Why We Sleep: Unlocking the Power of Sleep and Dreams QUOTES

82 " We try to recover one (NREM) a little sooner than the other (REM), but make no mistake, the brain will attempt to recoup both, trying to salvage some of the losses incurred. It is important to note, however, that regardless of the amount of recovery opportunity, the brain never comes close to getting back all the sleep it has lost. This is true for total sleep time, just as it is for NREM sleep and for REM sleep. 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, the saddening consequences of which I will describe in chapters 7 and 8. "

― Matthew Walker , Why We Sleep: Unlocking the Power of Sleep and Dreams

84 " Visit cultures that are untouched by electricity and you often see something rather different. 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. "

― Matthew Walker , Why We Sleep: Unlocking the Power of Sleep and Dreams

86 " If you were one of the individuals who were obtaining just five to six hours each night or less, you were 200 to 300 percent more likely to suffer calcification of your coronary arteries over the next five years, relative to those individuals sleeping seven to eight hours. "

― Matthew Walker , Why We Sleep: Unlocking the Power of Sleep and Dreams

88 " 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. "

― Matthew Walker , Why We Sleep: Unlocking the Power of Sleep and Dreams

90 " Downstairs in the body, sleep restocks the armory of our immune system, helping fight malignancy, preventing infection, and warding off all manner of sickness. Sleep reforms the body’s metabolic state by fine-tuning the balance of insulin and circulating glucose. Sleep further regulates our appetite, helping control body weight through healthy food selection rather than rash impulsivity. Plentiful sleep maintains a flourishing microbiome within your gut from which we know so much of our nutritional health begins. Adequate sleep is intimately tied to the fitness of our cardiovascular system, lowering blood pressure while keeping our hearts in fine condition. "

― Matthew Walker , Why We Sleep: Unlocking the Power of Sleep and Dreams

92 " Dijk and his prolific team examined gene expression in a group of healthy young men and women after having restricted them to six hours of sleep a night for one week, all monitored under strict laboratory conditions. After one week of subtly reduced sleep, the activity of a hefty 711 genes was distorted, relative to the genetic activity profile of these very same individuals when they were obtaining eight and a half hours of sleep for a week. "

― Matthew Walker , Why We Sleep: Unlocking the Power of Sleep and Dreams

94 " next-day fatigue and sleepiness can still occur because you are suffering from an undiagnosed sleep disorder, of which there are now more than a hundred. The most common is insomnia, followed by sleep-disordered breathing, or sleep apnea, which includes heavy snoring. Should you suspect your sleep or that of anyone else to be disordered, resulting in daytime fatigue, impairment, or distress, speak to your doctor immediately and seek a referral to a sleep specialist. Most important in this regard: do not seek sleeping pills as your first option. "

― Matthew Walker , Why We Sleep: Unlocking the Power of Sleep and Dreams

96 " It was once thought that sharks did not sleep, in part because they never closed their eyes. Indeed, they do have clear active and passive phases that resemble wake and sleep. We now know that the reason they never close their eyes is because they have no eyelids. "

― Matthew Walker , Why We Sleep: Unlocking the Power of Sleep and Dreams

98 " adolescents have a less rational version of an adult brain, one that takes more risks and has relatively poor decision-making skills. "

― Matthew Walker , Why We Sleep: Unlocking the Power of Sleep and Dreams

100 " One of the earliest studies found that using an iPad—an electronic tablet enriched with blue LED light—for two hours prior to bed blocked the otherwise rising levels of melatonin by a significant 23 percent. A more recent report took the story several concerning steps further. Healthy adults lived for a two-week period in a tightly controlled laboratory environment. The two-week period was split in half, containing two different experimental arms that everyone passed through: (1) five nights of reading a book on an iPad for several hours before bed (no other iPad uses, such as email or Internet, were allowed), and (2) five nights of reading a printed paper book for several hours before bed, with the two conditions randomized in terms of which the participants experienced as first or second. 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. "

― Matthew Walker , Why We Sleep: Unlocking the Power of Sleep and Dreams