Why We Sleep: Unlocking the Power of Sleep and Dreams by Matthew Walker
Review
I applaud Walker for his quest to make the world stop the modern decline of sleep length and quality. The knowledge about different phases of sleep and their impact on our everyday life and health are things that are rarely taught and have made me very aware of the utmost importance of sleep .
I do have to see it felt like some statistics were misinterpreted, sources were missing and I felt the need to crosscheck some of the facts, and I turned out not to be the only one (see https://guzey.com/books/why-we-sleep/). This might relieve some of the anxiety this book can produce. This still does not take away from the noble quest of better sleep that I’ll be an ambassador of from now on.
Why We Sleep
Chapter 1: To Sleep …
Quote
If sleep does not serve an absolutely vital function, then it is the biggest mistake the evolutionary process has ever made.
Chapter 2: Caffeine, Jet Lag, and Melatonin: Losing and Gaining Control of Your Sleep Rhythm
Quote
Consequently, the group as a whole is only collectively vulnerable (i.e., every person asleep) for just four rather than eight hours, despite everyone still getting the chance for eight hours of sleep.
Quote
Caffeine is not a food supplement. Rather, caffeine is the most widely used (and abused) psychoactive stimulant in the world.
Quote
Although the temperature drop helps to initiate sleep, the temperature change itself will rise and fall across the twenty-four-hour period regardless of whether you are awake or asleep
Quote
West or east, jet lag still places a torturous physiological strain on the brain, and a deep biological stress upon the cells, organs, and major systems of the body.
Chapter 3: Defining and Generating Sleep: Time Dilation and What We Learned from a Baby in 1952
Quote
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,
Quote
a key function of deep NREM sleep, which predominates early in the night, is to do the work of weeding out and removing unnecessary neural connections. In contrast, the dreaming stage of REM sleep, which prevails later in the night, plays a role in strengthening those connections.
Quote
The brain paralyzes the body so the mind can dream safely.
Chapter 4: Ape Beds, Dinosaurs, and Napping with Half a Brain: Who Sleeps, How Do We Sleep, and How Much?
Quote
However, 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.
Quote
At some point, the two end-guards will stand up, rotate 180 degrees, and sit back down, allowing the other side of their respective brains to enter deep sleep.
Quote
That humans (and all other species) can never “sleep back” that which we have previously lost is one of the most important take-homes of this book
Quote
if you bring that person into a sleep laboratory, or take them to a hotel—both of which are unfamiliar sleep environments—one half of the brain sleeps a little lighter than the other, as if it’s standing guard with just a tad more vigilance due to the potentially less safe context that the conscious brain has registered while awake
Quote
Hunter-gatherer tribes, such as the Gabra in northern Kenya or the San people in the Kalahari Desert, whose way of life has changed little over the past thousands of years, sleep in a biphasic pattern. Both these groups take a similarly longer sleep period at night (seven to eight hours of time in bed, achieving about seven hours of sleep), followed by a thirty- to sixty-minute nap in the afternoon.
Quote
the superior emotional brain gifts that REM sleep affords should be considered more influential in defining our hominid success
Quote
The brain will consume a larger portion of deep NREM sleep than of REM sleep on the first night after total sleep deprivation,
Quote
Individuals who are deliberately fasting will sleep less as the brain is tricked into thinking that food has suddenly become scarce.
Chapter 5: Changes in Sleep Across the Life Span
Quote
strong case can already be made for defending sleep time in our adolescent youth, rather than denigrating sleep as a sign of laziness
Quote
Many of the major psychiatric disorders, such as schizophrenia, bipolar disorder, major depression, and ADHD are now considered disorders of abnormal development, since they commonly emerge during childhood and adolescence
Quote
Alcohol is one of the most powerful suppressors of REM sleep that we know of.
Quote
An infant brain without sleep will be a brain ever underconstructed.
Quote
Autistic individuals show a 30 to 50 percent deficit in the amount of REM sleep they obtain, relative to children without autism.
Quote
poor sleep is one of the most underappreciated factors contributing to cognitive and medical ill health in the elderly, including issues of diabetes, depression, chronic pain, stroke, cardiovascular disease, and Alzheimer’s disease.
Quote
In the last two weeks of pregnancy, the fetus will ramp up its consumption of REM sleep to almost nine hours a day. In the last week before birth, REM-sleep amount hits a lifetime high of twelve hours a day.
Quote
elderly individuals fail to connect their deterioration in health with their deterioration in sleep, despite causal links between the two having been known to scientists for many decades.
Quote
Worryingly, if you disturb or impair the REM sleep of a developing infant brain, pre- or early post-term, there are consequences
Quote
Not until age three or four months will a newborn show modest signs of being governed by a daily rhythm
Quote
The changes in deep NREM sleep always precede the cognitive and developmental milestones within the brain by several weeks or months, implying a direction of influence: deep sleep may be a driving force of brain maturation, not the other way around.
Chapter 6: Your Mother and Shakespeare Knew: The Benefits of Sleep for the Brain
Quote
sleep is “the chief nourisher in life’s feast
Quote
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
Quote
sleep had delightfully cleared out the hippocampus, replenishing this short-term information repository with plentiful free space
Quote
By boosting the electrical quality of deep-sleep brainwave activity, the researchers almost doubled the number of facts that individuals were able to recall the following day, relative to those participants who received no stimulation.
Quote
a memory retention benefit of between 20 and 40 percent being offered by sleep, compared to the same amount of time awake.
Quote
Even daytime naps as short as twenty minutes can offer a memory consolidation advantage, so long as they contain enough NREM sleep.fn5
Chapter 7: Too Extreme for the Guinness Book of World Records: Sleep Deprivation and the Brain
Quote
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.
Quote
After ten days of just seven hours of sleep, the brain is as dysfunctional as it would be after going without sleep for twenty-four hours.
Quote
When participants were asked about their subjective sense of how impaired they were, they consistently underestimated their degree of performance disability
Quote
getting too little sleep across the adult life span will significantly raise your risk of developing Alzheimer’s disease.
Quote
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
Quote
even after three nights of ad lib recovery sleep, performance did not return to that observed at the original baseline assessment when those same individuals had been getting a full eight hours of sleep regularly
Quote
After four hours of sleep for six nights, participants’ performance was just as bad as those who had not slept for twenty-four hours straight—that is, a 400 percent increase in the number of microsleeps.
Chapter 8: Cancer, Heart Attacks, and a Shorter Life: Sleep Deprivation and the Body
Quote
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.
Quote
sleeping four hours a night for just six nights. By the end of that week, these (formerly healthy) participants were 40 percent less effective at absorbing a standard dose of glucose, compared to when they were fully rested.
Quote
participants were being punished twice for the same offense of short sleeping: once by having the “I’m full” signal removed from their system, and once by gaining the “I’m still hungry” feeling being amplified. As a result, participants just didn’t feel satisfied by food when they were short sleeping.
Quote
The less you sleep, the more you are likely to eat. In addition, your body becomes unable to manage those calories effectively, especially the concentrations of sugar in your blood.
Quote
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.
Quote
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.
Quote
Inadequate sleep is the perfect recipe for obesity: greater calorie intake, lower calorie expenditure.
Quote
the shorter your sleep, the shorter your life.
Chapter 9: Routinely Psychotic: REM-Sleep Dreaming
Quote
Between 35 and 55 percent of emotional themes and concerns that participants were having while they were awake during the day powerfully and unambiguously resurfaced in the dreams they were having at night
Chapter 10: Dreaming as Overnight Therapy
Quote
Without REM sleep and its ability to reset the brain’s emotional compass, those same individuals will be inaccurate in their social and emotional comprehension of the world around them, leading to inappropriate decisions and actions that may have grave consequences.
Quote
Through its therapeutic work at night, REM sleep performed the elegant trick of divorcing the bitter emotional rind from the information-rich fruit
Chapter 11: Dream Creativity and Dream Control
Quote
when I woke them up out of REM sleep, from the dreaming phase. Overall, problem-solving abilities rocketed up, with participants solving 15 to 35 percent more puzzles when emerging from REM sleep compared with awakenings from NREM sleep or during daytime waking performance!
Chapter 12: Things That Go Bump in the Night: Sleep Disorders and Death Caused by No Sleep
Quote
The two most common triggers of chronic insomnia are psychological: (1) emotional concerns, or worry, and (2) emotional distress, or anxiety.
Chapter 13: iPads, Factory Whistles, and Nightcaps: What’s Stopping You from Sleeping?
Quote
Memories remain vulnerable to disruption of sleep (including that from alcohol) even up to three nights after learning, despite two full nights of natural sleep prior.
Quote
People consuming even moderate amounts of alcohol in the afternoon and/or evening can inadvertently deprive themselves of dream sleep.
Quote
alcohol fragments sleep, littering the night with brief awakenings. Alcohol-infused sleep is therefore not continuous and, as a result, not restorative
Chapter 14: Hurting and Helping Your Sleep: Pills vs. Therapy
Quote
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
Quote
Nevertheless, for healthy sleep, the scientific evidence suggests that you should avoid going to bed too full or too hungry, and shy away from diets that are excessively biased toward carbohydrates (greater than 70 percent of all energy intake), especially sugar.
Quote
The older sleep medications—termed “sedative hypnotics,” such as diazepam—were blunt instruments. They sedated you rather than assisting you into natural sleep. Understandably, many people mistake the former for the latter.
Quote
Severe caloric restriction, such as reducing food intake to just 800 calories a day for one month, makes it harder to fall asleep normally, and decreases the amount of deep NREM sleep at night.
Chapter 15: Sleep and Society: What Medicine and Education Are Doing Wrong; What Google and NASA Are Doing Right
Quote
They discovered that naps as short as twenty-six minutes in length still offered a 34 percent improvement in task performance and more than a 50 percent increase in overall alertness.
Quote
There was another equally intriguing result: in the days after a supervisor had slept poorly, the employees themselves, even if well rested, became less engaged in their jobs throughout that day as a consequence.
Quote
They discovered that naps as short as twenty-six minutes in length still offered a 34 percent improvement in task performance and more than a 50 percent increase in overall alertness
Quote
Controlled sleep laboratory studies in smaller samples show that children with longer total sleep times develop superior IQ, with brighter children having consistently slept forty to fifty minutes more than those who went on to develop a lower IQ.
Quote
One in twenty residents will kill a patient due to a lack of sleep.
Quote
Insufficient sleep robs most nations of more than 2 percent of their GDP—amounting to the entire cost of each country’s military.
Quote
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.
Chapter 16: A New Vision for Sleep in the Twenty-First Century
Quote
The giant insurance company Aetna, which has almost fifty thousand employees, has instituted the option of bonuses for getting more sleep, based on verified sleep-tracker data
Quote
Over time, we could intelligently curate a tailored thermal sleep environment that is personalized to the circadian rhythms of each individual occupant of each bedroom
Quote
When it comes to the quantified self, it’s the old adage of “seeing is believing” that ensures longer-term adherence to healthy habits
Quote
we should be able to reduce the dose of narcotic drugs on our hospital wards by improving sleep conditions.