Why We Sleep

sleep is infinitely more complex, profoundly more interesting, and alarmingly more health-relevant.
Among these gifts are a consoling neurochemical bath that mollifies painful memories and a virtual reality space in which the brain melds past and present knowledge, inspiring creativity.
It is no coincidence that the likelihood of breaking an Olympic record has been clearly tied to time of day, being maximal at the natural peak of the human circadian rhythm in the early afternoon.
Your brain, it seems, is still capable of logging time with quite remarkable precision while asleep.
sleep is truly an object of awe.
signals of emotions, motivations, and memories (past and present) are all played out on the big screens of our visual, auditory, and kinesthetic sensory cortices in the brain
sleep is the state we must enter in order to fix that which has been upset by wake. But what if we turned this argument on its head? What if sleep is so useful—so physiologically beneficial to every aspect of our being—that the real question is: Why did life ever bother to wake up?
emotionally astute, stable, highly bonded, and intensely social communities of humans.
We can awake the next morning with new solutions to previously intractable problems or even be infused with radically new and original ideas. (Location 1237)
That’s how deterministic the link between sleep and memory consolidation can be.
targeted memory reactivation.
forgetting is the price we pay for remembering.
Practice does not make perfect. It is practice, followed by a night of sleep, that leads to perfection.
if you don’t snooze, you lose.
However, 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.
The recycle rate of a human being is around sixteen hours. After sixteen hours of being awake, the brain begins to fail. Humans need more than seven hours of sleep each night to maintain cognitive performance.
No matter what you may have heard or read in the popular media, there is no scientific evidence we have suggesting that a drug, a device, or any amount of psychological willpower can replace sleep.
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. (Location 2338)
striatum—associated with impulsivity and reward, and bathed by the chemical dopamine—had
“The best bridge between despair and hope is a good night’s sleep.”
mass versus spaced learning.
ratified the long-held concept of “beauty sleep.”
The scientists had turned the MRI machine into a very expensive version of the beautiful handmade dream-catchers that some Native American cultures will hang above their beds in the hopes of ensnaring the dream—and they had succeeded.
A theory that cannot be discerned true or false in this way will always be abandoned by science,
dreams do have a function, as we will read about in the next chapter. Indeed, journaling your waking thoughts, feelings, and concerns has a proven mental health benefit, and the same appears true of your dreams.
A meaningful, psychologically healthy life is an examined one, as Socrates so often declared.
there is a red-thread narrative that runs from our waking lives into our dreaming lives, it is that of emotional concerns.
Those who were dreaming, but not dreaming of the painful experience itself, could not get past the event, still being dragged down by a strong undercurrent of depression that remained.
required REM sleep with dreaming, but dreaming of a very specific kind: that which expressly involved dreaming about the emotional themes and sentiments of the waking trauma. It was only that content-specific form of dreaming that was able to accomplish clinical remission and offer emotional closure in these patients, allowing them to move forward into a new emotional future, and not be enslaved by a traumatic past.
Deprive an individual of their REM-sleep dreaming state, and the emotional tuning curve of the brain loses its razor-sharp precision.
During the dreaming sleep state, your brain will cogitate vast swaths of acquired knowledge,I and then extract overarching rules and commonalities—“the gist.” We awake with a revised “Mind Wide Web” that is capable of divining solutions to previously impenetrable problems.
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
it is one of the key operations differentiating your brain from your computer. Computers can store thousands of individual files with precision. But standard computers do not intelligently interlink those files in numerous and creative combinations
REM sleep is capable of creating abstract overarching knowledge and super-ordinate concepts out of sets of information.
Little wonder, then, that you have never been told to “stay awake on a problem.” Instead, you are instructed to “sleep on it.”
The content of one’s dreams, more than simply dreaming per se, or even sleeping, determines problem-solving success.
Rather, the dream algorithm was cherry-picking salient fragments of the prior learning experience, and then attempting to place those new experiences within the back catalog of preexisting knowledge. (Location 3695)
Like an insightful interviewer, dreaming takes the approach of interrogating our recent autobiographical experience and skillfully positioning it within the context of past experiences and accomplishments, building a rich tapestry of meaning. (Location 3697)
there is an upward hook in death risk once the average sleep amount passes nine hours, resulting in a tilted backward J shape: (Location 4198)
biological mechanisms that show sleep to be in any way harmful have been discovered. (Location 4206)
There is an adaptive balance to be struck between wakefulness and sleep. In humans, that appears to be around sixteen hours of total wakefulness, and around eight hours of total sleep, for an average adult. (Location 4213)
Nightly alcohol will disrupt your sleep, and the annoying advice of abstinence is the best, and most honest, I can offer. (Location 4393)
Through climate-controlled homes with central heat and air-conditioning, and the use of bedcovers and pajamas, we have architected a minimally varying or even constant thermal tenor in our bedrooms. (Location 4433)
Selectively warming the feet and hands by just a small amount (Location 4454)
sleep took hold of the participants in a significantly shorter time, (Location 4456)
Hot baths prior to bed can also induce 10 to 15 percent more deep NREM sleep in healthy adults. (Location 4471)
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. (Location 4708)
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. (Location 4739)
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. (Location 4820)
Sound sleep is clearly sound business. (Location 4901)
Nike and Google have both adopted a more relaxed approach to work schedules, allowing employees to time their daily work hours to match their individual circadian rhythms and their respective owl and lark chronotype nature. (Location 4908)
companies like Nike and Google are as shrewd as they are profitable. They embrace sleep due to its proven dollar value. (Location 4914)
Using common machine-learning algorithms applied over time, we should be able to intelligently teach the home thermostat what the thermal sweet spot is for each occupant in each bedroom, based on the biophysiology calculated by their sleep-tracking device (Location 5276)
One practice known to convert a healthy new habit into a permanent way of life is exposure to your own data. (Location 5336)
Not only will this markedly improve an individual’s immunity but also that of the community, through developing more effective “herd immune benefits.” (Location 5370)
If workers string together twenty seven-hour nights of sleep or more in a row, they receive a twenty-five-dollar-per-night bonus, for a (capped) total of five hundred dollars. (Location 5407)
net company benefit of a well-slept employee is considerable. (Location 5410)
The return on the sleep investment in terms of productivity, creativity, work enthusiasm, energy, efficiency—not to mention happiness, leading to people wanting to work at your institution, and stay—is undeniable. (Location 5411)
misconceptions about grinding down employees with sixteen- to eighteen-hour workdays, burning them out in a model of disposability and declining productivity, littered with sick days, all the while triggering low morale and high turnover rates. (Location 5412)
Many individuals value time off more than modest financial perks. (Location 5416)
combination of sleep amount and night-to-night sleep continuity. (Location 5421)