In one line: First read this book in 2019 when I met Matthew Walker at the TED Global Conference & revisit my notes every year–I am borderline dogmatic that SLEEP is far and away the MOST important element to your mental, physical, and emotional health.
In one more line: With the holidays here, it’s a good time to reassess our sleep habits & routines and prioritize rest & recovery.
In one last line: Skim these notes and PICK ONE idea to implement next year to be consistent with in improving your sleep quality; pulled 12 summary points for better sleep to the top!
12 TIPS FOR BETTER SLEEP:
- Stick to a sleep schedule (Matthew Walker says this is the most important tip for healthy sleep); set an alarm for bedtime not for waking up
- Exercise at least 30m/day but not later than 2-3 hours before bedtime
- Avoid caffeine and nicotine; effects take as long as 8 hours to wear off; nicotine is a stimulant causes smokers to sleep lightly and can cause early wake up because of nicotine withdrawal
- Avoid alcohol before bed; robs you of REM sleep keeping you in lighter stages of sleep; can also contribute to bad breathing at night and tendency to wake up middle of night once effects of alcohol have worn off
- Avoid large meals (can cause indigestion) and drinks at night
- If possible, avoid medicines; some prescriptions are disruptive to sleep
- No naps after 3pm; can help make up for lost sleep but too late makes it hard to sleep at night
- Relax before bed; don’t over schedule your day so there’s no time left to unwind; reading or listening to music should be part of your bedtime ritual
- Take a hot bath before bed; the drop in body temperature after getting out of the bath may help you feel sleepy; can help you relax and be ready for sleep
- Dark bedroom, cool bedroom, gadget and screen-free bedroom; get rid of anything in your room that may distract you from sleep—noises, bright lights, an uncomfortable bed, TVs, phones, computers, or warm temperatures
- Have the right sunlight exposure; daylight is key to regulating sleep patterns; min 30m/day of natural sunlight first thing in the morning OR use very bright lights; if possible, wake up with the sun; turn down the lights before bedtime
- Don’t lie in bed awake; if you find yourself still awake after staying in bed for more than 20min or if you’re feeling anxious or worried, get up and do some relaxing activity until you feel sleepy; the anxiety of not being able to sleep can make it harder to fall asleep
WHAT IS THE BENEFIT OF SLEEP AND WHAT IS ITS PURPOSE?
⁃ Increases our brains ability to learn and memorize
⁃ Helps us make logical choices and decisions
⁃ Re-calibrates our emotional circuits
⁃ Dreams nullify negative memories and inspire creativity
⁃ It restocks the body’s immune system helping fight malignancy and preventing disease/sickness
⁃ It regulates our metabolic state by fine tuning insulin levels and reduces impulsive behavior
⁃ Lowers our blood pressure
⁃ Cortisol in excess cultivates bad bacteria in your microbiome; sleep helps calm your nervous system/amygdala and keep your microbiome clean
UNDERSTANDING THE BRAIN:
⁃ Hippocampus — the memory inbox for fact-based learning; sleep loss deteriorates the DNA and brain cells on the hippocampus
⁃ Semantic memory – name, family, etc. (vs. episodic memory recall–specific moments)
⁃ Glymphatic system (situated alongside the neurons that generate electrical activity in your brain) — sewage system in the brain — collects and actively removes metabolic contaminants from your brain (similar to how the lymphatic system removes contaminants from your body — it has a 10-20 fold increase during deep Non-REM sleep)
⁃ Prefrontal cortex — rational, decision-maker
⁃ Thalamus — the sensory gate of the brain that needs to close in order for us to sleep
⁃ Brain stem — the alerting activation regions (this is shaped like an ice cream cone and the thalamus is the ice cream) — when it’s time to go to sleep, the brain stem closes the sensory gates to the thalamus
⁃ Hypothalamus — the “sleep/wake switch” which is located just below the thalamus — same region of the brain which houses our 24-hour master biological clock — this has a direct connection to the power activating regions of the brain stem and can flip them on and off — releases a chemical call orexin which switches off the brain stem
⁃ The language center in the brain is in the left hemisphere
⁃ The brain is made up of 100MM neurons — on their own they are not useful; it’s the neurons’ ability to communicate with one another—to export information through their axons and import information through their dendrites—that allows them to move up the ‘Emergence Tower’ and combine together into a single thinking system that’s far more powerful than the sum of its parts
⁃ Language is so magical because it allows individual brains to connect, like neurons, to form a larger thinking system. If a human’s Inner-Self is like a neuron, the Outer-Self’s ability to express itself gives the neuron its axons, and its ability to see or listen to the expression of others gives it dendrites
⁃ The brain has 100 billion cells
CHAPTER 1 – TO SLEEP:
⁃ Fatigue-related traffic accidents happen every hour in the US; more than those of alcohol-related vehicular accidents
⁃ We know why we eat, drink, and reproduce, but we have not known why we sleep from an evolutionary perspective
⁃ If sleep didn’t provide an absolutely necessary vital evolutionary purpose, it wouldn’t have survived
⁃“Answers are simply a way to the next question.”
CHAPTER 2 – CAFFEINE, JET LAG, & MELATONIN:
⁃ A study conducted in 1729 about our first discovery of plants gave us proof of own internal clock/circadian rhythm
⁃ Suprachiasmatic (supra which means above and kayism which means a crossing point) nucleus — the part of the brain above the eyes which connects the two optical nerves which come from your eyes into the brain which has 20,000 neurons / brain cells which receives the signal of light from the eyes which then passes back to our visual receptors in the brain hence creating our circadian rhythm
⁃ Why people have different biological clocks is largely driven by genetics — from an evolutionary perspective (the tribe sleeps at different times to protect each other–night owls vs. morning larks)
⁃ Jet lag — why we get it and what happens (covered at the end of the chapter)
CHAPTER 3 – THE EVOLUTION OF SLEEP:
“Nothing in biology makes any sense, except in the context of evolution.”
⁃ “If sleep is so useful, why did biology ever bother to wake up?”
⁃ Elephants need half the sleep of humans; tigers and lions 15 hours per day; bats 19 hours per day
⁃ The size of the nervous system, complexity of nervous system, dietary map, higher metabolic rates (think animals who have to hunt their prey intensely need more restorative sleep) and body mass are good predictors of need for sleep
⁃ One evolutionary function that demands we sleep is the need to service the ever-growing complex nervous system
⁃ “Absence of evidence is not evidence of absence.”
⁃ WE CAN NEVER RECOVER THE SLEEP WHICH WE LOST — one of most important takeaways of the book
⁃ Dolphin brains can uncouple during sleep and once they’ve rested on half they flip to let the other half rest
⁃ Bi-phasic sleep — we have a genetically hard-wired dip that occurs in the afternoon where there is a level of sleep bankruptcy — “blanket of drowsiness” — “post-prandial alertness” — innate drive to be sleeping/napping during the afternoon — this shift occurred in between the Agrarian Era and the Industrial Era
⁃ Bi-phasic sleep is our natural sleeping pattern trough evolution…I guess the Spanish have it right with siestas…
⁃ Homosapien is Latin for wise person
⁃ Homoerectus is what came before we evolved into homosapiens
⁃ 40mins to end of chapter (if audiobook) — explains the importance and purpose and evolution of REM sleep — how we evolved from chimps and apes to Homoerectus — we went from sleeping in trees to being the first upright species to ever live, to sleeping on the ground. Because it was more dangerous to be on the ground with predators, we evolved to increase our amount of REM sleep which enhances the brains connectivity and recalibration but also reduces the number of hours we need to sleep per day — we are the only primates who need as little as 8 hours of sleep. In addition, It is thought this is the inception of fire, created to keep away predators and the smoke would keep insects away
⁃ The 2nd part of this thought is that the increase in REM sleep is what allowed us to develop such a complex and advanced brain. This led the ability to increase our sociocultural capacities, our emotional intelligence and our brains complexity and functionality to continue to evolve to the top of the food chain
CHAPTER 5 – CHANGES IN SLEEP ACROSS LIFESPAN:
⁃ Non-REM/REM sleep: 80-20 split for most mature adults
⁃ Early on in our lives and in the womb we get much more REM sleep because this is the time when our brains are developing the neural pathways in our brain. REM sleep is like an internet service provider providing connections between all the different parts of the brain — the personal experiences and memories we have early on in our childhood provide the last set of synaptogenesis — the building and late stage development of our brains
⁃ Our brains develop from the back to the front (the back is what determines our visual and spatial perceptions whereas the front of the brain is what determines our rationality) — this is why it’s harder for older individuals to learn a new language, because our brains are much more malleable until we are teenagers
⁃ Deep sleep offers a neural pruning service for natural brain maturation
⁃ Our circadian rhythm shifts as we get older; there is a wave of melatonin which hits around 9pm for younger kids
⁃ Teenagers are biologically wired to sleep in different patterns than children
⁃ “No child needs caffeine”
⁃ ADVICE FOR SLEEP HELP: Look for a doctor who is BOARD CERTIFIED in sleep medicine to help with improving time and quality of sleep
⁃ Since our bladders get smaller as we age, harder to sleep efficiently because the need to go to the bathroom wakes us up if we don’t properly manage liquids
⁃ Atrophy — brain degeneration–deteriorations of the brain and loss of neurons
CHAPTER 6 – YOUR MOTHER AND SHAKESPEARE KNOW:
The Benefits of Sleep for the brain:
- helps you live longer
- enhances your memory and creativity
- keeps you slim and reduces food cravings
- Makes you look younger
- Protects you from cancer and dementia
- Lowers chance of heart attack and stroke
- can make you more attractive
- Wards off cold and the flu
- Makes you happier, less depressed and less anxious
⁃ “Sleep spindles” — electrical activity occurring between the hippocampus and neocortex serving as a transfer of fact based memories, clearing up space for new learning and memories — fewer sleep spindles means reduced capacity to learn the following day
⁃ “Targeted memory reactivation” — selecting specific memories from the day right before bed and reviewing them so they can be committed to long term memory
⁃ Muscle memory is a misnomer — the skill memory remains firmly in the brain
⁃ The last 2 hours of the night of Non-REM sleep we get can be some of the biggest busts of sleep spindles you get which are helping to obtain the skilled memories of the day
⁃ Stage 2 Non-REM sleep is what refines and improves our motor functions
CHAPTER 7 – SLEEP DEPRIVATION AND LOSS OF SLEEP:
⁃ One person dies every hour in a car crash that is sleep related; more people are killed in drowsy driving than drunk or drug related accidents — this makes sense because drunk drivers usually react late vs. drowsy drivers have lost complete control
⁃ People who are sleep deprived consistently underestimate the impact of losing sleep on their skills and cognitive abilities — the human mind cannot sense how sleep deprived it is
⁃ After 16 hours of being awake, the brain begins to fail
⁃ The number of people who can survive on 5 hours or less without impairment or reduced brain function is close to zero — you are far more likely to get struck by lightning (1/15,000) in your life then you are to be one of these people
⁃ Amygdala shows up to 60% amplification of emotional reactivity when sleep derived
⁃ The prefrontal cortex (brake) and amygdala (emotional gas pedal) are balanced when getting a full night sleep, however when sleep deprived the emotional center of our brain is more active then the rational decision making center of our brains (prefrontal cortex)
⁃ The striatum (above and behind amygdala) — deep emotional center of brain — associated with impulsivity and reward, inhibited with dopamine, has a heightened sensitivity when sleep deprived — we will swing more extremely in our emotions for incentives and rewards — can lead to irrational risk taking and other pleasure seeking behaviors
⁃ “The best bridge between despair and hope is a good nights sleep.”
⁃ Anhedonia — lack of ability to receive the rewards in pleasure centers — absence of positive emotions (which often leads to depression)
⁃ Amyloid protein builds up in the brain when you are not getting deep Non-REM sleep; when you don’t get deep NREM sleep the glymphatic system doesn’t have the chance to clean out the amyloid and other toxins in your brain; the build up of this protein is one of leading causes of Alzheimer’s
CHAPTER 8 – CANCER, HEART ATTACKS, & A SHORTER LIFE:
⁃ 2011 Study Conclusions — 500k+ people across all races and 8 different countries — progressive loss of sleep (6 hours or less) 45% increase in developing and or dying from coronary heart disease within 7-25 years from the study
⁃ Similar Japanese male worker study — sleeping 6 hours or less over 14 year period, 400-500% more likely to experience cardiac arrest or heart failure
⁃ Adults 45 years or older who sleep 6 hours or less per night are 200-300% more likely to have a heart attack or stroke
⁃ Hypertension kills 7 million people per year through heart failure
⁃ Loss of sleep results in overactive sympathetic nervous system — your amygdala is left in overdrive fight or flight mode — results in increase in cortisol which strains your blood vessels and increases blood pressure and your body will be unable to fix these cardiac functions which is why heart attacks and heart failure increase so much
⁃ Sleep loss and metabolism — the less you sleep, the more likely you are to eat and your body is unable to manage those calories effectively, especially the concentrations of sugars in your blood. In these two ways, sleeping less than 7-8 hours per night will increase probability of gaining weight, being overweight and significantly increase probability of type 2 diabetes
⁃ The global health cost of diabetes is $375 billion per year; obesity is over $2 trillion per year
⁃ Diabetes costs $85k per year and takes 10 years of your life span
⁃ Hormones that control your appetite:
1) Leptin — sends a signal of feeling full and your appetite is blunted
2) Ghrelin — triggers strong sensations of hunger
⁃ Loss of sleep triggers a loss of leptin and increase in ghrelin
⁃ It also causes the circulation of endocannabanoids which are similar to cannabis — creates a metabolic state of increased hunger
⁃ Over a third of adults in industrialized societies get less than 5-6 hours of sleep per night
⁃ When you’re losing sleep, the body preserves fat and sheds muscle mass for anyone who may be looking to lose weight / shed calories vs opposite effect occurs when getting 8 hours
⁃ Men who report lower sleep have a 29% lower sperm count, smaller testicles and lower testosterone
⁃ Study: 75,000 women over 11 years — 6 hours sleep or less resulting in an increase in cancer of 40%!
⁃ Sleep deprivation reduces your M1 cells (which help kill cancer cells) and increase your M2 cells (which are cancer inducing cells)
⁃ WHO has characterized night time shift work as a probable carcinogen
⁃ Thousands of DNA & genes in your brain are dependent on stable sleep
⁃ Sleep deprivation causes a drop in your HDLs which has been highly linked to cardiovascular disease
⁃ Neglecting sleep alters your genetic coding / is like performing a genetic engineering experiment on your DNA
PART 3 – HOW AND WHY WE DREAM:
⁃ Prefrontal cortex goes dark during REM sleep
⁃ Lucid dreaming — controlling what is happening in your dream
Chapter 11 — Dreaming & Creativity:
⁃ Dmitri Mendeleev — 1869 — a dream inspired periodic table of elements
⁃ Sleep inertia — the carryover of the prior sleeping brain state into wakefulness in the early minutes of waking up — this is the period that separates the state of sleeping from wakefulness
⁃ REM Sleep — the creative incubator; information alchemy
⁃ It is sleep that provides the connections between disparate information pieces that we cannot see the link between while awake
⁃ REM sleep is what allows our brains go from learning to comprehension
CHAPTER 12:
⁃ 1 in 9 Americans have insomnia
⁃ Part of this is genetics — certain people have an overactive sympathetic nervous system (which is in your amygdala and activates our fight or flight sensory) — this is not meant to put you in overdrive for any extended period of time otherwise it causes myriad health problems like:
⁃ Increased metabolic rate which results in increased body temperature (our bodies need to cool in order to go to sleep and stay asleep)
⁃ Increased blood pressure
⁃ Increased in release of cortisol
⁃ Increased heart rate
CHAPTER 13 — IPADS, FACTORY OUTLETS, & SLEEP LOSS:
5 main contributors to bad and loss sleep:
- Constant exposure of electric and LED light
- Regularized temperature
- Caffeine
- Alcohol
- Legacy of punching time cards
⁃ More than 1/3 of our brain is dedicated towards visual sensory
⁃ The pineal gland is triggered by darkness to release melatonin — when we have too much exposure to LED and other lights, it delays the release of melatonin which is one of the reasons people lose so much sleep or have trouble falling asleep
Philoso-Feed 