Imagine this: you're a power lifter, one of those big dudes at the Olympics that lifts very big things. You lift the big heavy thing, put it down. Crowd cheers. Do you immediately lift it again? Or do you rest for a few minutes?
You rest—if you want to be able to replenish the energy-boosting organic compounds in your muscles. So why not do the same thing in your workday?
"There is a reason why power lifters take five to six minutes to rest between sets, the energetic system takes that long to replenish properly," says 4-Hour Body author Tim Ferriss. "You have to have an awareness of the fact that just because you're not moving your body doesn't mean that you aren't working."
In other words, that mental work, like the kind you do toiling away at a desk all day, is in fact physical work, since your brain is physically firing neurotransmitters around as you make a thousand small decisions a day. And the brain gets exhausted—which leads to wandering attention and bad decisions.
Daniel Goleman, the psychologist who popularized the notion of "emotional intelligence," uses the Iditarod, that ridiculously epic dogsledding race, as an example:
The Iditarod dog sled race covers 1,100 miles of Arctic ice and takes more than a week. The standard strategy for mushers had been to run twelve hours at a stretch, then rest for twelve. That all changed because of Susan Butcher, a veterinarian’s assistant keenly aware of the biological limits of her dogs. She trained them to run in four-to-six hour spurts, and then rest for the same length of time, racing at that rhythm both night and day. She and her dogs won the race four times.
Even badass Alaskan huskies work best in bursts. This has been found in other studies of top performers: Anders Ericcson at the University of Florida has found that master violinists, chess players, and athletes practice deliberately for about four hours a day and then rest—and that is enough to become world class. And to not rest leads to worse performance.
"Top performance requires full focus, and sustaining focused attention consumes energy—more technically, your brain exhausts its fuel, glucose," Goleman says. "Without rest, our brains grow more depleted. The signs of a brain running on empty include, for instance, distractedness, irritability, fatigue, and finding yourself checking Facebook when you should be doing your work."
So if you're going to add a break to your day, it needs to be an actual lack of stimulation. Staring at your inbox isn't rest, neither is BuzzFeed. What we need to do is learn how to actually relax—so neurons can get nourished, allowing us to spend our attention on getting the best work done. Which probably doesn't involve checking Facebook.