Why We Sleep By Matthew Walker

 Unlocking The Power Of Sleep And Dream 

PART ONE

Chapter ONE

This thing is called sleep

To sleep...

Doctors and scientists could not give you a consistent or complete answer us why we sleep. Consider that we know the functions of the three other basic drives in life- to eat, to drink, and reproduce-for many tens if not hundreds of years now, yet the fourth main biological drive, common across the entire animal kingdom- the drive the sleep has continued to elude for millennia.

Chapter TWO

Caffeine, Jet Lag, and Melatonin

Got Rhythm?

Your twenty-four-hour tempo helps to determine when to be awake and when to be asleep. But it controls other rhythmic patterns too. These include our time preferences for eating and drinking, your moods and emotions, the amount of urine you produce, your core body temperature, your metabolic rate, and the release of hormones. It is no coincidence that the likelihood of breaking an Olympic record has been early tied of day. Being maximum at the natural peak human cardiac rhythm in the early afternoon. Even the timing of birth and deaths demonstrates cardiac rhythmicity due to the marked swings in key life-dependent metabolic, cardiovascular, temperature, and hormonal processes that this peacemaker controls.

The twenty-four-hour biological clock sitting in the middle of your brain is called the suprachiasmatic nucleus. As with much anatomical language, the name, while far from easy to pronounce is instructional: supra, meaning above, and charism meaning crossing point os that of the optic nerves coming out from eyeballs Those nerves then effectively switch sides. The suprachiasmatic nucleus use this reliable light information to rest its inherent time inaccuracy to crisp twenty-four-hour cycle preventing any drift.

For diurnal species that that are active during the day, such as humans, the circadian rhythm activates many brain and body mechanism in the brain and body during daylight hours that are designed to keep awake and alert. These processes are then ratcheted down at night time, removing, the alerting influence. I show one such example of circadian rhythm -that of our body temperature.

My Rhythm is Not Your Rhythm

You may colloquially know these two types of people as "morning larks" and "night owls" respectively. Unlike morning larks night owls are frequently incapable of falling asleep early at night, no matter how they try. It is only in the early morning hours that owls can drift-off. Having not fallen sleep until late. owls of course strongly dislike waking up early. They are unable to function well at this time, one cause of which despite being "awake" their brain remains in a more sleep-like state throughout the morning.

An adult's owlness or larkness, also known as their chronotype, is strongly determined by genetics. If you are a night owl, it's likely both of your parents are night owl. Sadly, society treats night owls rather unfairly.

Melatonin

Your suprachiasmatic nucleus communicates its repeating signal of night and day to your brain and body using a circulating messenger called melatonin. Melatonin has others name too that includes "The hormone of darkness" and "the vampire hormone". Not because it is sinister but because it released at night and gives our body the signal of night.

For this reason, melatonin is not a powerful sleeping aid in and of itself, at last not for healthy, not -jet-lagged individuals. once sleep is underway, melatonin slowly decreases in concertation across that night and into the morning hours. With dawn, as sunlight enters the brain through the eyes(even though the close lids), a brake pedals to pineal gland, thereby shutting off the release of melatonin.

Sleep pressure and caffeine

At this very moment, a chemical called adenosine is building up in your brain. It will continue to increase in concentration with every walking minute that elapses. The longer you are awake the more adenosine will accumulate.

Caffeine works by successfully battling with adenosine for the privilege of latching on to adenosine welcome sites-or receptors- in the brain. Caffeine blocks and effectively in activities the receptors acting as a masking agent.

During sleep, a mass evacuation gets under way as the brain has the chance to degrade and remove day's adenosine. Across the night, sleep lifts the heavyweight sleep pressure. lightning adenosine load. After approximately eight hours of healthy sleep in an adult, the adenosine purge is complete.

Am I getting enough sleep?

First waking up in the morning, could you fall asleep at ten or eleven a.m. ? If the answer is "yes" you are likely not sufficient sleep quantity or quality. Second, can you function optimally without caffeine before noon? If the answer is "no" then you are most likely of self-medicating your state of chronic sleep deprivation.

Other questions that can be drawn out to sign out insufficient sleep are: If you didn't set an alarm would you sleep past the time? ( If so you need more sleep than you are giving yourself). Do you find yourself at your computer screen reading and then reading ( perhaps reading again) the same sentence? This is often a sign of a fatigued, under-slept brain.

Chapter 3

When we have all determined someone is asleep, or that we have been asleep, the gold standard scientific verification of sleep requires the recording of signals, using electrodes, arising from three different regions: (1) brainwave activity (2) muscle activity (3) eye movement activity

The Sleep Cycle

There are two-stage of sleep (1)NREM (2) REM. Push-Pull battle for brain domination across the nights. The cerebral between these two is won and lost within every 90 minutes

Combine these two, and we have at least one parsimonious explanation for the two types of sleep cycle across the night, and why those cycles are initially dominated by NREM sleep early on, with REM sleep reigning supreme in the second half of the night.

Different species have different NRE-REM sleep cycle lengths. e are shorter than the humans. The functional purpose of the cycle length is another mystery of sleep. To date, the best predictor of NREM-REM sleep cycle length is the width of the brain stem, with those processing wider brain stem having longer cycle length.

Oddly during the transition from being awake into the light stage 1 NREM sleep, the eyes will gently and very slowly start to roll their socks in synchrony. It is hallmark indication of that inset of sleep inevitable

Chapter 4

Who Sleeps

Sleep is necessery for every species, at first it was thought that sharks did not sleep, in part becasue they never closed their eyes, Indeed they do have clear active and passive phase that resemble wake an sleep. We now know that the reason they never close their eyes because they have no eyelids.

We are special

As it turns out, we humans are special when it comes to sleep. Compare to old and New World monkeys as well as apes. Yet we have disproportion amount of REM sleep, the stage in which we dream. between 20 to 25 percent of our sleep time is dedicated to our REM sleep dreaming.

REM sleep dreaming fuels creativity. NREM sleep helps to transfer and make safe newly learned information into long-term storage sites of the brain. But it is REM sleep that takes these freshly minted memories and begins colliding them with the entire back catalog of your life's autobiography

Chapter 5

Changes of sleep across the life span

Sleep before Birth and childhood sleep

In the stage of utero development, most of the time is spent in sleep. The twenty-hour period contains a mishmash of approximately six hours of NREM-sleep, six hours of REM sleep, and twelve hours of intermediary sleep state than can not confidently say is REM or NREM, but certainly is not full wakefulness. It is only when the fetus enters the final trimester that the glimmers of real wakefulness emerge. For the less than would probably imagine, tho ugh-just two to three hours of each day are spent awake in the womb.

During the fourteen hours of total shut-eye per day that a six-month-old infant obtains, there is a 50/50 timeshare between NREM and REM sleep across the eleven hours of total daily slumber.A five-year-old will have a 70/30 split between NREM and REM sleep across the eleven hours of total daily slumber. This balance will finally be 80/20 NREM/REM sleep split by the late teen years, and so remain throughout early and mid-adulthood.

The older the child gets, The fewer, longer, and more the stable their sleep bouts become

Sleep and Adolescence

Adolescents face two other harmful challenges in their struggle to obtain sufficient sleep as their brains continue to develop. The first is their change in their circadian rhythm. The second is early school start times. As young child, we often wish to stay up early in the night so we could catch up the late-night tv show, or engage with parents and older siblings it whatever they were doing at night.

Sadly, neither our society nor parental attitudes are well designed to appreciate or accept that teenagers need more sleep than adults, and that they are biologically wired to obtain that sleep at different times from their parents.

Sleep in middle life and old age

The older adult simply needs less sleep is a myth. Older adults appear to need just as much sleep as they do in middle life. But are simply able to generate that ( still necessary) sleep. They still need full night sleep just as young adults.

The second hallmark of altered sleep we age, and one that older adults are more conscious of, is fragmentation. The older we get. the more frequently we wake up throughout the night. Due to the fragmentation, older individuals will suffer a reduction in sleep efficiency.

The preliminary results of our brain stimulation studies suggest that older adults needs more sleep than they themselves can naturally generate since they benefit from an improvement in sleep quantity.

Part 2

Chapter 6

Sleep for the brain

Sleep is not the absence of wakefulness, It is more than that.

Numerous functions of the brain are restored by and depend upon sleep. Each stage of sleep-light NREM sleep, Deep NREM, and REM- Offer different brain benefit s at different times of the night. Thus, no one type of sleep is more essential than another.

If we all slept enough? Our health care burden will plummet. We would had better mental health and fewer suicide. Our business would be more productive and global economic would be helthier, our roads would be safer and our children would be smarter .... Sleep is the best health isurance policy you could ever wish for - Matthew Walker, PHD

Sleep the night before learning

Sleep before learning refreshes our ability to initially make new memories. It does so each and every night. While we awake, the brain constantly acquiring and absorbing novel information (intentionally or otherwise).

Sleep restores the brain's capacity for learning, makes room for new memories. Analyzing the brain waves the memory refreshment was related to lighter, stage 2 NREM sleep, and are specifically short. powerful bursts of electrical activity called sleep spindles.

Sleep the night after learning

The second benefit of sleep for memory comes after learning, one that effectively clicks to "save" button on those newly created files.

It is curious fact, of of which the reason is not obvoius, that the interval of a single night will greatly increase the strength of the memory ..... Whenever the cause, things which could not be reacalled on the spot are easily coordinated the next day, and the time itself, which is generally accounted one of the cause of forgetfulness, actually serves to strengthen the memory

Infants, young kids, or adolescents and you see the very same overnight memory benefit of NREM sleep, sometimes even more powerful so. For those in middle life, forty to sixty years old, deep NREM sleep continues to help the brain to retain new information in this way, with this decline in deep NREM sleep and the deterioration in the ability to learn and retain memories in old age having already been discussed.

Sleep for other types of memory

The term "muscle memory" is a misnomer. Muscle themselves have no such memory: a muscle that is not connected to the brain cannot perform any skilled actions, nor does muscle store skilled routines

Muscle memory is, in fact, brain memory.

Ongoing sleep quality predicts the gradual return of motor function, and further determines the relearning of numerous movement skills. Should more such findings emerge, then more concerted effort to prioritize sleep as a therapeutic aid in patients who have suffered brain damage may be warranted? There is so much that sleep can do that we in medicine currently cannot. So long as the scientific evidence justifies it, we should make use of the powerful health tool that sleep represents in making our patients well.

Sleep for creativity

A final benefit of sleep for memory is arguably the most remarkable of all; creativity. Sleep provides a nighttime theatre in which your brain tests out and builds connections between vast stores of information. The sleeping brain fuses together the disparate sets of knowledge that foster impressive problem-solving abilities.

Chapter 7

Pay Attention

There are too many ways in which lack of sufficient sleep will kill you. Some would take time; others far more immediate. One brain function that buckles under even the smallest dose of sleep deprivation is concentration. The deadly societal consequences of these concertation failures play out most obviously and fatally in the form of drowsy driving.

Ten days of six hours of sleep a night was all it took to become as impaired in performance as going without sleep for twenty hours straight.

Currently, however, there is no drug that has the proven ability to replace those benefits that full night sleep infuses into the brain and body.

The best bridge between despair and hope is a good night sleep

Tired and Forgetful?

The very latest work has revealed that sleep deprivation impacts the DNA and the learning-related genes in the brain cell of the hippocampus itself. A lack of sleep, therefore, is a deeply penetrating and corrosive force that enfeebles the memory-making apparatus within your brain, preventing you from constructing lasting memory traces. It s rather like building sandcastle too close to the tide line- the consequences are inevitable.

Chapter 8

Cancer, Heart Attacks, and shorter Life Span

sleep is the third pillar of good health, alongside diet and exercise

Sleepless and the cardiovascular system

Unhealthy sleep, Unhealthy heart. Simple and true

Shorter sleep is associated with a 45 percent increased risk of developing and /or dying from coronary heart disease within seventy to twenty-five years. A Japanese study of over 4000 male workers. Over the 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.

The heart suffers so dramatically under the weight of sleep deprivation concerns blood pressure. High blood pressure is so common nowadays that we forget to the deathly toll it inflicts.

Beyond accelerating year heart rate and increasing your blood pressure, a lack of sleep further erodes the fabric of those strained blood vessels especially those that feed the heart itself, called the coronary arteries. These corridors of life need to be clean and open wide to supply your heart with blood at all times. Narrow or block those passageways and your heart can suffer a comprehensive and often fatal attack by blood oxygen starvation, colloquially known as a "massive coronary".

Sleep Less and Metabolism: Diabetes and Weight Gain

The less sleep , the more you likely to eat

The more you less sleep your body becomes less unable to manage those calories effectively, especially the concentration of sugar in your blood. Sleeping less than seven or eight hours a night will increase your probability of gaining weight, being overweight, or obese and significantly increase your likelihood of developing type 2 Of diabetes.

Diabetes

Sleep deprivation causes us to lower the power of absorbing a standard dose of glucose, compared to when they are fully rested. Restricting four to five hours of sleep for a week, the cells f these tired individuals had become far less respective to insulin. In this sleep-deprived state, the cells were stubbornly the message of insulin and refusing to open up their surface channels. The cells were then repelling rather than absorbing the high level of glucose, leading to rising tide blood sugar and pre-diabetes, and hyperglycemia.

Weight gain and obesity

When your sleep becomes you will gain weight. The first concerns two hormones controlling appetite: Leptin and Ghrelin. Leptin signals the feeling fully. Ghrelin, in contrast, triggers a strong sensation of hunger. So, too, does desire to eat. An imbalance of either one of these hormones can trigger increase eating and thus body weight. Perturb both in the wrong direction, and weight gain is more than probable.

Several studies have proven that short sleep will increase hunger and appetite, compromise control within the brain, increase food consumption ( especially of high-calorie foods ), decrease the feelings of food satisfaction after eating and prevent effective weight loss in dieting.

Sleep loss and immune system

Sleep fights against infection and sickness by deploying all manner of weaponry within your weapon arsenal, cladding you with protection. When you do fall ill, the immune system actively stimulates the sleep system, demanding more bed rest to help reinforce the war effort. Reduce sleep even for a single night and that invisible suit of immune resilience is rudely stripped from your body.

Poor sleep quality, therefore, increases the risk of cancer development and, if cancer is established, provides virulent fertilizers for its rapid and more rampant growth. Not getting sufficient sleep when fighting a battle against cancer can be linked to pouring gasoline on an already aggressive fire. That may sound alarmist, but the scientific evidence linking sleep disruption and cancer is now so damming that the World Health Organization has officially classified nighttime shift work as a "probable carcinogen".

Part 3

How and why we dream

Chapter 9

Your brain on dreams

Once your dream was on your own. We got to decide whether or not to share them with others and if we did which part to include and which part withhold. There may well be a time in the not too distant future where we can accurately readout and thus take ownership of a process that few people have volitional control over the dream. When this finally happens, and I'm sure it will do we hold the dreamer responsible for what they dream? Is it fair to judge what is it they are dreaming, since they are not the conscious architects of their dream? But if they were not, then who is? It is a perplexing and uncomfortable issue to face.

Do dreams have a function?

Through the combination of brain activity measures and rigorous experimental testing, we have finally begun to develop a scientific understanding of human dreams, their form, and content. Dreams do not have any function with REM sleep. But do dream themselves above and beyond REM sleep, actually they do anything for us? As a matter of scientific fact, yes they do.

Chapter 10

Dreaming as overnight therapy

When the human brain produces REM sleep in this specific way, It may also however produce this thing we call dreaming. Dreams may simply be epiphenomena of no use or consequences. They are merely unintended by-products of REM sleep.

Two core benefits of REM sleep. Both functional benefits require not just that you have REM sleep, but that you dream and dream about specific things. REM sleep is necessary but REM sleep is not sufficient. Dreams are by-products of REM sleep.

This first function involves nursing our emotional and mental health. The second problem is solving and creativity, the power of which some individuals try to harness more fully by controlling their dream.

Chapter 11

Dreaming: The creative incubator

Dreaming generates creativity and also sparks countless literary ideas and epics. When, then, scientific evidence establishing that sleep and specifically REM sleep and dreaming, provides from associative memory processing.

REM-sleep the fuzzy logic

The widening of our memory aperture is akin to peering through a telescope from the opposing end. When we are awake are looking through the wrong end of the telescope if transformational creativity is our goal. We take a myopic, hyperfocused, and narrow that can not capture the full informational cosmos on offer in the cerebrum. When we are awake, we see only a narrow set of all possible memory interrelationships. The opposite is true. however when we enter the dream state and start looking through the other (correct) end of the memory surveying telescope. Using the wide-angle dream lens, we can apprehend the full constellation of stored information and their diverse combinational possibilities all in creative servitude.

Memory melding the furnace of dreams

Some may consider this informational daisy-chaining to be trivial, but it is one of the key operations differentiating your brain from the computer. Your computer can store data of individual files with precision. But standard computers do not intelligently interlink those files in numerous and creative combinations. Instead, computer files sit like isolated islands. Our human memories are, on the other hand, richly interconnected in webs f associations that lead to flexible, predictive powers. We have REM sleep, and the act of dreaming, to thank much of that inventive hard work.

Controlling your dreams- Lucidity

The concept of lucid dreaming was once considered a sham. Scientists debated its very existence. You can understand the skepticism. The first assertion of conscious control over a normally non volitional process injects a heavy dose of ludicrous into the already preposterous experience we call dreaming.

It remains unclear that lucid dreaming is beneficial or detrimental since 80 percent of the general populace are not natural lucid dreamers. If gaining voluntary dream power were so useful, surely Mother Nature would have imbued the masses with skill.

Part 4

From Sleeping Pills to Society Transformed

Chapter 12

Somnambulism

The term "Somnambulism" refers to sleep (Somnus) disorders that involve some form of movement (ambulation). It encompasses the condition such as sleepwalking.

Understandably, most people believe that this event happens during the REM sleep as an individual is dreaming, and specifically acting out on going dreams, However all these events rises from the deepest stage of nondreaming (NREM) sleep and not dreaming (REM) sleep. If you rouse an individual from a sleepwalking event and ask them what was going through their mind, rarely they report a thing-no dream scenario, no mental experience.

For the most part, there is nothing pathological about sleepwalking or sleep talking. They are common in the adult population, and even more common in children. One explanation of the former is simply when we are young, and the satistical likelihood of sleepwalking and sleep talking experience is higher.

Insomnia

There are two types of Insomnia

1. Suffering from inadequate ability to generate sleep.
2. Allowing oneself the adequate opportunity to sleep.

People suffering from insomnia therefore cannot produce sufficient sleep quantity/quality, even though they gave them enough time to do so.

People diagnosis with insomnia should be checked for these:

• Dissatisfaction with sleep quantity or quality.
• Suffering significant distress in daytime impairment.
• Has insomnia at least three nights each week for more than three months.
• Does not have any coexisting mental disorders or medical conditions that could otherwise cause what appears insomnia.

The two most common triggers of chronic insomnia are psychological:

1. Emotional concerns, or worry
2. Emotional Distress, or anxiety

Sleep deprivation vs. Food deprivation

Allan Rechtschaffen, was once contacted by a well-known women's fashion magazine. The writer of the article wanted to know if total sleep deprivation offers an exciting, new, and effective way for women to lose weight. Struggling to comprehend the audacity of what had been asked for him, Rechtschaffen attempted to compose a response. Apparently, he admitted that enforced total sleep deprivation in rats results in weight loss, yes acute sleep deprivation for days on end des lead weight loss. However, in this combination o remarkable weight loss came skin wounds that wept lymph fluid, sores that had eviscerated the rat's feet, a decrypted that accelerate aging, together with catastrophic (and ultimately fatal) internal organ and immune-system collapse.

Chapter 13

The Dark Side of Modern Light

Artificial LED lights are harmful to our sleep, they have a great impact on our sleep quality and quantity.

Maintaining complete darkness throughout the night is equally critical, the easiest fix for which comes from blackout curtains. Finally, you can install software on your computer, p4

phones, tablets, and other devices that gradually desaturates the harmful blue LED light as the evening progresses.

Chapter

Sleeping Pills

The sleeping pills only produce "slight improvements in subjective and polysomnographic sleep latency"- that is, the time it takes to fall asleep. Even the newest sleeping pills of insomnia have improved minimally effectively. Future versions of this such drugs may offer meaningful sleep improvements, but for now, the specific data on prescription sleeping pills suggests that may not be the answer to returning sound sleep to those struggling to generate sleep on their own.

Sleep in Workplace

Several studies and research sleep deprivation has cost loss in productivity and problem solving of their worker and this cause great impact on GDP. Companies should put more focus on their worker's sleep habits in order to get more things done and the well-being of their company.

Sleep and education

As parents, we, therefore, have a judicial view of the need and importance of sleep in our children, sometimes even chastising or stigmatizing our desire to sleep enough, including their desperate, weekend to repay sleep debt that the school system has saddled them with not fault their own. I hope we can change. I hope we can break the parent-to-child transmission of sleep neglect and remove what the exhausted, fatigued brains our youth are so painfully starved of. When sleep is abundant, the mind flourishes. when it is deficient they don't.

Conclusion

Within the space of mere hundred years, human beings have abandoned their biologically mandated need for adequate sleep-one that evolution spent 3,400,4000 years perfecting in service of the life support function. As a result, the decimation of sleep throughout industrialized nations is having a catastrophic impact on our life expectancy, our safety, our productivity, and the education of our children.

I believe this is the time for us to reclaim our right to use full night sleep, without embarrassment r the damaging stigma of laziness.