How?
A growing body of research has established that we do our best at any given task for only a limited amount of time, energy, or attention, then our performance drops off, our attention wanders, and our motivation evaporates.2
But resting after a depleting activity eliminates the effects of fatigue.3
When you drop out of task-focused attention and into neutral, your “resting” brain is not doing nothing—far from it. In fact, there’s very little difference in the amount of energy used by your brain when you’re in the middle of doing your taxes and when you’re standing at the counter, mind wandering while you wait to be handed your takeout order.4
Running in the background of your awareness is what neuroscientists call the “default mode network,” a collection of linked brain areas that function as a kind of low-grade dreaming when your attention is not focused on a task.5 When your mind is “wandering,” your default mode network is online. It assesses your present state and it plans for the future, a little like a chess-playing computer, rapidly scanning the board and running simulations to see what would happen if you made a particular move. And it’s doing it without active intervention from you.
Life coach extraordinaire Martha Beck figured this out without the science. When her team is struggling at the office, the solution is to stop working, turn off their computers, and go play or rest. Where so many others would “dig in,” set up a command central and not stop until a solution was found, she asks her team to take a break.
“It works every time,” Beck told Bloomberg Businessweek.6 “I don’t know why, but it does, so I guess I don’t really need to know.”
The default mode network is why. (Also, some team members are probably completing their stress response cycles during the breaks, which allows them to be more creative and curious.)
Research on this network is very new and lots of questions remain unanswered about exactly what it does and how it works, but it’s increasingly clear that the more balanced the linkages between the different domains of the default mode network are, and the more fluidly a person can toggle from default to attentive, the more creative, socially skilled, and happy a person is likely to be.7
Mental rest is not idleness; it is the time necessary for your brain to process the world.8 So, for example, while writing this book, Emily would write for an hour or two, then go put in a load of laundry or dishes. Write for another hour or two and then empty the dishwasher or rotate the laundry. In the same way the laundry was running while Emily wrote, her default mode was running while she folded towels. The default mode network didn’t need her help—in fact, it needed her to stop writing, so that it could work on the puzzle she had given it, without her looking over its shoulder. Then when she came back to work, her default mode would hand her new insight. If she had stayed chained to her desk, insisting that she couldn’t move until she had reached a certain word count, she may have written more words, but they would have been lower-quality words.
And sometimes Emily wasn’t folding laundry like a good little housewife, she was playing a game on her phone, and that was fine, too, because what her brain needed was any low-demand task that allowed her default mode to come online.
Walking away from a task or a problem doesn’t mean you’re “quitting” or giving up. It means you’re recruiting all your brain’s processes for a particular task—including the capabilities that don’t involve your effortful attention.
Not everyone slips comfortably into default mode. This has been tested empirically in a series of fairly hilarious studies:9
Researchers first asked participants to experience a mild electrical shock, along with various other pleasant or unpleasant stimuli.
“Would you pay five dollars never to have to feel that shock again?” the researchers asked.
“Hellz yes,” the participant would say.
Then they took the participant into a quiet room that contained the electric shock device, and left them alone, with instructions to “entertain themselves with their thoughts” for fifteen minutes.
“The shock machine is here. You can touch it or not, it’s up to you,” they told the participant who had just said they’d pay money not to feel that shock again.
In fact, a quarter of the women and two-thirds of the men gave themselves an electric shock rather than simply sit there and “just think.” On average, they self-administered one or two shocks over the fifteen minutes.
Instead of being in default mode, research suggests these self-zapping participants were bored. Boredom is the discomfort you experience when your brain is in active-attention mode, but can’t latch on to anything to attend to.10 They were zapping themselves in desperation for something, anything, to pay attention to, even if it was uncomfortable.
Fortunately, there is active rest.
Active Rest
Everybody knows a muscle that isn’t used will atrophy. We all know a muscle that is worked constantly, without rest, will grow fatigued and eventually fail in exhaustion. And we all know a muscle that gets worked and rested and worked and rested will grow stronger.
But suppose you break your right leg, and while it’s healing in a cast, you exercise your left leg. The signal from the left leg travels up the spine and crosses from one side to the other, sparking growth in the right leg—not as much as in the left, but enough to prevent some of the atrophy of disuse.11 This is the original meaning of “cross-training”—literally, training across the spine.
But look, it’s even bigger than that: When you work your muscles—especially your biggest muscles—you strengthen not just the muscles you’re using but also your lungs and liver and brain. Exercising one part of you strengthens all of you; exercising the strongest parts of you strengthens the rest of you most efficiently. The same goes for cognitive, emotional, and social effort.
This is active rest: working one gear while resting the others.
So for example, sometimes the “rest” Emily’s brain needed was not a low-demand task like laundry or YouTube, but a different kind of writing. Result: She wrote a novel at the same time as writing this book. Amelia worked full-time as a professor of music and conducted a children’s choir, while writing the book. Most women are at least this productive—they rest certain gears while they work others, and this “active rest” makes us better at all the things we do.
People vary, including in what rest looks like for them.
But one universal need is sleep.
Why Sleep?
Sleep is really strange. How can it make sense that we lay our bodies down and lose awareness of the outside world for hours at a time, while who knows what lions and hippos and other threats may be lurking? During certain phases of sleep, our motor functioning is locked off, so that our bodies can’t respond to our brain’s activation. There we lie, in the dark, paralyzed, unresponsive, and limp to the bone, as our eyeballs ticktock behind our closed lids and our attention is funneled away from the outside world toward an intense, multisensory hallucination—a dream—that feels both real and urgent in the moment but will be forgotten by the waking mind within seconds of rousing.
Humans are designed to spend a third of their lives in this most vulnerable state—eight hours a day, every single day.
How can it make sense?