Book Notes : Why We Sleep?
Disclaimer : This is not a Book Summary but a collection of insights I’ve gathered while reading this book.
Neuroscientist and sleep expert Matthew Walker provides a revolutionary exploration of sleep, examining how it affects every aspect of our physical and mental well-being.
While sleeping, Brain transfers Information from Short Term Memory (Hippocampus) to Long Term Memory (Cortex) by using electrical brainwaves.
Humans sleep in two phases :
1. REM Sleep : Rapid Eye Movement Sleep.
2. NREM Sleep : Non Rapid Eye Movement Sleep.
Why some people are ‘Early Risers’ and others are ‘Night Owls’ ?
Historically, our Ancestors protected their Tribes in two ‘Shifts’. Morning Guards would wake up early and sleep early. Night Guards would do the opposite.
Period of Vulnerability: Period in which whole tribe is sleeping and is most vulnerable to Predators. Morning and Night shifts were formed to reduce this ‘Vulnerability Period’ and increase the chances of living.
These guards kept on passing their ‘Genes’ to next generations. So in Evolutionary context, DNA Hardwiring is more responsible for your natural sleep schedule.
Early Risers tend to be more productive in early hours of the day whereas Night Owls have peak productivity late in afternoon.
Unfortunately our Society only appreciates ‘Morning Type’ people. Since ‘Morning Type’ people reach their Peak Productivity level during Employment Schedules (9 to 5) whereas Night Owls are labelled as Lazy for waking up late and not being productive during Office Hours
Academics & Sleep:
- Teenagers get most of their REM Sleep in late morning hours.
- Because of early school timings, Teens have to wake up early losing their precious REM sleep.
- In an experiment, When schools started their classes late, Average SAT scores went up.
Caffeine & Sleep :
Caffeine blocks brain receptors from receiving Adenosine Signal (Hormone that signals brain to sleep according to day light)
Caffeine’s Half Life Period is 5 to 7 Hours. (Its Concentration reduces by 50 % in 5 to 7 Hours).
Caffeine Crash: Once the effect of Caffeine is over (After 5–7 Hours) Suddenly the brain receptors are flooded with Adenosine. Making our brain feel tired and sleepy.
Alcohol and Sleep : It is the largest suppressor of REM Sleep.
Drinks consumed by Pregnant mothers can significantly affect fetus’ REM sleep. Leading to a child being socially abnormal.
Unihemispheric Sleep (Half Brain Sleep) : Dolphins and Whales sleep with half brain at a time to stay alert from predators. Humans too, while sleeping in unknown place show signs of Unihemispheric Sleep.
Targeted Memory Reactivation (Memory Editing) :
In an experiment, Participants were shown 100 Images along with their characteristic sounds. For e.g. Cat -Meow, Dog-Bark, Car-Horn etc.
When participants were asleep, Sounds of only 40 Images were played near their ears. Once they woke up, Participants were asked about 100 Images shown yesterday. Surprisingly, They could majority of 40 Images whose sounds were played during sleep.
This phenomenon can be used to selectively strengthen human memory.
Click here to watch a TEDx Talk on this topic.
Subconscious Mind & Sleep:
Sleep automates routine movements. These movements will flow out of your subconscious effortlessly. Pianist struggling with a piece late in the night might play it with ease just after waking up in morning.
Lucid Dreaming :
Lucid Dreamers have control on their Dreams.
Author believes, It is the next iteration of Homo Sapiens Evolution which can be used for creative problem solving.
Atonia: Loss of Muscle activity during Dreaming phase. (Intentionally activated by Brain to prevent you from acting out of Dreams).
Modern Tech & Sleep:
- Light bulb gave humans control over light and dark. It is also responsible for disturbing sleep schedules almost all Humans.
- Reading on iPad before sleeping reduces Melatonin (Hormone responsible for sleep generation) release by 50%.
- Using LED lights inside home are twice harmful than yellow incandescent bulbs.
Inventions & Sleep :
1. Periodic Table: Dmitri Mendeleev played with cards, each representing an element to find an organizational logic. One night, The dream took held of his swirling cards and snapped them together in a grid today known as ‘Periodic Table’.
2. Otto Loewi: Dreamed of an experiment which revealed how nerve cells communicate with each other. Discovered Chemical transmission of Nerve Impulses.
3. Thomas Edison: Used to hold ball bearings in his hand while going to sleep on armchair. The moment he began dreaming, His muscle tone would relax and he would release bearings on floor. The noise woke him up. He noted down all ideas he saw in dreams and would work on them.
Many Similar Stories:
- Honda Jet Read here.
- Larry Page saw idea of Google in his dream Read here.
Diseases & Sleep :
1. Insomnia:
Inadequate ability to generate sleep even though allowing oneself the adequate opportunity to sleep.
Twice as much common in women than in men.
Generally triggered by Emotional worry, Anxiety.
2. Sleep Deprivation:
Adequate ability to generate sleep but having inadequate opportunity to sleep.
3. Somnambulism: Somnus (Sleep) + Ambulation (Move)
Sleepwalk/ Sleeptalk/ Sleepeat/ Sleeptext/ Sleepsex/ Sleephomicide
Quick Facts :
- People with habit of midday napping are 20% better at learning than people who don’t nap at all.
- Harvard Midday Nap study : 37 % increased risk of Heart Disease due to no Midday Nap.
- You can never reclaim sleep hours lost on weekdays by oversleeping on Weekends.
- Dark room, Cold Atmosphere are ideal conditions for good sleep.
- In USA, more people die due to drowsy driving than drunken driving. But drunken driving catches more attention on news.
Conclusion :
- Within the space of last hundred years, Human beings have abandoned their biologically mandated need for adequate sleep-one that evolution spent 3,400,000 years perfecting it in service of life support functions.
- This silent sleep loss epidemic is greatest public health challenge we face in 21st Century.
- I believe it is time for us to reclaim full night of sleep, without embarrassment or damaging stigma of laziness.
