Book notes: Why We Sleep by Matthew Walker

Why We Sleep by Matthew Walker book summary review and key ideas.

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

Synopsis:

“The first sleep book by a leading scientific expert – Professor Matthew Walker, director of UC Berkeley’s Sleep and Neuroimaging Lab – reveals his groundbreaking exploration of sleep, explaining how we can harness its transformative power to change our lives for the better.

Sleep is one of the most important but least understood aspects of our life, wellness, and longevity. Until very recently, science had no answer to the question of why we sleep, or what good it served, or why we suffer such devastating health consequences when we don’t sleep. Compared to the other basic drives in life – eating, drinking, and reproducing – the purpose of sleep remained elusive.

But an explosion of scientific discoveries in the last 20 years has shed new light on this fundamental aspect of our lives. Now, preeminent neuroscientist and sleep expert Matthew Walker gives us a new understanding of the vital importance of sleep and dreaming. Among so many other things, within the brain, sleep enriches our ability to learn, memorize, and make logical decisions. It recalibrates our emotions, restocks our immune system, fine-tunes our metabolism, and regulates our appetite. Dreaming mollifies painful memories and creates a virtual reality space in which the brain melds past and present knowledge to inspire creativity.

Walker answers important questions about sleep: How do caffeine and alcohol affect sleep? What really happens during REM sleep? Why do our sleep patterns change across a lifetime? How do common sleep aids affect us, and can they do long-term damage? Charting cutting-edge scientific breakthroughs and synthesizing decades of research and clinical practice, Walker explains how we can harness sleep to improve learning, mood, and energy levels; regulate hormones; prevent cancer, Alzheimer’s, and diabetes; slow the effects of aging; increase longevity; enhance the education and lifespan of our children, and boost the efficiency, success, and productivity of our businesses. Clear-eyed, fascinating, and immensely accessible, Why We Sleep is the crucial account on sleep that will forever change listeners’ minds on the subject.” -Audible


Opening thoughts:

I definitely heard of this book from Tim Ferriss’ podcast a while back so it has been on my list for a while. Seems like a good thing to read as I’m trying to refocus on my health and wellness in regards to eating better (plant-based), working out consistently, mindfulness through meditation, and now better sleep.


Key notes:

Part 1: This Thing Called Sleep

Chapter 1: To Sleep

  • Reader’s note: LOL this book starts off strong. Out the gate, it lists so many physical and mental health issues that come with a lack of good sleep
  • Lack of sleep makes you want to eat more as it increases the hormone that makes you feel hungry
  • Sleep deficiency is a proven recipe for weight gain
  • The shorter your sleep, the shorter your lifespan
  • Sleep is evolutionary puzzling because it doesn’t help you find food, find a mate to reproduce, and it leaves you vulnerable to predators
  • Sleep is the single most effective thing we can do to reset our brain and body health each day

Chapter 2: Caffeine, Jet Lag, and Melatonin – Losing and Gaining Control of Your Sleep Rhythm

  • The average circadian rhythm of a human is approximately 24 hours, but slightly more
  • Sunlight resets our biological clocks to precisely 24 hours each day
  • Morning Larks vs. Night Owls
    • The evolutionary advantage of having both Morning Larks and Night Owls is so the community as a whole is vulnerable/sleeping for a shorter period of time
  • Melatonin is the thing that signals the start of sleep
  • For jet lag, it takes your body about 1 day for every hour it has to adjust to a new sleep rhythm
  • It feels harder to acclimate to a new time zone when traveling eastward than when flying westward
    • Going East requires you to fall asleep earlier which is harder
    • Going West requires you to stay up later, which is easier
    • Because our natural circadian rhythms are slightly longer than a day, that makes it easier to stretch our day (stay up longer) than shrink it (sleep earlier)
  • Sleep deprivation also affects short term memory and forgetfulness
  • Studies show that frequently traveling through time zones negatively affect parts of the brain related to learning and memory because of the biological stress of time zone travel
    • Studies on pilots and cabin crew shows higher rates of cancer and diabetes
  • Sleep pressure is the 2nd force that will determine when you feel sleepy
    • Increasing adenosine in the brain, which happens continuously as you’re awake, increases your desire to sleep
  • Caffeine is the 2nd most traded commodity on the planet after oil
  • Half-life refers to the length of time it takes for the body to remove 50% of a drug’s concentration
    • Caffeine has an average half life of 5-7 hours
  • Hidden caffeine in the foods we eat is often the hidden culprit of our inability to get good sleep

Chapter 3: Defining and Generating Sleep – Time Dilation and What We Learn From a Baby in 1952

  • Even though we lose track of time when we sleep, our brain is still very aware of time and tracks it subconsciously
  • When it comes to information processing:
    • Wake State: reception – experiencing and constantly learning the world around you
    • N-REM sleep: reflection – storing and strengthening those raw ingredients of new facts and skills
    • REM sleep: integration – interconnecting these raw ingredients with each other, with all past experiences, and building an evermore accurate model of how the world works
  • Our body shuts off motor functions during REM sleep so that we don’t act out our dreams due to all the neurons firing in our brain from the activity

Chapter 4: Ape Beds, Dinosaurs, and Napping with Half a Brain – Who Sleeps, How Do We Sleep, and How Much?

  • Question: why do living organisms wake if sleep is so beneficial?
    • Theory: Perhaps sleep was the first state of life on the planet, and it was from sleep that wakefulness emerged
  • Sleep is of ancient origin
    • It appeared with earliest forms of planetary life
    • Sleep has remained a common bond uniting every creature in the animal kingdom
  • REM sleep doesn’t appear to be feasible or needed by aquatic mammals when in the ocean
  • Sleep rebound is when we try to respond to a sleep deficit and we sleep longer than usual to make up
    • N-REM sleep rebounds harder than REM, as the brain will consume a larger portion of it on the first night after total sleep deprivation
    • There is a lopsided hunger fro N-REM over REM
    • On subsequent days, however, there is a reversal and more REM sleep is consumed
    • Both types are needed, though one is recovered first
  • We sleep so poorly the first night in a new location because half of our brain is a little more awake than the other to maintain vigilance
    • The more nights in that location, the more similar the brain activity of each half becomes
    • REM sleep however requires participation of both half of the brain at the same time and to an equal degree
  • Some cultures untouched by civilization adopt different sleep patterns such as a normal, long period at night, and then a 30-60 minute nap in the afternoon
    • Others do this seasonally
    • Some sleep a couple hours after sunset and awake after dawn
    • An afternoon nap seems to be a normal part of the daily rhythm of life
      • A study showed that when a culture removed their afternoon naps, it resulted in a increase in heart disease
  • From a prescription written long ago in our ancestral gene code, the practice of natural biphasic sleep and a healthy diet appear to be the keys to a long, sustained life
  • Sleep, especially REM sleep and the act of dreaming, is a turnable yet under-appreciated factor underlying many elements that form our unique human ingenuity and accomplishments

Chapter 5: Changes in Sleep Across the Lifespan

  • Alcohol is one of the most powerful suppressors of REM sleep that we know of
  • There might also be a correlation between autism and a weaker/abnormal REM cycles, especially during early childhood development
  • REM sleep is not optional during early human life, but obligatory
  • Book reference: Go The Fuck To Sleep
  • The circadian rhythm of children makes them fall asleep first, followed by adults, and then last by teenagers
  • Poor memory and reduced deep sleep in aged adults are strongly interconnected

Part 2: Why Should You Sleep?

Chapter 6: Your Mother and Shakespeare knew – The Benefits of Sleep for the Brain

  • Reader’s note: At this point, I’m thinking this is a book for everyone, especially students who think cramming and staying up all night studying is a good thing. We all know that sleep helps with memory and stronger brain function, but this does a good job emphasizing how really important it is based on the science
  • The quantity of N-REM sleep helps the most with memory
    • Sleep transfers the memory from the short term and vulnerable storage site of the hippocampus to the long term and more safe neocortex
    • Even short naps can consolidate memories and free up limited chache of short term memory space as long as it contains enough N-REM sleep
  • Practice plus sleep makes perfect
    • If you don’t snooze, you lose
    • Even Olympic athletes have taken naps hours before breaking record and winning gold medals like Usain Bolt
  • Reader’s note: This reminds me of the book Peak Performance

Chapter 7: Too Extreme for the Guinness Book of World Records – Sleep Deprivation and the Brain

  • Traffic accidents are the leading causes of death for most 1st world nations
    • For each hour of sleep you lose, your chances of getting into an accident increase exponentially
  • The recycle rate of a human being is around 16 hours, and then the brain begins to fail
    • Humans need more than 7 hours of sleep each night
    • After just 10 days of just 7 hours, the brain is just as dysfunctional as if it were going without sleep for 24 hours
    • The human mind cannot accurately sense how sleep deprived it is when sleep deprived
  • Do NOT drive drowsy
    • It is not considered an accident as it is a predictable consequence
    • It is a myth to think tricks, techniques, or sheer force of will can overcome drowsiness while driving
  • A power nap is best taken proactively to hedge off drowsiness later in the evening rather than when it’s too late
  • Sleep deprivation also significantly increases emotional and uncontrolled reactivity in the fight or flight areas of the brain in the amygdala
  • Studies of adolescences have identified a link between sleep disruption and depression/suicidal thoughts
  • A lack of sleep can be the trigger of a manic or depressive state in bipolar people

“The best bridge between despair and hope is a good night’s sleep”

E. Joseph Cosman
  • The two most feared diseases throughout developed nations are dementia and cancer
    • Both are related to inadequate sleep
  • Sleep disturbance precedes the onset of Alzheimer’s disease, suggesting it may be an early warning sign or a contributor to it
  • N-REM sleep allows for a cleaning process to occur in the brain where harmful amaloid deposits that cause dementia are removed
  • Wakefulness is low level brain damage while sleep is neurological sanitation

Chapter 8: Cancer, Heart Attacks, and a Shorter Life – Sleep Deprivation and the Body

  • Sleep is not a pillar but the foundation on which the health bastions of nutrition and exercise sit
    • The effects of sleep deprivation will seep into every nook and cranny of biology
  • Many studies on millions of people show that the shorter your sleep, the shorter your life
  • Insufficient sleep proves ruinous to all major physiological systems of the human body:
    • cardiovascular
    • metabolic
    • immune
    • reproductive
  • Short sleep is a proven recipe for weight gain, and will:
    • Increase hunger and appetite
    • Compromise impulse control within the brain
    • Increase food consumption (especially high calorie foods)
    • Decrease feels of food satisfaction after eating
    • Prevent effective weight loss when dieting
  • Less sleep results in lower sperm count, testosterone, and libido
  • Women who suffer from lower quality and less sleep are more likely to have irregular menstrual cycles and lower fertility
  • Physical attractiveness is decreased by lack of sleep
    • “Beauty sleep” is real
  • Less sleep weakens and compromises your immune system
    • Reduced sleep increases your risk of getting various forms of cancer
  • A lack of sleep triggers a sympathetic nervous system response which creates a sustained inflammation response

Part 3: How and Why We Dream

Chapter 9: Routinely Psychotic – REM Sleep Dreaming

“A meaningful, psychologically healthy life is an examined one”

Socrates
  • One thread that connects our waking lives into our dreaming lives is that of our emotional concerns

Chapter 10: Dreaming as Overnight Therapy

  • One function of REM sleep is as therapy for emotionally traumatic events
  • REM sleep helps to re-calibrate our ability to accurately assess and decode other people’s emotions and intent through facial expressions

Chapter 11: Dream Creativity and Dream Control

  • Another benefit of REM sleep and the act of dreaming is intelligent information processing that inspires creativity and promotes problem solving
  • Lucid dreaming is being aware you’re dreaming but can also refer to being able to control your dream

Part 4: From Sleeping Pills to Society Transformed

Chapter 12: Things That Go Bump in the Night – Sleep Disorders and Death Caused by No Sleep

  • Sleep deprivation is not insomnia as sleep deprived individuals simply don’t give themselves the time to sleep
  • Sleep onset insomnia is difficulty falling asleep
    • Sleep maintenance insomnia is difficulty staying asleep

Chapter 13: iPads, Factory Whistles, and Nightcaps – What’s Stopping You From Sleeping

  • 5 Key Factors that have changed how much and how well we sleep
    1. Constant electric light and LED light
    2. Constant temperature
    3. Caffeine
    4. Alcohol
    5. A legacy of punching time cards
  • Cooling the body using your heat dispersing extremities of your hands, feet, and head help you fall asleep as your core body temperature needs to drop by a few degrees to transition into sleep
    • This is also why splashing your face with water helps to lower your body temp
  • The alarm clock and snooze function inflicts a cardiovascular assault, spike in blood pressure, and illicit a fight or flight response in the nervous system

Chapter 14: Hurting or Helping Your Sleep – Pills vs. Therapy

  • CBTI = Cognitive Behavioral Therapy for Insomnia

Chapter 15: Sleep and Society – What Medicine and Education Are Doing Wrong, What Google and NASA Are Doing Right

  • Employees who get enough sleep every night are more productive and profitable for companies

Chapter 16: A New Vision for Sleep in the 21st Century

  • Businesses and workplaces should not only incentivize total and consistent sleep, but also accommodate flexible hours for larks vs owls
  • A lack of sleep also makes you more sensitive to pain
  • Helping to create a more conducive environment to sleep in hospitals will decrease pain sensitivity and improve the immune system and recovery of patients

12 Tips for Healthy Sleep

  1. Stick to a consistent sleep schedule
    • Wake up and go to bed at the same time each day, including weekends
  2. Exercise is great, but not too late in the day
    • Try to exercise 30 minutes each day, but not 2-3 hours before bedtime
  3. Avoid caffeine and nicotine
  4. Avoid alcoholic drinks before bed
  5. Avoid large meals and beverages late at night
  6. If possible, avoid medicines and medications that delay or disrupt sleep
  7. Don’t take naps after 3PM
  8. Relax before bed
    • Don’t over-schedule yourself late in the day
  9. Take a hot bath before bed
    • This helps cool down your body temperature
  10. Dark bedroom, cool bedroom, gadget-free bedroom
  11. Have the right sunlight exposure
    • Try to get outside and natural sunlight for at least 30 minutes each day
    • Try to wake up with the sun and use bright lights in the morning
  12. Don’t lie in bed awake
    • Try to do some other relaxing activity outside of bed until you feel sleepy
    • Limit non-sleep time in bed

Main ideas / Themes:

  • The shorter your sleep, the shorter your lifespan
  • Sleep is the single most effective thing we can do to reset our brain and body health each day
  • Wake State: reception – experiencing and constantly learning the world around you
  • N-REM sleep: reflection – storing and strengthening those raw ingredients of new facts and skills
  • REM sleep: integration – interconnecting these raw ingredients with each other, with all past experiences, and building an evermore accurate model of how the world works
  • the practice of natural biphasic sleep and a healthy diet appear to be the keys to a long, sustained life
  • The circadian rhythm of children makes them fall asleep first, followed by adults, and then last by teenagers
  • The quantity of N-REM sleep helps the most with memory
  • Practice plus sleep makes perfect
  • The recycle rate of a human being is around 16 hours, and then the brain begins to fail
  • Wakefulness is low level brain damage while sleep is neurological sanitation
  • Sleep is not a pillar but the foundation on which the health bastions of nutrition and exercise sit
  • Less sleep weakens and compromises your immune system
  • REM sleep helps to re-calibrate our ability to accurately assess and decode other people’s emotions and intent through facial expressions
  • Another benefit of REM sleep and the act of dreaming is intelligent information processing that inspires creativity and promotes problem solving
  • The alarm clock and snooze function inflicts a cardiovascular assault, spike in blood pressure, and illicit a fight or flight response in the nervous system

Closing thoughts:

What I really liked about this book is that it’s relevant to pretty much everyone. We all have heard that sleep is important, but this book does a great job in breaking down WHY it’s so critical to overall health and wellness. Not only does it help with the immune system, but it also helps with memory, retention, cognitive processes, health benefits, mood, mental and physical health overall.

On a scary note, it also explains the myriad of health risks that come with not getting a full 8 hours of sleep and constantly being sleep deprived. Not gooing to lie, this book makes me terrified of the short and long term effects of not sleeping a full 8 hours. It keeps me up at night.

That was a joke btw.

But seriously, since I started reading this, I made it more of a priority to go to sleep on time and take the recommended measures to ensure a successful wind down process before sleeping. It’s also interesting the science of how to make ourselves sleepy, like with making sure your body temperature is cooled.

Overall, a fantastic book that I highly recommend to everyone to read. It’s a bit long and there’s a lot of studies, stories, and examples, but the core ideas of the book are valuable to everyone.


One Takeaway / Putting into practice:

My one takeaway is one I’ve already mentioned. It’s the basis of the whole book:

  • Consistently get 8 hours of sleep every night

Sometimes it’s easier said than done as I get distracted by social media or other things, and before I know it, it’s wayyy past my bedtime. But I think putting into place a wind down routine and setting it early in the evening will help out a lot.


Nutshell:

Why we sleep, why it’s important to sleep, and a ton of reasons why you should be terrified of not consistently getting 8 hours of an undisturbed, REM & N-REM-filled sleep every night.


Similar books:


Rating:

Rating: 4 out of 5.

4.5/5


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