The self-help shelves at bookstores and libraries are teeming with titles about how to successfully do x, y and z. This book is less about “how to” and more about “when to.” Daniel Pink’s When is the synthesis of over 700 studies from fields as diverse as biology, neuroscience, anthropology, economics and social psychology. His aim is to show that timing in life is not an art, but a science. Pink’s book is full of fascinating facts and practical suggestions for when it is best to take action.

Some of life’s patterns hide in plain view, so commonplace that we don’t even notice them. Two professors of sociology from Cornell discovered one such pattern fairly recently while studying Twitter trends. These scholars analyzed half a billion tweets from over 2 million users in 84 countries to find what people were feeling and when they usually had those feelings.

They found that there is a pattern of peak, trough and rebound during the course of a day for most people. The morning tweets tended to be more positive, hopeful and energetic. This positivity would taper off during the afternoon until about 5 p.m., and then pick back up by early evening. This pattern was the same across time zones, cultures, climates, religious value systems and geographical location. This positive affect was generally higher on weekends, but the basic shape of the curve remained intact: peak, trough, rebound.

Other studies have examined factors related to positive and negative affect, like feelings of happiness, warmth toward others, general enjoyment of life and emotional stability. Unlike the Cornell study, which extrapolated mood from tweets, these studies involved self-reported feelings on a pre-established rating system, which increases accuracy of the findings (although it’s hard to beat a sample size of 500 million tweets!). In all these cases, the shape of the curve was extremely similar.

These findings have remarkable and important implications for life and when to make decisions.

Typically when people hear the phrase circadian rhythm, they think of wake-sleep cycles, but that is just one of many. The word “circadian” is derived from the Latin words circa (around, about) and diem (day).

Many of the most critical circadian rhythms are regulated by a tiny portion of the brain called the suprachiasmatic nucleus. Amazingly, these bio-clocks not only track internal rhythms, but harmonize them with external patterns like social queues such as work and transportation schedules, and with environmental indicators like the sun’s position. This is a completely unconscious, involuntary process known as entrainment. There are broad patterns, but the syncing process varies significantly from person to person. 

People perform better at different times of day. Some people are morning people; others enjoy staying up late; most everyone falls somewhere in between. A person’s chronotype plays a big role in determining windows of optimal performance. The three chronotypes are morning lark, night owl and “third birds.”

Genetics is the primary determinant of chronotype. Another factor is age - children tend to be larks, and drift toward later starts as they move into adolescence. Another factor is season of birth: Those born in fall and winter tend to be larks, while those born in spring or summer tend to be night owls.

Scientists have given the intersection of time and biology more attention since the 1970s. There are involved tests to determine chronotype like the Munich Chronotype Questionnaire, but the simplest way to determine your chronotype is answering three questions: If there are no tasks that would obligate you to rise earlier than you’d prefer, what time would you usually go to bed? wake up? Lastly, what is the mid-point between those times? So, if you usually fall asleep around 11:00 p.m. and wake up around 7:00 a.m., then your midpoint is 3:00 a.m.

This is significant because peak performance hours will vary with chronotype. Larks will maximize output by doing analytical tasks early in the morning; saving insight-oriented tasks for the late afternoon or early evening; and making important decisions in the early morning. For the third birds — which is most of you — take on your analytical tasks mid-morning, and insight tasks in the early evening. Make important decisions in the early or mid-morning. Night owls, save your analytical tasks for the late afternoon or evening, insight-oriented tasks for the morning, and decision-making for the late afternoon and evening. Unfortunately for the night owls, the best time to make impressions is always the morning, given the near-universal morning peak in positivity and emotional stability. 

Afternoon hours in hospitals are not always a pretty sight. Maybe you have not noticed a discernible difference, but studies have shown that critical oversights are far more likely in the afternoon than the morning: misdiagnoses, unhelpful or even harmful prescriptions, diminished powers of observation and decision-making. Lethal doses of anesthesia are administered three times more often in the afternoon than in the morning.

Every hour after twelve noon signals a five percent decline in chances of discovering polyps in a colonoscopy procedure, thus diminishing the chances of an accurate, potentially life-saving diagnosis.

The University of Michigan Medical Center is aware of this common propensity, and has taken measures to ensure that their doctors and surgeons stay sharp. They have introduced mandatory “time-outs” or vigilance breaks, which give personnel a quick pause before performing sensitive procedures that require clear thinking and precision. Surgical mortality rate decreased by 18 percent.

Since integrating protocols that mandate pauses and double-checks, University of Michigan’s Medical Unit has noticed a significant drop in logistical and procedural mistakes, improvement in patient care and more positive doctor-patient vibes. So if that important surgery is scheduled for the afternoon, it’s advisable to get that time changed.

Of course it’s not just the doctors’ performance that suffers during this rut. Car accidents are extremely frequent between 2 p.m. and 4:00 pm. People tend to be more prone to moral failure in the afternoon than the morning, a phenomenon social psychologists refer to as “morning morality effect.”

In schools where students get 20- or 30-minute breaks to socialize and play before exams, scores tend to be higher. Some Scandinavian countries require four or more breaks during the course of the day.

Unfortunately, courts are not unaffected. Breaks tend to effect leniency of rulings. Judges are far more likely to issue a ruling in favor of the defendant—or at least a lenient sentence—immediately after midday or afternoon breaks. Those chances dwindle over time, until another break refreshes and ushers in a new wave of goodwill.

There are no hard-and-fast rules about taking vigilance breaks. Generally speaking, a small break is better than no break; movement is preferable to staying stationary; a social element is preferable to isolation; and taking a break outside is better than staying indoors. That Vitamin D and glimpse of nature have rejuvenating effects. 

Life is better understood as a collection of seasons than a neat and tidy linear progression. When we look back on these seasons, their beginnings and ends are clearly defined by images and events, but the middle is usually hazier.

It is common for these midpoints to be disorienting—many people get antsy; start spinning their wheels; and lose sight of why they started a project in the first place. Perhaps the most infamous midpoint is the mid-life crisis. An obscure Canadian psychoanalyst named Elliott Jaques coined the term in 1965 in an essay that raised the question of why a number of prolific artists like Mozart, Raphael, van Gogh and other notables died at the age of thirty-seven—sometimes quite tragically. Jaques concluded that when people reach their life’s midpoint, they experience a period of depression as they face their mortality with fresh eyes. The two paths that people take are to accept their fate, or run and hide from it by indulging in extravagant distractions.

The so-called midlife crisis has become an entrenched cultural convention, but research is now showing a pattern that’s far less dramatic than many have come to believe. Studies have shown that sense of wellbeing does dip around middle age, but this is far from the precipitous plunge that Jaques (and now pop culture) has detailed. Across cultures, continents, social and economic strata, the pattern is the same: a soft U-shaped curve that declines over the thirties and forties but then rebounds from fifty onward. In fact, life satisfaction is generally higher among octogenarians than among college students.

Whether the curve is shallow or steep, however, it still affects us—not just over a lifespan, but in smaller projects and life events as well. Halfway through just about anything we start, zeal dips at the midpoint. Why does this slump take place?

Some theorize that it’s fear of unfulfilled hopes and expectations. Others offer a more social explanation—that we want people to think well of us, so we try hard to make good first and final impressions, but to sustain it is impossible.

Whatever the explanation, it seems that in all these instances there’s something mysterious that overtakes us and hijacks our autonomy. The half-time lull is a virtual inevitability, but we don’t need to view the outcomes of the lull in a fatalistic light.

The midpoint can be a slump, but it can also be transformed into an invigorating spark. Your best shot at making a comeback is to view midpoints as “uh-oh” moments rather than “oh, no” moments. The first is a wake-up call; the second is surrender.

The mental alarm bells that go off are not the death knell but a call to action. Use the stress to your advantage. Studies show that the period of time immediately following that midpoint alarm is often the most productive. When that alarm goes off, pretend (though maybe you won’t have to pretend) that you’re a bit behind—but not by much. This will generate the spark to up your game instead of up and run away.

Timing matters not only for individuals but also for groups. Learning how to make the most of beginnings, midpoints, and endings is critical; but so many facets of life require coordination and cooperation with others. Far from an obstacle, this process of syncing with groups is essential to surviving and thriving as humans.

There is a “high” that comes from being synced with others. Activities that can foster the sync are singing with a choir, running with others, dancing, doing yoga or cooking with friends. The tremendous physical benefits of some of these are obvious enough. Running provides exercise, socializing and keeping pace with your fellow runners. Yoga increases control of breath, which helps with hormone and stress regulation. Studies have even found surprising physical benefits to singing in a choir, such as a relaxed heart rate, an uptick in endorphins, increased immunity, even lessening the effects of irritable bowel syndrome.

The psychological benefits of syncing activities are also significant. They help provide a sense of belonging to a tribe, where individual identities are healed and enriched, where people feel connected to something bigger than themselves. Doing something together (and learning to do it well) also contributes to positive mood and alleviation of depression. To build in-group rapport, respond to messages promptly, share stories of personal hardship and develop unique group customs. Adding special garb, insignia, codes and affirming physical touch all help strengthen group bonds.

These insights are just an introduction. If you're ready to dive deeper, pick up a copy of When: The Scientific Secrets of Perfect Timing here. And since we get a commission on every sale, your purchase will help keep this newsletter free.