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Notes from 'Why We Sleep'

I first read Why We Sleep: Unlocking the Power of Sleep and Dreams about two years ago. It immediately led me to prioritize sleep over almost everything else.

Most of us don’t get enough sleep, and are worse for it. Usually when the topic of sleep comes up, I say

Hey, there’s this great book I read on sleep. You should read it, and then sleep more…

The people most in need of more sleep are also usually the people most unable to make time to read a book about sleep. So, here’s an effort to help these people save time, prioritize sleep, and then maybe give the book a read anyway.

I hope to use this post to accomplish two things:

  1. Convince you that sleep is massively important and you should sleep more
  2. Convince you to read the book. If you find anything below compelling, you’ll find it even more compelling if you read the whole book yourself.

Everything that follows is a quote from Why We Sleep.

If I add my own comments, they’ll be inline and italicized, like this:

Josh: here’s a comment I’m adding

Index

I’ve quoted from this book, extensively. I don’t recommend reading this post top-to-bottom, but rather jumping around the post, from this following index, to a section that looks interesting, then going back to the top, jumping to a different section, etc.

Quotes from Why We Sleep:

Two-thirds of adults throughout all developed nations fail to obtain the recommended eight hours of nightly sleep.


This is the grab-bag of negative impacts on sleeping too little. From the first chapter. The author expands on all of these points later in the book.

  • Routinely sleeping less than six or seven hours a night demolishes your immune system, more than doubling your risk of cancer.
  • Insufficient sleep is a key lifestyle factor determining whether or not you will develop Alzheimer’s disease.
  • Inadequate sleep — even moderate reductions for just one week — disrupts blood sugar levels so profoundly that you would be classified as pre-diabetic.
  • Short sleeping increases the likelihood of your coronary arteries becoming blocked and brittle, setting you on a path toward cardiovascular disease, stroke, and congestive heart failure.
  • Fitting Charlotte Brontë’s prophetic wisdom that “a ruffled mind makes a restless pillow,” sleep disruption further contributes to all major psychiatric conditions, including depression, anxiety, and suicidality.
  • Perhaps you have also noticed a desire to eat more when you’re tired? This is no coincidence. Too little sleep swells concentrations of a hormone that makes you feel hungry while suppressing a companion hormone that otherwise signals food satisfaction. Despite being full, you still want to eat more. It’s a proven recipe for weight gain in sleep-deficient adults and children alike.
  • Worse, should you attempt to diet but don’t get enough sleep while doing so, it is futile, since most of the weight you lose will come from lean body mass, not fat.

Add the above health consequences up, and a proven link becomes easier to accept: the shorter your sleep, the shorter your life span.

The old maxim “I’ll sleep when I’m dead” is therefore unfortunate. Adopt this mind-set, and you will be dead sooner and the quality of that (shorter) life will be worse.


But can we go so far as to say that a lack of sleep can kill you outright? Actually, yes…[one way sleep deprivation can kill you] is the deadly circumstance of getting behind the wheel of a motor vehicle without having had sufficient sleep.

Drowsy driving is the cause of hundreds of thousands of traffic accidents and fatalities each year.

And here, it is not only the life of the sleep-deprived individuals that is at risk, but the lives of those around them.

Tragically, one person dies in a traffic accident every hour in the United States due to a fatigue-related error.

It is disquieting to learn that vehicular accidents caused by drowsy driving exceed those caused by alcohol and drugs combined.

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Don’t let people shame you with the ‘early to bed early to rise’ concept.

Some people can go to bed early and wake up early. Others cannot. It’s not a moral issue, it’s genetics.

An adult’s owlness or larkness, also known as their chronotype, is strongly determined by genetics.

If you are a night owl, it’s likely that one (or both) of your parents is a night owl.

Sadly, society treats night owls rather unfairly on two counts.

First is the label of being lazy, based on a night owl’s wont to wake up later in the day, due to the fact that they did not fall asleep until the early-morning hours.

Others (usually morning larks) will chastise night owls on the erroneous assumption that such preferences are a choice, and if they were not so slovenly, they could easily wake up early.

However, night owls are not owls by choice. They are bound to a delayed schedule by unavoidable DNA hardwiring. It is not their conscious fault, but rather their genetic fate.

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How does caffeine work?

It fills adenosine receptors in the brain, preventing actual adenosine from getting in. This masks the sleep-stimulating effect of adenosine

Caffeine works by successfully battling with adenosine for the privilege of latching on to adenosine welcome sites—or receptors—in the brain. Once caffeine occupies these receptors, however, it does not stimulate them like adenosine, making you sleepy. Rather, caffeine blocks and effectively inactivates the receptors, acting as a masking agent.


Best practice might be to refrain from caffeine anytime after the mid-morning.

What is problematic [about caffeine] is the persistence of caffeine in your system. In pharmacology, we use the term “half-life” when discussing a drug’s efficacy. This simply refers to the length of time it takes for the body to remove 50 percent of a drug’s concentration.

Caffeine has an average half-life of five to seven hours. Let’s say that you have a cup of coffee after your evening dinner, around 7:30 p.m. This means that by 1:30 a.m., 50 percent of that caffeine may still be active and circulating throughout your brain tissue. In other words, by 1:30 a.m., you’re only halfway to completing the job of cleansing your brain of the caffeine you drank after dinner.

There’s nothing benign about that 50 percent mark, either. Half a shot of caffeine is still plenty powerful, and much more decomposition work lies ahead throughout the night before caffeine disappears.

Sleep will not come easily or be smooth throughout the night as your brain continues its battle against the opposing force of caffeine. Most people do not realize how long it takes to overcome a single dose of caffeine, and therefore fail to make the link between the bad night of sleep we wake from in the morning and the cup of coffee we had ten hours earlier with dinner.

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Lots of folks think they’re getting enough sleep

Here’s a starting point to evaluate that statement

Am I getting enough sleep?

Setting aside the extreme case of sleep deprivation, how do you know whether you’re routinely getting enough sleep? While a clinical sleep assessment is needed to thoroughly address this issue, an easy rule of thumb is to answer two simple questions.

First, after waking up in the morning, could you fall back asleep at ten or eleven a.m.?

If the answer is “yes,” you are likely not getting sufficient sleep quantity and/or quality.

Second, can you function optimally without caffeine before noon?

If the answer is “no,” then you are most likely self-medicating your state of chronic sleep deprivation.

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Sleep as an aid to learn new things

This is particularly relevant to Turing students

Sleep has proven itself time and again as a memory aid: both before learning, to prepare your brain for initially making new memories, and after learning, to cement those memories and prevent forgetting.


The author explains the methodology of many sleep-and-memory-related studies. I’ll include the high points for you.

Later that day, at six p.m., all participants performed another round of intensive learning where they tried to cram yet another set of new facts into their short-term storage reservoirs (another one hundred face-name pairs).

Our question was simple:

Does the learning capacity of the human brain decline with continued time awake across the day and, if so, can sleep reverse this saturation effect and thus restore learning ability?

Those who were awake throughout the day became progressively worse at learning, even though their ability to concentrate remained stable (determined by separate attention and response time tests).

In contrast, those who napped did markedly better, and actually improved in their capacity to memorize facts. The difference between the two groups at six p.m. was not small: a 20 percent learning advantage for those who slept.

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On Sleep the night after learning

The second benefit of sleep for memory comes after learning, one that effectively clicks the “save” button on those newly created files.

In doing so, sleep protects newly acquired information, affording immunity against forgetting: an operation called consolidation…

The experimental results of Jenkins and Dallenbach have now been replicated time and again, with a memory retention benefit of between 20 and 40 percent being offered by sleep, compared to the same amount of time awake.

This is not a trivial concept when you consider the potential advantages in the context of studying for an exam, for instance, or evolutionarily, in remembering survival-relevant information such as the sources of food and water and locations of mates and predators.


Using MRI scans, we have since looked deep into the brains of participants to see where those memories are being retrieved from before sleep relative to after sleep.

It turns out that those information packets were being recalled from very different geographical locations within the brain at the two different times.

Before having slept, participants were fetching memories from the short-term storage site of the hippocampus - that temporary warehouse, which is a vulnerable place to live for any long duration of time if you are a new memory.

But things looked very different by the next morning. The memories had moved.

After the full night of sleep, participants were now retrieving that same information from the neocortex, which sits at the top of the brain - a region that serves as the long-term storage site for fact-based memories, where they can now live safely, perhaps in perpetuity.

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The benefits of sleep to forget things

Up to this point, we have discussed the power of sleep after learning to enhance remembering and avoid forgetting.

However, the capacity to forget can, in certain contexts, be as important as the need for remembering, both in day-to-day life (e.g., forgetting last week’s parking spot in preference for today’s) and clinically (e.g., in excising painful, disabling memories, or in extinguishing craving in addiction disorders).

Moreover, forgetting is not just beneficial to delete stored information we no longer need.

It also lowers the brain resources required for retrieving those memories we want to retain, similar to the ease of finding important documents on a neatly organized, clutter-free desk. In this way, sleep helps you retain everything you need and nothing that you don’t, improving the ease of memory recollection.

Said another way, forgetting is the price we pay for remembering.


sleep helps us remember what we want, and clears out memories of unimportant or painful events

The results were clear. Sleep powerfully, yet very selectively, boosted the retention of those words previously tagged for “remembering,” yet actively avoided the strengthening of those memories tagged for “forgetting.” Participants who did not sleep showed no such impressive parsing and differential saving of the memories.

We had learned a subtle, but important, lesson: sleep was far more intelligent than we had once imagined.

Counter to earlier assumptions in the twentieth and twenty-first centuries, sleep does not offer a general, nonspecific (and hence verbose) preservation of all the information you learn during the day.

Instead, sleep is able to offer a far more discerning hand in memory improvement: one that preferentially picks and chooses what information is, and is not, ultimately strengthened.

Sleep accomplishes this by using meaningful tags that have been hung onto those memories during initial learning, or potentially identified during sleep itself.

Numerous studies have shown a similarly intelligent form of sleep-dependent memory selection across both daytime naps and a full night of sleep.

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Sleep for learning complex and novel skills, like typing, piano, etc

The term “muscle memory” is a misnomer.

Muscles themselves have no such memory: a muscle that is not connected to a brain cannot perform any skilled actions, nor does a muscle store skilled routines.

Muscle memory is, in fact, brain memory.

Training and strengthening muscles can help you better execute a skilled memory routine, but the routine itself — the memory program — resides firmly and exclusively within the brain.

Years before I explored the effects of sleep on fact-based, textbook-like learning, I examined motor skill memory.

[A] transformative experience happened some years later while I was obtaining my PhD. It was 2000, and the scientific community had proclaimed that the next ten years would be “The Decade of the Brain,” forecasting (accurately, as it turned out) what would be remarkable progress within the neurosciences.

I had been asked to give a public lecture on the topic of sleep at a celebratory event… After my lecture, a distinguished-looking gentleman with a kindly affect, dressed in a tweed suit jacket with a subtle yellow-green hue that I still vividly recall to this day, approached me.

It was a brief conversation, but one of the most scientifically important of my life.

He thanked me for the presentation, and told me that he was a pianist. He said he was intrigued by my description of sleep as an active brain state, one in which we may review and even strengthen those things we have previously learned.

Then came a comment that would leave me reeling, and trigger a major focus of my research for years to come.

“As a pianist,” he said, “I have an experience that seems far too frequent to be chance. I will be practicing a particular piece, even late into the evening, and I cannot seem to master it. Often, I make the same mistake at the same place in a particular movement. I go to bed frustrated. But when I wake up the next morning and sit back down at the piano, I can just play, perfectly.”

“I can just play.”

The words reverberated in my mind as I tried to compose a response. I told the gentleman that it was a fascinating idea, and it was certainly possible that sleep assisted musicianship and led to error-free performance, but that I knew of no scientific evidence to support the claim.

He smiled, seeming unfazed by the absence of empirical affirmation, thanked me again for my lecture, and walked toward the reception hall.

I, on the other hand, remained in the auditorium, realizing that this gentleman had just told me something that violated the most repeated and entrusted teaching edict: practice makes perfect.

Not so, it seemed.

Perhaps it was practice, with sleep, that makes perfect?

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Studies and evidence for sleep leading to mastery of difficult material

The author goes into the studies he did to determine the effects of sleep on “finishing” the work that’s begun with deliberate practice

I took a large group of right-handed individuals and had them learn to type a number sequence on a keyboard with their left hand, such as 4-1-3-2-4, as quickly and as accurately as possible.

Like learning a piano scale, subjects practiced the motor skill sequence over and over again, for a total of twelve minutes, taking short breaks throughout.

Unsurprisingly, the participants improved in their performance across the training session; practice, after all, is supposed to make perfect.

We then tested the participants twelve hours later. Half of the participants had learned the sequence in the morning and were tested later that evening after remaining awake across the day. The other half of the subjects learned the sequence in the evening and we retested them the next morning after a similar twelve-hour delay, but one that contained a full eight-hour night of sleep.

Those who remained awake across the day showed no evidence of a significant improvement in performance.

However, fitting with the pianist’s original description, those who were tested after the very same time delay of twelve hours, but that spanned a night of sleep, showed a striking 20 percent jump in performance speed and a near 35 percent improvement in accuracy.

Importantly, those participants who learned the motor skill in the morning—and who showed no improvement that evening—did go on to show an identical bump up in performance when retested after a further twelve hours, now after they, too, had had a full night’s sleep.

In other words, your brain will continue to improve skill memories in the absence of any further practice. It is really quite magical. Yet, that delayed, “offline” learning occurs exclusively across a period of sleep, and not across equivalent time periods spent awake, regardless of whether the time awake or time asleep comes first.

Practice does not make perfect. It is practice, followed by a night of sleep, that leads to perfection.

We went on to show that these memory-boosting benefits occur no matter whether you learn a short or a very long motor sequence (e.g., 4-3-1-2 versus 4-2-3-4-2-3-1-4-3-4-1-4), or when using one hand (unimanual) or both (bimanual, similar to a pianist).

Analyzing the individual elements of the motor sequence, such as 4-1-3-2-4, allowed me to discover how, precisely, sleep was perfecting skill.

Even after a long period of initial training, participants would consistently struggle with particular transitions within the sequence. These problem points stuck out like a sore thumb when I looked at the speed of the keystrokes.

There would be a far longer pause, or consistent error, at specific transitions.

For example, rather than seamlessly typing 4-1-3-2-4, 4-1-3-2-4, a participant would instead type: 4-1-3 [pause] 2-4, 4-1-3 [pause] 2-4.

They were chunking the motor routine into pieces, as if attempting the sequences all in one go was just too much.

Different people had different pause problems at different points in the routine, but almost all people had one or two of these difficulties. I assessed so many participants that I could actually tell where their unique difficulties in the motor routine were just by listening to their typing during training.

When I tested participants after a night of sleep, however, my ears heard something very different.

I knew what was happening even before I analyzed the data: mastery. Their typing, post-sleep, was now fluid and unbroken. Gone was the staccato performance, replaced by seamless automaticity, which is the ultimate goal of motor learning: 4-1-3-2-4, 4-1-3-2-4, 4-1-3-2-4, rapid and nearly perfect.

Sleep had systematically identified where the difficult transitions were in the motor memory and smoothed them out.

This finding rekindled the words of the pianist I’d met: “but when I wake up the next morning and sit back down at the piano, I can just play, perfectly.”

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What do you lose, if you “chop off” the last hour or two of your planned sleep time?

My final discovery, in what spanned almost a decade of research, identified the type of sleep responsible for the overnight motor-skill enhancement, carrying with it societal and medical lessons.

The increases in speed and accuracy, underpinned by efficient automaticity, were directly related to the amount of stage 2 NREM, especially in the last two hours of an eight-hour night of sleep (e.g., from five to seven a.m., should you have fallen asleep at eleven p.m.).

Indeed, it was the number of those wonderful sleep spindles in the last two hours of the late morning — the time of night with the richest spindle bursts of brainwave activity — that were linked with the offline memory boost.

More striking was the fact that the increase of these spindles after learning was detected only in regions of the scalp that sit above the motor cortex (just in front of the crown of your head), and not in other areas. The greater the local increase in sleep spindles over the part of the brain we had forced to learn the motor skill exhaustively, the better the performance upon awakening.

Many other groups have found a similar “local-sleep”-and-learning effect. When it comes to motor-skill memories, the brainwaves of sleep were acting like a good masseuse—you still get a full body massage, but they will place special focus on areas of the body that need the most help. In the same way, sleep spindles bathe all parts of the brain, but a disproportionate emphasis will be placed on those parts of the brain that have been worked hardest with learning during the day.

Perhaps more relevant to the modern world is the time-of-night effect we discovered.

Those last two hours of sleep are precisely the window that many of us feel it is okay to cut short to get a jump start on the day. As a result, we miss out on this feast of late-morning sleep spindles.

It also brings to mind the prototypical Olympic coach who stoically has her athletes practicing late into the day, only to have them wake in the early hours of the morning and return to practice.

In doing so, coaches may be innocently but effectively denying an important phase of motor memory development within the brain — one that fine-tunes skilled athletic performance.

When you consider that very small performance differences often separate winning a gold medal from a last-place finish in professional athletics, then any competitive advantage you can gain, such as that naturally offered by sleep, can help determine whether or not you will hear your national anthem echo around the stadium.

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Sleep and physical performance

I back up these claims with examples from the more than 750 scientific studies that have investigated the relationship between sleep and human performance, many of which have studied professional and elite athletes specifically.

Obtain anything less than eight hours of sleep a night, and especially less than six hours a night, and the following happens:

  • time to physical exhaustion drops by 10 to 30 percent, and aerobic output is significantly reduced.
  • Similar impairments are observed in limb extension force and vertical jump height, together with decreases in peak and sustained muscle strength.

Add to this marked impairments in cardiovascular, metabolic, and respiratory capabilities that hamper an underslept body, including faster rates of lactic acid buildup, reductions in blood oxygen saturation, and converse increases in blood carbon dioxide, due in part to a reduction in the amount of air that the lungs can expire.

Even the ability of the body to cool itself during physical exertion through sweating — a critical part of peak performance — is impaired by sleep loss.


Even teams that are aware of sleep’s importance before a game are surprised by my declaration of the equally, if not more, essential need for sleep in the days after a game.

Post-performance sleep accelerates physical recovery from common inflammation, stimulates muscle repair, and helps restock cellular energy in the form of glucose and glycogen.

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Sleep deprivation and driving

One brain function that buckles under even the smallest dose of sleep deprivation is concentration.

The deadly societal consequences of these concentration failures play out most obviously and fatally in the form of drowsy driving.

Every hour, someone dies in a traffic accident in the US due to a fatigue-related error.

There are two main culprits of drowsy-driving accidents:

The first is people completely falling asleep at the wheel. This happens infrequently, however, and usually requires an individual to be acutely sleep-deprived (having gone without shut-eye for twenty-plus hours).

The second, more common cause is a momentary lapse in concentration, called a microsleep. These last for just a few seconds, during which time the eyelid will either partially or fully close.

They are usually suffered by individuals who are chronically sleep restricted, defined as getting less than seven hours of sleep a night on a routine basis.

During a microsleep, your brain becomes blind to the outside world for a brief moment—and not just the visual domain, but in all channels of perception.

Most of the time you have no awareness of the event. More problematic is that your decisive control of motor actions, such as those necessary for operating a steering wheel or a brake pedal, will momentarily cease.

As a result, you don’t need to fall asleep for ten to fifteen seconds to die while driving.

Two seconds will do it. A two-second microsleep at 30 mph with a modest angle of drift can result in your vehicle transitioning entirely from one lane to the next. This includes into oncoming traffic. Should this happen at 60 mph, it may be the last microsleep you ever have.

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We underestimate your sleep-deprivation-induced performance disability

“I’m not sleep deprived”, you say. “Besides, even if I am sleep deprived, I’m still OK at doing what I need to “do.

The third key finding, common to both of these studies, is the one I personally think is the most harmful of all.

When participants were asked about their subjective sense of how impaired they were, they consistently underestimated their degree of performance disability.

It was a miserable predictor of how bad their performance actually, objectively was.

It is the equivalent of someone at a bar who has had far too many drinks picking up his car keys and confidently telling you, “I’m fine to drive home.”

Similarly problematic is baseline resetting.

With chronic sleep restriction over months or years, an individual will actually acclimate to their impaired performance, lower alertness, and reduced energy levels.

That low-level exhaustion becomes their accepted norm, or baseline. Individuals fail to recognize how their perennial state of sleep deficiency has come to compromise their mental aptitude and physical vitality, including the slow accumulation of ill health.

A link between the former and latter is rarely made in their mind. Based on epidemiological studies of average sleep time, millions of individuals unwittingly spend years of their life in a sub-optimal state of psychological and physiological functioning, never maximizing their potential of mind or body due to their blind persistence in sleeping too little.

Sixty years of scientific research prevent me from accepting anyone who tells me that he or she can “get by on just four or five hours of sleep a night just fine.”

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Driving while sleep deprived is about as bad as driving drunk

Sleep deprivation is about the same as being legally drunk. If you’d consider it unethical to get drunk and drive, or drunk while working, or drunk while trying to work through a hard conversation with your significant other, consider getting more sleep

In a disturbing later study, researchers in Australia took two groups of healthy adults, one of whom they got drunk to the legal driving limit (.08 percent blood alcohol), the other of whom they sleep-deprived for a single night.

Both groups performed the concentration test to assess attention performance, specifically the number of lapses.

After being awake for nineteen hours, people who were sleep-deprived were as cognitively impaired as those who were legally drunk.

Said another way, if you wake up at seven a.m. and remain awake throughout the day, then go out socializing with friends until late that evening, yet drink no alcohol whatsoever, by the time you are driving home at two a.m. you are as cognitively impaired in your ability to attend to the road and what is around you as a legally drunk driver.

In fact, participants in the above study started their nosedive in performance after just fifteen hours of being awake (ten p.m. in the above scenario).

Drunk driving and drowsy driving are deadly propositions in their own right, but what happens when someone combines them?

It is a relevant question, since most individuals are driving drunk in the early-morning hours rather than in the middle of the day, meaning that most drunk drivers are also sleep-deprived.

We can now monitor driver error in a realistic but safe way using driving simulators.

With such a virtual machine, a group of researchers examined the number of complete off-road deviations in participants placed under four different experimental conditions:

(1) eight hours of sleep (2) four hours of sleep (3) eight hours of sleep plus alcohol to the point of being legally drunk (4) four hours of sleep plus alcohol to the point of being legally drunk

Those in the eight-hour sleep group had few, if any, off-road errors.

Those in the four-hour sleep condition (the second group) had six times more off-road deviations than the sober, well-rested individuals.

The same degree of driving impairment was true of the third group, who had eight hours of sleep but were legally drunk.

Driving drunk or driving drowsy were both dangerous, and equally dangerous.

A reasonable expectation was that performance in the fourth group of participants would reflect the additive impact of these two groups: four hours of sleep plus the effect of alcohol (i.e., twelve times more off-road deviations). It was far worse.

This group of participants drove off the road almost thirty times more than the well-rested, sober group.

The heady cocktail of sleep loss and alcohol was not additive, but instead multiplicative.

They magnified each other, like two drugs whose effects are harmful by themselves but, when taken together, interact to produce truly dire consequences.


This coming week, more than 2 million people in the US will fall asleep while driving their motor vehicle.

That’s more than 250,000 every day, with more such events during the week than weekends for obvious reasons. More than 56 million Americans admit to struggling to stay awake at the wheel of a car each month.

As a result, 1.2 million accidents are caused by sleepiness each year in the United States.

Said another way: for every thirty seconds you’ve been reading this book, there has been a car accident somewhere in the US caused by sleeplessness.

It is more than probable that someone has lost their life in a fatigue-related car accident during the time you have been reading this chapter.

You may find it surprising to learn that vehicle accidents caused by drowsy driving exceed those caused by alcohol and drugs combined.

Drowsy driving alone is worse than driving drunk.

That may seem like a controversial or irresponsible thing to say, and I do not wish to trivialize the lamentable act of drunk driving by any means.

Yet my statement is true for the following simple reason: drunk drivers are often late in braking, and late in making evasive maneuvers.

But when you fall asleep, or have a microsleep, you stop reacting altogether.

A person who experiences a microsleep or who has fallen asleep at the wheel does not brake at all, nor do they make any attempt to avoid the accident. As a result, car crashes caused by drowsiness tend to be far more deadly than those caused by alcohol or drugs. Said crassly, when you fall asleep at the wheel of your car on a freeway, there is now a one-ton missile traveling at 65 miles per hour, and no one is in control.

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Sleep and emotions

Many of us know that inadequate sleep plays havoc with our emotions. We even recognize it in others.

Consider another common scenario of a parent holding a young child who is screaming or crying and, in the midst of the turmoil, turns to you and says, “Well, Steven just didn’t get enough sleep last night.”

Universal parental wisdom knows that bad sleep the night before leads to a bad mood and emotional reactivity the next day…

Analysis of the brain scans revealed the largest effects I have measured in my research to date. A structure located in the left and right sides of the brain, called the amygdala — a key hot spot for triggering strong emotions such as anger and rage, and linked to the fight-or-flight response — showed well over a 60 percent amplification in emotional reactivity in the participants who were sleep-deprived.

In contrast, the brain scans of those individuals who were given a full night’s sleep evinced a controlled, modest degree of reactivity in the amygdala, despite viewing the very same images.

It was as though, without sleep, our brain reverts to a primitive pattern of uncontrolled reactivity.

We produce unmetered, inappropriate emotional reactions, and are unable to place events into a broader or considered context.

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Sleep and Substance Abuse

Sleep disturbance is a recognized hallmark associated with addictive substance use.

Insufficient sleep also determines relapse rates in numerous addiction disorders, associated with reward cravings that are unmetered, lacking control from the rational head office of the brain’s prefrontal cortex.

Relevant from a prevention standpoint, insufficient sleep during childhood significantly predicts early onset of drug and alcohol use in that same child during their later adolescent years, even when controlling for other high-risk traits, such as anxiety, attention deficits, and parental history of drug use.

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Sleep and Alzheimers

Around the same time that we were conducting our studies, Dr. Maiken Nedergaard at the University of Rochester made one of the most spectacular discoveries in the field of sleep research in recent decades.

Working with mice, Nedergaard found that a kind of sewage network called the glymphatic system exists within the brain. Its name is derived from the body’s equivalent lymphatic system, but it’s composed of cells called glia (from the Greek root word for “glue”).

Glial cells are distributed throughout your entire brain, situated side by side with the neurons that generate the electrical impulses of your brain.

Just as the lymphatic system drains contaminants from your body, the glymphatic system collects and removes dangerous metabolic contaminants generated by the hard work performed by neurons in your brain, rather like a support team surrounding an elite athlete.

Although the glymphatic system — the support team — is somewhat active during the day, Nedergaard and her team discovered that it is during sleep that this neural sanitization work kicks into high gear.

Associated with the pulsing rhythm of deep NREM sleep comes a ten- to twentyfold increase in effluent expulsion from the brain.

In what can be described as a nighttime power cleanse, the purifying work of the glymphatic system is accomplished by cerebrospinal fluid that bathes the brain.

Nedergaard made a second astonishing discovery, which explained why the cerebrospinal fluid is so effective in flushing out metabolic debris at night.

The glial cells of the brain were shrinking in size by up to 60 percent during NREM sleep, enlarging the space around the neurons and allowing the cerebrospinal fluid to proficiently clean out the metabolic refuse left by the day’s neural activity.

Think of the buildings of a large metropolitan city physically shrinking at night, allowing municipal cleaning crews easy access to pick up garbage strewn in the streets, followed by a good pressure-jet treatment of every nook and cranny.

When we wake each morning, our brains can once again function efficiently thanks to this deep cleansing.

So what does this have to do with Alzheimer’s disease? One piece of toxic debris evacuated by the glymphatic system during sleep is amyloid protein—the poisonous element associated with Alzheimer’s disease.

Other dangerous metabolic waste elements that have links to Alzheimer’s disease are also removed by the cleaning process during sleep, including a protein called tau, as well as stress molecules produced by neurons when they combust energy and oxygen during the day.

Should you experimentally prevent a mouse from getting NREM sleep, keeping it awake instead, there is an immediate increase in amyloid deposits within the brain. Without sleep, an escalation of poisonous Alzheimer’s-related protein accumulated in the brains of the mice, together with several other toxic metabolites.

Phrased differently, and perhaps more simply, wakefulness is low-level brain damage, while sleep is neurological sanitation.

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From this cascade comes a prediction: getting too little sleep across the adult life span will significantly raise your risk of developing Alzheimer’s disease.

Precisely this relationship has now been reported in numerous epidemiological studies, including those individuals suffering from sleep disorders such as insomnia and sleep apnea.

Parenthetically, and unscientifically, I have always found it curious that Margaret Thatcher and Ronald Reagan — two heads of state that were very vocal, if not proud, about sleeping only four to five hours a night — both went on to develop the ruthless disease.

The current US president, Donald Trump — also a vociferous proclaimer of sleeping just a few hours each night — may want to take note.


Daylight Savings Time helps us see what a single-hour reduction in sleep brings about

In the Northern Hemisphere, the switch to daylight savings time in March results in most people losing an hour of sleep opportunity.

Should you tabulate millions of daily hospital records, as researchers have done, you discover that this seemingly trivial sleep reduction comes with a frightening spike in heart attacks the following day.

Impressively, it works both ways. In the autumn within the Northern Hemisphere, when the clocks move forward and we gain an hour of sleep opportunity time, rates of heart attacks plummet the day after.

A similar rise-and-fall relationship can be seen with the number of traffic accidents, proving that the brain, by way of attention lapses and microsleeps, is just as sensitive as the heart to very small perturbations of sleep.

Most people think nothing of losing an hour of sleep for a single night, believing it to be trivial and inconsequential. It is anything but.

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Sleep Deprivation and Insulin Resistence

insulin resistance as the root of metabolic syndrome (obesity, heart disease, etc is covered in great depth in The Case Against Sugar and Why We Get Fat)

By taking small tissue samples, or biopsies, from participants at the end of the above experiments, we can examine how the cells of the body are operating.

After participants had been restricted to four to five hours of sleep for a week, the cells of these tired individuals had become far less receptive to insulin.

In this sleep-deprived state, the cells were stubbornly resisting the message from insulin and refusing to open up their surface channels.

The cells were repelling rather than absorbing the dangerously high levels of glucose.

The roadside drains were effectively closed shut, leading to a rising tide of blood sugar and a pre-diabetic state of hyperglycemia.

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Sleep Deprivation and the Immune System

Prather retrospectively separated the participants into four sub-groups on the basis of how much sleep they had obtained in the week before being exposed to the common cold virus:

  • less than five hours of sleep
  • five to six hours of sleep
  • six to seven hours of sleep
  • seven or more hours of sleep

There was a clear, linear relationship with infection rate.

The less sleep an individual was getting in the week before facing the active common cold virus, the more likely it was that they would be infected and catch a cold. In those sleeping five hours on average, the infection rate was almost 50 percent. In those sleeping seven hours or more a night in the week prior, the infection rate was just 18 percent.

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Sleep and Emotional Intelligence

Having had a full night of sleep, which contained REM sleep, participants demonstrated a beautifully precise tuning curve of emotional face recognition, rather like a stretched out V shape.

When navigating the cornucopia of facial expressions we showed them inside the MRI scanner, their brains had no problem deftly separating one emotion from another across the delicately changing gradient, and the accuracy of their own ratings proved this to be similarly true.

It was effortless to disambiguate friendly and approachable signals from those intimating even minor threat as the emotional tide changed toward the foreboding. Confirming the importance of the dream state, the better the quality of REM sleep from one individual to the next across that rested night, the more precise the tuning within the emotional decoding networks of the brain the next day.

Through this platinum-grade nocturnal service, better REM-sleep quality at night provided superior comprehension of the social world the next day.

But when those same participants were deprived of sleep, including the essential influence of REM sleep, they could no longer distinguish one emotion from another with accuracy.

The tuning V of the brain had been changed, rudely pulled all the way up from the base and flattened into a horizontal line, as if the brain was in a state of generalized hypersensitivity without the ability to map gradations of emotional signals from the outside world…

By removing REM sleep, we had, quite literally, removed participants’ levelheaded ability to read the social world around them.

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Sleep and Creativity

Perhaps the most striking proof of sleep-inspired insight, and one I most frequently describe when giving talks to start-up, tech, or innovative business companies to help them prioritize employee sleep, comes from a study conducted by Dr. Ullrich Wagner at the University of Lübeck, Germany.

Trust me when I say you’d really rather not be a participant in these experiments.

Not because you have to suffer extreme sleep deprivation for days, but because you have to work through hundreds of miserably laborious number-string problems, almost like having to do long division for an hour or more.

Actually “laborious” is far too generous a description. It’s possible some people have lost the will to live while trying to sit and solve hundreds of these number problems!

I know, I’ve taken the test myself.

You will be told that you can work through these problems using specific rules that are provided at the start of the experiment.

Sneakily, what the researchers do not tell you about is the existence of a hidden rule, or shortcut, common across all the problems.

If you figure out this embedded cheat, you can solve many more problems in a far shorter time.

I’ll return to this shortcut in just a minute. After having had participants perform hundreds of these problems, they were to return twelve hours later and once again work through hundreds more of these mind-numbing problems.

However, at the end of this second test session, the researchers asked whether the subjects had cottoned on to the hidden rule.

Some of the participants spent that twelve-hour time delay awake across the day, while for others, that time window included a full eight-hour night of sleep.

After time spent awake across the day, despite the chance to consciously deliberate on the problem as much as they desired, a rather paltry 20 percent of participants were able to extract the embedded shortcut.

Things were very different for those participants who had obtained a full night of sleep—one dressed with late-morning, REM-rich slumber.

Almost 60 percent returned and had the “ah-ha!” moment of spotting the hidden cheat—which is a threefold difference in creative solution insight afforded by sleep!

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Insomnia

Other factors, however, come from within a person, and are innate biological causes of insomnia.

Noted in the clinical criteria described above, these factors cannot be a symptom of a disease (e.g., Parkinson’s disease) or a side effect of a medication (e.g., asthma medication).

Rather, the cause(s) of the sleep problem must stand alone in order for you to be primarily suffering from true insomnia. The two most common triggers of chronic insomnia are psychological:

(1) emotional concerns, or worry (2) emotional distress, or anxiety.

In this fast-paced, information-overloaded modern world, one of the few times that we stop our persistent informational consumption and inwardly reflect is when our heads hit the pillow.

There is no worse time to consciously do this. Little wonder that sleep becomes nearly impossible to initiate or maintain when the spinning cogs of our emotional minds start churning, anxiously worrying about things we did today, things that we forgot to do, things that we must face in the coming days, and even those far in the future.

That is no kind of invitation for beckoning the calm brainwaves of sleep into your brain, peacefully allowing you to drift off into a full night of restful slumber.

Since psychological distress is a principal instigator of insomnia, researchers have focused on examining the biological causes that underlie emotional turmoil.

One common culprit has become clear: an overactive sympathetic nervous system, which, as we have discussed in previous chapters, is the body’s aggravating fight-or-flight mechanism.

The sympathetic nervous system switches on in response to threat and acute stress that, in our evolutionary past, was required to mobilize a legitimate fight-or-flight response.

The physiological consequences are increased heart rate, blood flow, metabolic rate, the release of stress-negotiating chemicals such as cortisol, and increased brain activation, all of which are beneficial in the acute moment of true threat or danger.

However, the fight-or-flight response is not meant to be left in the “on” position for any prolonged period of time.

As we have already touched upon in earlier chapters, chronic activation of the flight-or-flight nervous system causes myriad health problems, one of which is now recognized to be insomnia.

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Light (specifically blue light, or light from screens) and sleep

stop looking at your phone right before going to bed. Please.

Compared to reading a printed book, reading on an iPad suppressed melatonin release by over 50 percent at night.

Indeed, iPad reading delayed the rise of melatonin by up to three hours, relative to the natural rise in these same individuals when reading a printed book.

When reading on the iPad, their melatonin peak, and thus instruction to sleep, did not occur until the early-morning hours, rather than before midnight.

Unsurprisingly, individuals took longer to fall asleep after iPad reading relative to print-copy reading.

But did reading on the iPad actually change sleep quantity/quality above and beyond the timing of melatonin?

It did, in three concerning ways.

  • First, individuals lost significant amounts of REM sleep following iPad reading.
  • Second, the research subjects felt less rested and sleepier throughout the day following iPad use at night.
  • Third was a lingering aftereffect, with participants suffering a ninety-minute lag in their evening rising melatonin levels for several days after iPad use ceased—almost like a digital hangover effect.

Using LED devices at night impacts our natural sleep rhythms, the quality of our sleep, and how alert we feel during the day.

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Sleep and Alcohol

I used to regularly have a glass of wine in the evenings, shortly before bed. I stopped doing that.

Give alcohol a little more time, and it begins to sedate other parts of the brain, dragging them down into a stupefied state, just like the prefrontal cortex.

You begin to feel sluggish as the inebriated torpor sets in. This is your brain slipping into sedation. Your desire and ability to remain conscious are decreasing, and you can let go of consciousness more easily.

I am very deliberately avoiding the term “sleep,” however, because sedation is not sleep.

Alcohol sedates you out of wakefulness, but it does not induce natural sleep.

The electrical brainwave state you enter via alcohol is not that of natural sleep; rather, it is akin to a light form of anesthesia.

Yet this is not the worst of it when considering the effects of the evening nightcap on your slumber.

More than its artificial sedating influence, alcohol dismantles an individual’s sleep in an additional two ways:

First, alcohol fragments sleep, littering the night with brief awakenings.

Alcohol-infused sleep is therefore not continuous and, as a result, not restorative. Unfortunately, most of these nighttime awakenings go unnoticed by the sleeper since they don’t remember them. Individuals therefore fail to link alcohol consumption the night before with feelings of next-day exhaustion caused by the undetected sleep disruption sandwiched in between. Keep an eye out for that coincidental relationship in yourself and/or others.

Second, alcohol is one of the most powerful suppressors of REM sleep that we know of.

When the body metabolizes alcohol it produces by-product chemicals called aldehydes and ketones. The aldehydes in particular will block the brain’s ability to generate REM sleep. It’s rather like the cerebral version of cardiac arrest, preventing the pulsating beat of brainwaves that otherwise power dream sleep.

People consuming even moderate amounts of alcohol in the afternoon and/or evening are thus depriving themselves of dream sleep…

You don’t have to be using alcohol to levels of abuse, however, to suffer its deleterious REM-sleep-disrupting consequences, as one study can attest.

Recall that one function of REM sleep is to aid in memory integration and association: the type of information processing required for developing grammatical rules in new language learning, or in synthesizing large sets of related facts into an interconnected whole.

To wit, researchers recruited a large group of college students for a seven-day study. The participants were assigned to one of three experimental conditions. On day 1, all the participants learned a novel, artificial grammar, rather like learning a new computer coding language or a new form of algebra. It was just the type of memory task that REM sleep is known to promote.

Everyone learned the new material to a high degree of proficiency on that first day—around 90 percent accuracy.

Then, a week later, the participants were tested to see how much of that information had been solidified by the six nights of intervening sleep.

What distinguished the three groups was the type of sleep they had.

In the first group — the control condition — participants were allowed to sleep naturally and fully for all intervening nights.

In the second group, the experimenters got the students a little drunk just before bed on the first night after daytime learning. They loaded up the participants with two to three shots of vodka mixed with orange juice, standardizing the specific blood alcohol amount on the basis of gender and body weight.

In the third group, they allowed the participants to sleep naturally on the first and even the second night after learning, and then got them similarly drunk before bed on night 3.

Note that all three groups learned the material on day 1 while sober, and were tested while sober on day 7.

This way, any difference in memory among the three groups could not be explained by the direct effects of alcohol on memory formation or later recall, but must be due to the disruption of the memory facilitation that occurred in between.

On day 7, participants in the control condition remembered everything they had originally learned, even showing an enhancement of abstraction and retention of knowledge relative to initial levels of learning, just as we’d expect from good sleep.

In contrast, those who had their sleep laced with alcohol on the first night after learning suffered what can conservatively be described as partial amnesia seven days later, forgetting more than 50 percent of all that original knowledge.

This fits well with evidence we discussed earlier: that of the brain’s non-negotiable requirement for sleep the first night after learning for the purposes of memory processing.

The real surprise came in the results of the third group of participants. Despite getting two full nights of natural sleep after initial learning, having their sleep doused with alcohol on the third night still resulted in almost the same degree of amnesia—40 percent of the knowledge they had worked so hard to establish on day 1 was forgotten.

The overnight work of REM sleep, which normally assimilates complex memory knowledge, had been interfered with by the alcohol.

More surprising, perhaps, was the realization that the brain is not done processing that knowledge after the first night of sleep.

Memories remain perilously vulnerable to any disruption of sleep (including that from alcohol) even up to three nights after learning, despite two full nights of natural sleep prior. Framed practically, let’s say that you are a student cramming for an exam on Monday.

Diligently, you study all of the previous Wednesday. Your friends beckon you to come out that night for drinks, but you know how important sleep is, so you decline.

On Thursday, friends again ask you to grab a few drinks in the evening, but to be safe, you turn them down and sleep soundly a second night.

Finally, Friday rolls around — now three nights after your learning session — and everyone is heading out for a party and drinks. Surely, after being so dedicated to slumber across the first two nights after learning, you can now cut loose, knowing those memories have been safely secured and fully processed within your memory banks.

Sadly, not so. Even now, alcohol consumption will wash away much of that which you learned and can abstract by blocking your REM sleep.

How long is it before those new memories are finally safe? We actually do not yet know, though we have studies under way that span many weeks. What we do know is that sleep has not finished tending to those newly planted memories by night 3.

I elicit audible groans when I present these findings to my undergraduates in lectures. The politically incorrect advice I would (of course never) give is this: go to the pub for a drink in the morning. That way, the alcohol will be out of your system before sleep.

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Sleep and Sleeping Pills

Most relevant, and a key focus of this chapter, is the (ab)use of prescription sleeping pills. Sleeping pills do not provide natural sleep, can damage health, and increase the risk of life-threatening diseases. We will explore the alternatives that exist for improving sleep and combating insipid insomnia.

No past or current sleeping medications on the legal (or illegal) market induce natural sleep.

Don’t get me wrong — no one would claim that you are awake after taking prescription sleeping pills. But to suggest that you are experiencing natural sleep would be an equally false assertion.

The older sleep medications — termed “sedative hypnotics,” such as diazepam — were blunt instruments. They sedated you rather than assisting you into sleep.

Understandably, many people mistake the former for the latter.

Most of the newer sleeping pills on the market present a similar situation, though they are slightly less heavy in their sedating effects.

Sleeping pills, old and new, target the same system in the brain that alcohol does — the receptors that stop your brain cells from firing — and are thus part of the same general class of drugs: sedatives.


If you compare natural, deep-sleep brainwave activity to that induced by modern-day sleeping pills, such as zolpidem (brand name Ambien) or eszopiclone (brand name Lunesta), the electrical signature, or quality, is deficient.

The electrical type of “sleep” these drugs produce is lacking in the largest, deepest brainwaves.

Adding to this state of affairs are a number of unwanted side effects, including next-day grogginess, daytime forgetfulness, performing actions at night of which you are not conscious (or at least have partial amnesia of in the morning), and slowed reaction times during the day that can impact motor skills, such as driving.

True even of the newer, shorter-acting sleeping pills on the market, these symptoms instigate a vicious cycle.

The waking grogginess can lead people to reach for more cups of coffee or tea to rev themselves up with caffeine throughout the day and evening.

That caffeine, in turn, makes it harder for the individual to fall asleep at night, worsening the insomnia. In response, people often take an extra half or whole sleeping pill at night to combat the caffeine, but this only amplifies the next-day grogginess from the drug hangover.

Even greater caffeine consumption then occurs, perpetuating the downward spiral.

Another deeply unpleasant feature of sleeping pills is rebound insomnia.

When individuals stop taking these medications, they frequently suffer far worse sleep, sometimes even worse than the poor sleep that led them to seek out sleeping pills to begin with.

The cause of rebound insomnia is a type of dependency in which the brain alters its balance of receptors as a reaction to the increased drug dose, trying to become somewhat less sensitive as a way of countering the foreign chemical within the brain. This is also known as drug tolerance.

But when the drug is stopped, there is a withdrawal process, part of which involves an unpleasant spike in insomnia severity.

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Sleeping Pills vs Placebos

A recent team of leading medical doctors and researchers examined all published studies to date on newer forms of sedative sleeping pills that most people take.

They considered sixty-five separate drug-placebo studies, encompassing almost 4,500 individuals.

Overall, participants subjectively felt they fell asleep faster and slept more soundly with fewer awakenings, relative to the placebo.

But that’s not what the actual sleep recordings showed.

There was no difference in how soundly the individuals slept. Both the placebo and the sleeping pills reduced the time it took people to fall asleep (between ten and thirty minutes), but the change was not statistically different between the two.

In other words, there was no objective benefit of these sleeping pills beyond that which a placebo offered.

Summarizing the findings, the committee stated that sleeping pills only produced “slight improvements in subjective and polysomnographic sleep latency”—that is, the time it takes to fall asleep.

The committee concluded the report by stating that the effect of current sleeping medications was “rather small and of questionable clinical importance.”

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Sleeping Pills and Damage to the Immune System

One frequent cause of mortality appears to be higher-than-normal rates of infection. Also discussed in earlier chapters, natural sleep is one of the most powerful boosters of the immune system, helping ward off infection.

Why, then, do individuals who are taking sleeping pills that purportedly “improve” sleep suffer higher rates of various infections, when the opposite is predicted?

It is possible that medication-induced sleep does not provide the same restorative immune benefits as natural sleep.

This would be most troubling for the elderly. Older adults are far more likely to suffer from infections. Alongside newborns, they are the most immunologically vulnerable individuals in our society.

Older adults are also the heaviest users of sleeping pills, representing more than 50 percent of the individuals prescribed such drugs.

Based on these coincidental facts, it may be time for medicine to reappraise the prescription frequency of sleeping pills in the elderly.

Another cause of death linked to sleeping pill use is an increased risk for fatal car accidents. This is most likely caused by the non-restorative sleep such drugs induce and/or the groggy hangover that some suffer, both of which may leave individuals drowsy while driving the next day.


Shouldn’t drug companies be more transparent about the current evidence and risks surrounding sleeping pill use?

Unfortunately, Big Pharma can be notoriously unbending within the arena of revised medical indications. This is especially true once a drug has been approved following basic safety assessments, and even more so when profit margins become exorbitant.

Consider that the original Star Wars movies—some of the highest-grossing films of all time — required more than forty years to amass $3 billion in revenue. It took Ambien just twenty-four months to amass $4 billion in sales profit, discounting the black market.

That’s a large number, and one I can only imagine influences Big Pharma decision-making at all levels.

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How, then, should one treat insomnia?

Currently, the most effective of these is called cognitive behavioral therapy for insomnia, or CBT-I, and it is rapidly being embraced by the medical community as the first-line treatment.

Working with a therapist for several weeks, patients are provided with a bespoke set of techniques intended to break bad sleep habits and address anxieties that have been inhibiting sleep.

CBT-I builds on basic sleep hygiene principles that I describe in the appendix, supplemented with methods individualized for the patient, their problems, and their lifestyle. Some are obvious, others not so obvious, and still others are counterintuitive.

The obvious methods involve reducing caffeine and alcohol intake, removing screen technology from the bedroom, and having a cool bedroom.

In addition, patients must (1) establish a regular bedtime and wake-up time, even on weekends, (2) go to bed only when sleepy and avoid sleeping on the couch early/mid-evenings, (3) never lie awake in bed for a significant time period; rather, get out of bed and do something quiet and relaxing until the urge to sleep returns, (4) avoid daytime napping if you are having difficulty sleeping at night, (5) reduce anxiety-provoking thoughts and worries by learning to mentally decelerate before bed, and (6) remove visible clockfaces from view in the bedroom, preventing clock-watching anxiety at night.

One of the more paradoxical CBT-I methods used to help insomniacs sleep is to restrict their time spent in bed, perhaps even to just six hours of sleep or less to begin with.

By keeping patients awake for longer, we build up a strong sleep pressure—a greater abundance of adenosine. Under this heavier weight of sleep pressure, patients fall asleep faster, and achieve a more stable, solid form of sleep across the night.

In this way, a patient can regain their psychological confidence in being able to self-generate and sustain healthy, rapid, and sound sleep, night after night: something that has eluded them for months if not years.

Upon reestablishing a patient’s confidence in this regard, time in bed is gradually increased. While this may all sound a little contrived or even dubious, skeptical readers, or those normally inclined toward drugs for help, should first evaluate the proven benefits of CBT-I before dismissing it outright.

Results, which have now been replicated in numerous clinical studies around the globe, demonstrate that CBT-I is more effective than sleeping pills in addressing numerous problematic aspects of sleep for insomnia sufferers.

CBT-I consistently helps people fall asleep faster at night, sleep longer, and obtain superior sleep quality by significantly decreasing the amount of time spent awake at night.

More importantly, the benefits of CBT-I persist long term, even after patients stop working with their sleep therapist. This sustainability stands in stark contrast to the punch of rebound insomnia than individuals experience following the cessation of sleeping pills.

Here’s the link to these 12 tips, as a single page: nih.gov

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Sleep and Effectiveness at Work

Interestingly, participants in the above studies do not perceive themselves as applying less effort to the work challenge, or being less effective, when they were sleep-deprived, despite both being true.

They seemed unaware of their poorer work effort and performance — a theme of subjective misperception of ability when sleep-deprived that we have touched upon previously in this book.

Even the simplest daily routines that require slight effort, such as time spent dressing neatly or fashionably for the workplace, have been found to decrease following a night of sleep loss.

Individuals also like their jobs less when sleep-deprived — perhaps unsurprising considering the mood-depressing influence of sleep deficiency.

Under-slept employees are not only less productive, less motivated, less creative, less happy, and lazier, but they are also more unethical.

Reputation in business can be a make-or-break factor. Having under-slept employees in your business makes you more vulnerable to that risk of disrepute.

Previously, I described evidence from brain-scanning experiments showing that the frontal lobe, which is critical for self-control and reining in emotional impulses, is taken offline by a lack of sleep. As a result, participants were more emotionally volatile and rash in their choices and decision-making.

This same result is predictably borne out in the higher-stakes setting of the workplace. Studies in the workplace have found that employees who sleep six hours or less are significantly more deviant and more likely to lie the following day than those who sleep six hours or more.

Seminal work by Dr. Christopher Barns, a researcher in the Foster School of Business at Washington University, has found that the less an individual sleeps, the more likely they are to create fake receipts and reimbursement claims, and the more willing to lie to get free raffle tickets.

Barns also discovered that under-slept employees are more likely to blame other people in the workplace for their own mistakes, and even try to take credit for other people’s successful work: hardly a recipe for team building and a harmonious business environment.

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Sleep and the k-12 educational system

[A school district experimented with starting school later in the day…]

Yet something even more profound has happened in this ongoing story of later school start times — something that researchers did not anticipate: the life expectancy of students increased.

The leading cause of death among teenagers is road traffic accidents, and in this regard, even the slightest dose of insufficient sleep can have marked consequences, as we have discussed.

When the Mahtomedi School District of Minnesota pushed their school start time from 7:30 to 8:00 a.m., there was a 60 percent reduction in traffic accidents in drivers sixteen to eighteen years of age.

Teton County in Wyoming enacted an even more dramatic change in school start time, shifting from a 7:35 a.m. bell to a far more biologically reasonable one of 8:55 a.m.

The result was astonishing—a 70 percent reduction in traffic accidents in sixteen- to eighteen-year-old drivers. To place that in context, the advent of anti-lock brake technology (ABS)—which prevents the wheels of a car from seizing up under hard braking, allowing the driver to still maneuver the vehicle—reduced accident rates by around 20 to 25 percent. It was deemed a revolution.

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Sleep and ADHD

An added reason for making sleep a top priority in the education and lives of our children concerns the link between sleep deficiency and the epidemic of ADHD (attention deficit hyperactivity disorder). Children with this diagnosis are irritable, moodier, more distractible and unfocused in learning during the day, and have a significantly increased prevalence of depression and suicidal ideation.

If you make a composite of these symptoms (unable to maintain focus and attention, deficient learning, behaviorally difficult, with mental health instability), and then strip away the label of ADHD, these symptoms are nearly identical to those caused by a lack of sleep.

Take an under-slept child to a doctor and describe these symptoms without mentioning the lack of sleep, which is not uncommon, and what would you imagine the doctor is diagnosing the child with, and medicating them for?

Not deficient sleep, but ADHD. There is more irony here than meets the eye. Most people know the name of the common ADHD medications: Adderall and Ritalin.

But few know what these drugs actually are.

Adderall is amphetamine with certain salts mixed in, and Ritalin is a similar stimulant, called methylphenidate. Amphetamine and methylphenidate are two of the most powerful drugs we know of to prevent sleep and keep the brain of an adult (or a child, in this case) wide awake.

That is the very last thing that such a child needs.

As my colleague in the field, Dr. Charles Czeisler, has noted, there are people sitting in prison cells, and have been for decades, because they were caught selling amphetamines to minors on the street.

However, we seem to have no problem at all in allowing pharmaceutical companies to broadcast prime-time commercials highlighting ADHD and promoting the sale of amphetamine-based drugs (e.g., Adderall, Ritalin).

To a cynic, this seems like little more than an uptown version of a downtown drug pusher. I am in no way contesting the disorder of ADHD, and not every child with ADHD has poor sleep. But we know that there are children, many children, perhaps, who are sleep-deprived or suffering from an undiagnosed sleep disorder that masquerades as ADHD.

They are being dosed for years of their critical development with amphetamine-based drugs.

One example of an undiagnosed sleep disorder is pediatric sleep-disordered breathing, or child obstructive sleep apnea, which is associated with heavy snoring. Overly large adenoids and tonsils can block the airway passage of a child as their breathing muscles relax during sleep. The labored snoring is the sound of turbulent air trying to be sucked down into the lungs through a semi-collapsed, fluttering airway.

The resulting oxygen debt will reflexively force the brain to awaken the child briefly throughout the night so that several full breaths can be obtained, restoring full blood oxygen saturation.

However, this prevents the child from reaching and/or sustaining long periods of valuable deep NREM sleep.

Their sleep-disordered breathing will impose a state of chronic sleep deprivation, night after night, for months or years on end.

As the state of chronic sleep deprivation builds over time, the child will look ever more ADHD-like in temperament, cognitively, emotionally, and academically. Those children who are fortunate to have the sleep disorder recognized, and who have their tonsils removed, more often than not prove that they do not have ADHD.

In the weeks after the operation, a child’s sleep recovers, and with it, normative psychological and mental functioning in the months ahead. Their “ADHD” is cured.

Based on recent surveys and clinical evaluations, we estimate that more than 50 percent of all children with an ADHD diagnosis actually have a sleep disorder, yet a small fraction know of their sleep condition and its ramifications.

A major public health awareness campaign by governments — perhaps without influence from pharmaceutical lobbying groups — is needed on this issue.

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Sleep and Medical Errors

If you are about to receive medical treatment at a hospital, you’d be well advised to ask the doctor: “How much sleep have you had in the past twenty-four hours?”

The doctor’s response will determine, to a statistically provable degree, whether the treatment you receive will result in a serious medical error, or even death.

All of us know that nurses and doctors work long, consecutive hours, and none more so than doctors during their resident training years.

Few people, however, know why. Why did we ever force doctors to learn their profession in this exhausting, sleepless way?

The answer originates with the esteemed physician William Stewart Halsted, MD, who was also a helpless drug addict.

Halsted founded the surgical training program at Johns Hopkins Hospital in Baltimore, Maryland, in May 1889. As chief of the Department of Surgery, his influence was considerable, and his beliefs about how young doctors must apply themselves to medicine, formidable.

There was to be a six-year residency, quite literally. The term “residency” came from Halsted’s belief that doctors must live in the hospital for much of their training, allowing them to be truly committed in their learning of surgical skills and medical knowledge.

Fledgling residents had to suffer long, consecutive work shifts, day and night.

To Halsted, sleep was a dispensable luxury that detracted from the ability to work and learn. Halsted’s mentality was difficult to argue with, since he himself practiced what he preached, being renowned for a seemingly superhuman ability to stay awake for apparently days on end without any fatigue. But Halsted had a dirty secret that only came to light years after his death, and helped explain both the maniacal structure of his residency program and his ability to forgo sleep. Halsted was a cocaine addict.

It was a sad and apparently accidental habit, one that started years before his arrival at Johns Hopkins. Early in his career, Halsted was conducting research on the nerve-blocking abilities of drugs that could be used as anesthetics to dull pain in surgical procedures.

One of those drugs was cocaine, which prevents electrical impulse waves from shooting down the length of the nerves in the body, including those that transmit pain.

Addicts of the drug know this all too well, as their nose, and often their entire face, will become numb after snorting several lines of the substance, almost like having been injected with too much anesthetic by an overly enthusiastic dentist.

Working with cocaine in the laboratory, it didn’t take long before Halsted was experimenting on himself, after which the drug gripped him in an ceaseless addiction. If you read Halsted’s academic report of his research findings in the New York Medical Journal from September 12, 1885, you’d be hard pressed to comprehend it. Several medical historians have suggested that the writing is so discombobulated and frenetic that he undoubtedly wrote the piece when high on cocaine.

[…]

Halsted inserted his cocaine-infused wakefulness into the heart of Johns Hopkins’s surgical program, imposing a similarly unrealistic mentality of sleeplessness upon his residents for the duration of their training. The exhausting residency program, which persists in one form or another throughout all US medical schools to this day, has left countless patients hurt or dead in its wake — and likely residents, too.

That may sound like an unfair charge to level considering the wonderful, lifesaving work our committed and caring young doctors and medical staff perform, but it is a provable one.

Many medical schools used to require residents to work thirty hours. You may think that’s short, since I’m sure you work at least forty hours a week. But for residents, that was thirty hours all in one go.

Worse, they often had to do two of these thirty-hour continuous shifts within a week, combined with several twelve-hour shifts scattered in between. The injurious consequences are well documented.

Residents working a thirty-hour-straight shift will commit 36 percent more serious medical errors, such as prescribing the wrong dose of a drug or leaving a surgical implement inside of a patient, compared with those working sixteen hours or less.

Additionally, after a thirty-hour shift without sleep, residents make a whopping 460 percent more diagnostic mistakes in the intensive care unit than when well rested after enough sleep.

Throughout the course of their residency, one in five medical residents will make a sleepless-related medical error that causes significant, liable harm to a patient.

One in twenty residents will kill a patient due to a lack of sleep. Since there are over 100,000 residents currently in training in US medical programs, this means that many hundreds of people — sons, daughters, husbands, wives, grandparents, brothers, sisters — are needlessly losing their lives every year because residents are not allowed to get the sleep they need.

As I write this chapter, a new report has discovered that medical errors are the third-leading cause of death among Americans after heart attacks and cancer. Sleeplessness undoubtedly plays a role in those lives lost.


Of course, medical institutions put forward other arguments to justify the old-school way of sleep abuse.

The most common harkens back to a William Halsted–like mind-set: without working exhaustive shifts, it will take far too long to train residents, and they will not learn as effectively. Why, then, can several western European countries train their young doctors within the same time frame when they are limited to working no more than forty-eight hours in one week, without continuous long periods of sleeplessness? Perhaps they are just not as well trained?

This, too, is erroneous, since many of those western European medical programs, such as in the UK and Sweden, rank among the top ten countries for most medical practice health outcomes, while the majority of US institutes rank somewhere between eighteenth and thirty-second.

As a matter of fact, several pilot studies in the US have shown that when you limit residents to no more than a sixteen-hour shift, with at least an eight-hour rest opportunity before the next shift, the number of serious medical errors made—defined as causing or having the potential to cause harm to a patient—drops by over 20 percent.

Furthermore, residents made 400 to 600 percent fewer diagnostic errors to begin with.

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