When: The Scientific Secrets of Perfect Timing(13)

Flat on the operating room table is a twenty-something man with a smashed jaw badly in need of repair. On a nearby wall is a large-screen television with the names of the five other people in hospital greens—nurses, physicians, a technician—who surround the table. At the top of the screen, in maize letters against a blue background, is the patient’s name. The surgeon, an intense, wiry man in his thirties, is itching to begin. But before anybody does anything, as if this team were playing college basketball at the school’s Crisler Center two miles away, they call a time-out.

Almost imperceptibly, each person takes one step backward. Then, looking at either the big screen or a wallet-size plastic card hanging from their waists, they introduce themselves to one another by first name and proceed through a nine-step “Pre-Induction Verification” checklist that ensures they’ve got the right patient, know his condition and any allergies, understand the medications the anesthesiologist will use, and have any special equipment they might need. When everyone is finished introducing themselves and all the questions are answered—the whole process takes about three minutes—the time-out ends and the young anesthesia resident cracks open supplies from sealed pouches to begin to put the patient, already partly sedated, fully to sleep. It’s not easy. The patient’s jaw is in such dreadful condition, the resident must intubate him through the nose instead of the mouth, which proves vexing. Tremper, who has the long, slender fingers of a pianist, steps in and steers the tube into the nasal cavity and down the patient’s throat. Soon the patient is out, his vital signs are stable, and the surgery can begin.

Then the team steps back from the operating table once again.

Each person reviews the steps on the “Pre-Incision Time Out” card to make sure everyone is prepared. They regain their individual and collective focus. And only then does everyone step back to the operating table and the surgeon begins repairing the jaw.



I 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.


Afternoons are the Bermuda Triangles of our days. Across many domains, the trough represents a danger zone for productivity, ethics, and health. Anesthesia is one example. Researchers at Duke Medical Center reviewed about 90,000 surgeries at the hospital and identified what they called “anesthetic adverse events”—either mistakes anesthesiologists made, harm they caused to patients, or both. The trough was especially treacherous. Adverse events were significantly “more frequent for cases starting during the 3 p.m. and 4 p.m. hours.” The probability of a problem at 9 a.m. was about 1 percent. At 4 p.m., 4.2 percent. In other words, the chance of something going awry while someone is delivering drugs to knock you unconscious was four times greater during the trough than during the peak. On actual harm (not only a slipup but also something that hurts the patient), the probability at 8 a.m. was 0.3 percent—three-tenths of one percent. But at 3 p.m., the probability was 1 percent—one in every one hundred cases, a threefold increase. Afternoon circadian lows, the researchers concluded, impair physician vigilance and “affect human performance of complex tasks such as those required in anesthesia care.”1

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.3 What’s more, other research has shown that doctors are significantly less likely even to fully complete a colonoscopy when they perform it in the afternoon.4

Basic health care also suffers when its practitioners sail into the day’s Bermuda Triangle. Doctors, for example, are much more likely to prescribe antibiotics, including unnecessary ones, for acute respiratory infections in the afternoons than in the mornings.5 As the cumulative effect of dealing with patient after patient saps doctors’ decision-making resolve, it’s far easier just to write the scrip than suss out whether the patient’s symptoms suggest a bacterial infection, for which antibiotics might be appropriate, or a virus, for which they’d have no effect.

We expect important encounters with experienced professionals like physicians to turn on who is the patient and what is the problem. But many outcomes depend even more forcefully on when is the appointment.

What’s going on is a decline in vigilance. In 2015, Hengchen Dai, Katherine Milkman, David Hoffman, and Bradley Staats led a massive study of handwashing at nearly three dozen U.S. hospitals. Using data from sanitizer dispensers equipped with radio frequency identification (RFID) to communicate with RFID chips on employee badges, researchers could monitor who washed their hands and who didn’t. 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.6