Editors’ Note: Portions of this post appeared in similar form in an October, 2011, post by Jonah Lehrer for Wired.com, in an August, 2008, column by Lehrer for the Boston Globe, and in his previously published book “Imagine.” We regret the duplication of material.

Humans are a daydreaming species. According to a recent study led by the Harvard psychologists Daniel Gilbert and Matthew A. Killingsworth, people let their minds wander forty-seven per cent of the time they are awake. (The scientists demonstrated this by developing an iPhone app that contacted twenty-two hundred and fifty volunteers at random intervals during the day.) In fact, the only activity during which we report that our minds are not constantly wandering is “love making.” We’re able to focus for that.

At first glance, such data seems like a confirmation of our inherent laziness. In a culture obsessed with efficiency, mind-wandering is often derided as useless—the kind of thinking we rely on when we don’t really want to think. Freud, for instance, described daydreams as “infantile” and a means of escaping from the necessary chores of the world into fantasies of “wish-fulfillment.”

In recent years, however, psychologists and neuroscientists have redeemed this mental state, revealing the ways in which mind-wandering is an essential cognitive tool. It turns out that whenever we are slightly bored—when reality isn’t quite enough for us—we begin exploring our own associations, contemplating counterfactuals and fictive scenarios that only exist within the head.

Virginia Woolf, in her novel “To The Lighthouse,” eloquently describes this form of thinking as it unfolds inside the mind of a character named Lily:

Certainly she was losing consciousness of outer things. And as she lost consciousness of outer things … her mind kept throwing up from its depths, scenes, and names, and sayings, and memories and ideas, like a fountain spurting.^1^

A daydream is that fountain spurting, spilling strange new thoughts into the stream of consciousness. And these spurts turn out to be surprisingly useful. A forthcoming paper in Psychological Science led by Benjamin Baird and Jonathan Schooler at the University of California at Santa Barbara helps explain why. The experiment itself was simple: a hundred and forty-five undergraduate students were given a standard test of creativity known as an “unusual use” task, in which they had two minutes to list as many uses as possible for mundane objects such as toothpicks, bricks, and clothes hangers.

Subjects were then randomly assigned to one of four different conditions. In three of those conditions, participants were given a twelve-minute break that entailed either: resting in a quiet room, performing a difficult short-term memory task, or doing something so boring that it would elicit mind-wandering. In a final control condition, participants were given no break at all. Finally, all subjects were given another round of creative tests, including the unusual-use tasks they had worked on only a few minutes before.^2^

Here’s where things get interesting: those students assigned to the boring task performed far better when asked to come up with additional uses for everyday items to which they had already been exposed. Given new items, all the groups did the same. Given repeated items, the daydreamers came up with forty-one per cent more possibilities than students in the other conditions.

What does this mean? Schooler argues that it’s clear evidence that those twelve minutes of daydreaming allowed the subjects to invent additional possibilities, as their unconscious minds pondered new ways to make use of toothpicks. This is why the effect was limited to those items that the subjects had previously been asked about—the question needed to marinate in the mind, “incubating” in those subterranean parts of the brain we can barely control.

On a more practical note, the scientists argue that their data show why “creative solutions may be facilitated specifically by simple external tasks that maximize mind-wandering.” The benefit of these simple tasks is that they consume just enough attention to keep us occupied, while leaving plenty of mental resources left over for errant daydreams. (When people are left alone, such as those subjects forced to sit by themselves, they tend to perseverate on their problems. Unfortunately, all this focus backfires.) Consider the ping-pong tables that now seem to exist in the lobby of every Silicon Valley startup. While it’s easy to dismiss such interior decorations as mere whimsy, the game turns out to be an ideal mind-wandering activity, at least when played casually. Another task that consistently leads to extended bouts of daydreaming is reading Tolstoy. In Schooler’s earlier work on mind-wandering, he gave subjects a boring passage from “War and Peace.” The undergraduates began zoning out within seconds.

Although Schooler has previously demonstrated a correlation between daydreaming and creativity—those who are more prone to mind-wandering tend to be better at generating new ideas, at least in the lab—this new paper shows that our daydreams seem to serve a similar function as night dreams, facilitating bursts of creative insight. Take a 2004 paper published in Nature by the neuroscientists Ullrich Wagner and Jan Born. The researchers gave a group of students a tedious task that involved transforming a long list of number strings into a new set of number strings. Wagner and Born designed the task so that there was an elegant shortcut, but it could only be uncovered if the subject had an insight about the problem. When people were left to their own devices, less than twenty per cent of them found the shortcut, even when given several hours to mull over the task. The act of dreaming, however, changed everything: after people were allowed to lapse into R.E.M. sleep, nearly sixty per cent of them discovered the secret pattern. Kierkegaard was right: sleeping is the height of genius.

If this all sounds like scientific justification for afternoon naps, long showers, and Russian literature, you’re right. “We always assume that you get more done when you’re consciously paying attention to a problem,” Schooler told me. “That’s what it means, after all, to be ‘working on something.’ But this is often a mistake. If you’re trying to solve a complex problem, then you need to give yourself a real break, to let the mind incubate the problem all by itself. We shouldn’t be so afraid to actually take some time off.”

Schooler has tried to apply this hypothesis to his own life. Although he used to take piles of work with him on vacation—he’d read papers and grant proposals on the beach—he now finds that he has better ideas when he lets himself really get away. “The good news is that there’s no reason to feel guilty when taking a break or not checking your e-mail,” he says. “Because it turns out that even when you’re on vacation, the unconscious is probably still working on the problem.”

A daydream, in this sense, is just a means of eavesdropping on those novel thoughts generated by the unconscious. We think we’re wasting time, but, actually, an intellectual fountain really is spurting.

Editors’ Notes:

^1^The quotation from Virginia Woolf was transcribed incorrectly in the initial version.

^2^Subjects were randomly assigned to four, not three, different conditions, as originally reported. A twelve-minute break was given to only three of those four groups. A final control condition not originally reported entailed participants being given no break at all.

Photograph by Peter Marlow/Magnum.