Why We Sleep — book review and scientifically proven insights

Zane Salim
Aug 6, 2018 · 6 min read

We spend approximately a third of our lives sleeping. In my case thats over 10 years of sleep so far! Yet we know so little about why we sleep, its benefits or how to get the most out of it.

Surprising, there is little or no sleep education, despite it being something that takes up a significant proportion of our lives. Not just us. Sleep is universal — just like breathing, eating, and aging — all animals sleep in some form or other. So its clearly of vital importance to life and living.

Like many, I’ve often wondered, how much sleep do we need. And have struggled to get enough or build a regular routine. What is the cost of insufficient sleep? Or irregular sleep? Is it worth improving? Whats the best way to improve it?

These are some of the questions that inspired me to read “Why We Sleep” — one of the best selling neuroscience books on Amazon by Dr. Matthew Walker. Its an incredibly thorough and eye opening account, and takes the reader through a journey of all the most significant scientific experiments that have informed most of what we know about sleep.

I think most of us intuitively know that sleep is important, and than humans should get somewhere around 8–9 hours of sleep every night. However the thorough explanation of everything sleep researchers have learnt from experiments on just how important sleep is left me alarmed and motivated to better understand my own sleep patterns, and make a deliberate effort tp sleep more every night.

Here are my biggest learnings and insights from the book, followed by changes I’m making to my own life to improve the quality of my sleep.

  1. Sleep is critical to the healthy functioning of the mind and body. And is critical for effective learning, memory, problem solving, creativity, emotion regulation and immune system functioning. The deterioration in all of these areas in people who are sleep deprived even just a few hours a night is alarming — 20–50% in many cases, and several orders of magnitude in other cases (eg: well rested individuals are 2x more resilient to the flu). Whats more, as humans we are not good at knowing if we have gotten enough sleep. But the effects of performance deterioration are very clear in 100s of scientific experiments.
  2. The body works on a natural circadian rhythm — which influences natural sleep tendencies and this is different for people who consider themselves early risers and night owls. I was surprised to learn that whether someone is an early riser or night owl is actually based on hereditary genetic traits. Evolutionarily this helped ensure that any group of hunter gatherers staggered the time when people slept, therefore ensuring that when early birds slept, night owls could keep watch, and vice-versa, reducing the risk from external threats when the group was sleeping. The body’s circadian rhythm releases several hormones that build up sleep pressure throughout the day and signal preparation and onset of sleep — like drowsiness, lowering body temperature, etc. Things like caffeine and alcohol can be very disruptive to both the natural rhythm, and also effectiveness of sleep.
  3. Sleep is not a linear or monolithic process. In fact its a very active process where the mind and body cycle through repeated states of NREM and REM sleep. NREM is deep sleep, and REM is a more active state where we dream. One good way to think about it is with the analogy of a sculptor — who starts with a big blob of clay, then removes chunks of clay to start providing some shape to the figure, followed by sculpting and shaping, and then more removing of clay and so on in multiple cycles. NREM sleep performs the function of moving memories from short-term to long term storage (like removing blobs of clay), and REM sleep performs the work of integrating them into the mind for comprehension and retention (sculpting and shaping). Additionally dreaming helps the mind process and blunt strong emotional responses from the day and separating the retention of memories from re-triggering those responses upon retention. In a sense dreaming is a form of active therapy to power cleanse emotional residue from the mind and make it ready for the next day. The most surprising learning for me was that the sleep is predominantly NREM in the early hours of the night, and REM in the later hours of the night. And the body needs both equally to have properly rested and recovered. So under sleeping by 20% is not just 20% worse but more like 50% worse because the body doesn’t get enough REM sleep and so the process is incomplete. The result: worse emotional resilience, poorer learning and retention from the previous days work, and significantly lowered comprehension and creativity. When sleep is abundant, minds flourish! And when its not its a sad downward spiral that affects IQ, EQ, learning, memory, health, immune system… literally every body function!

My first reaction from finishing this book was regret that I didn’t sleep more in my formative years in high school and college. It likely wouldn’t have required much by way of lifestyle changes, and could very well have had a significant impact on my learning, performance and overall health.

My next biggest reaction was to make some changes to my life to improve the daily quality of my life. Better late than never!

Here’s some things I’ve started trying, some of which are already helping me be more deliberate about managing the sleeping third of my life.

  1. Started measuring my sleep. I looked into a variety of sleep trackers — from free and paid android apps, to add-on devices like the Emfit QS+Active ($250), to integrated solutions like the Eight Sleep mattress ($700). Ultimately I went with the Sleep app and paid $6.99 for the ad-free full featured version. I already love it and am learning so much about my sleep habits. Besides the sleep tracking functionality it also has some really well designed reminders for when to sleep, tracking sleep trends, breakdown of NREM vs REM sleep and lots of other cool stuff. Geeking out on the data is fun and also helping me make better sleep decisions every night and every morning.
  2. Optimizing for the full 8 hours everyday. I’m now being extra careful to go to bed early to get the full 8 hours to avoid short-changing myself of REM sleep. When needed I’m pushing back the start of my day to get the full 8 hours. Knowing that sleep is not a linear process has really changed my mindset and approach.
  3. Limiting caffeine after 3pm, and alcohol at night. Its well known that caffeine has a long half life and makes it hard to fall asleep. So I’m starting to eliminate it in the afternoon. Turns out alcohol is even worse — as it both reduces sleep quality and inhibits REM sleep. So I’m giving up alcohol in the evenings. Scientifically, its better to have a drink in the morning or not at all than to have one with dinner! This is actually easier for me than limiting caffeine since I don’t consume much alcohol these days anyway.

Its remarkable to me how simple lifestyle changes can have such significant improvements to our health and yet there is so little awareness or discipline in these areas. Simple things like better sleep, better nutrition and exercise can significantly improve daily performance and lifespan. Over the course of this year, I’ve started to delve into the best scientific research in these areas and have been having a lot of fun finding ways to apply them to my everyday life.

With modern technology its so easy to measure how we sleep, and make small adjustments to improve sleep quality and accrue all the restorative benefits that come with it. Its quite mind blowing.

For an essential and universal human need, sleep seems largely untouched by modern technology. As awareness around its importance grows, I feel convinced everyone can benefit from more data and insights on their own sleep behavior, its daily impact and ways to get better sleep.

What a time to be alive — with so much amazing research available at our fingertips, and incredible solutions just a tap away in the app store. At the same time, I also can’t wait for all the amazing integrated home products that will emerge over the next few years and make it almost automatic, and 100x easier for anyone and everyone to better understand their daily lifestyle, behaviors, and make better decisions.

Zane Salim

Written by

Founder/ceo. Writing helps me think. Past: ycombinator, thumbtack, twitter, microsoft, umich.

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