD, I don't. These symptoms don't come on quickly. They arrive after forty-five minutes to two hours of intense concentration, depending on what I'm doing. With all the recent focus on ADD, many people have lost track of the fact that a human mind which is functioning perfectly still has a limited attention span.

Studies performed on successful college students have proven that forty-five minutes is about the average limit for the amount of time that a human being can focus meaningfully on a given task. After that we're just staring into space or reading the same lines over and over again, failing to take much of anything in.

People who specialize in academic success teach students to physically get up and walk around when they start to feel their attention waning, and the same applies to corporate environments. The mind needs a break in order to regain its focus.

But recent studies on the causes of ADD have also proven this mind-body connection: children suffering from ADD who engage in certain physical exercises on a regular basis show marked improvement in general attentiveness and prolonged task focus. (See Exercising a Longer Attention Span, published in May by The Boston Globe.) And countless neurological studies have shown that the brain needs a variety of stimulation in its physical environment in order to keep generating new connections.

The implications to the corporate world are revolutionary. In short, employees need to be encouraged to take frequent breaks. People don't need to leave the building for an hour at a time, but they do need to go do something else once in a while.

In an office environment, people need to be able to get up and walk around when they need to--and the office culture needs to encourage this behavior. In retail, tasks such as working the cash registers, greeting customers, and restocking shelves should be rotated frequently, with occasional breaks away from the public eye. And the principles apply equally to physical labor. Both mind and body need frequent breaks from repetitive activity.

The idea of frequent breaks may raise some eyebrows, but it is the only way to maintain true efficiency. Trying to keep working when you're feeling "squidgy" significantly reduces your overall productivity, which will continue to deteriorate until the mind gets the break it needs.

So it turns out that my supervisor was right to encourage me in my solitaire habit. He had a strict "quality of life" policy, and it worked brilliantly. We stuck to our forty-hour work weeks, we went out of the office for lunch, we took breaks whenever we needed to, and our team managed to bring our three-year project to fruition both on time and under budget, a feat virtually unheard of in the industry.

Managers who understand the need for varied activity will encourage their team members to take plenty of breaks from the daily grind, which in turn allows them to come back fresh, keeping productivity levels high.

On the other hand, the constant interruptions of the modern workplace can lead to tremendous inefficiencies if the need for temporary relief goes unfulfilled. When a human being can't take genuine breaks, the mind will innocently manufacture fake ones in the form of unnecessary e-mails, phone calls and "consultations" with colleagues--anything to avoid the drudgery for as long as possible.

This kind of "busy-work" fails to give the mind a real rest and results in losses that have been estimated to cost the economy over half a trillion dollars every year in the United States alone. With so much at stake, companies need to make a conscious effort to understand and embrace the underlying nature of human productivity.