Introduction The Resting Brain What your brain is up to when you think you''re doing nothing Abolfazl was six years old when he first understood kar, Farsi for "work." Standing beside his mother under the domed arches of Tehran''s Grand Bazaar, he sensed it was important. Something noble. "Kar taj ast," his mother would say ("Work is a crown"). Around them, merchants worked tirelessly to sell everything from fruits and nuts to hand-made leather shoes, delicious spices, wooden abacuses, and exquisite hand-woven Persian rugs. Old men sat cross-legged on cushioned corners, sipping tea through cubes of sugar and sharing stories of Persian kings and poets. Later, when he was a bit older, Abolfazl heard his father snoring through a long midday nap and felt compelled to wake him. He approached the bedroom door and reached for the handle, only to be met with a hand blocking his way.

His mother gazed at him with an intensity he remembers to this day. "aram hekmat ast," she said firmly ("Rest is wisdom"). Fifteen years later, Abolfazl is sitting in a small office cubicle in a high-rise tower on the outskirts of Bristol, England. The 1980s had swept him, like many of his compatriots, into a vast Iranian diaspora. With a mind for mathematics, he secured a job in computer programming, got married, had two children, and set out to make his family in Iran proud. His days were long, punctuated by tapping keyboards, shuffling papers, and an unmistakable feeling of being watched. Interactions were minimal, often limited to terse emails and brief, impersonal meetings. The storytelling tea breaks he''d witnessed in Iran were replaced with lone trips to a vending machine or quick chats by a kettle in a cramped kitchen.

This new world was efficient, yes, but desolate. Time passed slowly, weeks blending into months, months into years. Before long, the soul-crushing monotony and exhausting tasks began to erode his mental health. What was meant to be a dream of a better life in England gradually morphed into a waking nightmare of stress and burnout. The breaking point came one ordinary afternoon, two decades into his career, when Abolfazl, my father, came home early from another grueling day at the office. I was just fourteen at the time and could sense something amiss the moment he walked through the door. His usual tired smile was gone, replaced with a look of panic and overwhelming sorrow. What happened next is a blur, but I do remember a shouting I had never heard before.

Frantic, confused, and gravely depressed, he unleashed his frustrations on my mother, who, struggling with her own work burnout, tried to calm him down. "You just need to rest, Ab," I remember her saying through tears. "I don''t even know how to rest anymore," he hurled back. A smashing sound erupted. I''m ashamed to admit it now, but I was so scared I grabbed my bike and fled. The next day, my father quit work and never went back. The doctor diagnosed him with major depressive disorder, likely caused by overwork and burnout, handed him some pills, and told him to find time to rest-truly rest. Now he sleeps through most mornings, says very little, does very little, and tries to manage his condition one day at a time.

All because he couldn''t heed his mother''s advice: to lay down the crown and rest. It took me a long time to realize the importance of rest. When I was a research scientist at the University of Washington, I would spend my days conducting lab experiments, writing papers, and mentoring students-finishing at 7 p.m., only to head straight to a nearby coffee shop and work on grants and my first book until ten or eleven. It was exhausting, with my goals always seeming just out of reach. I often felt totally wiped out. Looking back, I can see I was forcing myself to take on such a heavy workload because I felt an immense, self-imposed pressure to achieve.

It was making me pretty miserable. But I was in that phase of my life when all the old formulas seemed so relevant. You think that the faster you run, the better you''re going to do; that if you work harder and harder, you''ll succeed. Unsurprisingly, this way of life took its toll on my mental and physical health. My memory, focus, creativity, and cognitive abilities faded, making it increasingly hard to think about the problems I was hired to solve. My anxiety skyrocketed, making it difficult to concentrate on tasks and causing sleepless nights filled with racing thoughts. My energy levels plummeted, leaving me fatigued and grouchy, and my immune system weakened, causing frequent colds and headaches. On paper I was excelling; in reality, I was a mess.

As the years went by, it became clear that I couldn''t sustain this pace indefinitely. Like my father, I was heading toward burnout and a serious mental-health condition. My brain was sending urgent signals, and it was about time I listened. So I started to ease off work. I stopped staying late just to be seen. I stopped working while ill just to prove my dedication. I stopped going the extra mile just to look good when, in truth, no one really noticed or cared. Gradually, I began to let go of the pressure of presenteeism and the constant need to achieve.

Eventually, I decided to leave academia and pursue writing full-time. With a more relaxed attitude to work, my health has improved dramatically. I sleep better, my energy has returned, and I am ill far less often. What''s more, my ability to focus, solve problems, be creative, and write fluidly has soared. Incredibly, I''m now more productive and efficient than ever before. Rest, I have realized, is the key to my health and productivity. But why and how is this the case? What lies behind the wisdom of rest that my grandmother encouraged all those years ago? Guided by my knowledge as a neuroscientist and driven by my family''s toxic relationship with work, I started to explore the neuroscience of rest-and what I discovered was extraordinary. Throughout history people have extolled the benefits of rest.

Charles Darwin spent considerable time fishing and taking breaks alongside his studying and writing. Maya Angelou championed "a day away" for long baths, leisurely strolls, and time spent on park benches ("observing the mysterious world of ants and the canopy of treetops"). Karl Marx worked extensively, yet believed that rest would lead to a blossoming of universal creativity. Jane Austen, Virginia Woolf, and Georgia O''Keeffe valued relaxation and downtime. Leonardo da Vinci was a contemplative genius, reportedly staring at The Last Supper for hours before adding a single brushstroke and walking away. For a long time we have been taught that such inertia is the opposite of success-an indulgent, unprincipled, even irresponsible way of behaving. But what if I told you that people often succeed in life not despite their inactivity but because of it? What if I told you that, far from being indulgent and unproductive, rest is actually the key to human flourishing? In this book I want to show you how doing nothing has profound benefits for your brain, and that when you disengage from a task, your brain activates a network vital for your mental and physical health. We call this network the default network: a circuit of neurons (brain cells that communicate through electrical and chemical signals) that enables us to daydream, mind wander, think reflectively, and imagine the future.

It fans out across the brain, occupying the frontal, parietal, and temporal lobes. Crucially, the default network is only active when we are not focused on an exerting task; when the brain is cycling through thoughts not associated with our immediate environment; when, in short, our minds simply roam free. Activating the default network can enhance your intelligence, creativity, social empathy, and long-term productivity. It can improve your health and help stave off neurological disease. It is your brain''s hidden superpower, recharging and rehabilitating your overworked mind. This astonishing new understanding of the brain is changing the way we work for the better, and redefining what it means to "think." To see the default network in action, consider a group of eighty people who were asked to pick the best car from a set of four, based on a variety of mechanical specifications. Half of the people were given five minutes to concentrate on the task, while the other half were told to chill out, take a break, and think about unrelated things.

Following the break, researchers from the University of Amsterdam found that the latter group scored far higher on the task, working through the problem in a more efficient way. Another example comes from observing fifty-two doctors and nurses working a twelve-hour night shift. Half of the team were told to take a forty-minute nap, while their colleagues worked continuously. Researchers at Stanford University found that the group that rested performed better on tests of attention and simulated medical tests, including inserting a catheter into a virtual patient. By doing nothing, they got better at doing everything. While the time needed to tap into the benefits of the default network is still unclear, we know that people given twenty minutes'' rest during a so-called consequence test, where people are asked to list as many consequences as they can for a possible scenario, perform much better than people who do not rest. People even perform better with only ten minutes'' rest. (A.