PART ONE. THE DAY 1.
THE HIDDEN PATTERN OF EVERYDAY LIFE
What men daily do, not knowing what they do!
âWILLIAM SHAKESPEARE,
Much Ado About Nothing
If you want to measure the worldâs emotional state, to find a mood ring large enough to encircle the globe, you could do worse than Twitter. Nearly one billion human beings have accounts, and they post roughly 6,000 tweets every second.1 The sheer volume of these minimessagesâwhat people say and how they say itâhas produced an ocean of data that social scientists can swim through to understand human behavior.
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 peopleâs emotionsâ in particular, how âpositive affectâ (emotions such as enthusiasm, confidence, and alertness) and ânegative affectâ (emotions such as anger, lethargy, and guilt) varied over time. The researchers didnât read those half a billion tweets one by one, of course. Instead, they fed the posts into a powerful and widely used computerized text-analysis program called LIWC (Linguistic Inquiry and Word Count) that evaluated each word for the emotion it conveyed.
What Macy and Golder found, and published in the eminent journal Science, was a remarkably consistent pattern across peopleâs waking hours. Positive affectâlanguage revealing that tweeters felt active, engaged, and hopefulâgenerally rose in the morning, plummeted in the afternoon, and climbed back up again in the early evening. Whether a tweeter was North American or Asian, Muslim or atheist, black or white or brown, didnât matter. âThe temporal affective pattern is similarly shaped across disparate cultures and geographic locations,â they write. Nor did it matter whether people were tweeting on a Monday or a Thursday. Each weekday was basically the same. Weekend results differed slightly. Positive affect was generally a bit higher on Saturdays and Sundaysâand the morning peak began about two hours later than on weekdaysâbut the overall shape stayed the same.2 Whether measured in a large, diverse country like the United States or a smaller, more homogenous country like the United Arab Emirates, the daily pattern remained weirdly similar. It looked like this:
Across continents and time zones, as predictable as the ocean tides, was the same daily oscillationâa peak, a trough, and a rebound. Beneath the surface of our everyday life is a hidden pattern: crucial, unexpected, and revealing.
Understanding this patternâwhere it comes from and what it meansâbegins with a potted plant, a Mimosa pudica, to be exact, that perched on the windowsill of an office in eighteenth-century France. Both the office and the plant belonged to Jean-Jacques dâOrtous de Mairan, a prominent astronomer of his time. Early one summer evening in 1729, de Mairan sat at his desk doing what both eighteenth-century French astronomers and twenty-first-century American writers do when they have serious work to complete: He was staring out the window. As twilight approached, de Mairan noticed that the leaves of the plant sitting on his windowsill had closed up. Earlier in the day, when sunlight streamed through the window, the leaves were spread open. This patternâleaves unfurled during the sunny morning and furled as darkness loomedâspurred questions. How did the plant sense its surroundings? And what would happen if that pattern of light and dark was disrupted?
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 andâmon Dieu!âthe 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 pudicaâs leaves opened in the morning, closed in the evening. The plant wasnât reacting to external light. It was abiding by its own internal clock.3
Since de Mairanâs discovery nearly three centuries ago, scientists have established that nearly all living thingsâfrom single-cell organisms that lurk in ponds to multicellular organisms that drive minivansâhave biological clocks. These internal timekeepers play an essential role in proper functioning. They govern a collection of what are called circadian rhythms (from the Latin circa [around] and diem [day]) that set the daily backbeat of every creatureâs life. (Indeed, from de Mairanâs potted plant eventually bloomed an entirely new science of biological rhythms known as chronobiology.)
For you and me, the biological Big Ben is the suprachiasmatic nucleus, or SCN, a cluster of some 20,000 cells the size of a grain of rice in the hypothalamus, which sits in the lower center of the brain. The SCN controls the rise and fall of our body temperature, regulates our hormones, and helps us fall asleep at night and awaken in the morning. The SCNâs daily timer runs a bit longer than it takes for the Earth to make one full rotationâabout 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 âentrainment.â
The result is that, like the plant on de Mairanâs windowsill, human beings metaphorically âopenâ and âcloseâ at regular times during each day. The patterns arenât identical for every personâjust as my blood pressure and pulse arenât exactly the same as yours or even the same as mine were twenty years ago or will be twenty years hence. But the broad contours are strikingly similar. And where theyâre not, they differ in predictable ways.
Chronobiologists and other researchers began by examining physiological functions such as melatonin production and metabolic response, but the work has now widened to include emotions and behavior. Their research is unlocking some surprising time-based patterns in how we feel and how we performâwhich, in turn, yields guidance on how we can configure our own daily lives.
MOOD SWINGS AND STOCK SWINGS
For all their volume, hundreds of millions of tweets cannot provide a perfect window into our daily souls. While other studies using Twitter to measure mood have found much the same patterns that Macy and Golder discovered, both the medium and the methodology have limits.5 People often use social media to present an ideal face to the world that might mask their true, and perhaps less ideal, emotions. In addition, the industrial-strength analytic tools necessary to interpret so much data canât always detect irony, sarcasm, and other subtle human tricks.
Fortunately, behavioral scientists have other methods to understand what we are thinking and feeling, and one is especially good for charting hour-to-hour changes in how we feel. Itâs called the Day Reconstruction Method (DRM), the creation of a quintet of researchers that included Daniel Kahneman, winner of the Nobel Prize in Economics, and Alan Krueger, who served as chairman of the White House Council of Economic Advisers under Barack Obama. With the DRM, participants reconstruct the previous dayâchronicling everything they did and how they felt while doing it. DRM research, for instance, has shown that during any given day people typically are least happy while commuting and most happy while canoodling.6
In 2006, Kahneman, Krueger, and crew enlisted the DRM to measure âa quality of affect that is often overlooked: its rhythmicity over the course of a day.â They asked more than nine hundred American womenâa mix of races, ages, household incomes, and education levelsâto think about the previous âday as a continuous series of scenes or episodes in a film,â each one lasting between about fifteen minutes and two hours. The women then described what they were doing during each episode and chose from a list of twelve adjectives (happy, frustrated, enjoying myself, annoyed, and so on) to characterize their emotions during that time.
When the researchers crunched the numbers, they found a âconsistent and strong bimodal patternââtwin peaksâduring the day. The womenâs positive affect climbed in the morning hours until it reached an âoptimal emotional pointâ around midday. Then their good mood quickly plummeted and stayed low throughout the afternoon only to rise again in the early evening.7
Here, for example, are charts for three positive emotionsâhappy, warm, and enjoying myself. (The vertical axis represents the participantsâ measure of their mood, with higher numbers being more positive and lower numbers less positive. The horizontal axis shows the time of day, from 7 a.m. to 9 p.m.)
The three charts are obviously not identical, but they all share the same essential shape. Whatâs more, that shapeâand the cycle of the day it representsâlooks a lot like the one on page 10. An early spike, a big drop, and a subsequent recovery.
On a matter as elusive as human emotion, no study or methodology is definitive. This DRM looked only at women. In addition, what and when can be difficult to untangle. One reason âenjoying myselfâ is high at noon and low at 5 p.m. is that we tend to dig socializing (which people do around lunchtime) and detest battling traffic (which people often do in the early evening). Yet the pattern is so regular, and has been replicated so many times, that itâs difficult to ignore.
So far Iâve described only what DRM researchers found about positive affect. The ups and downs of negative emotionsâfeeling frustrated, worried, or hassledâwere not as pronounced, but they typically showed a reverse pattern, rising in the afternoon and sinking as the day drew to a close. But when the researchers combined the two emotions, the effect was especially stark. The following graph depicts what you might think of as ânet good mood.â It takes the hourly ratings for happiness and subtracts the ratings for frustration.
Once again, a peak, a trough, and a rebound.
Moods are an internal state, but they have an external impact. Try as we might to conceal our emotions, they inevitably leakâand that shapes how others respond to our words and actions.
Which leads us inexorably to canned soup.
If youâve ever prepared a bowl of cream of tomato soup for lunch, Doug Conant might be the reason why. From 2001 to 2011, Conant was the CEO of Campbell Soup Company, the iconic brand with those iconic cans. During his tenure, Conant helped to revitalize the company and return it to steady growth. Like all CEOs, Conant juggled multiple duties. But one he handled with particular calm and aplomb is the rite of corporate life known as the quarterly earnings call.
Every three months, Conant and two or three lieutenants (usually the companyâs chief financial officer, controller, and head of investor ...