⭐ Key Notes: 12 tips for healthy sleep

1. Stick to a sleep schedule.
2. Exercise for at least 30 minutes each day, but not later than 2 hours before bedtime.
3. Avoid caffeine and nicotine.
4. Avoid alcohol before bed.
5. Avoid large meals and beverages late at night.
6. Avoid medicines that delay or disrupt sleep.
7. Do not take naps after 3pm.
8. Relax before bed – add reading or music to your bedtime ritual.
9. Take a hot bath before bed.
10. Bedroom environment – dark, cool, and gadget-free.
11. Have the right sunlight exposureoe – get 30 minutes of natural sunlight each day. Wakeup with the sun, or use very bright lights in the morning.
12. Do not lie in bed awake.

Part 1: This Thing Called Sleep

😴 Chapter 1: to sleep…

• The shorter you sleep, the shorter your life span.
• Sleep is the single most effective thing we can do to reset the health of our brain and body.
• Humans are the only species that will deliberately deprive themselves of sleep, without any legitimate gain.

☕ Chapter 2: caffeine, jet lag, and melatonin

Factors that determine when we want to sleep

1. Suprachiasmatic nucleus – an internal 24-hour body clock located within your brain [wake drive].
2. Adenosine – a chemical that builds up in your brain to create sleep pressure [sleep drive]

• The urge to be awake is greatest in the morning, when the gap between the wake drive and sleep drive are small.
• The urge to sleep is greatest at night, when the gap between the wake drive and sleep drive are largest.

Melatonin

• Mealtonin helps regulate the timing of when sleep occurs, by signalling darkness throughout your body.
• Melatonin has little influence on the generation of sleep itslef – it is not a powerful sleeping aid in itself.
• The suprachiasmatic nucleaus instructs the release of melatonin into the bloodstream after dusk.

Sleep pressure and caffeine

• Adenosine is a chemical that builds up in your brain throughout the day – it increases your desire to sleep.
• Caffeine works by battling with adenosine for the priviledge of latching onto adenosine receptors in the brain.
• By hijacking these receptors, caffeien blocks the sleepiness signal that is normally communicated to the brain by adenosine.
• Some people process caffeine faster than others, and we become less efficient as we age.

Circadian rhythm

• All living organisms have a neural circadian rhythm to keep time.
• The circadian rhytm is not dependent on external cues, such as sunlight.
• The human circadian rhythm is slightly longer than 24 hours.

Identify sleep deficiency

• If you did not set an alarm clock, would you wake up on time?
• Do you find yourself re-reading things?
• Can you function optimally before noon without caffeine?
• Could you fall back asleep at 10-11am?

👁 Chapter 3: defining and generating sleep

• The thalamus is the sensory gate of the brain. It puts a perceptual barricade to block incoming sensory signals while you sleep.
• Sleeping organisms – adopt a stereotypical position, have lowered muscle tone, and show no over displays of responsivity.
• The subconscious brain is capable of logging time.

Two types of sleep

1. NREM – non-rapid eye movement.
   • 4 stages of increasing depth.
   • removes unneccessary neural connections.
2. REM – rapid eye movement.
   • Brain activity is almost identical to awake state.
   • Associated with dreaming.
   • Strengthens neural connections.

Sleep cycle

• REM and NREM stages play out a recurring battle for domination across 90 minute intervals.

Generating sleep

• Wakefulness = reception
• NREM sleep = reflection
• REM sleep = integration

🦍 Chapter 4: ape beds, dinosaurs, and napping with half a brain

• Not all species experience all stages of sleep.
• All have measurable NREM sleep stages.
• Most reptiles, amphibians, fish, and insects show no clear signs of REM sleep.
• Cetaceans and brids sleep with half a brain at a time – it only applied to NREM sleep.
• Starvation will cause the need for food to supersede the need for sleep.

How should we sleep?

• Hunter-gatherer tribes sleep in a biphasic pattern. They take a longer sleep period at night (7-8 hours), followed by a 30-60 minute nap in the afternoon.
• They go to sleep 2-3 hours after sunset (around 9pm).
• Midnight is supposed to be the middle of the sleep cycle.
• Humans have a hardwired dip in alertness that occurs mid-afternoon.

👶🏻 Chapter 5: changes in sleep across the life span

Childhood

• Infants display polyhasic sleep – many short snippets of sleep throughout day and night.
• The csprachiasmatic nucleus, which controls our circadian rhythm, takes a considerable time to develop.

Adolescence

• During puberty – NREM sleep increases to promote efficiency and effectiveness.
• Deep sleep may be a driving force of brain maturation.
• The circadian rhythm shifts forward – making teenagers want to stay up longer.
• Asking a teenager to go to sleep at 10pm is equivalent of asking an adult to sleep at 7pm.

Midlife and old age

• Older adults need as much sleep, but are less able to generate it.
• NREM sleep is in decline by the late twenties.
• Sleep fragmentation – the older we get, the more frequently wake up throughout the night (most commondly due to weakened bladder).
• Lower sleep efficiency leads to higher mortality risk, worse physical health, less energy, and lower cognitive function.

Part 2: Why Should You Sleep?

🎓 Chapter 6: your mother and Shakespeare knew

• Sleep restores the brain’s capacity for learning – to prepare the bran for making new memories and cementing previous memories.
• Sleep protects newly acquired information against forgetting.
• NREM brainwaves transport memory from the temporary hippocampus to the more permanent cortex.
• Sleep clears the cache of short term memory.
• Sleep discerns what memories to remember and which to forget.
• Lack of sleep decreases time to physical exhaustion and aerobic output.
• Post-performance sleep accelerates physical recovery.

🚗 Chapter 7: too extreme for the Guinness Book of World Records

Concentration

• The brain function that suffers most under sleep deprivation is concentration.
• Sleep deprived people underestimate the degree to which their performance is reduced.
• Humans need more than 7 hours of sleep to maintain cognitive performance.
• Behicle accidents caused by drowsy driving exceeds those caused by alcohol and drugs combined.
• After being awake for 19 hours, sleep-deprived people are as cognitively impaired as those who are legally drunk.

Salvaging sleep deprivation

• Power naps and caffeine may momentarily increase basic concentraiton during sleep deprivaiton.
• The more complex functions cannot be salvaged by naps or caffeine – learning, memory, complex reasoning, decision-making.

Foregtfulness and alzheimer’s

• Students who stay up late cramming for tests experience a 40% deficit in their ability to make new memories relative to those that get a full nights sleep.
• Wakefulness is low-level brain damage, whereas sleep is neurological sanitation.
• Getting too little sleep will increse the risk of developing alzheimer’s disease.

🦠 Chapter 8: cancer, heart attacks, and a shorter life

Impact on the body

• Poor sleep has been observed to increase the risk of heart attack.
• Sleep deprivation also increases the likelihood of infections.
• Unhealthy sleep leads to an unhealthy heart and a weakened immune system.
• Testosterone levels drop relative to a fully rested baseline.

Impact on weight gain

• Less sleep increases the likelihood of eating.
• Chronic sleep deprivation is a major contributor to type 2 diabetes.
• Short sleep causes the body to deplete muscle mass and retain fat.

Part 3: How and Why We Dream

🥼 Chapter 9: routinely psychotic

• REM sleep accounts for the hallucinogenic, emotional, and bizzare experiences.
• REM sleep is a state characterised by strong activation in visual, motor, emotional, and autobiographical memory regions of the brain.
• MRI scans can be used to predict the content of your dreams, by matching images of brain activity to baseline templates.
• Daytime emotions have some influence over the emotional themes of our dreams.

🔮 Chapter 10: dreaming as overnight therapy

• REM sleep is the only time when your brain is completely devoid of noradrenaline – an anxiety-triggering molecule.
• Noradrenaline is the brain equivalent of adrenaline.
• REM sleep helps us divorce emotions from experience, by readjusting the brain’s emotional state.
• Dreaming about difficult life events helps people gain clinical resolution from their despair.

💭 Chapter 11: dream creativity and dream control

• Sleep builds connections between distantly related information elements that are not obvious during the waking day.
• Relational memory processing is accelerated during REM sleep.
• Lucid dreaming is possible, whereby the person can control when and what they dream.

Part 4: From Sleeping Pills to Society Transformed

😰 Chapter 12: things that go bump in the night

Somnabulism

• Sleep disorders that involve movement, such as sleepwaking and sleep talking.

Insomnia

• Clinical difficulty falling asleep or staying asleep.
• Often triggered by worry or anxiety.

Narcolepsy

1. Excessive daytime sleepiness – sudden and irresisible urges to sleep.
2. Sleep paralysis – loss of ability to talk or move when waking up from sleep.
3. Cataplexy – sudden loss of muscle control. Caused by body paralysis of REM sleep, without the sleep of the REM state itself.

⏰ Chapter 13: iPads, factory whistles, and nightcaps – what is stopping you from sleeping?

1. Electric light
2. Alcohol
3. Regularised temperature
4. Caffeine
5. Punching time cards

Artificial light

• Artificial light will fool your suprachiasmatic nucleus into believing that the sun has not yet set.
• Melatonin is not released on schedule.
• Blue LED light has twice the harmful impact on nighttime melatoninsuppression than warm yellow light.
• Maintaining complete darkness throughout the night is also critical.

Alcohol

• Alcohol fragments sleep.
• Non-continuous sleep is not restorative.
• Alcohol is a powerful REM suppressor that deprives dream sleep.

Temperature

• A bedroom temperature of 18,3 Celsius / 65 Fahrenheit is ideal for the sleep of most people.
• Core body temperature must decrease 2-3 degrees Farenheit to initiate sleep.
• Body temperature is controlled by your hands, feet, and head. Warming these areas will draw heat from the innner core.
• Hot baths prior to bed can induce 10-15% more deep NREM sleep.
• Hot baths lowers our core body temperature – ddiluted blood vessels help radiate out inner heat.

Artificial wakeup

• Being artificially woken up by alarm clocks spikes our blood pressure and suddenly accelerates the heart rate.
• The fight or flight nervous system is triggered.
• Snoozing through multiple alarms will repeat this shock over and over again.

💊 Chapter 14: hurting and helping your sleep

Sleeping pills

• Those taking sleeping pills have a higher mortlity rate.
• Sleeping pills are addictive and almost always cause more harm than benefit.

Good sleep practices

• Establish a regular and consistent bedtime and wake-up time.
• Go to be only when sleepy.
• Do not lie awake in bed for a significant peiord of time.
• Avoid daytime napping, if you have difficulty sleeping at night.
• Reduce anxiety-provoking thoughts and worries.
• Remove visible clock faces from view in the bedroom.

📉 Chapter 15: what medicine and education are doing wrong; what Google and NASA are doing right

Business

• The brain can never recover all the sleep it has been deprived of.
• Business leaders often mistake hours for productivity.
• A study across four US companies found that insufficient sleep cost almost $2,000 in lost productivity, per employee per year.
• Insufficiant sleep robs some nations of over 2% of GDP.
• Creativity, intelligence, motiovation, effort, efficiency, collaboration, emotional stability, sociability, and honesty are all impacted by insufficient sleep.
• Sleep deprived individuals generate fewer and less accurate solutions.
• People are more likely to lie, cheat, and steal when sleeping less than six hours.

Education

• Teenagers in America routinely wakeup at 5:30am or earlier, to get to school.
• Delaying school start times by one hour leads to higher grades, increased life expectancy (due to less car crashes), and increased attendance.
• Adolescence is the most susceptible phase of life for developing chronic or mental illness.
• More than 50% of children with an ADHD diagnosis actually have a sleep disorder.

Healthcare

• The number of errors vastly increases when residents and doctors are deprived of sleep.
• Medics themselves are more likely to die in a traffic accident after a long shift.
• Before undergoing any serious surgery – ask your doctor how much sleep they have had.
• One cannot learn how to overcome a lack of sleep or develop resilience.

🎁 Chapter 16: a new vision for sleep in the twenty-first century

• Increase sleep awareness and teach it in schools.
• Incentivise employees to get better sleep.
• Offer flexibility in business hours and schools.
• Reward good sleep with lower health insurance costs.
• Link individual sleep trackers with connected devices, like thermostats and lighting.

📹 Video Summary