The Secret World of Sleep: The Surprising Science of the Mind at Rest

by Penelope A. Lewis

In recent years neuroscientists have uncovered the countless ways our brain trips us up in day-to-day life, from its propensity toward irrational thought to how our intuitions deceive us. The latest research on sleep, however, points in the opposite direction. Where old wives tales have long advised to "sleep on a problem," today scientists are discovering the truth behind these folk sayings,and how the busy brain radically improves our minds through sleep and dreams. In The Secret World of Sleep, neuroscientist Penny Lewis explores the latest research intothe nighttime brain to understand the real benefits of sleep. She shows how, while our body rests, the brain practices tasks it learned during the day, replays traumatic events to mollify them, and forges connections between distant concepts. By understanding the roles that the nocturnal brain plays in our waking life, we can improve the relationship between the two, and even boost creativity and become smarter. This is a fascinating exploration of one of the most surprising corners of neuroscience that shows how science may be able to harness the power of sleep to improve learning, health, and more.

Genres: Nonfiction, Science, Health, Psychology, Neuroscience, Self Help, Brain

219 pages, Kindle Edition

First published July 23, 2013

Reviews

[Lois Bujold · Rating 4 out of 5]

Good book, but I kept falling asleep while trying to read it...

Seriously, it had a quality I value in pop science writing; everything was written as simply as possible but no simpler. So I'm going to need a second go at it to take in all the underlying brain structure and chemistry fast-forward tutorials embedded. (Or a couple of PBS specials which show moving pictures and diagrams might help.)

It didn't have as much practical advice as I want, but that wasn't the book's mandate. That's what the sleep clinic is going to be for, I hope, when I eventually toddle off to one. With luck (and perhaps a reread), I may be better prepared to understand whatever I end up being told there.

My Kindle purchase was extremely convenient, but the illustrations came out really tiny.

Ta, L.

[Alex · Rating 4 out of 5]

This was a solid overview of sleep: its evolutionary usefulness, the neurochemical basis for it, its role in learning and memory, how to get more and better sleep... and also that creepy table of violent crimes people have committed while completely asleep. I appreciated Lewis explaining complicated concepts in a way a layperson could understand. I was impressed with how much I was able to understand about the workings of the brain and neurons - those were probably my favorite chapters. I had a bit of a hard time following some explanations, largely because I kept forgetting the function of each stage of sleep. But Lewis usually reminds you about fundamentals covered earlier in the book.

The book did feel a little disconnected - past the first few chapters, it seemed to branch off in different directions with each subsequent chapter. On the bright side, this means the book doesn't have to be read strictly in order - it would be easy to read a random chapter without needing too much context from prior chapters. Plus, although Lewis occasionally gets bogged down in seemingly unnecessary details of study methodology, each chapter strikes a decent balance between just summarizing studies and explaining the implications of those studies. The tips in the last chapter about how to get enough or better sleep were useful; most of them can be easily found online, but it's nice to have them validated by logical explanations from an actual neuroscientist.

[Brooke · Rating 3 out of 5]

I'm a fan of pop science books (books that provide scientific information to lay people, usually in an entertaining way), so I requested a copy of this book through LibraryThing's Early Reviews program. Penelope Lewis is a neuroscientist who runs the Sleep and Memory Lab at the University of Manchester, according to her biography. Her book on sleep and memory is a quick and easy-ish read, though not nearly as fun as some of the other pop science books I've read. She really tries quite hard to distill the information down to small bites the average non-scientist can absorb easily - the information presented doesn't go too deep, chapters are very short, and they end in brief summaries that remind the reader about all the topics the chapter covered. She reports quite a bit about other scientist's research, but she mostly leaves herself out of it. It left me wondering about her - what does she do while running her lab? Is she conducting any research herself? How did she end up studying sleep and memory? I think pop science works best when the author injects some of his or her personality into the book and provides a human connection to the subject matter. Overall, a solid three stars - I liked it and found it worth reading.

[Shelly · Rating 2 out of 5]

I didn't love this book. Lots of interesting information, but definitely presented for the "nonscientist" in a way that felt to me like dumbing it down. Plus, I was irritated by the summaries at the end of each (rather short) chapter. I'm going to listen to the Fresh Air interview instead and I'll probably come away with the same level of depth in much less time.

[Damaskcat · Rating 5 out of 5]

This is a short book but an interesting one. It contains a lot of information about how the brain works during sleep, the different types of sleep and information about some of the research which has been carried out into what happens to the brain and the body during sleep. There are plenty of line drawings throughout the text which help to explain certain points.

The author looks at the efficacy of sleeping on a problem – it is quite effective. She also explains that when each individual wants to fall asleep and whether they function best in mornings or evenings is genetically programmed. Not that such information will impress my partner who firmly believes that I deliberately act like a zombie when I first wake up!

I thought the chapters on dreams and on whether sleep and dreaming can help sufferers with PTSD were the most interesting in the book. I also found the chapter on getting the most out of your sleep of use. There are notes on the text for anyone who wants to follow up any of the references. If you want a fairly straightforward book on sleep then I can recommend this one.

[Nancy · Rating 3 out of 5]

Disclosures:
This book was a goodreads win.

I found the book both interesting and irritating so skipped through it looking for the "good parts" thus not actually read all of it.

I suspect this book was written with middle school students as one target audience. The descriptions are quite accessible for someone without a science background and it has lots of analogies to help explain brain functions. The analogies are what irritated me. Lewis seemed to be anthropomorphizing cells. This could be helpful for young people and for adults tackling a completely foreign subject,but it put me off.

The book also contains a helpful chapter on how to get the sleep you need. For some people, that alone is reason to read the book.

[Agustina Cardozo · Rating 4 out of 5]

"If sleep does not serve an absolutely vital function then it is the biggest mistake the evolutionary process has ever made." (page 3)

This is a great book. It gives you an insight into many things such as why it is important to get enough sleep and the effects of sleep deprivation, the relation between memories and sleep and their consolidation, the remembering and forgetting of dreams... Among many interesting things that all of us should know. Despite being a science book, it is understandable for almost everybody and also has pictures and diagrams that help you to have a better understanding and a closer approach. I highly recommend it!

[Shiloh · Rating 4 out of 5]

Received via LibraryThing's Early Reviewer Program

It should be emphasized that this book is written for the interested layperson—so even though there is significant emphasis on neural processes and intimidating-sounding stuff like "neurotransmitters" and "acetylcholine" and "action potentials", it gets explained within the first few chapters. This means that it's potentially a little boring to people who are more familiar with the brain, but also means it's much more accessible to those who aren't!

Also of note is that this isn't a book on how to improve your sleep, but I think that much should be obvious from the title—it's about the functionality of sleep and what aspects of consciousness it contributes to. So if you're a layperson suffering from insomnia and want to improve your sleep habits, you should NOT pick up this book. But if you're the average person who wants to know more about what goes on when you're sleeping, by all means, this is the kind of book you want!

This book is divided roughly into three parts: About the brain, the brain and sleeping/dreaming, and ways to improve your sleep (either overall or to get your sleep to work for you).

The "about the brain" section is extremely basic, but it's also written clearly for the kind of information that the author is trying to get across. I admired the author on this point, since she knew exactly what the uninitiated reader needed to know to understand the rest of the book, and describes only that and nothing else. (This may be disappointing to those who wanted to know a little more about the brain, however.)

The brain and sleep/dreaming section is likely the reason why the book was bought in the first place. Like the author states several times, sleep (and dreaming!) is a rather mysterious beast that we don't know a whole lot about yet, but it seems to be exceedingly important in the functioning of memory and learning. Dreams also have some effect. The author goes into detail about a few particular studies, likely chosen to have a wow factor, since detailing a lot of research would have an unintended soporific effect. Another bonus is that there are a few highly contentious cases that the author details the arguments (and research) for and against a particular research question. It's easy to tell the side that she takes, since she goes into much more detail at that point, but I appreciate that she makes an effort to disclose both sides.

The "improving your sleep" section spans two chapters, the first on how to get your sleep to work for you, and the second on how to improve your sleep in general. I don't think there's anything particularly special in these two chapters; the latter is information that you can get from a rousing Google search, but the former is more interesting.

In the end, this book is tightly written and doesn't have a lot of extraneous material—in fact, it left me a little dissatisfied because I wanted to know more. I would have liked a little more connection between the neurological and psychological findings regarding sleep, since this book focuses mainly on the brain and less on the mind (and I know there are interesting psychological theories of sleep!); however, that may have detracted from the to-the-point quality of the book that I did enjoy. The figures and diagrams weren't the most helpful or clear (or practical, from an academic standpoint), so I eventually just stopped looking at them altogether. The author writes clearly enough that I never felt like I needed a visual explanation.

[Lianne · Rating 3 out of 5]

I received a copy of this book courtesy of the publishers via the LibraryThing Early Reviewers programme in exchange for an honest review.

The Secret World of Sleep is a very useful and informative book. It provides non-science readers and students an update on what’s been researched recently about everything sleep-related and the brain’s role in these functions. As I’ve been taking anatomy and physiology recently for my programme, the book served as a nice recap of the brain’s functions and capabilities as well as the physiological role and importance of sleep. At the same time, there’s so much that we still don’t know, so many things that researchers are still investigating.

This volume is very accessible and the information is broken down quite nicely in layman’s terms. I wish the last chapter on how to make the most of your nightly sleep was longer since it’s the most applicable to our everyday lives. Nonetheless, The Secret World of Sleep was an interesting read and I recommend it if you’re into neuroscience, anatomy, science in general or you just want to know more about what goes on when you sleep.

This review was originally posted on caffeinatedlife.net: http://www.caffeinatedlife.net/blog/2...

[Shelley Riley · Rating 4 out of 5]

This small book is packed with interesting insight into the working of the brain when we’re sleeping. I have often wondered why I dream, and why some of those dreams are so bizarre. When I worked as a new car sales manager, some nights I dreamed VIN numbers (vehicle identification number) repetitively during the night. This book didn’t tell me exactly why, but it certainly gave me insight into the process.
Detailed enough to be a textbook, but written in such a way it doesn’t feel like one. I entered a free giveaway and won this book, and I’m glad I did.

[Toby · Rating 4 out of 5]

Absolutely excellent introduction to the neuropsychology of sleep. Definitely need a scientific mind though, as it goes right from neuronal firing up to stages of sleep etc. Highly recommended for anyone who has an interest in how sleep works in the brain, the only downside is that the coverage of disorders is a little thin.

[Tim · Rating 5 out of 5]

Wow! Everyone should read this power-packed nugget of treasures on sleep. Lewis clearly explains the science and physics of sleep, what is happening in our body and why it is so important. Her matter of fact writing is insightful and a joy to read. She explores the current areas of contention in sleep and help us remember how important sleep is.

[Thomas Jackson · Rating 4 out of 5]

Short book packed with lots of information I enjoyed the read and definitely learned a few new things about sleep Cycle's and the importancy of sleep in general and how much of I'm not getting, lol. The rest of which I already knew but put in a definition of importance.

[Gail Kennon · Rating 2 out of 5]

swerves between academic and a bit simplistic.

[Rossdavidh · Rating 3 out of 5]

There was a time when sleep researchers had to sit by the bedside of a volunteer sleeper, wait for them to fall asleep, and then watch for eye movements. It is hard to imagine a more boring job than watching someone do nothing, for eight hours, in the middle of the night, and while you're at it make sure you don't make any noise or you'll wake them up. Fortunately for sleep researchers like Penelope Lewis, there are a lot more tools available to them now besides just graduate students.

There is a chapter at the end of the book where Lewis puts aside the more theoretical discussions, and tells you how you can maximize your chance of getting good sleep. She gives that chapter a title that starts with "Brief Notes on...", though, because this isn't primarily a how-to book. This is a book about our efforts to figure out what sleep is for. It is a basic human process, on the level with eating, breathing, and other basic biological processes that have to happen on a regular basis to keep us going, and yet we knew until very recently very little about its purpose. Even still, there is a great deal of uncertainty about something so basic. It isn't just resting, which is why even though we do a great deal less physical labor than our great-great-grandparents (and every generation before them) did, we still require nearly the same amount of sleep.

So, here are some of the leading theories on what sleep is for:
1) memory consolidation, where we take short-term memories and put them into long-term storage
2) sorting out the important memories from the unimportant ones, and deleting the latter
3) dealing with large negative or positive emotional memories from recent days
4) replaying (bits of) memories to aid with learning, without interfering with our ability to tell what's going on around us

Most likely, it's a bit of all of these and more. Sleep might just be the equivalent of restarting your computer, where changes can happen to anything which is too complicated or too dangerous to change while it's running. But given the many ways we now have to monitor what's going on in your brain while you sleep (at the very least, to tell which parts of the brain are working harder than others, and when), it is now time for us to start learning what's really going on when we sleep.

Lewis does a good job of taking us through the last twenty years or more of sleep research, and helping to translate the nearly unreadable scholastic journals where this kind of research is discussed, into something a non-expert in the field can understand. She also does, I think, a good job of admitting the degree of uncertainty which still exists. Sleep research appears to be one of those in-between areas, neither so nebulous as macroeconomics (which is largely experiment-free) nor so well characterized as most parts of physics. There are a lot of experiments going on in sleep research, it appears, and a lot being learned, but the generation who is finally starting to put the pieces together to figure out the big picture is the generation that is at work right now.

There will, of course, still be plenty unknown when this generation of scientists is retiring, and this brings up an uncomfortable analogy with the study of eating. It turns out that, by and large, everything that we did which was based on the science of nutrition in the last 50 years or so, was wrong. We knew just enough to be dangerous; taking vitamins without eating the foods they were normally found in, and then discovering decades later that when we take them that way we don't get nearly the benefit. Trying to eat low-fat diets, and then learning that this was probably the opposite of what we needed. Trying to eat low-sodium or low-cholesterol diets, and then learning that maybe neither of those was a very good idea. Which brings us to the idea that Lewis only hints at: sleep engineering.

If sleep is good for consolidating memory, could we make it do that job better? Could we become better language learners, engineers, or even athletes while we sleep? If sleep is important for processing intense emotion, could psychotherapists help you get the most benefit from your sleep for your mental health? All interesting questions, which I think I would not trust the answers to, for at least fifty years.

In the meantime, though, it is worth learning something about how sleep works (or fails to), and how to improve our odds. For example, cut down on the screen time (computer, TV, or phone) in the hours just before going to bed. Oops, I am writing this review on my laptop, and it is after 9:30 pm. Well, anyway, Lewis gives an enjoyable and exceedingly well-informed look at something you spend about 1/3 of your life doing, but probably don't know much about.

[Dave Reads · Rating 4 out of 5]

It wasn’t until the 1970s before the study of science seemed to capture the imagination of scientists and the general public alike. It was then that researchers at the Stanford University Sleep Disorders Clinic began looking for the causes of sleep problems in their patients. Since then, much has been written about what they and many others have learned. There are many books available on the subject, and some are more technical than others. “The Secret World of Sleep: The Surprising Science of the Mind At Rest” is more of a consumer's guide to our sleep rather than something out of an academic journal. Author Penelope A. Lewis is a neuroscientist by training but shares concepts that the layperson can easily understand.

The book begins with a discussion of why sleep is essential and why a lack of sleep is similar to a brain impaired by alcohol. If you miss enough sleep, you can become depressed or psychopathic. Our senses are dulled, and our judgment weakens.

Younger people are better at dealing with a lack of sleep than their elders.

For those who want more detailed science, there is a chapter on how the brain works. While still understandable for the non-scientist, we learn how brain cells work with synaptic plasticity. We get a good explanation of the neurochemistry behind sleep.

Lewis discusses the importance of serotonin in sleep. Too much restricts REM sleep. Too little, and you get too much REM sleep. It is non-REM sleep that dulls synapses in the brain, which weakens your memories. REM sleep is defined as ‘rapid eye movement, which our brain activity increases and our eyes dart around and our blood pressure increases. This is when we do most of our dreaming as our brain is working hard to process what we have learned and experienced.

When something happens in our life that we remember, a sequence of synapses fires. When we think back to that memory, the same neurons fire.

There is also a fascinating chapter on dreaming and why we have difficulty remembering most of them. We forget dreams when the connection between our hippocampus to the cortex is weakened. While we sleep, new connections are formed, which play a crucial role in helping us remember new things but also help us with creative problem-solving.

This is a fascinating book that will likely make the reader want more.

Here are a couple of my favorite quotes from the book:

Children younger than five years old tend to have unstructured dreams with poor narrative development; in the dreams of five- to eight-year-olds, these properties are predicted by measures of visuospatial intelligence.

If you want slow wave sleep to strengthen your neural representations of specific bits of knowledge, then it would be sensible to take a nap in the afternoon. On the other hand, if you want to strengthen emotional memories, it might be better to sleep longer in the morning, or take a morning nap.

Temperature As a rule of thumb, 16 to 19 degrees Celsius (61 to 66 degrees Fahrenheit) is an optimal room temperature for sleep. Your body temperature always cools slightly when you go to sleep, and artificially triggering this cooling can help you to fall asleep because it tricks your body into the right general state for snoozing. A counterintuitive strategy for getting your body to cool down at just the right time is to heat yourself up a little before going to bed. A hot bath starting about an hour and a half before bedtime is one of the best ways to ensure you’ll fall asleep.

[Geoff Young · Rating 3 out of 5]

Useful overview of a sometimes overlooked topic crucial to our survival as a species. Material is presented in layperson's terms, which makes it easy to digest but also limits its depth. End notes are included to suggest further reading if deeper understanding is desired.

One conceit of the book that didn't work well for me was the presentation of a particular theory that had been later disproved by another. The author correctly (and somewhat pedantically) notes that science often contradicts itself, but I found myself on more than one occasion rereading passages to determine which theory was the one currently in vogue.

Then again, this probably speaks to my own preferences more than anything else. I learned a lot from this slim volume and feel ready to tackle more robust investigations on the topic as a result of having read it.

[Cheryl]

Carefully skimmed, as it's written as if to teens and so is unsatisfying to me. Also it's over ten years old; a lot of stuff she writes about should be better understood by now. Of course, we already know that good sleep is important for so many reasons so she didn't need to spend quite as many paragraphs on that theme.

"Many animals actually warm up during hibernation in order to obtain a proper snooze. This means they are investing energy in order to get some sleep- suggesting that such slumber can't exist simply to make energy savings."

"... dreams don't occur only in REM sleep; they occur throughout the night in all stages of sleep."

"Many effective antidepressant drugs actually suppress REM, which could mean that they partially fight depression by preventing pernicious overconsolidation of the negative."

August 2024

[Susan Aldridge · Rating 3 out of 5]

The words 'secret' and 'surprising' in the title led me to believe this might be a fascinating book about sleep, covering all the latest research. It's thorough and well-researched, to be sure, with masses of references at the end. But I found it a little dull, I have to say. Starts off with too much about the basic anatomy of the brain and then the final chapter, with tips on better sleep, seemed a bit thin. I'd have preferred more anecdotes, quotes and case histories. But if it helps anyone better understand this vital aspect of good health, then it'll have done the job...

[Juan Aranaga]

My sister gifted me this when I started to enjoy reading books.

I was going through rough times and this book served as a distraction.

I read it somewhere in 2021, therefore, I can't recall almost anything, I do remember some facts, or at least fragments of them. It was really, really scientific--but at the same time, simple.

I consider it to be a good choice if you want to start digging into how the brain works; although it may seem like a complex topic--which it is--, this book gives the impression of the opposite.

[Allison Roy · Rating 3 out of 5]

Picked this up on honeymoon in Vermont at my fave bookstore. Mostly because SLEEP IS THE GREATEST THING. It seems a lot of books I've been reading lately are about brains and brain research. This was good, easy to understand. It mostly went on about how sleep is important for memory retention/clearing up/etc. Only touched on dreaming but I mean, how deep can you go when most brain research is still in the peak of discovery. Basically this was just a good book about my favorite life process.

[Chelsea · Rating 4 out of 5]

This was a brilliant brief overview of the science of sleep. It would make a fantastic quick reference guide and covers many popular questions and concerns people have about sleep, but I think I would have to read it once or twice again to absorb all the information presented in this slim FAQ guide. I personally feel, however, that the title should have been less sensationalized. It almost put me off it, but there is undeniable value in this introductory read.

[Jacob Moss · Rating 3 out of 5]

(I'll be honest I gave up halfway through reading this book) It was interesting at times, then other sections dragged on. Also, it's from 2013. The science isn't so cutting edge anymore. If you want that maybe get a book written this decade.

On to something that actually piques my interest. Wasn't the book for me, but it might be for you!

[Shahid · Rating 5 out of 5]

I'm definitely not qualified to review this and don't share the same taste as the other. What I liked about the book was how it read like a scientist rambling in detail. It's so packed with with information yet left me wanting more. I hope we get a sequel soon.

[Kayleigh Medhurst · Rating 5 out of 5]

This book was assigned as a textbook for my Science of Sleep class but I was enjoyable. It is very approachable for anyone and provides a basic but comprehensive overview of sleep. The author does a good job describing different concepts and each chapter is short and concise.

[Ellen Marie · Rating 3 out of 5]

Not as enthralling as I hoped. Interesting, but I struggled a bit to finish it.

[Cassie Trapp · Rating 2 out of 5]

This book put me to sleep.💤

[Janine · Rating 3 out of 5]

Thank you to Goodreads for the ARC! Review forthcoming.

[Luz · Rating 4 out of 5]

Enjoyed this introductory scientific look at the fascinating world of sleep and it's benefits. Academic enough but also relatable.

[Dan Liggins · Rating 3 out of 5]

The surprising science of the mind at rest – as Penelope quotes this book; I have to say, it is definitely true. You will be surprised about a lot of what Penelope Lewis has to say & explain as you read this interesting book about how, why, what… all the questions about sleeping.
From dreaming to the neuroscience behind the building blocks of the brain, Lewis covers it all.

This book is very interesting in parts if you have even a small interest into sleeping & how the brain really works whilst we drift into our sleep. (A sleep pattern that differs from person to person & has multiple stages).
I personally enjoyed this book more so because I am at the same time studying Psychology in the UK & therefore, a lot of the semantics & case studies Lewis discusses were a lot more understanding to me & some of them new – helping me get more information on the memory aspect of psychology & now Lewis’s input with her amazing knowledge on neuroscience.

This book is very science based. You would expect nothing else! It is explaining the brain during sleep. However, even for somebody like me studying psychology, you can at times, drift into autopilot when you come across certain chapters that are either too science heavy or are just not as interesting as the other chapters.
This is a good layout basis to the book though. Lewis has divided this book all into chapters that can be read on their own – you will not miss the conceptual elements Penelope Lewis wants to discuss. Along with seemingly easy to understand illustrations by Thomas Shafee, even the complex science can be understood more easily.
When you read parts of the book, any reference to older described information is also noted with what chapter it is in so you can flick back & read that part if you want that knowledge if you do not read this book in chronological order.
This is not saying the book is an easy read to those who have little knowledge or interest in neuroscience. Sadly, my personal rating is only a 3 based purely on my bias on science.
I am not taking away any credit to Penelope Lewis for her expertise at all. I just found the book in parts, not easy to read for me. However, it would not be a science book if it did not include these aspects!

Overall, I was impressed with Lewis & her easy to read layout – especially the summing up parts at the end of each chapter – I have taken away a lot of new knowledge on the brain during sleep.
It is very informative & very well structured!
Hats off to Penelope A Lewis for this book. I have not seen or read a book about sleeping that matches this one yet!
A good read & nice book to keep on the shelf if you want to remember why or what happened after you wake-up annoyed that you had a ‘poor sleep’. This book will most likely have those answers & give you insights into how to sleep better in the future & chronically become a healthier sleeper.