Dr. Matthew Edlund, author of The Power of Rest: Why Sleep Alone is Not Enough
Even though rest is how your body rebuilds, there's virtually no time or space to do it at work. We really do need rest, but much of the population is sleep-deprived. And, being severely rest-deprived fouls up mood, performance and health. If you overdo it, you'll feel overwhelmed. If you allow rest-deprivation to happen over and over, you'll become exhausted.
Taking breaks is often the only way to prevent the error that being tired and ill-rested can cause, yet it's hard for most workers to rest -- and still be efficient -- at work. You have to take the right kinds of breaks.