Why does your brain
need you to zone out?
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The full narration of the video.
For about half your waking hours, your mind is somewhere else. In meetings, at the sink, lying in bed at night, your thoughts drift away. Most of us call that a lazy brain.
But when scientists looked inside, they found something odd. A person lies in a scanner, doing nothing, and a few brain areas get busier. Give them a task, and those areas go quiet.
Idle, they work harder than during the task. Is the brain just idling, wasting power? The brain is two percent of your weight, yet burns a fifth of your energy.
Hard thinking adds only a tiny bit on top of that. Something that costly isn't left running for nothing. So what is it doing? Picture a room in your home.
All day you carry things in: words you heard, things you saw, half-finished thoughts. The door stays open, people come and go, no time to tidy. The moment you zone out, the door closes, and the brain starts tidying.
It puts today's things back on the shelves, firmly, so they're easy to find. One experiment shows this nicely. People heard a story. Then one group rested with eyes closed for ten minutes, the other played spot-the-difference.
A week later, the group that rested remembered clearly more. While tidying, it also sets two things side by side. An old problem meets a new memory, and an idea pops up.
No wonder so many good ideas show up in the shower or on a walk. These tidying areas have a name: the default mode network. Default, because it switches on whenever you do nothing.
It runs down the middle of your head, from behind the forehead to the back. The room is your memory. Closing the door to tidy is this network at work. Still, mind-wandering isn't all good.
When it drifts to worries, people tend to feel worse. And exactly how it tidies is still not fully worked out. The hard part now: our phones fill every spare moment at night.
Many people can't stand sitting alone for fifteen minutes. Some would rather give themselves a small shock. Leave the door open, and the room stays a mess. Tonight before bed, put your phone face down, do nothing, and drift for five minutes.
Where do you zone out most during your day?
About half your waking time,
your mind wanders
Researchers pinged over 2,000 people on their phones at random: "What are you thinking about right now?" Nearly half the time, it was not the thing they were doing.
In meetings, washing dishes, lying in bed at night, the mind drifts. Most of us think that is the brain slacking off.
When you do nothing,
some brain areas get busier
Something this costly does not run for nothing.
It closes the door
and tidies the room
Think of memory as a room at home. All day you carry things in: words you heard, things you saw, half-finished thoughts. The door stays open, people come and go, no time to tidy.
The moment you zone out, the door closes. Your brain puts today's things back in the cabinet, one by one, so you can find them later.
Things in a cabinet just sit there. Memories don't: once stored, they get pulled out and linked to others. No wonder so many good ideas come in the shower or on a walk.
Rest 10 minutes, eyes closed,
remember more a week later
Researchers told people a short story. Then one group rested quietly with eyes closed for 10 minutes; the other played spot-the-difference. A week later, the rested group remembered clearly more.
The bars only show which group remembered more. They are not real numbers.
Its real name:
the default mode network
The areas that "close the door and tidy" are called the default mode network. "Default" because it switches on by itself when you do nothing.
It runs along the middle of the brain, from behind the forehead to the back of the head. The three yellow spots in picture 2 are its main hubs.
The room is your memory. Closing the door to tidy is this network at work.
Mind-wandering is not always good
Our quiet evening gaps
get filled by phones
Many people can't stand sitting alone with their thoughts for just 6 to 15 minutes. In one study, many chose to press a button and give themselves a mild electric shock instead.
If the door never closes, the room never gets tidy.
and zone out for 5 minutes.
Quick check
When you do nothing and your mind drifts, what is your brain doing?
While you zone out, the default mode network is more active than during a task. It is tidying up today's memories.
