CHAPTER THREE
Cause Three: The Rise of Physical and Mental Exhaustion
The first thing I heard when I opened my eyes was the sound of the ocean lapping in the distance. Then I felt the sun flooding my bed, bathing me in light. Every morning in Provincetown, when this happened, I felt something strange in my body. It took me more than a month to realize what it was.
Ever since I went through puberty, I’d thought of sleep as something I wrestled myself into and fought my way out of. I would go to bed sometime between one and three in the morning and immediately bunch up the pillows so they supported my hunched shoulders. Then I would try to stop my mind jangling as it ran through all the things that had happened that day, and all the things I would need to do when I woke up, and all the things to worry about in the world. To take my mind off this internal electrical storm, I’d usually watch a noisy TV show on my laptop. Sometimes that would lull me to sleep, but more often, it would awaken a new wave of anxious energy, and I would start emailing or researching again for another few hours. Finally, on most nights, I would power down by taking a few melatonin gummies, and finally pass out.
Once I was in Zimbabwe and I spoke to some rangers who—as part of their jobs—had to knock out rhinos in order to give them medical treatment. They explained that they did it by darting them with a very powerful tranquilizer. As they described how the rhinos would stagger about in a panicked funk and then crash to the ground, I thought, hey, that’s my sleep routine too.
After my chemical crash, I would be woken up six or seven hours later by a tag team of loud alarms. First, a radio alarm playing the BBC World Service would jolt me with the horrors of the day’s news; then ten minutes later my phone would play a loud clanging alert; ten minutes after that another alarm clock would howl. When my ability to out-sleep all three finally wore off, I would stagger to my feet and immediately douse myself with enough caffeine to kill a small herd of cows. I lived on the permanent cliff-edge of exhaustion.
In Provincetown, when night fell, I would return to my little rooms to find there was no noise to rouse me and no portal to let in the wider world. I would go to lie in my bedroom, where the only source of light was a small reading lamp next to a pile of books. I would lie there reading and feel the paroxysms of the day slowly wend their way out of my body as I gently eased out of consciousness. I realized I had left my melatonin unused in the bathroom cabinet.
One day I woke up without any alarms after sleeping for nine hours and realized that I didn’t want any coffee. This was such an alien sensation that it made me stop for a moment and stand there in my boxer shorts in the kitchen in front of the unboiling kettle, staring at it. Then it finally occurred to me what I was feeling—I had awoken from my sleep feeling fully refreshed. My body didn’t feel heavy. I was alert. As the weeks passed, I realized that I felt like this every day now. The last time I remembered feeling like this was when I was a child.
For a long time, I had been trying to live by the rhythms of machines—going endlessly, day or night, until finally the battery conked out. Now I was living by the rhythm of the sun. As the sky went dark, I gradually wound down and finally rested, and when the sun came up, I woke naturally.
This was making something shift in my understanding of my body. I could see now it craved far more sleep than I normally allowed it, and when sleep came without any chemical nudging, my dreams were more vivid. It was as though my body and my mind were unclenching, and then replenishing.
I wondered if this was playing a role in why I was able to think more clearly, and for much longer stretches, than I had for years. I decided to explore the best scientific evidence about how the mysterious long stretches of unconsciousness our bodies crave—and that we so often deny them—might affect our ability to pay attention.
In 1981, in a lab in Boston, a young research scientist was keeping people awake all through the night and all through the following day, in long, yawn-strewn stretches. His job was to make sure they stayed conscious and, as he did it, to give them tasks to carry out. They had to add up numbers, and then sort cards into different groups, and then take part in memory tests. For example, he would show them a picture, then take it away, and ask: What color was the car in the picture I just showed you? Charles Czeisler—a tall, long-limbed man with wire-framed glasses and a deep voice—had, until this moment, never been interested in studying sleep. He had been taught in his medical training that when you are asleep, you are mentally “switched off.” This is how lots of us see sleep—as a purely passive process, a mental dead zone in which nothing of consequence happens. Who, he shrugged, would want to study switched-off people? He was researching something he thought was much more important—it was a technical investigation of what time of day certain specific hormones are released in the human body. This required keeping people awake.
But as the days and nights went on, Charles couldn’t help but notice something. When people are kept awake, “one of the first things to go is the ability to focus our attention,” he told me, in a teaching room at Harvard. He had been giving his test subjects really basic tasks, but with each hour that passed, they were losing their ability to carry them out. They couldn’t remember things he’d just told them or focus enough to play very simple card games. He told me: “I was just stunned by how performance would deteriorate. It’s one thing to say that the average performance on a memory task would be twenty percent worse, or thirty percent worse. But it’s another thing to say that your brain is so sluggish that is takes ten times longer for your brain to reply to something.” As people stayed awake, it seemed their ability to focus fell off a cliff. In fact, if you stay awake for nineteen hours straight, you become as cognitively impaired—as unable to focus and think clearly—as if you had gotten drunk. He found that when they were kept awake for one whole night and continued walking about the next day, instead of taking a quarter of a second to respond to a prompt, the participants in his experiment were taking four, five, or six seconds. “It’s kind of amazing,” he said.
Charles was intrigued. Why would this be? He switched to studying sleep, and over the next forty years he would go on to become one of the leading figures in the world on this question, making several key breakthroughs. He runs the unit on sleep problems at one of the major hospitals in Boston, teaches at Harvard Medical School, and advises everyone from the Boston Red Sox to the U.S. Secret Service. He came to believe that, as a society, we are currently getting sleep all wrong—and it is ruining our focus.
With each passing year, he warned, this has become more urgent. Today 40 percent of Americans are chronically sleep-deprived, getting less than the necessary minimum of seven hours a night. In Britain, an incredible 23 percent are getting less than five hours a night. Only 15 percent of us wake up from our sleep feeling refreshed. This is new. Since 1942, the average amount of time a person sleeps has been slashed by an hour a night. Over the past century, the average child has lost eighty-five minutes of sleep every night. There’s a scientific debate about the precise scale of our sleep loss, but the National Sleep Foundation has calculated that the amount of sleep we get has dropped by 20 percent in just a hundred years.
One day Charles had an idea. He wondered if, when you are tired, you begin to experience what he called “attentional blinks.” This is where, initially for just a fraction of a second, you lose your ability to pay attention. To see if this is true, he started to study both alert and tired people using sophisticated technology that can track their eyes to see what they are focusing on—and at the same time, it can also scan your brain, to see what is happening there. He discovered something remarkable. As you become tired, your attention will indeed blink out, for a simple reason. People think you’re either awake or asleep, he told me, but he found that even if your eyes are open and you are looking around you, you can lapse—without knowing it—into a state called “local sleep.” This is where “part of the brain is awake, and part of the brain is asleep.” (It’s called local sleep because the sleep is local to one part of the brain.) In this state, you believe you are alert and mentally competent—but you aren’t. You are sitting at your desk and you look awake, but parts of your brain are asleep, and you are not able to think in a sustained way. When he studied people in this state, he found “amazingly, sometimes their eyes were open, but they couldn’t see what was in front of them.”
The effects of sleep deprivation, Charles found, are especially terrible for children. Adults usually respond by becoming drowsy, but kids usually respond by becoming hyperactive. He said: “We’re chronically sleep-depriving them, so it’s no shock they’re exhibiting all the symptoms of sleep deficiency—the first and foremost of which is the [in]ability to pay attention.”
There has now been a lot of scientific investigation into this, and there’s a broad scientific consensus that if you sleep less, your attention will likely suffer. I went to the University of Minneapolis to interview professor of neuroscience and psychology Roxanne Prichard, who has produced some cutting-edge work on these questions. When she started teaching college students full-time in 2004, the first thing that struck her, she told me, was “how just exhausted young adults were.” They would often fall asleep the moment the lecture-theater lights were dimmed, and they were visibly struggling to stay awake and focused on anything. She began to study how much sleep they were getting. She discovered that on average, a typical student has the same sleep quality as an active-duty soldier or a parent of a newborn baby. As a result, the majority of them were “constantly fighting off this drive to sleep…. They’re not able to access their neural resources.”
She decided to teach them the science of why their bodies need sleep—but she found herself in a strange position. The students knew they were bone-tired, but “the problem is—they’ve been accustomed to that since puberty, basically.” They have seen their parents and grandparents chronically sleep-depriving themselves too. “They’ve grown up being accustomed to being exhausted and trying to medicate that away [with caffeine or other stimulants] as a state of normal. So I’m fighting against a current that says it’s normal to be exhausted all the time.” She started to show them some experiments. You can test the time it takes for a person to react to something—a picture that changes on a screen, say, or a ball that’s thrown to them. “The people with the quickest reaction times are the ones sleeping the most,” she shows them—and the less they sleep, the less they see or react. This is just one way, of many, that shows that “you are more efficient when you are rested—that it takes you less time to do things. That you don’t need to have six screens or tabs open when you’re doing your homework just to keep yourself awake.”
At first, when I talked with Charles and Roxanne and other sleep experts, I thought, yes, this is bad, but they are talking about really exhausted people, an outlying group of the truly knackered. But they kept explaining to me that it only takes a small amount of sleep loss for these negative effects to kick in. Roxanne showed me that if you stay awake for eighteen hours—so you woke up at 6 a.m. and went to sleep at midnight—by the end of the day, your reactions are equivalent to if you had 0.05 percent blood alcohol. She said: “Stay up another three hours, and you’re [the equivalent of being] legally drunk.” Charles explained: “Many people say, ‘Well, I don’t stay up all night, so I’m fine,’ but in fact, if you miss a couple of hours of sleep every night and you do this night after night, within a week or two, you’re at the same level of performance and impairment as you would be staying up all night. Everybody falls apart with two nights of missed sleep—or you can get to that same point by sleeping four or five hours a night and going for a couple of weeks.” As he said this, I remembered: 40 percent of us live on the brink of that.
“If you’re not sleeping well, your body interprets that as an emergency,” Roxanne said. “You can deprive yourself of sleep and live. We could never raise children if we couldn’t drop down on our sleep, right? We’d never survive hurricanes. You can do that—but it comes at a cost. The cost is [that] your body shifts into the sympathetic nervous system zone—so your body is like, ‘Uh-oh, you’re depriving yourself of sleep, must be an emergency, so I’m going to make all these physiological changes to prepare yourself for that emergency. Raise your blood pressure. I’m going to make you want more fast food, I’m going to make you want more sugar for quick energy. I’m going to make your heart-rate [rise].’…So it’s like all this shifts, to say—I’m ready.” Your body doesn’t know why it’s staying awake. “Your brain doesn’t know you’re sleep-deprived because you’re goofing off and watching Schitt’s Creek, right? It doesn’t know why you’re not sleeping—but the net effect is a physiological sort of alarm bell.”
In this bodily emergency, your brain doesn’t just cut back on immediate short-term focus. It cuts off resources to other longer-term forms of focus too. When we sleep, our minds start to identify connections and patterns from what we’ve experienced during the day. This is one of the key sources of our creativity—it’s why narcoleptic people, who sleep a lot, are significantly more creative. Sleep deprivation damages memory as well. When you go to bed tonight, your mind will start to transfer the things you have learned during the day into your long-term memory. Xavier Castellanos, who I interviewed at New York University, where he is a professor of child and adolescent psychiatry, explained to me that you can get rats to learn a maze, and that night, you can monitor what happens in their brains as they sleep. What you find is that they are retracing their steps in the maze, one by one, encoding them into their long-term memory. The less you sleep, the less this happens, and the less you will be able to recall.
These effects are especially powerful for children. If you deprive kids of sleep, they begin to show attention problems rapidly, and often go into a manic state.
For years I believed I could cheat my way into getting all the benefits of proper sleep through technical fixes. The most obvious is caffeine. I once heard an almost certainly apocryphal story about Elvis—that in the last years of his life, his doctor would wake him up by injecting caffeine directly into his veins. When I heard this, I didn’t think: How awful. I thought: Where’s that doctor been all my life? For years I reasoned—okay, I don’t sleep enough, but I make up for it with coffee, Coke Zero, and Red Bull. But Roxanne explained to me what I was really doing when I drank all this. Throughout the day, in your brain, a chemical called adenosine is building up, and it signals to you when you are sleepy. Caffeine blocks the receptor that picks up on the level of adenosine. “I liken it to putting a Post-it note over your fuel-gauge indicator. You’re not giving yourself more energy—you’re just not realizing how empty you are. When the caffeine wears off, you’re doubly exhausted.”
The less you sleep, the more the world blurs in every way—in your immediate focus, in your ability to think deeply and make connections, and in your memory. Charles told me that even if nothing else were changing in our society, this decline in how much we sleep is on its own enough to prove that our crisis in focusing and paying attention is real. “It’s very sad to watch this play out and not be able to stop this,” he said. “It’s like watching a crash that’s happening.”
Every expert I spoke to said this transformation explains, in part, our declining attention. Dr. Sandra Kooij is one of the leading experts on adult ADHD in Europe, and when I went to interview her in The Hague, she told me bluntly: “Our Western society is a bit ADHD-ish because we’re all sleep-deprived…. It’s huge. And it means something for us. So we’re all in a hurry, we’re all impulsive, we’re easily irritated in traffic. You see it everywhere around you…. This has been studied and proven in laboratories: you think you’re thinking clearly, but you’re not. You’re much less clear than you could be.” She added that “when we sleep better, a lot of problems get less—like mood disorders, like obesity, like concentration problems…. It repairs a lot of damage.”
As I learned all this, I had some obvious questions. The first was—why does our lack of sleep damage our ability to focus so much? Surprisingly, this is a relatively new research question. Roxanne told me: “In 1998, when I chose [the subject of sleep] to focus on for my dissertation, there wasn’t a lot of research on what sleep was for. We knew what it was and we all do it…and it’s kind of mysterious. You’re spending a third of your life unconscious, not engaging with the world…. It was just this mystery—it seems like a waste of resources.”
Charles had been told when he was a young man there was no point studying sleep because it’s a passive process—but in fact, he learned, sleep is an incredibly active process. When you go to sleep, all sorts of activities take place in your brain and body—and these are necessary for you to be able to function and focus. One of the things that happens is that during sleep, your brain cleans itself of waste that has accumulated during the day. “During slow-wave sleep, your cerebral spinal fluid channels open up more and remove metabolic waste from your brain,” Roxanne explained to me. Every night, when you go to sleep, your brain is rinsed with a watery fluid. This cerebrospinal fluid washes through your brain, flushing out toxic proteins and carrying them down to your liver to get rid of them. “So when I’m talking to college students, I call this brain-cell poop. If you can’t focus well, it might be you have too much brain-cell poop circulating.” That can explain why, when you are tired, “you get a hung-over sort of feeling”—you are literally clogged up with toxins.
This positive kind of brainwashing can only happen when you are asleep. Dr. Maiken Nedergaard, at the University of Rochester, told one interviewer: “The brain only has limited energy at its disposal, and it appears that it must choose between two different functional states—awake and aware, or asleep and cleaning up. You can think of it as like having a house party. You can either entertain the guests or clean up the house, but you can’t really do both at the same time.” A brain that hasn’t been through this necessary cleaning process becomes more clogged and less able to concentrate. Some scientists suspect this is why people who are under-slept are at greater risk, in the long term, of developing dementia. When you are sleeping, Roxanne says, “you’re repairing.”
Another thing that happens during sleep is that your energy levels are restored and replenished. Charles told me that “the prefrontal cortex is the judgment area of the brain, and that seems to be particularly sensitive to sleep loss…. You see that, with even one night of sleep loss, that area of the brain is just not utilizing glucose, which is the main energy source of the brain. It’s sort of going stone-cold.” Without renewing your sources of energy, you can’t think clearly.
But for me, the most intriguing process that happens when we sleep is that we dream—and this, I learned, also performs an important function. I went to Montreal to interview Tore Nielsen, who is a professor of psychiatry there. He often tells people he has a “dream job” and asks them to guess what it is. After they’ve run through the list—racing-car driver? chocolate-taster?—he tells them: he runs the Dream Lab at the University of Montreal. He told me that some scientists in the field believe that “dreaming somehow helps you to adapt emotionally to waking events.” When you dream, you can revisit stressful moments, but without stress hormones flooding your system. Over time, those scientists believe, this can make it easier to handle stress—which we know makes it easier to focus. Tore emphasizes that there seems to be some evidence supporting this theory and some contradicting it, and we need to know more to be sure.
But if it is correct, then we have a problem—because as a society, we are dreaming less and less. Dreams occur most during the stage known as rapid eye movement (REM) sleep. Tore told me: “The longest and most intense REM periods are the ones that occur toward the seven- or eight-hour mark of the sleep cycle. So if you’re curtailing your sleep down to five or six hours, chances are good that you’re not getting those long, intense REM periods.” As he said this, I wondered: What does it mean to be a society and culture so frantic that we don’t have time to dream?
As we find ourselves wired and unable to sleep, more and more of us are turning to drugs to knock ourselves out—whether it’s melatonin or alcohol or Ambien. Nine million Americans—4 percent of adults—are using prescription sleeping pills, and vastly more are using over-the-counter sleep aids, like I did for many years. But Roxanne told me bluntly: “If you chemically induce sleep, it’s not the same kind of sleep.” Remember—sleep is an active process, in which your brain and body do lots of things. Many of these things don’t happen, or happen far less, in drugged or drunk sleep. The different ways of artificially inducing sleep can have different effects. If you take five milligrams of melatonin—which is often a standard dose that’s sold over the counter in the U.S.—Roxanne said you risk “blowing out your melatonin receptors,” which would make it harder to sleep without them.
Bigger effects kick in with the harder stuff. Of Ambien and the other prescribed sedatives, she warns: “Sleep is a really important balance of many, many neurotransmitters, and if you artificially…pump up one, it changes the balance of that sleep.” You will likely have less REM sleep, and fewer dreams, and so you lose all the benefits that come from this crucial stage. You are likely to be groggy throughout the day—which is why sleeping pills increase your risk of death from all causes; you’re more likely to get into a car accident, for example. “If you’ve ever had surgery and recovered from that, like coming off anesthesia,” Roxanne said, you don’t say, “Oh, I feel so refreshed.” Knocking yourself out is like taking a minor anesthetic. Your body doesn’t rest and clean and refresh and dream like it needs to.
Roxanne told me that there are some legitimate uses for sleeping pills—for example, taking them for a short time after you’ve had a traumatic bereavement might be sensible. But she warned, “It’s definitely not the solution for insomnia,” and that’s why doctors are not supposed to prescribe them over the long term.
It’s a sign of how dysfunctional we have become when it comes to sleep that the people who should be warning us most about this crisis—doctors—are in fact required to become sleep-deprived to get their qualifications. As part of their medical training, doctors have to do grueling twenty-four-hour shifts on call—they nickname it “doing a Jack Bauer,” after the TV show 24, where Kiefer Sutherland can’t sleep because he’s chasing terrorists. This endangers their patients. But we have become a culture where even the people who should know best about sleep fetishize staying sleepless beyond the point of reason, just like the rest of us.
The second question I found myself asking was: Given that lack of sleep is so harmful, and at some level we all know it, why are we doing it less? Why would we give up on one of our most basic needs?
There’s a big scientific debate about this, and several factors seem to be having an effect. Some are going to come up later in this book. One of them—unexpectedly—is our relationship with physical light. Charles made some of the key breakthroughs on this. Until the nineteenth century, the lives of almost all humans were shaped primarily by the rise and fall of the sun. Our natural rhythms evolved to match it—we would get a rush of energy when it got light, and we would feel sleepy after it got dark. For almost all of human history, our ability to intervene in this cycle was pretty limited—we could light fires, but that was it. As a result, humans evolved to be as sensitive to changes of light, Charles says, as algae and cockroaches. But suddenly, with the invention of the electric lightbulb, we gained the power to control the light we are exposed to—and this power has started to scramble our internal rhythms.
Here’s a clear example. We evolved to get a rush of energy—a “surge of waking drive,” Charles says—when the sun began to set. This was very helpful to our ancestors. Imagine you’re out camping, and the sun starts to fall—it’s very useful if you then feel a rush of wakefulness, because then you’ll be able to set up your tent before it’s too dark to do it. In the same way, our ancestors got a fresh rush of energy just as the light waned so they could safely get back to their tribe and finish the things they needed to do that day. But now we control the light. We decide when sunset happens. So if we keep bright lights switched on right until the moment we decide to go to sleep, or we watch TV on our phones in bed, when we switch them off we accidentally trigger a physical process—our bodies think this sudden waning of the light is the arrival of sunset, so they release a rush of fresh energy to help you get back to your cave.
“Now this surge of waking drive, instead of happening at three or four o’clock in the afternoon before the sun sets at six, is now happening at ten, eleven, midnight,” Charles says. “You have the surge of waking energy at the time you’re deciding whether to go to sleep. Now you get up in the morning; you feel like you’re going to die. You swear to God that you’re going to get more sleep the next day, but you’re not tired the next evening,” because you’ve watched more TV on your laptop in bed, and triggered the same process all over again. “The surge is very powerful, and so people are like, ‘I’m fine,’ and the morning is a blur that they’ve forgotten.” Charles believes that—as he said to another interviewer—“every time we turn on a light, we are inadvertently taking a drug that affects how we will sleep.” This goes on day after day. “That’s a major contributing factor to this epidemic of sleep deficiency—because we’re exposing ourselves to light later and later,” he explained. Indeed, 90 percent of Americans look at a glowing electronic device in the hour before they go to bed—triggering precisely this process. We are now exposed to ten times the amount of artificial light that people were exposed to just fifty years ago.
I wondered if one of the reasons why I slept so much better on Cape Cod was because I returned to something closer to this natural rhythm. When the sun sets on Provincetown, the town gets much darker, and by my beach house there was almost no artificial light, barely even a streetlamp. The orange haze of air pollution that lights up the sky in every place I have ever lived was gone, and there was only the gentle light of the moon and the stars.
But Charles told me you can only really understand our crisis of sleep if you understand it in a much bigger context. At first glance, he says, what we are doing is crazy: “We wouldn’t deprive children of nutrition. We wouldn’t think of doing that. Why are we depriving them of sleep?” But it makes a dark kind of sense when you see it as part of a broader picture. In a society dominated by the values of consumer capitalism, “sleep is a big problem,” he told me. “If you’re asleep, you’re not spending money, so you’re not consuming anything. You’re not producing any products.” He explained that “during the last recession [in 2008]…they talked about global output going down by so many percent, and consumption going down. But if everybody were to spend [an] extra hour sleeping [as they did in the past], they wouldn’t be on Amazon. They wouldn’t be buying things.” If we went back to sleeping a healthy amount—if everyone did what I did in Provincetown—Charles said, “it would be an earthquake for our economic system, because our economic system has become dependent on sleep-depriving people. The attentional failures are just roadkill. That’s just the cost of doing business.” I only really understood how significant this point was toward the end of writing this book.
All this leads to one last big question about sleep—how do we solve this crisis? There are several layers to the solution. The first is personal and individual. As Charles explains, you need to radically limit your exposure to light before you go to sleep. He believes you should have no sources of artificial light in your bedroom at all, and you should avoid the blue light of screens for at least two hours before you go to bed.
We also need, all the sleep experts told me, to have different relationships with our phones. Roxanne told me that to lots of us, “it’s like your baby, right? So as a new parent, you’re like—I’ve got to be vigilant for this thing. I’ve got to pay attention. I’m not sleeping as deeply. Or you are like a firefighter who’s listening for a call.” We’re constantly a little tensed to see: “Did something happen?” She says your phone should always recharge overnight in a different room, where you can’t see or hear it. Then you need to make sure your room is the right temperature—it should be cool, almost cold. This is because your body needs to cool its core to send you to sleep, and the harder that is, the longer it takes.
These are helpful (and relatively well-known) tips—but, as every expert I spoke to acknowledged, they are not enough for most people. We live in a culture that is constantly amping us up with stress and stimulation. You can tell people all this, and explain the health benefits of a good long night in bed, and they will agree, and then they say, “Do you want me to list everything I need to do in the next twenty-four hours? And you want me to spend nine hours sleeping too?”
As I learned about several of the things we need to do to improve our focus, I realized that we live in an apparent paradox. Many of the things we need to do are so obvious they are banal: slow down, do one thing at a time, sleep more. But even though at some level we all know them to be true, we are in fact moving in the opposite direction: toward more speed, more switching, less sleep. We live in a gap between what we know we should do and what we feel we can do. The key questions, then, are: What’s causing that gap? Why can’t we do the obvious things that would improve our attention? What forces are stopping us? I spent a large part of the rest of my journey uncovering the answers.