What do decades of clinical sleep research tell us about the importance of sleep?

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How many hours of sleep do I need a night? Does Melatonin really work? Why can’t I resist sleeping in? What are dreams? Should I cram for my test or get some rest? Sleep and alcohol? Blue-Light (“Personality”) Glasses? Drowsy Driving? I’ve been sleeping 6 hours a night for as long as I can remember… is that bad? I LOVE CAFFEINE!

In some capacity, a number of these thoughts have passed through all of our minds as we pull an all-nighter to complete the project we procrastinated, devour the irresistible new Netflix series, or party all hours in spite of the early morning alarm that is waiting.

I am as skewed toward the night-owl/nocturnal camp as one can really get. I find the peace and quiet of the early morning second to none, so much so that my queue to get some rest during parts of quarantine has been the morning birds chirping and the sun peaking over the trees. As such, you can imagine my guttural aversion to morning lifts at school or the 9 AM classes...

Sleep is in all probability the most universal topic out there. Every species from a fly to a blue whale needs some shut-eye. In spite of this universality, developed countries' education and resources on the topic are fledgling at best.

Recently, I stumbled across *Why We Sleep: Unlocking the Power of Sleep and Dreams, *a book on sleeping and dreaming by neuroscientist and sleep researcher, Dr. Matthew Walker. It compiles and explains the takeaways from the last few decades of sleep research and answers any and all questions regarding sleep habits that may be detrimental to one’s long-term health.

I had always assumed sleep was important, but recent findings highlight an undeniable link between sleep deprivation and chronic illnesses (type-2 diabetes, cancer, Alzheimer's, heart disease), reduced athletic performance, learning capacity, and cognitive development and health.

“I was once fond of saying, ‘Sleep is the third pillar of good health, alongside diet and exercise.’ I have changed my tune. Sleep is more than a pillar; it is the foundation on which the other two health bastions sit. Take away the bedrock of sleep, or weaken it just a little, and careful eating or physical exercise become less than effective” (*Why We Sleep, *164).

In this piece, I want to share the topics and related quotes that resonated with me from Matthew Walker’s work. Immediately after finishing this book, my sleep habits changed out of necessity. His conclusions are thorough as they are unsparing. There is no safe and healthy way to cheat yourself of the sleep you need, and the consequences of believing the contrary are dire.

To all the gym rats who spend all day in the gym and health nuts who shirk carb-heavy meals at every turn, it all may be for naught if you are not giving your body the 8-hours of sleep a night it needs.

For me, this book uprooted the flimsy conceptions of sleep I amassed from the conventional wisdom I learned growing up. I hope you too find Dr. Walker’s words and insights as illuminating as I did.

If you want to explore the experimental design and quantitative conclusions from the studies he cites, I would recommend picking up a copy for yourself. With any luck, this will be a one-stop shop for all inquiries sleep-related!

Sleep well!!

DD

Outline

Sleep Across a LifeSpan

• Chronotypes: Are you a Night Owl or a Morning Lark
• Puberty Changes: Teens Sleeping-in
• Biphasic Sleep and Long Life

Caffeine, Melatonin, and Jetlag

• Caffeine
• Melatonin
• Jetlag

Benefits of Sleep in the Brain

• Short Term to Long Term Memory
• Practice + Sleep Makes Perfect
• Good Forgetting

Sleep Deprivation on the Mind

• Baseline Resetting
• Drowsy Driving
• Inhibited Emotional Regulation
• Sleep-Deprived Learning
• Sleep and Alzheimer’s

Sleep Deprivation on the Body

• Heart Attacks
• Type 2 Diabetes
• Weight Loss and Over-Eating
• Cancer

Sleep and Dream Creativity

• NREM vs REM Sleep
• Problem Solving

What is Stopping You from Sleeping

• Blue Lights, LEDs, Screens
• Alcohol
• Alcohol and Learning
• Bedroom Temperature
• Alarms
• Sleeping Pills

Sleep and Society

• Losses in Revenue and GDP
• School Start Times

What Can We Do!

• Advice
• Seeing is Believing

Sleep Across a LifeSpan

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Chronotypes: Are you a Night Owl (Late Riser) or a Morning Lark (Early Riser)

An adults ‘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… However, night owls are not owls by choice. They are bound to a delayed schedule by unavoidable DNA hardwiring.

Second is the engrained, un-level playing field of society’s work scheduling, which is strongly biased towards early start times that punish owls and favor larks… Consequently, the job performance of owls as a whole is far less optimal in the mornings, and they are further prevented from expressing their true performance potential in the late afternoon and early evening as standard world hours end prior to its arrival. (Why We Sleep, 21)

Conclusion: If you are a night owl, don’t be ashamed you are exhausted in the morning and cannot get to bed “on time.” It is not your fault. Your chronotype is genetic. Although the cards may be stacked against late risers with early start times, it is critical to find the time to get the sleep you need to mitigate the long term effects of sleep deprivation.

Puberty Changes: Teens Sleeping-in

Parents want their teenager to be awake at a ‘reasonable’ hour of the morning. Teenagers, on the other hand, having only been capable of initiating sleep some hours after their parents, can still be in their circadian downswing. Like an animal prematurely wrenched out of hibernation too early, the adolescent brain still needs more sleep and more time to complete the circadian cycle before it can operate efficiently, without grogginess.

If this remains perplexing to parents, a different way to frame and perhaps appreciate the mismatch is this: asking your teenage son or daughter to go to bed and fall asleep at ten p.m. is the circadian equivalent of asking you, their parent to go to sleep at seven or eight p.m. (93)

Central to the goal of adolescent development is the transition from parental dependence to independence, all the while learning to navigate the complexities of peer-group relationships and interactions… One way in which Mother Nature has perhaps helped adolescent development unbuckle themselves from their parents is to march their circadian rhythms forward in time, past that of their adult mothers and fathers. This ingenious biological solution selectively shifts teenagers to a later phase when they can, for several hours, operate independently––and do so as a peer-group collective. (94)

Conclusion: Teens sleep in because they are programmed to stay up later during their adolescent years to learn to navigate the world socially with peers and without parents. Additionally, the need and desire to sleep in is natural and critical for cognitive and social development.

Biphasic Sleep and Long Life

The practice of biphasic sleep is not cultural in origin. It is deeply biological. All humans, irrespective of culture or geographical location, have a genetically hard-wired dip in alertness that occurs in the midafternoon hours. Observe any post-lunch meeting around a boardroom table and this fact will become clear…. [This is] called the post-prandial alertness dip. This brief descent from high-degree wakefulness to low-level alertness reflects an innate drive to be asleep and napping in the afternoon, and not working. It appears to be a normal part of the daily rhythm of life.

[University’s School of Public Health] researchers focused on cardiovascular outcomes, tracking the group across a six-year period as the siesta practice came to an end for many of them…. Those that abandoned regular siestas went on to suffer a 37 percent increased risk of death from heart disease across the six-year period, relative to those who maintained regular daytime naps. The effect was especially strong in workingmen, where the ensuing mortality risk of not napping increased by well over 60 percent. Apparent from this remarkable study is this fact: when we are cleaved from the innate practice of biphasic sleep, our lives are shortened. (71)

Conclusion: Humans are biologically predisposed to biphasic sleep, which entails sleeping through the night with an afternoon nap. Straying from this natural sleep pattern has proven health consequences at an advanced age. Viva la siesta!

Caffeine and Melatonin and Jetlag

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Caffeine

Caffeine — which is not only prevalent in coffee, certain teas, and many energy drinks, but also foods such as dark chocolate and ice cream, as well as drugs such as weight-loss pills and pain relievers — is one of the most common culprits that keep people from falling asleep easily and sleeping soundly thereafter, typically masquerading as insomnia, an actual medical condition. Also be aware that de-caffeinated does not mean non-caffeinated. One cup of decaf usually contains 15 to 30 percent of the dose of a regular cup of coffee, which is far from caffeine-free. Should you drink three to four cups of decaf in the evening, it is just as damaging to your sleep as one regular cup of coffee.

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. (28)

Based in large part on genetics, some people have a more efficient version of the enzyme that degrades caffeine, allowing the liver to rapidly clear it from the bloodstream….Others, however, have a slower-acting version of the enzyme. It takes far longer for their system to eliminate the same amount of caffeine…. Aging also alters the speed of caffeine clearance: the older we are, the longer it takes our brain and body to remove caffeine, and thus the more sensitive we become in later life to caffeine’s sleep-disrupting influence. (30)

Conclusion: The half-life of caffeine is 5 to 7 hours, so drinking coffee in the afternoon and evening will mitigate your sleepiness that night. Based on our genetics, our abilities to eliminate caffeine from the bloodstream vary widely. With age, it is more difficult to remove caffeine from your bloodstream, which leads to increased caffeine sensitivity over longer periods of time as you get older.

Melatonin

Melatonin helps regulate the timing of when sleep occurs by systemically signaling darkness throughout the organism. But melatonin has little influence on the generation of sleep itself: a mistaken assumption that many people hold. To make clear this distinction, think of sleep as the Olympic 100-meter race. Melatonin is the voice of the timing official that says “Runners, on your mark,” and then fires the starting pistol that triggers the race. That timing official (melatonin) governs when the race (sleep) begins, but does not participate in the race.

There may be little if any, quality melatonin in the pill. That said, there is a significant sleep placebo effect of melatonin… Equally important to realize is the fact that over-the-counter melatonin is not commonly regulated by governing bodies around the world, such as the US Food and Drug Administration (FDA). Melatonin concentrations [can] range from 83 percent less than that claimed on the label to 478 percent more than that stated. (25)

Conclusion: Melatonin controls the timing of your sleepiness and can be highly effective for combatting the jarring effects of traveling between time zones. Be aware, however, that Melatonin is rarely regulated so the listed dosage may be inaccurate.

Jetlag

For every day you are in a different time zone, your suprachiasmatic nucleus can only readjust by about one hour.

Scientists have studied airplane cabin crews who frequently fly on long-haul routes and have little chance to recover. Two alarming results have emerged. First, parts of their brains — specifically those related to learning and memory — had physically shrunk, suggesting the destruction of brain cells caused by the biological stress of time-zone travel. Second, their short-term memory was significantly impaired. They were considerably more forgetful than individuals of similar age and background who did not frequently travel through time zones. (26)

Conclusion: It takes a day in a new time zone to adjust your internal clock one hour closer to the new time zone. Frequently flying between disparate time zones can have short and long term effects on memory and learning capacity.

Benefits of Sleep in the Brain

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Short Term to Long Term Memory

We observed a strikingly reliable loop of electrical current pulsing throughout the brain that repeated every 100 to 200 milliseconds. The pulses kept weaving a path back and forth between the hippocampus, with its short-term, limited storage space, and the far larger, long-term storage site of the cortex (analogous to a large-memory hard drive). In that moment, we had just become privy to an electrical transaction occurring in the quiet secrecy of sleep: one that was shifting fact-based memories from the temporary storage depot (the hippocampus) to a long-term secure vault (the cortex). In doing so, sleep had delightfully cleared out the hippocampus, replenishing this short-term information repository with plentiful free space….The learning of new facts could begin again, anew, the following day. (110)

Conclusion: The hippocampus is responsible for short-term memory recall. Through Non-Rapid Eye Movement (NREM) or Deep Sleep, you convert short term hippocampus memories into long-term memories stored in the cortex. The cortex is responsible for long term memory recall. In short, sleep is critical for long term memory formation and retention.

Practice + Sleep Makes Perfect

Those who remained awake across the day showed no evidence of a significant improvement in performance. However… 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. (125)

Conclusion: Without a full night’s sleep to synthesize what you have learned the day before, an improvement in recollection or proficiency at a given task is negligible. Only with a good night’s sleep does practice begin to reflect improvement, so when deciding to cram all night or sleep before a test, the latter should win every time.

Good Forgetting

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.

When we analyzed the sleep records of those individuals who napped, we gained another insight. Contrary to Francis Crick’s prediction, it was not REM sleep… [but] rather, it was NREM sleep, and especially the very quickest of the sleep spindles that helped bend apart the curves of remembering and forgetting. The more of those spindles a participant had during a nap, the greater the efficiency with which they strengthened items tagged for remembering and actively eliminated those designated for forgetting. (121)

Conclusion: NREM Deep Sleep is also instrumental in our capacity to forget useless information. When asleep, our minds can distinguish what information needs to be remembered and what can be forgotten which is critical for learning especially at young ages.

Sleep Deprivation on the Mind

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Baseline Resetting

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. (137)

Conclusion: If you don’t give yourself the 8-hours of sleep you need, you’re baseline performance, alertness, and energy levels will lower without your noticing. Performing and feeling suboptimal will become the new normal.

Drowsy Driving

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. (138)

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, and (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. (139)

Conclusion: Minor sleep deprivation by even an hour compounded over the duration of the waking hours will impair a driver the same as having a BAC of 0.08. Frighteningly, the effects of alcohol and sleep deprivation are not additive but MULTIPLICATIVE!

Inhibited Emotional Regulation

After a full night of sleep, the prefrontal cortex — the region of the brain that sits just above your eyeballs; is most developed in humans, relative to other primates; and is associated with rational, logical thought and decision-making — was strongly coupled to the amygdala, regulating this deep emotional brain center with inhibitory control. With a full night of plentiful sleep, we have a balanced mix between our emotional gas pedal (amygdala) and brake (prefrontal cortex). Without sleep, however, the strong coupling between these two brain regions is lost. We cannot rein in our atavistic impulses — too much emotional gas pedal (amygdala) and not enough regulatory brake (prefrontal cortex). Without the rational control given to us each night by sleep, we’re not on a neurological — and hence emotional — even keel. (147)

Conclusion: It is very difficult to regulate your emotions without proper sleep. Whether you are flush with overly positive or overly negative emotions, your amygdala, the emotional gas pedal, is not adequately tempered by our cortex, the emotional brake pedal, when you are sleep deprived.

Sleep-Deprived Learning

If you don’t sleep the very first night after learning, you lose the chance to consolidate those memories, even if you get lots of “catch-up” sleep thereafter. In terms of memory, then, sleep is not like the bank. You cannot accumulate a debt and hope to pay it off at a later point in time. Sleep for memory consolidation is an all-or-nothing event. It is a concerning result in our 24/7, hurry-up, don’t-wait society. (157)

Conclusion: Memory consolidation is an all-or-nothing event. If you do not sleep properly after learning you will lose critical amounts of what you have learned.

Sleep and Alzheimer’s

We discovered a chain-reaction effect. Those individuals with the highest levels of amyloid deposits in the frontal regions of the brain had the most severe loss of deep sleep and, as a knock-on consequence, failed to successfully consolidate those new memories. Overnight forgetting, rather than remembering, had taken place. The disruption of deep NREM sleep was therefore a hidden middleman brokering the bad deal between amyloid and memory impairment in Alzheimer’s disease. A missing link. (159)

Glial cells are distributed throughout your entire brain, situated side by side with the neurons that generate the electrical impulses of your brain… 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… 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. (160)

Nedergaard’s findings completed the circle of knowledge that our findings had left unanswered. Inadequate sleep and the pathology of Alzheimer’s disease interact in a vicious cycle. Without sufficient sleep, amyloid plaques build up in the brain, especially in deep-sleep-generating regions, attacking and degrading them. The loss of deep NREM sleep caused by this assault therefore lessens the ability to remove amyloid from the brain at night, resulting in greater amyloid deposition. More amyloid, less deep sleep, less deep sleep, more amyloid, and so on and so forth.

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. (161)

Conclusion: Sleep is likely the missing link or exacerbating factor in the creation or advancement of Alzheimer’s disease. Sleep begets amyloid (plaque) deposition, which interrupts quality sleep and brain cleansing worsening amyloid deposition. The vicious cycle continues leading to Alzheimer’s disease.

Sleep Deprivation on the Body

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Heart Attacks

Unhealthy sleep, unhealthy heart. Simple and true. Take the results of a 2011 study that tracked more than half a million men and women of varied ages, races, and ethnicities across eight different countries. Progressively shorter sleep was associated with a 45 percent increased risk of developing and/or dying from coronary heart disease within seven to twenty-five years from the start of the study. A similar relationship was observed in a Japanese study of over 4,000 male workers. Over a fourteen-year period, those sleeping six hours or less were 400 to 500 percent more likely to suffer one or more cardiac arrests than those sleeping more than six hours. (165)

Conclusion: Sleep deprivation increases one’s risk of heart disease and cardiac arrest.

Type 2 Diabetes

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. (171)

Conclusion: Long term sleep deprivation can desensitize cells and prevent the capture and storage of excess glucose leaving you in a pre-diabetic state of hyperglycemia.

Weight Loss and Over-Eating

Although weight loss occurred under both conditions, the type of weight loss came from very different sources. When given just five and a half hours of sleep opportunity, more than 70 percent of the pounds lost came from lean body mass — muscle, not fat. Switch to the group offered eight and a half hours’ time in bed each night and a far more desirable outcome was observed, with well over 50 percent of weight loss coming from fat while preserving muscle. When you are not getting enough sleep, the body becomes especially stingy about giving up fat. Instead, muscle mass is depleted while fat is retained. Lean and toned is unlikely to be the outcome of dieting when you are cutting sleep short.

The upshot of all this work can be summarized as follows: short sleep (of the type that many adults in first-world countries commonly and routinely report) will increase hunger and appetite, compromise impulse control within the brain, increase food consumption (especially of high-calorie foods), decrease feelings of food satisfaction after eating, and prevent effective weight loss when dieting. (178)

Conclusion: Sleep deprivation makes weight loss exceedingly difficult because your body will shed lean muscle, not the fat you are aiming to burn. With proper sleep, your burn fat not the muscle you want to maintain. Moreover, impulse control diminishes and craving for high-calorie food increases with sleep deprivation making dieting and weight loss that much harder.

Cancer

Examining healthy young men, Irwin demonstrated that a single night of four hours of sleep — such as going to bed at three a.m. and waking up at seven a.m. — swept away 70 percent of the natural killer cells circulating in the immune system, relative to a full eight-hour night of sleep. That is a dramatic state of immune deficiency to find yourself facing, and it happens quickly, after essentially one “bad night” of sleep. You could well imagine the enfeebled state of your cancer-fighting immune armory after a week of short sleep, let alone months or even years.

With each passing year of research, more forms of malignant tumors are being linked to insufficient sleep. A large European study of almost 25,000 individuals demonstrated that sleeping six hours or less was associated with a 40 percent increased risk of developing cancer, relative to those sleeping seven hours a night or more. (184)

The sleep-deprived mice suffered a 200 percent increase in the speed and size of cancer growth, relative to the well-rested group. (185)

World Health Organization has officially classified nighttime shift work as a “probable carcinogen.” (186)

Conclusion: Sleep deprivation by as little as an hour a night over an extended period increases the likelihood of developing a range of cancers dramatically, weakens your body's immune response to tumors, and increases the size and metastatic spread of cancer.

Sleep and Dream Creativity

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NREM vs REM Sleep

When it comes to information processing, think of the wake state principally as reception (experiencing and constantly learning the world around you), NREM sleep as reflection (storing and strengthening those raw ingredients of new facts and skills), and REM sleep as integration (interconnecting these raw ingredients with each other, with all past experiences, and, in doing so, building an ever more accurate model of how the world works, including innovative insights and problem-solving abilities). (53)

Conclusion: NREM (Deep) Sleep stores the raw ingredients (memories, emotions, sensory input) for REM Sleep to connect and make sense of them. As such the first 4-hours of sleep are weighted toward NREM Sleep and the latter 4 hours are more REM-heavy.

Problem Solving

It should come as no surprise by now that those participants who took a nap showed superior memory performance on the maze task. They could locate the navigation clues with ease, finding their way around and out of the maze faster than those who had not slept. The novel result, however, was the difference that dreaming made. Participants who slept and reported dreaming of elements of the maze, and themes around experiences clearly related to it, showed almost ten times more improvement in their task performance upon awakening than those who slept just as much, and also dreamed, but did not dream of maze-related experiences. (230)

It is the difference between knowledge (retention of individual facts) and wisdom (knowing what they all mean when you fit them together). Or, said more simply, learning versus comprehension. REM sleep allows your brain to move beyond the former and truly grasp the latter. (227)

Sleep provides a nighttime theater in which your brain tests out and builds connections between vast stores of information. This task is accomplished using a bizarre algorithm that is biased toward seeking out the most distant, nonobvious associations, rather like a backward Google search. (132)

Conclusion: REM sleep will continue problem-solving tasks as you sleep in an associative way which is different from the more narrow conscious thought we are used to when awake. This enables you to come to novel solutions upon waking. REM sleep is chiefly responsible for your connecting the dots and gaining wisdom from the information you have collected when awake.

What is Stopping You from Sleeping

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“Beyond longer commute times and “sleep procrastination” caused by late-evening television and digital entertainment — both of which are not unimportant in their top-and-tail snipping of our sleep time and that of our children — five key factors have powerfully changed how much and how well we sleep: (1) constant electric light as well as LED light, (2) regularized temperature, (3) caffeine (discussed in chapter 2), (4) alcohol, and (5) a legacy of punching time cards.” (265)

Blue Lights, LEDs, Screens

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. The 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. (270)

Conclusion: Using Blue-Light LED screens near bedtime stalls your melatonin peak making it harder to get to sleep on time and reducing your quality of sleep. The melatonin peak shift will last several days after the over-exposure event. In our hyper-productivity world where LED exposure is common at night, our melatonin peaks are chronically shifted back, making it harder to get to sleep.

Alcohol

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. (272)

Conclusion: Alcohol is one of the most powerful suppressors of REM sleep and has an extreme fragmenting effect on the sleeping mind. It only takes a few alcoholic beverages to rob you entirely of REM sleep that night, leaving you feeling groggy the following day in part to the fact that you were unknowingly awake all throughout the night. Alcohol does not help you sleep it sedates you.

Alcohol and Learning

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… Sadly, not so. Even now, alcohol consumption will wash away much of that which you learned and can abstract by blocking your REM sleep. (274)

Conclusion: Alcohol, due to its REM inhibiting properties, can corrupt memory formation which is critical for learning new material as many as three days following the learning event. New information that needs to be processed by REM sleep is not secure for at least three nights after learning. Bad news for the philosophy behind the typical college mantra: Work Hard, Play Hard.

Bedroom Temperature

A bedroom temperature of around 65 degrees Fahrenheit (18.3°C) is ideal for the sleep of most people, assuming standard bedding and clothing. This surprises many, as it sounds just a little too cold for comfort. Of course, that specific temperature will vary depending on the individual in question and their unique physiology, gender, and age. But like calorie recommendations, it’s a good target for the average human being. Most of us set ambient house and/or bedroom temperatures higher than are optimal for good sleep and this likely contributes to the lower quantity and/or quality of sleep than you are otherwise capable of getting. (279)

Conclusion: Our bodies cool off about 2 to 3 degrees F to fall asleep. Primarily, this heat comes off our hands, feet, and head (body parts that allow a lot of blood to spread across the surface area of the skin), so if the room temperature is too warm cooling off becomes more difficult, forestalling sleep.

Alarms

No other species demonstrates this unnatural act of prematurely and artificially terminating sleep, and for good reason. Compare the physiological state of the body after being rudely awakened by an alarm to that observed after naturally waking from sleep. Participants artificially wrenched from sleep will suffer a spike in blood pressure and a shock acceleration in heart rate caused by an explosive burst of activity from the fight-or-flight branch of the nervous system. Most of us are unaware of an even greater danger that lurks within the alarm clock: the snooze button. If alarming your heart, quite literally, were not bad enough, using the snooze feature means that you will repeatedly inflict that cardiovascular assault again and again within a short span of time. Step and repeat this at least five days a week, and you begin to understand the multiplicative abuse your heart and nervous system will suffer across a life span. (280)

Conclusion: Alarm clocks shock your heart into a fight-or-flight response that is not good for you in the long term. So if you are going to use an alarm, get up when it first goes off. Do not hit the snooze button and repeatedly stress your body when waking up.

Sleeping Pills

The older sleep medications — termed “sedative hypnotics,” such as diazepam — were blunt instruments. They sedated you rather than assisting you in 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. Sleeping pills effectively knock out the higher regions of your brain’s cortex. (282)

Conclusion: Never take sleeping pills. They are sedatives in the way alcohol is a sedative. The restful state they induce is not sleeping.

Sleep and Society

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Losses in Revenue and GDP

A study across four large US companies found that insufficient sleep costs almost $2,000 per employee per year in lost productivity. That amount rose to over $3,500 per employee in those suffering the most serious lack of sleep. That may sound trivial, but speak to the bean counters that monitor such things and you discover a net capital loss to these companies of $54 million annually. (298)

Insufficient sleep robs most nations of more than 2 percent of their GDP — amounting to the entire cost of each country’s military.

Numerous employee traits determine these measures, but commonly they include: creativity, intelligence, motivation, effort, efficiency, effectiveness when working in groups, as well as emotional stability, sociability, and honesty. All of these are systematically dismantled by insufficient sleep. (299)

Conclusion: Sleep is costing companies and countries a lot of money every year but has more dire consequences on the mood, productivity, and performance of workers who are undersleeping and, consequently, underperforming.

School Start Times

Research findings have also revealed that increasing sleep by way of delayed school start times wonderfully increases class attendance, reduces behavioral and psychological problems, and decreases substance and alcohol use. In addition, later start times beneficially mean a later finish time. This protects many teens from the well-researched “danger window” between three and six p.m., when schools finish but before parents return home. This unsupervised, vulnerable time period is a recognized cause of involvement in crime and alcohol and substance abuse.

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. (313)

Without change, we will simply perpetuate a vicious cycle wherein each generation of our children are stumbling through the education system in a half-comatose state, chronically sleep-deprived for years on end, stunted in their mental and physical growth as a consequence, and failing to maximize their true success potential, only to inflict that same assault on their own children decades later. (314)

Conclusion: Later school start times would protect teens' key REM sleep that helps them to develop critical social skills. It would also mitigate behavior and psychological stresses, reduce early morning driving accidents, and enable kids to reach their true academic and athletic potential.

What Can We Do!

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“[Reduce] caffeine and alcohol intake, [remove] screen technology from the bedroom, and [have] 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.

If you can only adhere to one of these each and every day, make it: going to bed and waking up at the same time of day no matter what. It is perhaps the single most effective way of helping improve your sleep, even though it involves the use of an alarm clock.” (291)

More Advice

In younger, healthy adults, exercise frequently increases total sleep time, especially deep NREM sleep. It also deepens the quality of sleep, resulting in more powerful electrical brainwave activity. Similar, if not larger, improvements in sleep time and efficiency are to be found in midlife and older adults, including those who are self-reported poor sleepers or those with clinically diagnosed insomnia. (293)

One brief note of caution regarding physical activity: try not to exercise right before bed. Body temperature can remain high for an hour or two after physical exertion. Should this occur too close to bedtime, it can be difficult to drop your core temperature sufficiently to initiate sleep due to the exercise-driven increase in metabolic rate. (294)

Conclusion: Consistent exercise helps increase total sleep time and deep sleep. Do not exercise too close to bedtime. Your internal body temperature will be too high to cool off for sleep. Blue light glasses and built-in Night-Shift screen toggles on devices will help reduce Blue-light LED exposure near bedtime.

Seeing is Believing

One practice known to convert a healthy new habit into a permanent way of life is exposure to your own data. Research in cardiovascular disease is a good example. If patients are given tools that can be used at home to track their improving physiological health in response to an exercise plan — such as blood pressure monitors during exercise programs, scales that log body mass index during dieting efforts, or spirometry devices that register respiratory lung capacity during attempted smoking cessation — compliance rates with rehabilitation programs increase. Follow up with those same individuals after a year or even five, and more of them have maintained their positive change in lifestyle and behavior as a consequence. When it comes to the quantified self, it’s the old adage of “seeing is believing” that ensures longer-term adherence to healthy habits. (329)

Conclusion: Gaining access to your data is especially helpful in seeing how your changing habits impact how you feel and perform.

To this effect, there are a lot of sleep tracking devices on the market to help you gain these insights such as Whoop Strap, Oura Ring, and Apple Watch Sleep Tracking. I have the Whoop strap and it has been so helpful for gaining insight into how I am recovering from workouts, how my cardiovascular health is, and how I am sleeping. If you would like to learn more about what is offered and how it could be helpful to you in reforming your own habits, do not hesitate to reach out!

Walker, Matthew. Why We Sleep: Unlocking the Power of Sleep and Dreams. Scribner. Kindle Edition.