When: The Scientific Secrets of Perfect Timing

by Daniel H. Pink

Had Britain intentionally placed the Lusitania in harm’s way, or even conspired to sink the ship, to drag the United States into the war? Was the ship, which carried some small munitions, actually being used to transport a larger and more powerful cache of arms for the British war effort? Was Britain’s top naval official, a forty-year-old named Winston Churchill, somehow involved? Was Captain Turner, who survived the attack, just a pawn of more influential men, “a chump [who] invited disaster,” as one surviving passenger called him? Or had he suffered a small stroke that impaired his judgment, as others alleged? Were the inquests and investigations, the full records of which still haven’t been released, massive cover-ups?4 Nobody

Maybe, seen through the fresh lens of twenty-first-century behavioral and biological science, the explanation for one of the most consequential disasters in maritime history is less sinister. Maybe Captain Turner just made some bad decisions. And maybe those decisions were bad because he made them in the afternoon.

I will show that timing is really a science—an emerging body of multifaceted, multidisciplinary research that offers fresh insights into the human condition and useful guidance on working smarter and living better. Visit any bookstore or library, and you will see a shelf (or twelve) stacked with books about how to do various things—from win friends and influence people to speak Tagalog in a month. The output is so massive that these volumes require their own category: how-to. Think of this book as a new genre altogether—a when-to book.

We inhabit a planet that turns on its axis at a steady speed in a regular pattern, exposing us to regular periods of light and dark. We call each rotation of Earth a day. The day is perhaps the most important way we divide, configure, and evaluate our time.

A few years ago, two Cornell University sociologists, Michael Macy and Scott Golder, studied more than 500 million tweets that 2.4 million users in eighty-four countries posted over a two-year period. They hoped to use this trove to measure people’s emotions—in particular, how “positive affect” (emotions such as enthusiasm, confidence, and alertness) and “negative affect” (emotions such as anger, lethargy, and guilt) varied over time.

What Macy and Golder found, and published in the eminent journal Science, was a remarkably consistent pattern across people’s waking hours. Positive affect—language revealing that tweeters felt active, engaged, and hopeful—generally rose in the morning, plummeted in the afternoon, and climbed back up again in the early evening.

So in what would become an act of historically productive procrastination, de Mairan removed the plant from the windowsill, stuck it in a cabinet, and shut the door to seal off light. The following morning, he opened the cabinet to check on the plant and—mon Dieu!—the leaves had unfurled despite being in complete darkness. He continued his investigation for a few more weeks, draping black curtains over his windows to prevent even a sliver of light from penetrating the office. The pattern remained. The Mimosa pudica’s leaves opened in the morning, closed in the evening. The plant wasn’t reacting to external light. It was abiding by its own internal clock.3

The SCN’s daily timer runs a bit longer than it takes for the Earth to make one full rotation—about twenty-four hours and eleven minutes.4 So our built-in clock uses social cues (office schedules and bus timetables) and environmental signals (sunrise and sunset) to make small adjustments that bring the internal and external cycles more or less in synch, a process called “entrainment.”

Each person would take a seat along one of the sides of a long rectangular table. At the center of the table sat a speakerphone, the staging ground for a one-hour conference call. At the other end of the speakerphone were one hundred or so investors, journalists, and, most important, stock analysts, whose job is to assess a company’s strengths and weaknesses. In the first half hour, Conant would report on Campbell’s revenue, expenses, and earnings the previous quarter. In the second half hour, the executives would answer questions posed by analysts, who would probe for clues about the company’s performance. At Campbell Soup and all public companies, the stakes are high for earnings calls. How analysts react—did the CEO’s comments leave them bullish or bearish about the company’s prospects?—can send a stock soaring or sinking. “You have to thread the needle,” Conant told me. “You have to be responsible and unbiased, and report the facts. But you also have a chance to champion the company and set the record straight.” Conant says his goal was always to “take uncertainty out of an uncertain marketplace. For me, these calls introduced a sense of rhythmic certainty into my relationships with investors.”

“[A]n important takeaway from our study for corporate executives is that communications with investors, and probably other critical managerial decisions and negotiations, should be conducted earlier in the day.”11 Should the rest of us heed this counsel? (Campbell, as it happens, typically held its earnings calls in the morning.) Our moods cycle in a regular pattern—and, almost invisibly, that affects how corporate executives do their job. So should those of us who haven’t ascended to the C-suite also frontload our days and tackle our important work in the morning? The answer is yes. And no.

Nor is it a matter of opinion. It’s entirely a matter of logic. Bank tellers who are also feminists—just like bank tellers who yodel or despise cilantro—are a subset of all bank tellers, and subsets can never be larger than the full set they’re a part of.* In 1983 Daniel Kahneman, he of Nobel Prize and DRM fame, and his late collaborator, Amos Tversky, introduced the Linda problem to illustrate what’s called the “conjunction fallacy,” one of the many ways our reasoning goes awry.12

All the “jurors” read the same set of facts. But for half of them, the defendant’s name was Robert Garner, and for the other half, it was Roberto Garcia. When people made their decisions in the morning, there was no difference in guilty verdicts between the two defendants. However, when they rendered their verdicts later in the day, they were much more likely to believe that Garcia was guilty and Garner was innocent. For this group of participants, mental keenness, as shown by rationally evaluating evidence, was greater early in the day. And mental squishiness, as evidenced by resorting to stereotypes, increased as the day wore on.14

First, our cognitive abilities do not remain static over the course of a day. During the sixteen or so hours we’re awake, they change—often in a regular, foreseeable manner. We are smarter, faster, dimmer, slower, more creative, and less creative in some parts of the day than others.

Third, how we do depends on what we’re doing. “Perhaps the main conclusion to be drawn from studies on the effects of time of day on performance,” says British psychologist Simon Folkard, “is that the best time to perform a particular task depends on the nature of that task.”

For most of us, those sharp-minded analytic capacities peak in the late morning or around noon.17

Alertness and energy levels, which climb in the morning and reach their apex around noon, tend to plummet during the afternoons.

Students scored higher in the mornings than in the afternoons. Indeed, for every hour later in the day the tests were administered, scores fell a little more. The effects of later-in-the-day testing were similar to having parents with slightly lower incomes or less education—or missing two weeks of a school year.19 Timing wasn’t everything. But it was a big thing.

But before you go rearranging your own work schedules to cram all the important stuff before lunchtime, beware. All brainwork is not the same. To illustrate that, here’s another pop quiz.

Two American psychologists, Mareike Wieth and Rose Zacks, presented this and other insight problems to a group of people who said they did their best thinking in the morning. The researchers tested half the group between 8:30 a.m. and 9:30 a.m. and the other half between 4:30 p.m. and 5:30 p.m. These morning thinkers were more likely to figure out the coin problem . . . in the afternoon. “Participants who solved insight problems during their non-optimal time of day . . . were more successful than participants at their optimal time of day,” Wieth and Zacks found.21 What’s going on?

For analytic problems, lack of inhibitory control is a bug. For insight problems, it’s a feature.

Some have called this phenomenon the “inspiration paradox”—the idea that “innovation and creativity are greatest when we are not at our best, at least with respect to our circadian rhythms.”

Let’s begin with personality, including what social scientists call the “Big Five” traits—openness, conscientiousness, extraversion, agreeableness, and neuroticism. Much of the research shows morning people to be pleasant, productive folks—“introverted, conscientious, agreeable, persistent, and emotionally stable” women and men who take initiative, suppress ugly impulses, and plan for the future.33 Morning types also tend to be high in positive affect—that is, many are as happy as larks.34 Owls, meanwhile, display some darker tendencies. They’re more open and extroverted than larks. But they’re also more neurotic—and are often impulsive, sensation-seeking, live-for-the-moment hedonists.35 They’re more likely than larks to use nicotine, alcohol, and caffeine—not to mention marijuana, ecstasy, and cocaine.36

What ultimately matters, then, is that type, task, and time align—what social scientists call “the synchrony effect.”44 For instance, even though it’s obviously more dangerous to drive at night, owls actually drive worse early in the day because mornings are out of synch with their natural cycle of vigilance and alertness.

In short, all of us experience the day in three stages—a peak, a trough, and a rebound. And about three-quarters of us (larks and third birds) experience it in that order. But about one in four people, those whose genes or age make them night owls, experience the day in something closer to the reverse order—recovery, trough, peak.

The Hospital of Doom may not be a real name. But it is a real place. Everything I’ve described is what happens in modern medical centers during the afternoons compared with the mornings.

call time-outs like these “vigilance breaks”—brief pauses before high-stakes encounters to review instructions and guard against error. Vigilance breaks have gone a long way in preventing the University of Michigan Medical Center from transmogrifying into the Hospital of Doom during the afternoon trough.

Tremper says that in the time since he implemented these breaks, the quality of care has risen, complications have declined, and both doctors and patients are more at ease.

Or consider colonoscopies. I’ve reached the age where prudence calls for submitting to this procedure to detect the presence or possibility of colon cancer. But now that I’ve read the research, I would never accept an appointment that wasn’t before noon. For example, one oft-cited study of more than 1,000 colonoscopies found that endoscopists are less likely to detect polyps—small growths on the colon—as the day progresses. Every hour that passed resulted in a nearly 5 percent reduction in polyp detection. Some of the specific morning versus afternoon differences were stark. For instance, at 11 a.m., doctors found an average of more than 1.1 polyps in every exam. By 2 p.m., though, they were detecting barely half that number even though afternoon patients were no different from the morning ones.2 Look at those numbers and tell me when you’d schedule a colonoscopy.

In all, they studied more than 4,000 caregivers (two-thirds of whom were nurses), who over the course of the research had nearly 14 million “hand hygiene opportunities.” The results were not pretty. On average, these employees washed their hands less than half the time when they had an opportunity and a professional obligation to do so. Worse, the caregivers, most of whom began their shifts in the morning, were even less likely to sanitize their hands in the afternoons. This decline from the relative diligence of the mornings to the relative neglect of the afternoon was as great as 38 percent. That is, for every ten times they washed their hands in the morning, they did so only six times in the afternoon.

Unfortunately, Danish schools, like many around the world, offer only two breaks each day. Worse, legions of school systems are cutting back on recess and other restorative pauses for students in the name of rigor and—get ready for the irony—higher test scores. But as Harvard’s Francesca Gino, one of the study’s authors, puts it, “If there were a break after every hour, test scores would actually improve over the course of the day.”13 Many younger students underperform during the trough, which risks both providing teachers with an inaccurate sense of their progress and prompting administrators to attribute to what and how students are learning something that is really an issue of when they’re taking a test. “We believe these results to have two important policy implications,” say the researchers who studied the Danish experience.

The following chart shows what happened. Early in the day, judges ruled in favor of prisoners about 65 percent of the time. But as the morning wore on, that rate declined. And by late morning, their favorable rulings dropped to nearly zero. So a prisoner slotted for a 9 a.m. hearing was likely to get parole while one slotted for 11:45 a.m. had essentially no chance at all—regardless of the facts of the case. Put another way, since the default decision on boards is typically not to grant parole, judges deviated from the status quo during some hours and reinforced it during others.

The researchers say they cannot identify precisely what’s driving this phenomenon. It could be that eating restored judges’ glucose levels and replenished their mental reserves. It could be that a little time away from the bench lifted their mood. It could be that the judges were tired and that rest reduced their fatigue. (Another study of U.S. federal courts found that on the Mondays after the switch to Daylight Saving Time, when people on average lose roughly forty minutes of sleep, judges rendered prison sentences that were about 5 percent longer than the ones they handed down on typical Mondays.15)

High performers, its research concludes, work for fifty-two minutes and then break for seventeen minutes. DeskTime never published the data in a peer-reviewed journal, so your mileage may vary. But the evidence is overwhelming that short breaks are effective—and deliver considerable bang for their limited buck. Even “micro-breaks” can be helpful.19

For example, people who take short walks outdoors return with better moods and greater replenishment than people who walk indoors. What’s more, while people predicted they’d be happier being outside, they underestimated how much happier.26 Taking a few minutes to be in nature is better than spending those minutes in a building. Looking out a window into nature is a better micro-break than looking at a wall or your cubicle. Even taking a break indoors amid plants is better than doing so in a green-free zone.

By now, it’s well known that 99 percent of us cannot multitask. Yet, when we take a break, we often try to combine it with another cognitively demanding activity—perhaps checking our text messages or talking to a colleague about a work issue. That’s a mistake. In the same South Korean study mentioned earlier, relaxation breaks (stretching or daydreaming) eased stress and boosted mood in a way that multitasking breaks did not.

Detachment—both psychological and physical—is also critical. Staying focused on work during lunch, or even using one’s phone for social media, can intensify fatigue, according to multiple studies, but shifting one’s focus away from the office has the opposite effect.

Yet, even after absorbing this evidence, I remained a nap skeptic. One reason I so disliked naps is that I woke up from them feeling as if someone had injected my bloodstream with oatmeal and replaced my brain with oily rags. Then I discovered something crucial: I was doing it wrong.

Slightly longer naps were also effective. But once the nap lasted beyond about the twenty-minute mark, our body and brain began to pay a price.52 That price is known as “sleep inertia”—the confused, boggy feeling I typically had upon waking. Having to recover from sleep inertia—all that time spent splashing water on my face, shaking my upper body like a soaked golden retriever, and searching desk drawers for candy to get some sugar into my system—subtracts from the nap’s benefits, as this chart makes clear.

One study makes this case. The experimenters divided participants into three groups and gave them all a thirty-minute midafternoon break before sitting them at a driving simulator. One group received a placebo pill. The second received two hundred milligrams of caffeine. The third received that same two hundred milligrams of caffeine and then took a brief nap. When it came time to perform, the caffeine-only group outperformed the placebo group. But the group that ingested caffeine and then had a nap easily bested them both.55 Since caffeine takes about twenty-five minutes to enter the bloodstream, they were getting a secondary boost from the drug by the time their naps were ending. Other researchers have found the same results—that caffeine, usually in the form of coffee, followed by a nap of ten to twenty minutes, is the ideal technique for staving off sleepiness and increasing performance.56

It means protecting and extending recess for schoolchildren rather than eliminating it. It might even mean following the lead of Ben & Jerry’s, Zappos, Uber, and Nike, all of which have created napping spaces for employees in their offices. (Alas, it probably does not mean legislating a one-hour break each week for employees to go home and have sex, as one Swedish town has proposed.59)

Most of all, it means changing the way we think about what we do and how we can do it effectively. Until about ten years ago, we admired those who could survive on only four hours of sleep and those stalwarts who worked through the night. They were heroes, people whose fierce devotion and commitment revealed everyone else’s fecklessness and frailty. Then, as sleep science reached the mainstream, we began to change our attitude. That sleepless guy wasn’t a hero. He was a fool. He was likely doing subpar work and maybe hurting the rest of us because of his poor choices.

Schedule it—Plan a regular walk or visit to a coffee joint or weekly gossip session with colleagues you like. A fringe benefit of social breaks is that you’re more likely to take one if someone else is counting on you. Or go Swedish and try what Swedes call a fika—a full-fledged coffee break that is the supposed key to Sweden’s high levels of employee satisfaction and productivity.5 Don’t schedule it—If your schedule is too tight for something regular, buy someone a coffee one day this week. Bring it to her. Sit and talk about something other than work for five minutes.

Some 40 percent of U.S. schools (particularly schools with large numbers of low-income students of color) have eliminated recess or combined it with lunch.10 With futures on the line, the thinking goes, schools can’t afford the frivolity of playtime. For example, in 2016 the New Jersey legislature passed a bipartisan bill requiring merely twenty minutes of recess each day for grades kindergarten to 5 in the state’s schools.

The evidence of harm is so massive that in 2014 the American Academy of Pediatrics (AAP) issued a policy statement calling for middle schools and high schools to begin no earlier than 8:30 a.m.5 A few years later, the CDC added its voice, concluding that “delaying school start times has the potential for the greatest population impact” in boosting teenage learning and well-being.

Even the price is right. When an economist studied the Wake County, North Carolina, school system, he found that “a 1 hour delay in start time increases standardized test scores on both math and reading tests by three percentile points,” with the strongest effects on the weakest students.12 But being an economist, he also calculated the cost-benefit ratio of changing the schedule and concluded that later start times delivered more bang for the educational buck than almost any other initiative available to policy makers, a view echoed by a Brookings Institution analysis.13

But beneath those excuses is a deeper, and equally troubling, explanation. We simply don’t take issues of when as seriously as we take questions of what. Imagine if schools suffered the same problems wrought by early start times—stunted learning and worsening health—but the cause was an airborne virus that was infecting classrooms. Parents would march to the schoolhouse to demand action and quarantine their children at home until the problem was solved. Every school district would snap into action.

The school start time issue isn’t new. But because it’s a when problem rather than a what problem such as viruses or terrorism, too many people find it easy to dismiss. “What difference can one hour possibly make?” ask the forty- and fifty-year-olds. Well, for some students, it means the difference between dropping out and completing high school. For others, it’s the difference between struggling with academics and mastering math and language courses—which can later affect their likelihood of going to college or finding a good job. In some cases, this small difference in timing could alleviate suffering and even save lives.

Daniel Kahneman draws a distinction between thinking fast (making decisions anchored in instinct and distorted by cognitive biases) and thinking slow (making decisions rooted in reason and guided by careful deliberation). Temporal landmarks slow our thinking, allowing us to deliberate at a higher level and make better decisions.20

Organizations, too, can enlist this technique. Recent research has shown that the fresh start effect applies to teams.24 Suppose a company’s new quarter has a rough beginning. Rather than waiting until the next quarter, an obvious fresh start date, to smooth out the mess, leaders can find a meaningful moment occurring sooner—perhaps the anniversary of the launch of a key product—that would relegate previous screwups to the past and help the team get back on track. Or suppose some employees are not regularly contributing to their retirement accounts or failing to attend important training sessions. Sending them reminders on their birthdays rather than on some other day could prompt them to start acting. Consumers might also be more open to messages on days framed as fresh starts, Riis found.25 If you’re trying to encourage people to eat healthier, a campaign calling for Meatless Mondays will be far more effective than one advocating Vegan Thursdays.

The total cost, in inflation-adjusted terms, of graduating in a bad year rather than a good year averaged about $100,000. Timing wasn’t everything—but it was a six-figure thing.