preface
As you may have seen in the table already, this book represents a 10/10 for me. It did take me two years–or rather two attempts–to fully get through the book, I’ve started in the summer of 2022 but didn’t get further than two chapters and then in the spring of 2024 I’ve managed to finish it within a week.
It is a very dense book initially and the first try I suppose I just wasn’t ready for the rather scientific nature, but with reading through the chapters it slowly dawned on me that the discussion of sleep is of utter importance to basically anyone. And seeing the value in it I’ve started to pick up the excitement Walker was able to encapsulate within his writing.
As in the last review I’ll lay down my notes and talk about some related things and my ideas throughout them, and what’s left of my opinion and such will get it’s related own section at the end to also be mentioned.
notes
Chapter one starts with some ideas and thoughts about why we sleep at all, setting it as a hypothesis to answer throughout the rest of the book. It is a question that scientists have struggled even with up until modernity.
But during the last few decades the science of sleep has discovered that sleep is quintessential for most processes within the body.
In chapter two one gets walked a bit through the cycles the human body offers related to sleep and what factors influence them.
Most prevalent is the circadian rhythm, our “internal clock”, which acts depending on the hormone melatonin. That builds up throughout the day and tries to tell the hypothalamus (evaluating instance) that it’s time for sleep and falling asleep.
But the production of melatonin can be influenced by us, e.g. it’s delayed by the intake of caffeine or bright light. That also means it can be “manipulated” by it (which I found the most interesting), if you want to get up early you want the melatonin to produce earlier, that you can influence by not having caffeine intake on the later half of the day, avoid bright light (or light at all) through the later parts of the day and early to get up try to expose yourself to bright (sun)light to shift the rhythm to an earlier time.
Another important chemical to consider is adenosine, which you could say is in charge for your “sleep drive”. It’s concentration increases throughout waking hours and depletes while asleep.
Chapter three introduces different phases of sleep, notably REM (rapid eye movement, dreaming) and NREM 1-4 (non REM, not dreaming).
Due the technicality there I don’t find it worth getting more into that here, if you want to know, then read the book, it has good graphs about it.
But what is there still to note is that REM sleep mostly reoccurs throughout the night in 90 minute periods of NREM phases in between, building up from down to 4 and back up to 1 and then REM.
Chapter 4 & 5 mention the differences in sleep throughout different ages. Notable here is that old people on average have worse sleep than their younger counterparts and infants and children in mentally developing ages have a multitude of REM sleep in comparison to all the ages above to build cognitive and motor abilities. This process is called “(exuberant) synaptogenesis”. It’s the first step to build an initial frame for the brain.
Part two of four then starts to talk about why we should sleep. In this part the reader gets walked through all the cool things sleep does. I’ve noted some of those points which I’ll just list.
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Sleeping before learning (cognitive or motoric) refreshes the capability to create new “memories” which is as useful as it sounds. This works just the same with a nap as with a full night of sleep.
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The upsides for learning are not limited to learning before sleep, just as well for sleeping after learning, so the other way around. Noted here I have that it acts as “pressing a save button”. But not just that, also achieve the opposite and do some garbage collection which is pretty useful because if you’d remember every single thing you’d probably have a too troubled mind to think straight.
An example most of us will probably know from themselves arises when you’ve learned something for a long period without any progress but then suddenly are better at it the following morning.
I’ve had that most prominent when learning a new keyboard layout in which I could put a exact number on progress with the metric of “words per minute”, what I’ve seen is that I could spent two hours a day practicing without any progress and then be a 1-4 wpm faster, but just on the following day, after giving my brain time to build the required connections to “relearn” the ability of typing partially. If you went through such a thing or play an instrument you’ll be very familiar with that process.
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At last I’ve also noted that sleep helps with physical exercise. In the sense of speeding up recovery and enabling more exhaustive loads on the body.
At this point (chapter 7/16) I’ve decided to stop the summary of contents as the later part goes a lot into disorders such as insomnia, dreaming, consequences of sleeping aid and other problems.
Cool topics but I’ll rather continue with my own experiences and I got tired to further summarize.
conclusion
Maybe I’ve conveyed some of my excitement already. I’ve given the book a perfect rating because since I’ve read it some months ago, my sleep quality has increased tremendously and it feels like there came a lot of benefits with it.
I have used the methods explained earlier to shift my circadien rhythm to be earlier, I’ve had more solid sleep due to less noise during sleeping, started to wear earplugs whenever there was noise around in the night, stopped to use an alarm clock to be less stressed when waking up, always getting 8 hours, etc.
Many things transpired from just changing sleep around a bit. It’s one of the changes that feels like if I’ll just keep that up (and I don’t see a reason to not do that), I’ll easier live a healthier and better life.
Just due to some awareness that Walker was able to bring me in specific actions related to sleep.
I’d wish you have some better sleep to. I highly recommend to read the book, reach out, or just listen to one of the many podcasts that Walker has given in recent years.
I hope you’ve enjoyed my rambling,
have a good night.