It must have taken some getting used to, if you were a staffer in the socially conservative early 1960s. Lyndon Baines Johnson, 36th president of the United States and leader of the free world, routinely closed the door to his office in the midafternoon and put on his pajamas. He then proceeded to take a 30-minute nap. Rising refreshed, he would then resume his role as commander in chief. Such presidential behavior might seem downright weird. But if you asked a sleep researcher like William Dement, his response might surprise you: It was LBJ who was acting normally. The rest of us, who refuse to bring our pajamas to work, are the abnormal ones.

LBJ was responding to something experienced by nearly everyone on the planet. It goes by many names — the midday yawn, the post-lunch dip, the afternoon “sleepies.” We’ll call it the nap zone, a period of time in the midafternoon when we experience transient sleepiness. It can be nearly impossible to get anything done during this time, and if you attempt to push through, which is what most of us do, you can spend much of your afternoon fighting a gnawing tiredness. It’s a fight because the brain really wants to take a nap and doesn’t care what its owner is doing. The concept of “siesta,” institutionalized in many other cultures, may have come as an explicit reaction to the nap zone.

At first, scientists didn’t believe the nap zone existed except as an artifact of sleep deprivation. That has changed. We now know that some people feel it more intensely than others. We know it is not related to a big lunch (although a big lunch, especially one loaded with carbs, can greatly increase its intensity). We also know that when you chart the process S curve and process C curve, you can see that they flatline in the same place — in the afternoon. The biochemical battle reaches a climactic stalemate. An equal tension now exists between the two drives, which extracts a great deal of energy to maintain. Some researchers, though not all, think this equanimity in tension drives the need to nap. Some think that a long sleep at night and a short midday nap represent default human sleep behavior, that it is part of our evolutionary history.

Regardless of the cause, the nap zone matters, because our brains don’t work as well during it. If you are a public speaker, you already know it is darn near fatal to give a talk in the midafternoon. The nap zone also is literally fatal: More traffic accidents occur during it than at any other time of the day.

If you embrace the need to nap rather than pushing through, as LBJ found, your brain will work better afterward. One NASA study showed that a 26-minute nap reduced a flight crew’s lapses in awareness by 34 percent, compared to a control group who didn’t nap. Nappers also saw a 16 percent improvement in reaction times. And their performance stayed consistent throughout the day rather than dropping off at the end of a flight or at night. (The flight crew was given a 40-minute break, it took about six minutes for people to fall asleep, and the average nap lasted 26 minutes.) Another study showed that a 45-minute nap produces a similar boost in cognitive performance, a boost lasting more than six hours. Also, napping for 30 minutes before pulling an all-nighter keeps your mind sharper in the wee hours.

Listen to an excerpt of the sleep chapter from John Medina’s Brain Rules audiobook (via

Respect the nap zone

Don’t schedule meetings or classes during the time when the process C and process S curves are flatlined. Don’t give high-demand presentations or take critical exams anywhere near the collision of these two curves. Can you actually get a nap? That’s often easier said than done. College students can perhaps get back to their dorm rooms. Stay-at-home parents might be able to sleep when baby does. Some employees sneak out to their cars.

Even better would be if schools and businesses deliberately planned downshifts during the nap zone. Naps would be accorded the same deference that businesses reluctantly treat lunch, or even potty breaks: a necessary nod to an employee’s biological needs. Companies could create a designated space for employees to take one half-hour nap each workday. The advantage would be straightforward. People hired for their intellectual strength would be allowed to keep that strength in tip-top shape. “What other management strategy will improve people’s performance 34 percent in just 26 minutes?” said Mark Rosekind, the NASA scientist who conducted that eye-opening research on naps and pilot performance.

This post was adapted from Brain Rules (Updated and Expanded): 12 Principles for Surviving and Thriving at Work, Home, and School.

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