On Monday, PepsiCo CEO Indra Nooyi announced that she was going to step down after a remarkable 12-year-run as the company's visionary leader.
Nooyi is, in some ways, the antithesis of what we might picture an American CEO to be: She is a woman, a mother, an Indian-American, a charismatic persona who pushed a company peddling sugar and junk food into healthy territory rather than doubling down on the brand's trademark claim to fame.
But Nooyi is surprisingly similar to her fellow CEOs on the S&P 500 in one critical way: She runs on just four hours of sleep per night in order to extract as much productivity out of the finite 24 hours handed to her every day. As The Atlantic noted in a piece marking Nooyi’s departure from the already tiny group of female S&P 500 executives, “One of the habits for which Indra Nooyi is most admired is that she wakes up at four o’clock in the morning and works until midnight.”
She's certainly not the only one to brag about her four hour sleep schedule: Virgin CEO Richard Branson, Yahoo! head Marissa Mayer, and President Donald Trump all have noted in public that they sleep three, four, maybe five hours at best.
So who are these four hour sleepers? And how do they work?
Ying-Hui Fu is a biologist and geneticist at the University of California, San Francisco who has spent her career studying "short sleepers," or people who are capable of sleeping for very short periods of time—and actually being able to operate cogently and healthily.
Fu said that she can't comment on Nooyi or other CEOs who claim to be able to sleep for four hours a night without interviewing and studying them. But she said that there certainly are people who can sleep four to six hours a night "and function well, very well, and live a long and healthy life."
Much of that comes down to genetics—but sleep research is frustratingly unsure about exactly how or what creates unique sleep patterns in human beings. "We don't know how sleep is regulated, we don't know why we need eight hours of sleep, we don't know why we need sleep for a long, healthy life," she said. "We have some idea of the function of sleep, and it regenerates cells. What I hope to do is understand how our sleep is regulated and relieve those problems for people who have insomnia or to help people sleep more efficiently."
Fu's research has shown that those who are genetically able to sleep just four hours a day are surprisingly... normal.
"They are very optimistic and energetic," Fu ticked off. "They do very well and live a long life." The characteristics might seem surprising given they flip every single stereotype we might have about people who don't get enough sleep.
Fu said that while it's true that some people can train themselves to survive on four hours of sleep, most of us aren't genetically programmed to actually do well on four hours of sleep. She uses herself as an example. "I need eight hours of sleep but I don't consistently get eight hours of sleep, so I try to do six," she said, mirroring a problem many of us struggle with daily. "After two weeks, my cognitive function is 70 percent and that might affect me. I might not live a long time. [Lack of sleep] might cause diseases. If you are truly not a natural short sleeper, not sleeping can be a big problem."
But science doesn't back up the claims that so many CEOs claim to be just as effective and healthy getting just a few hours of sleep every night.
David Dinges is chief in the division of sleep and chronobiology at the University of Pennsylvania and has studied limited sleep cycles extensively. In particular, his laboratory studies how sleep cycles and circadian rhythms affect human behavior.
Dinges thinks that the brigade of CEOs claiming their surviving—and thriving—on four hours of sleep is a whole bunch of hooey. That's because his experiments on healthy adults who have reduced their sleep intake clearly show that it can't be the case.
"We've looked at hundreds of people in various experiments," Dinges told The Daily Beast. "These people live in the laboratory for a week, two weeks." From these experiments, Dinges has learned how restricting sleep purposely can affect not only our performance but our baseline health.
One of his frequent experiments look at healthy adults who are randomized into one of four sleeping groups: those who got eight hours of sleep a night, six hours of sleep a night, four hours of sleep a night (like our CEOs), and (horrifically) no sleep for 72 to 80 hours.
These subjects are measured physiologically, cognitively, and medically, with constant supervision. Dinges said that the subjects are all healthy, normal people who are screened to make sure they reflect the average person—middle of the road sleepers, as it were. "We looked at their cognitive functioning and moods and physiology," Dinges said.
His team found that, almost universally, less sleep made a person not only cranky but also a bit slower on basic tasks. The lucky eight hours of sleep group "showed minimal to no deficits across days"—they were able to perform memory and cognitive tasks quite well over the course of several days, no problem.
But the eight hour group isn't the interesting group. The ones that are the groups who were restricted on their sleep. One might think the first group, the six hour one, would do fairly comparable to the eight hours of sleep a night group. After all, they're just losing a couple hours of sleep a night, right? If the average American's sleeping patterns are any indication, then the six hour sleepers are the ones to keep an eye on.
Dinges' study results showed clearly and resoundingly that six hours of sleep definitely affects alertness and function. Those 120 minutes of lost shuteye means that while the six hour snoozers were able to operate for about five to seven days, they started to get progressively worse. Your body, it seems, can handle a few days of restricted sleep and bounce back fine, but a string of these make for worse performance.
Those four hour sleepers? Even worse—they made the six hour group look fresh and revitalized in comparison. "They showed deficits almost immediately," Dinges said. "They just went off the scale. They became very, very impaired and had trouble being vigilant and thinking fast."
Dinges' research showed that it wasn't just the lost hours of sleep that affected the four hours of sleep, but rather the quality of sleep they were getting. "We measured their sleep physiologically, and there's only slow wave sleep."
Dinges is referring here to the five stages of sleep that humans cycle through in a normal night. Stage 1 occurs right when a person is falling asleep, still a bit aware of the outside world; Stage 2 is a little bit deeper, where the sleeper is less likely to be awakened. And then there's Stages 3 and 4, the deepest stages of sleep, referred to as "slow wave sleep." That's when the sleeper is very difficult to awaken and reaps the deepest, most intense benefits of sleep—cleansing of the mind, revitalization of cells, and that inexplicable, joyful feeling of having a good night's rest that very few people ever claim to have but surprises you with delight after an especially restful night of Stage 3 and 4 sleep.
What makes slow wave sleep that much more intriguing and important with relation to four hour sleepers is that it's in fact a highly restorative, key part of sleeping. If you're sleeping for four hours, you're probably not engaging in a lot of deep sleep; what's more, aging makes it difficult to reach that deep part of sleep, so you’re less likely to be able to reach that deeply restorative aspect of sleep without clocking in more hours.
"Fifty percent of sleep in Stage 2 doesn't have high voltage slow waves," Dinges continued. "At four hours, you're losing the more critical stages of sleep." With reduced sleep, the body is unable to go into the deeper, more restful Stage 2 sleep, where recovery to damaged cells and deep rest occurred. The brain, in particular, is unable to bounce back with just four hours of sleep, which is why so many of us feel so groggy with a night of almost no zzz's.
Dinges said that the experiment and their analysis showed one clear thing: The quality of the sleep affected the brain, and that quality was directly related to the amount of time a person was able to sleep. "It's not how much you sleep—it's how much you're awake," Dinges pointed out. "The price we pay for short sleep is biological and behavioral, and it's made worse by our not being alert.”
And if you thought that sleep debt was terrible at four hours, well, as you can imagine, people who didn't sleep at all for three days were "catastrophic," Dinges said.
That's perhaps not surprising, but what is and what should be noted is that having four hours of sleep was fairly similar in impairment level to getting no sleep for a few days. The CEO diet of sleep was almost the same in terms of functionality as just having no slept all.
Ok, you might think, maybe you can get trained into sleeping less and operating well? In Nooyi’s case, she was a receptionist from midnight through 5 a.m. while also attending Yale, and she’s allegedly stuck with that sleep schedule since.
It’s a good hypothesis, and one that makes sense and might work. But Dinges found that differences between hours of sleep—five versus four, for example—are incrementally small and still don't compare at all to a full night of sleep in the range of seven or eight hours. What's more is that differences in age, or having subjects return at different times of year, or repeating the process over and over again didn't seem to affect the baseline result.
Simply put, if you don't sleep around eight hours a night, there are significant, detrimental effects to alertness and functioning.
"It's not that some people are resistant to the effects of this," Dinges said. "It's the same response."
There's surely a bit of a genetic component at play here. Researchers have long been fascinated by a group of people who are known as elite sleepers, or those who are seemingly capable of sidestepping these negative side effects of a reduced amount of sleep but are healthy and alert. Not only that, these elite sleepers seem incapable of sleeping more than a few hours a night.
That's perhaps the key point here in how sleep might differ between elite sleepers and those who sleep a restricted schedule of four hours a night, though: While four hour sleepers would probably be rewarded mentally and physically by the longer snooze time, the elite sleepers just don't seem to match the case. Elite sleepers are most alert at night because their circadian rhythms seem to have an almost vampiric quality to them. Four hour sleepers can't do that.
Fu has hypothesized in her work that some of it might come down to a single protein that somehow functions differently from that of "normal" sleepers and makes them want to sleep less than the normal amount others might.
That's key. These short sleepers just can't sleep more than a few hours a night. It’s not that they want to sleep less, they simply cannot do so.
That's in opposition to those who actively restrict their sleeping schedule but physically desire more hours in bed. There's evidence that short sellers might run in families, Fu said, though demographic differences don't seem to exist, which makes tracking who is more likely to be a short sleeper and who is not is difficult.
What's more is that the mutation for short sleepers doesn't necessarily actually show. "Even if you have the mutation [for short sleep], if you don't take care of yourself or you hurt yourself in some way, that mutation might not manifest," Fu said. "It's a complicated state."
But elite sleepers are far and few between, and almost none of us can claim to be an elite sleeper.
Dinges has another hypothesis: The 4-hour CEO sleep legend is one that is heavily hedged with naps. He said that he's seen this with others who claim they sleep less than they actually do. Just look at this Bureau of Labor Statistics fact sheet, which shows Americans actually admit to sleeping more than they might say. "When we track them with devices or study them with prolonged conditions, you see that they actually nap throughout the day," he said. "If you get a nap in, even for a few minutes, you're getting a bit more than what you're getting at night. The important thing is to look at all the sleep people get."
It's certainly possible that at least some of the CEOs are elite sleepers, but statistically, realistically, that's probably not the case. As Dinges said, the boasting of how little sleep we get is "sleep braggadocio," a sort of way to not-so-subtly hint to others that sleeping is a waste of time, and that CEOs are somehow capable of wringing the same amount of rest into a shorter amount of time.
That's simply, scientifically untrue.
This "sleep braggadocio," as Dinges refers to it, is toxic. CEOs routinely boast the limited winks they get per night, a sort of sleep dick contest meant to showcase how powerful and capable a person is able to be on the least amount of sleep. And that's dangerous. The fact that Nooyi is “admired” for sleeping on a four hour sleep schedule and has restricted her sleep to be able to establish herself as one of America’s groundbreaking business leaders causes pause. Perhaps Nooyi is an elite sleeper, and without medical testing, that sort of assumption is next to impossible to prove.
Rather, the idea that a person who must sleep four hours a night and slip it in conversation to prove that, yes, she is capable of being a tough, visionary leader of a major global brand is disheartening and problematic. With Nooyi, in particular, the bragging rights to a four hour sleep schedule is one that is especially damaging for women, who often carry the load of childcare and housework. Granted, people at a similarly high level in their careers almost always have help: nannies to watch kids, cooks to prepare meals, maids to clean. Suggesting that four hours of sleep is necessary to success implies productivity at all times, that sleep is somehow a waste of the precious 24 hours we’re given in a day. That's toxic.
Which couldn’t be further from the truth, ironically. Unless you’re magically programmed to be an elite sleeper, sleep is far from a waste of time, and scientists are increasingly showing evidence that spending about one-third of your day horizontal with your eyes shut and lost in a series of slow wave sleep cycles could possibly be the best thing for your health and productivity. In a world where we are constantly required to do something for our health—Move for at least 30 minutes a day! Eat a lot of vegetables! Avoid sugar and fat!—perhaps the best, easiest thing we can do to amplify our productivity is to actually do nothing at all and fall asleep.
That’s, of course increasingly difficult with a work schedule that is fuzzy thanks to email allowing employees and their bosses to be in touch all day, globalization, and workplace aids like Slack that stack pings on top of the other pings from various apps that are nagging you about a meeting, a project to work on, a dinner you have to go to, a task to finish.
There’s a movement to stop making short sleep schedules sexy. Arianna Huffington wrote a book called The Sleep Revolution; the wellness and self-care movements have emphasized sleep’s regenerative, “natural” role in health; and Silicon Valley notoriously operates on a delayed schedule, with techie CEOs sleeping in and advocating for nap rooms. But sleep often slips into becoming a synonym for lazy or lax, with workers darkly repeating, “I’ll sleep when I’m dead.”
The thing is, not sleeping will cause death—along with reduced productivity, strained relationships, feeling like crap, and more. Simply put, the best way to be a productive CEO is actually the easiest: Go to sleep—for eight hours.