Why We Sleep
Why We Sleepby Matthew Walker
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Why We Sleep
Why We Sleep
by Matthew Walker
p.22
Melatonin simply provides the official instruction to commence the event of sleep, but does not participate in the sleep race itself.
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David King@dk﹒9mo
So melatonin is just for sleep signaling/initiation, but not an agent for deepening the quality of sleep.
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Why We Sleep
Why We Sleep
by Matthew Walker
p.21
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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David King@dk﹒9mo
We have a lot of societal narratives around these "types" which don't really serve everyone well.
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Why We Sleep
Why We Sleep
by Matthew Walker
p.5
Addressing the question of why we sleep from an evolutionary perspective only compounds the mystery. No matter what vantage point you take, sleep would appear to be the most foolish of biological phenomena. When you are asleep, you cannot gather food. You cannot socialize. You cannot find a mate and reproduce. You cannot nurture or protect your offspring. Worse still, sleep leaves you vulnerable to predation. Sleep is surely one of the most puzzling of all human behaviors.
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David King@dk﹒9mo
Sleep as a phenomenon is not explained well from an evolutionary perspective.
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Why We Sleep
Why We Sleep
by Matthew Walker
My favorite, however, is the shredder. You take a paper bill— let's say $20-and slide it into the front of the clock at night. When the alarm goes off in the morning, you have a short amount of time to wake up and turn the alarm off before it begins shredding your money. The brilliant behavioral economist Dan Ariely has suggested an even more fiendish system wherein your alarm clock is connected, by Wi-Fi, to your bank account. For every second you remain asleep, the alarm clock will send $10 to a political organization... that you absolutely despise.
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Ceci Liu@ceci﹒11mo
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Why We Sleep
Why We Sleep
by Matthew Walker
Hot baths prior to bed can also induce 10 to 15 percent more deep NREM sleep in healthy adults.*
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Why We Sleep
Why We Sleep
by Matthew Walker
Selectively warming the feet and hands by just a small amount (1°F or about 0.5°C) caused a local swell of blood to these regions, thereby charming heat out of the body's core, where it had been trapped. The result of all this ingenuity: sleep took hold of the participants in a significantly shorter time, allowing them to fall asleep 20 percent faster than was usual, even though these were already young, healthy, fast-sleeping individuals. *
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Ceci Liu@ceci﹒11mo
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Why We Sleep
Why We Sleep
by Matthew Walker
A bedroom temperature of around 65 degrees Fahrenheit (18.3°C) is ideal for the sleep of most people, assuming standard bedding and clothing.
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Why We Sleep
Why We Sleep
by Matthew Walker
The need to dump heat from our extremities is also the reason that you may occasionally stick your hands and feet out from underneath the bedcovers at night due to your core becoming too hot, usually without your knowing. Should you have children, you've probably seen the same phenomenon when you check in on them late at night: arms and legs dangling out of the bed in amusing (and endearing) ways, so different from the neatly positioned limbs you placed beneath the sheets upon first tucking them into bed. The limb rebellion aids in keeping the body core cool, allowing it to fall and stay asleep.
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Ceci Liu@ceci﹒11mo
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Why We Sleep
Why We Sleep
by Matthew Walker
To successfully initiate sleep, as described in chapter 2, your core temperature needs to decrease by 2 to 3 degrees Fahrenheit, or about 1 degree Celsius. For this reason, you will always find it easier to fall asleep in a room that is too cold than too hot, since a room that is too cold is at least dragging your brain and body in the correct (downward) temperature direction for sleep.
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Ceci Liu@ceci﹒11mo
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Why We Sleep
Why We Sleep
by Matthew Walker
Second, alcohol is one of the most powerful suppressors of sleep that we know of. When the body metabolizes alcohol it produs 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.
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Ceci Liu@ceci﹒11mo
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Why We Sleep
Why We Sleep
by Matthew Walker
First, alcohol fragments sleep, littering the night with brief awakenings. Alcohol-infused sleep is therefore not continuous and, as a result, not restorative
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Ceci Liu@ceci﹒11mo
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Why We Sleep
Why We Sleep
by Matthew Walker
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.
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Ceci Liu@ceci﹒11mo
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Why We Sleep
Why We Sleep
by Matthew Walker
...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...Furthermore, asking that same teenager to wake up at seven the next morning and function with intellect, grace, and good mood is the equivalent of asking you, their parent, to do the same at four or five a.m.
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Dave Mongan@dvm﹒1y
Turns out we’re unnecessarily cruel to teenagers. This book could use some trimming. Many wordy, repetitive sentences, which is why I self-trimmed the paragraph above with ellipses.
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Why We Sleep
Why We Sleep
by Matthew Walker
Let's say that you go to bed this evening at midnight. But instead of waking up at eight a.m., getting a full eight hours of sleep, you must wake up at six a.m. because of an early-morning meeting or because you are an athlete whose coach demands early-morning practices. What percent of sleep will you lose? The logical answer is 25 percent, since waking up at six a.m. will lop off two hours of sleep from what would otherwise be a normal eight hours. But that's not entirely true. Since your brain desires most of its REM sleep in the last part of the night, which is to say the late-morning hours, you will lose 60 to 90 percent of all your REM sleep, even though you are losing 25 percent of your total sleep time.
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Dave Mongan@dvm﹒1y
Assuming a normal rhythm of 8hrs, 6hrs of sleep misses 60-90% of REM sleep.
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Why We Sleep
Why We Sleep
by Matthew Walker
A team of researchers from Harvard University's School of Public Health decided to quantify the health consequences of this radical change in more than 23,000 Greek adults, which contained men and women ranging in age from twenty to eighty-three years old. The 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. As with countless Greek tragedies, the end result was heartbreaking, but here in the most serious, literal way. None of the individuals had a history of coronary heart disease or stroke at the start of the study, indicating the absence of cardiovascular ill health. 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. 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. It is perhaps unsurprising that in the small enclaves of Greece where siestas still remain intact, such as the island of Ikaria, men are nearly four times as likely to reach the age of ninety as American males. These napping communities have sometimes been described as "the places where people forget to die." From a prescription written long ago in our ancestral genetic code, the practice of natural biphasic sleep, and a healthy diet, appear to be the keys to a long-sustained life.
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Richard Chen@rchen8﹒1y
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Why We Sleep
Why We Sleep
by Matthew Walker
p.233
During REM sleep, however, all voluntary muscles are paralyzed, preventing the dreamer from acting out ongoing mental experience. Yet, the muscles that control the eyes are spared from this paralysis, and give this stage of sleep its frenetic name. Lucid dreamers were able to take advantage of this ocular freedom, communicating with the researchers through eye movements. Pre-defined eye movements would therefore inform the researchers of the nature of the lucid dream (e.g., the participant made three deliberate leftward eye movements when they gained lucid dream control, two rightward eye movements before clenching their right hand, etc.). Non-lucid dreamers find it difficult to believe that such deliberate eye movements are possible while someone is asleep, but watch a lucid dreamer do it a number of times, and it is impossible to deny.
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Linda Xie@linda﹒1y
Lucid dreamers are able to communicate to researchers that they have started the lucid dream.
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Why We Sleep
Why We Sleep
by Matthew Walker
p.232
Edison would allegedly position a chair with armrests at the side of his study desk, on top of which he would place a pad of paper and a pen. Then he would take a metal saucepan and turn it upside down, carefully positioning it on the floor directly below the right-side armrest of the chair. If that were not strange enough, he would pick up two or three steel ball bearings in his right hand. Finally, Edison would settle himself down into the chair, right hand supported by the armrest, grasping the ball bearings. Only then would Edison ease back and allow sleep to consume him whole. At the moment he began to dream, his muscle tone would relax and he would release the ball bearings, which would crash on the metal saucepan below, waking him up. He would then write down all of the creative ideas that were flooding his dreaming mind. Genius, wouldn't you agree?
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Linda Xie@linda﹒1y
Thomas Edison used his dream states as a source for his ideas. He was also a big believer in taking daytime naps to increase creativity.
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Why We Sleep
Why We Sleep
by Matthew Walker
p.198
The scientists were able to predict with significant accuracy the content of participants' dreams at any one moment in time using just the MRI scans, operating completely blind to the dream reports of the participants. Using the template data from the MRI images, they could tell if you were dreaming of a man or a woman, a dog or a bed, flowers or a knife. They were, in effect, mind reading, or should I say, dream reading.
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Linda Xie@linda﹒1y
Scientists measured the brain activity of participants viewing different pictures while awake and were then able to pattern match the brain activity while participants were dreaming.
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Why We Sleep
Why We Sleep
by Matthew Walker
p.65
Things get even more interesting when birds group together. In some species, many of the birds in a flock will sleep with both halves of the brain at the same time. How do they remain safe from threat? The answer is truly ingenious. The flock will first line up in a row. With the exception of the birds at each end of the line, the rest of the group will allow both halves of the brain to indulge in sleep. Those at the far left and right ends of the row aren't so lucky. They will enter deep sleep with just one half of the brain (opposing in each), leaving the corresponding left and right eye of each bird wide open. In doing so, they provide full panoramic threat detection for the entire group, maximizing the total number of brain halves that can sleep within the flock. 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
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Linda Xie@linda﹒1y
Ingenious way that birds sleep
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Why We Sleep
Why We Sleep
by Matthew Walker
p.21
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. Second is the engrained, un-level playing field of society's work scheduling, which is strongly biased toward early start times that punish owls and favor larks. Although the situation is improving, standard employment schedules force owls into an unnatural sleep-wake rhythm. Consequently, 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 work hours end prior to its arrival. Most unfortunately, owls are more chronically sleep-deprived, having to wake up with the larks, but not being able to fall asleep until far later in the evening. Owls are thus often forced to burn the proverbial candle at both ends.
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Linda Xie@linda﹒1y
One of the biggest boosts to my productivity was working at a Silicon Valley startup where my hours were more flexible since I get my best thinking done at night and have a harder time in the morning. It shouldn’t be shamed if this is how you work best.
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