The Secret World of Sleep: The Surprising Science of the Mind at Rest Hardcover – Aug 27 2013
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“There is much to fascinate in this nippy primer on the biology and behaviour associated with snoozing…from the latest on narcolepsy to the sleep-inhibiting qualities of smoked meat, this is wide-awake science” ―Nature
About the Author
Penelope A. Lewis is a neuroscientist at the University of Manchester, where she runs the Sleep and Memory Lab. She has written for a number of popular science publications, including New Scientist. Her research has been featured on the BBC, and she's received funding from top institutes, including the Wellcome Trust and Unilever. She lives in Manchester, United Kingdom.
Most Helpful Customer Reviews on Amazon.com (beta)
I have a different perspective on the book, which makes Penelope Lewis' first book an important contribution as scientists learn more about sleep and this knowledge filters down to those many people with sleep deprivation. I had originally read and reviewed David Randall's "Dreamland: Adventures in the Strange Science of Sleep" as research when interviewing for a training manager job at a mattress retailer. I wanted to learn what I could about why people struggle with insomnia, aches and pains, sleep apnea and assorted sleep problems. Randall is a journalist and professional writer, and his book was a good read.
I got that job and for the last year have been exposed to many mattress customers in-person and through their survey feedback after purchasing from us. There is clearly ... clearly a general and intense lack of knowledge about sleep. Customers think they're looking for a magic mattress that will solve all their sleep problems. For many people, there is a great need out there for books like Randall's and now Lewis' "The Secret World of Sleep." Ironically, I had spent the three days leading up to Lewis' NPR interview listening to a sleep doctor we brought in to educate our sales force on why consumers struggle with sleep and the lack of support. Many of the points Terry Gross and Lewis were discussing in that interview were in line with what our sleep doctor had discussed, and so I was excited to get and read the book.
Lewis aspires to go much further in explaining the physiological and chemical functioning of the brain as it passes through different stages and cycles of sleep. Her focus in most of the book is not so much on how to sleep better as it is how we can learn and create memories better through strategic sleep. Probably the reason the NPR interview may have baited these disappointed listeners to buy this book is that Terry Gross asked more "pop questions" about sleeping and dreaming than what are actually covered in the book.
Where Randall had gone out as a journalist to interview others in the sleep industry, Lewis focuses more on scientific research that she is more involved in herself or aware of through her colleagues. As I read, I chose to take notes--not so much on the science as--on more practical observations that consumers might benefit from as they search for better sleep. Or in my case, how we might educate our customers as they come into our sleep stores.
The result? This is an interesting book for laymen who want a little bit of the science in figuring out how they can sleep better. Lewis gives us enough of a scientific explanation to serve as a basis for understanding what's going on as we learn, sleep and then remember. This can help people learn more about sleep and help them avoid many of the charlatan efforts Randall described in his book.
Penelope Lewis does an excellent job of accomplishing what she set out to do ... "convincing you that sleep is essential to our physical and mental well-being ... [so you will] consider giving sleep some kind of priority in your life." Read this book to see how clever our brains are in restoring our bodies and remembering what's important every night. I'm convinced that people who understand some of this science will be well on their way to sleeping better and knowing why that's important.
I pre-ordered this book based on someone telling me about the author's interview on NPR Fresh Air's Terry Gross interview. Perhaps if I were not a medical professional, or had listened to the interview myself (it is still available as a podcast), my expectations would have been lower, but I was under the impression that it would reveal some dramatic new facts about sleep and memory in a clear and concise way. Perhaps my expectations were too high because I am currently reading Frank Wilczek & Betsy Devine's amazingly well written Longing for the Harmonies: Themes and Variations from Modern Physics, the epitome of style and scientific content. However, even discounting for perhaps unrealistic expectations, "The Secret World of Sleep" was a huge disappointment and the first time I actually considered investigating Amazon.com's new book return policy.
According to the paper book cover, the author's sole qualifications are that Ms. Lewis is a "neuroscientist" and "runs" the Sleep and Memory lab at the University of Manchester. While writing this review, I did a quick google and the only biographical information I could find is from the publisher's website which gives no more information than the book cover.
The content is disjointed. By page 8 we are knee deep in EEG wave forms and sleep stages, yet the author only much later decides that it is necessary to tell us about brain nerve cell anatomy and function (p. 25+) which cause these waves. This seems to be a fundamental organizing principle of the book: Make some hazy offhand statements, then back up and try to provide some possible explanations full of caveats and hedges. Seldom with clear success. The topic of brain anatomy does not start until about p. 38 (chapter 4), before which we have already discussed neurotransmitters and the aforementioned personal recreational drug use (pp 35-37). The book appears to be an attempt to summarize various limited aspects of sleep research, yet it does not take enough of a stand on any issue to be very readable or usable by a layperson. Nor is it rich in content enough to satisfy any but the must uninformed medical person. This book is the equivalent of an extended popular science magazine article yet without the clarity. It does have end notes, but chapters 4 and 11 have only one note each. It also has a decent end index, which is a plus, but I did not assess its completeness.
The repetitive end of chapter summaries are particularly irritating and pedantic. It is as if the intended reader is a school child and requires a review of the preceding (often unclear) prose. Well written books do not require such repetition. Furthermore, the summaries are not very confidence building. For example, the summary of Chapter 8, the chapter that includes the author's own iOtA theory (information overlap to abstract), and presumably a subject about which the author is knowledgeable, is presented as a tentative question rather than a chapter summary:
Does sleeping on a complex problem really help us to solve it? The type of integration and abstraction which we've discussed here, and which can be explained by the iOtA model, may not help with every single problem you ever encounter in your life---but it would normally be worth at least giving it a chance (e.g. by getting a night or two of sleep) before you decide the issue is insoluble" (p. 112-113).
Wow! Such a profoundly informative, confidence building, and ground breaking summary! And the chapter never clearly delineates the differences between the iOtA theory and previously discussed theories of slow wave sleep.
Speaking of repetition, because this book could have been titled "Sleep, Memory, and Emotion", it is especially ironic that the author and editor of the book both seem to have either a short term memory deficit or completely forgotten to read the draft before publishing. This is obvious because there are repetitions appearing in close proximity to each other in the text which should have been edited down or out. This is especially unfortunate for a book of such diminutive size. For example, on p 117:
"if the neural connection from amygdala to hippocampus is blocked (something that most commonly occurs when a callous scientist administers drugs that clog up the receptors which mediate communication between these structures), emotional memories lose their edge-- they are remembered only as well as run of the mill everyday memories. This could mean for example, that you remembered your first kiss only as well as the first time you did something fairly mundane, like eating tuna fish or putting on a specific pair of unexciting shoes"
then the same example is essentially repeated with only slight expansion later on p. 119 as if the reader has no memory of what was discussed two pages earlier:
"manipulating amygdala responses after the fact can alter how well the event is remembered later on. For example, injecting something to excite or inhibit amygdala activity about ten minutes after your first kiss could prevent that memory from achieving the special status it should normally have as a strongly emotional memory. Sadly enough, if the connection between amygdala and hippocampus is blocked immediately after this highly emotional memory is formed, it will be forgotten at the same rate as a mundane, everyday memory (think again of your initial experiences of tuna fish or putting on those rather boring shoes)."
and a different example from p.92
"a more recently described phenomenon called the dream-lag effect refers to the extraordinary observation that, after its initial appearance as a day residue, the likelihood that a specific memory will be incorporated into dreams decreases steadily across the next few nights after the memory was formed, then increases again across the following few nights"
The same concepts are repeated in the very next paragraph (on same page 92)
"The likelihood of such incorporation decreases gradually across the next few nights, with few memories incorporated into dreams three to five days after they occurred. Extraordinarily, however, the probability that a memory will be incorporated into a dream increases again on nights six and seven after it was initially experienced."
Such repetition might be useful in an oral lecture, or in a very large book, but this book is so tiny and woefully short of content that repetition only subtracts from space which could have been used for more relevant content.
For example, there is not a single word mention of RLS (restless leg syndrome), and only two sentences, added almost as an afterthought on the penultimate page (p. 184), mentioning sleep apnea. And those two sentences are woefully inadequate to the tasks they should perform, especially coming from someone who is claiming to run a sleep clinic. Here, in its entirety, is all that was said about sleep apnea, a common condition, in the book:
"If you snore loudly, often need to go to the toilet at night, or commonly wake with a morning headache and a dry mouth and feel tired during the day, you may be suffering from sleep-disordered breathing. Some of these symptoms can be relieved by aggressive weight loss programs, but in many instances, it would be prudent to have them checked out by your doctor or request a referral to a sleep clinic." (p. 184)
As you may already know, not all sleep apnea is caused by obesity. The book shockingly does not mention other interesting causes of sleep apnea nor the very real probability of dramatic benefits of the clinically recommended continuous positive airway pressure treatment for this common but sometimes overlooked sleep disorder.
Lastly, and perhaps most revealingly, for someone reportedly running a sleep clinic, this book is remarkable for its paucity of actual clinical examples. Ordinarily a book of this type would regale the reader with fascinating but anonymized actual stories of people to serve as examples and assist the reader in identifying with the clinical impact of research information. Not sharing actual examples perhaps was a conscious philosophical choice resulting from excessive European patient privacy concerns, but one gets the impression instead that the author does not actually deal with real living patients.
The author's substitution of a hypothetical reader in situations where a real life example might have been appropriate was off-putting and at times even disturbing. For example, the author attempted to illustrate a situation with negative emotions by inviting the reader to imagine a bleeding little girl dying in the reader's arms. (Chap 10, p. 131). Negative emotions, yes. Gruesome in detail, yes. Was it really necessary? No. Where did that callous example come from? Why not a favorite pet or something less extreme? Furthermore, the suggested remedy (basically, get some sleep) seemed woefully inadequate for the situation described. In fact, the author here seems to be treading very close to PTSD (Post Traumatic Stress Disorder) territory. The author in fact does mention PTSD four pages later and on several subsequent pages without clearly identifying what PTSD is or actually mentioning some of the therapies found to actually be effective (such as beta blockers immediately after the event) to block or reduce the emotional storage of negative memories.
The author's intended audience is not clear. It is mostly written in a pseudo-personal style which implies or assumes that the lay reader is personally stupid enough to be using drugs ("what does this little tablet [ecstasy] actually do to your brain?" p. 35) but at other times inexplicably falls back onto pseudo-intellectual Latin based language ("rules which describe a corpus of events" pp 102-103) In other words, it is neither as informative as a textbook or as readable as a popular book clearly written for the lay person.
This book has multiple grammatically questionable phrases such as "lots of" when "many" would have worked better, and "since" when "because" would have been more accurate. Books by British authors are usually well written, perhaps as a result of their educational system which requires careful thought and essay style exam answers rather than multiple choice. But after reading this book, the poor writing style and disorganization cast doubt on any ideas that Ms. Lewis might possibly be British. Some of these are minor points, but mentioned here to support my theory that the author may not be British and obviously could not afford an editor (more examples above).
The hardcover physical dimensions are surprisingly small: 5.75 x 8.5 inches. It has only 185 pages of actual text, and is annoyingly printed in extra widely spaced (1.5X?) lines and widish margins that scream 'not enough material for a real book'. These facts alone would not be entirely negative, because a carefully edited small book with spacious layout can be beautiful if well written. Unfortunately, this book is not.
My recommendation would be to wait the local library to get a copy. Or at least the paperback.
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.
The first two chapters are the best. They discuss the consequences of sleep deprivation, why sleep matters, explains the sleep cycle, and introduces the idea of sleep and memory. Of particular note, the sleep deprived brain is much like an alcohol impaired brain. Every five hours you are awake is about the same as one alcoholic drink - after 20 hours, it is as though you have a 0.08 alcohol level. Younger people tolerate sleep deprivation less well than older people.
Miss enough sleep, and an otherwise healthy person can be classified on a particular day as depressed or as a psychopath. Senses are dulled, creativity damaged, and dulls moral judgement. The reward system (chocolate, sex, etc) is ramped up, while negatives don't elicit the same reaction in the brain's punishment system - leading to more risky behavior and bad decision making. It impairs learning. You will be less prone to "think and act proactively, control impulses, feel positive about yourself, empathize with others, and generally use emotional intelligence. Sleep deprived people are more easily frustrated, intolerant, unforgiving, uncaring, and self-absorbed than they would be if they were properly rested." (pg 20) When tested on a list of words, the sleep deprived remembered the negative words much better than the positive.
Chapter 3 and 4 are the weakest chapters. Chapter 3 is a technical chapter on how the brain works, too short to be truly informative, technical enough to drive people away, and of little use during the rest of the book. She describes brain cells, explains how an action potential works, and synaptic plasticity. I actually love this stuff, but the author does a poor job with the material. In chapter four the author attempts to explain the neurochemistry behind sleeping. Too brief for a real explanation, too long in that it is technical without being helpful, many people probably quit here. Just skip it if you don't like it.
One thing that was interesting though was the role of serotonin in sleep. Too much will inhibit REM sleep, too little and you spend too much time in REM sleep. SSRIs can be helpful if you do not have enough serotonin, but also disturbs sleep continuity and "induce periodic limb movements" (p45). Also interesting: alcohol can help you fall asleep, but is often followed by lots of waking and an increase in dreaming, especially nightmares as the alcohol leaves your system. Interestingly, the neurotransmitter acetylcholine which is involved in wakefulness seems to inhibit transmission from the hippocampus (memory) to the cortex. During sleep memory consolidation can occur more effectively with acetylcholine levels lower (i.e. the transfer of short term hippocampus learning into long-term storage in the cortex).
This last observation leads nicely into the next few chapters on how memory is affected by sleep. Slow wave sleep (i.e. nonREM) downscales synapses in the brain - making all of your memories weaker, then selects the most important things to improve. This allows you to retain important information about, say, something your wife really didn't like or the fact that your kid went into anaphylactic shock when he ate peanuts. To be able to access memories we need to be able to sort through the clutter - what you ate for breakfast two weeks ago has no real relevance and is thus forgotten. There are more sleep waves in sections of the brain that were used more during the day - if one arm was in a sling, the cortical areas controlling that arm will experience less slow wave sleep. It turns out that parts of your brain can "exhibit properties of slow wave sleep even when you're wide awake." (pg 54)
When you recall a memory the same neurons fire in the same way as when you first experienced it, and then is reconsolidated. In rats, disrupting the brain regions involved in this (the hippocampus especially) can cause the memory to be lost instead of reconsolidated. This also forms the basis for how our memories literally change over time - when recalled they are plastic, and susceptible to change.
The role of dreaming is discussed, and why we usually forget our dreams (connection between the hippocampus to the cortex is weakened).
In sleep we often form new connections. It plays a critical role in memory, but also in creativity and problem solving. There seems to be a conflict over whether sleep helps or makes worse our experience of traumatic memories. People who are depressed get more REM sleep than "normal," possibly overstrengthening negative memories during REM - many antidepressants suppress REM, which may help avoid this by reducing the amount of REM sleep. On the other hand, during sleep norepinephrine levels are low, which allow us to relive memories without the associated stress levels, thus making memories theoretically less debilitating. Lacking the ability for REM sleep increases the risk of PTSD.
Yet this is far from settled - people don't necessarily feel less emotional about their memories after sleep. In rats, sleep deprivation may even prevent the consolidation of traumatic memories. One possible answers lies in stress itself - not everyone experiences a lessening of cortisol in their sleep, which would negate sleep's potential advantage for allowing the safe replay of traumatic memories (this concept is easier to understand if you get how the amygdala works - short version, safely facing your fears reduces fear, but she doesn't explain this all that well). Possibly the fact that in studies where the person was asked to recall the memory they showed no improvement in emotional ratings of traumatic memories plays; for those who were not asked to recall, but just rate, their emotional ratings went down. The act of recall may be what eliminates sleep's advantage. [Note: In PTSD you can't help but recall what you experience though; rumination is a risk factor for depression. Though she doesn't say this, if the mere act of recall negates the advantage, then it really isn't much of an advantage.]
Chapter 11 was, along with CH1-2, one of the best. There are larks and owls (common knowledge). What was interesting though was that this is genetically determined, and that larks have more trouble when sleep deprived than owls. You get two copies of the gene that governs this disposition - two one the lark gene and you are a lark, two owls genes and you are an owl, one of each (like 50% of the population) and you will be somewhere in between. As you age later in life you need less sleep; adolescents need lots of sleep, more than children. Sleep spindles (oscillations during slow wave, i.e. nonREM, sleep) are more common in people with higher IQ, and more extreme in people with learning disabilities. Sleep spindle density increases after learning, if it was a challenge - over the structure that did the learning, not the whole brain. Chapter 12 discusses how to "get the most out of your sleep." Not helpful really, but the fact that if you nap in the morning you will go into REM sleep, in the afternoon you will go into slow-wave sleep may matter if you are trying to get a specific type of sleep for the purposes of learning. I recommend this book,How We Learn: The Surprising Truth About When, Where, and Why It Happens, if you want to learn how sleep impacts learning.
The last chapter discusses how to improve your sleep - just basic sleep hygiene/cognitive behavioral therapy stuff. Only use your bed for sleep/sex. Get light during the day, avoid blue light especially before bed (like that in most monitor screens). Temperature should be somewhat lower, noise makers (white noise) often help.
In all, I learned some interesting stuff -- which I have managed to fit into this short review -- but it wasn't a great read. I have learned more from other sources, such as the Teaching Company course on sleep science. However, it is brief, a significant virtue for a book that isn't great. I didn't feel like it was a total waste.
1) The Secret World of Sleep: The Surprising Science of the Mind at Rest by Penelope A. Lewis
2) Dreamland: Adventures in the Strange Science of Sleep by David K. Randall
3) Sleep: A Very Short Introduction by Steven W. Lockley
4) The Secret Life of Sleep by Kat Duff
I was looking mainly for scientific information, in conjunction, perhaps, with interesting anecdotes. Dreamland by David Randall was the closest to what I thought I was looking for and I highly recommend it for anyone interested in sleep. The Secret World of Sleep by Penelope Lewis and Sleep: A Very Short Introduction by Steven Lockley were a little more purely scientific. However, among these two I strongly preferred the no-nonsense style of Sleep: A Very Short Introduction. By comparison, The Secret World of Sleep feels like an academic paper that has been hastily modified by a copy-editor to read more like a popular science book. The result is not-very-exciting writing that is larded with "accessible" descriptions and analogies. The amygdala is referred to at least a dozen times by the epithet "almond shaped". The first time was fine, the fifth time was patronizing. But I powered through.
I cannot recommend Kat Duff's book, because of passages that give serious credence to the explanation that hypnogogic hallucinations are in fact visitations by evil spirits. See my review there for more details.