12 May 2019
Executive Summary
In today’s materialism-driven culture, our collective mindset is experiencing a shift: we become preoccupied with being busy (and not necessarily productive) as this is allegedly going to bring us greater financial or material gains, while our time and attention spent outside of the office is the targeted product of profit-seekers. This fierce competition for an individual’s time and attention takes a toll on the most natural, biologically necessary state, that of sleep, as there is no profit to be made if people were asleep.
Matthew Walker’s Why We Sleep offers a re-appreciation of how we spend that third our lives. Walker, a leading expert in sleep science himself, uses the two sides of the same coin to place sleep back on a pedestal in our collective conscious: on the one hand, he cites sobering statistics of everything that goes wrong when you are sleep deprived, and on the other hand, he emphasizes the array of benefits when you get bountiful sleep. Overcoming the cultural neglect of sleep is the goal of this sleep diplomat (as Walker calls himself). Apart from being written in an extraordinarily engaging manner (that does not make you fall asleep, ironically enough), the book offers deep and research-based insights into the fundamental questions of sleep.
In Part 1, Matthew Walker introduces the phenomenon of sleep. He introduces what circadian rhythms are (larks vs night owls) and how melatonin and adenosine interact to simultaneously, but independently, generate sleep pressure, which makes you fall asleep. He then goes on to differentiate between the two types of sleep – NREM & REM – and how they alternate harmoniously throughout the night so that you reap maximum benefits. Matthew then turns to the animal kingdom to ask the question how necessary is sleep for all biological life. His answers is short and stark: in one form or another, sleep is present in all animal species. Part 1 ends with an appreciation of sleep in all age-related life stages – from babies and teens to adults and the elderly – all of which points to the absolute necessity of sleep for healthy development.
In Part 2, Walker focuses on the benefits of sleep and the downsides of sleep deprivation with stacks of research behind his back. Sleep helps form new memories faster but also to solidify previous ones, sleep helps us learn motor tasks faster, it helps us forget unnecessary information; sleep deprivation, on the other hand, impairs attention and concentration, contributes to worse mood and emotion regulation, increases chances of Alzheimer’s disease, all kinds of heart disease, obesity, diabetes, weight gain. Sleep deprivation also affects the reproductive system (males have small testicles and lower testosterone when sleep-deprived, while females have problems with fertility and abnormality in menstrual cycles), the immune system (immune response is 3 times stronger with sufficient sleep), cancer (more likely to have one and if you have one it is more likely to grow faster), and even our genes (sleep deprivation upregulates genes related to inflammation, stress and other cardiovascular problems while it downregulates genes responsible for metabolism and optimal immune response). On top of this massive list suggesting that sleep is indeed the swiss-army knife of health and wellbeing, Matthew adds a pinch of irony: insidiously enough, we seem to be unaware that we are sleep deprived, when we are sleep deprived.
In Part 3, Matthew Walkers takes even a deeper dive into sleep – specifically the state of REM-sleep, when dreaming typically occurs. He introduces all the weirdness associated with dreaming by comparing it to a psychotic-like state due to its hallucinatory, disorienting nature. He then goes on to describe the various benefits of dreaming for emotional amelioration, emotional stability, creativity and problem-solving among others.
Thus far, Walker has overviewed the basics of sleep (Part 1) and has thoroughly discussed the importance of it (Part 2). Then he took a deep dive into the sleep realm itself (Part 3). Now, in Part 4, Walkers spans back out to re-consider the place of sleep in today’s culture. He takes into account our dark-deprived everyday life and how light (especially blue LED light) relates to sleep, our control and demand for constant temperature (which adversely affects sleep onset), the normalization of alcohol, the constant need for alarms and the shock they cause to our cardiovascular system, the ubiquitous use of caffeine, the growing trend of using sleeping pills (which are so far useless for generating natural sleep) and many other aspects. In terms of the infrastructure of our society, Matthew is critical of the way we approach work, education and healthcare, where sleep is scarce among professionals – and this costs us not only billions of dollars, but also many, many lives.
Matthew Walker’s vision for sleep in the twenty-first century is ambitious, but necessary. To elevate sleep in our cultural priority list, we need to 1) embrace technology and utilize it to personalize sleep for each and every individual; 2) educate the masses of the importance of sleep (e.g. have it as a mandatory subject in schools); 3) re-organize and re-prioritize our public policies and society – from private and public organizations to insurance companies and healthcare providers – so as to encourage sleep.
Critical Review
Matthew Walker’s Why We Sleep indeed comes at a very important point in our societal development. When individual wellbeing is being neglected by corporations and politicians, scientists, philosophers and writers of all kinds jump in to remind us that we are sovereign individuals and our individual, as well as collective, lives matter. Matthew Walker’s book does precisely that – it reminds us that sleep is a necessary building block of life, part of nature. And, as I have discusses previously in my book review on Marcus Aurelius’ Mediations, that, which is according to nature, is good. However, the book still seems to lack in some respects.
To begin with, to argue for a cultural shift to a better appreciation of sleep, we must first be certain that we have a problem. Walker claims that 1/3 of people are not getting the recommended 7-9 of sleep and that “in the UK and Japan 39 and 66 percent, respectively, of all adults report sleeping fewer than seven hours”. However, this does not appear to be such a straightforward issue. For one, epidemiological, self-reported data on sleep duration is not likely to be reliable – people have been found to overestimate the quantity of their sleep. But doesn’t that make the situation even more dire: given that people self-report sleep deprivation so often, the fact that even this is an overestimation should be alarming? Maybe not. One comparison of sleep quantity of 1985 vs 2012 found that the average sleep time dropped by mere 10-15minutes. Not too big of a difference, if you ask me… However, more disturbing was that the same comparison also found that the amount of people who sleep less than 7 hours has increased by 12% over those 3 decades. To top it off, most of the data in such epidemiological studies come from high-income countries and societies; data from low and middle income countries are scarce, which limits the generalizability of the findings. All of this points, I think, to the fact that we need higher quality data but we still seem to have a problem in terms of how we, as a society, think about sleep which is only going to get worse if we don’t address it.
Another thing in Matthew’s book that could have been improved was the limited number of references he provides for his claims. He is, after all, a sleep scientist so I am personally willing to take some (or even most) of his claims based on his expertise. However, this does not allow me to critically evaluate his data and interpretations if I wanted to. One problem that might is that sleep research can be limited in its generalizability. Sleep studies are expensive and large samples are hard to come by. Therefore, underpowered studies, which are more likely to show an effect that does not really exist (false positive), are problematic for a more rigorous understanding of sleep and extrapolation to the general population.
I also found another limitation in his discussion of dreaming and its possible functions. Albeit, an exhaustive account of dreams was definitely beyond the scope of the book, I also did not appreciate his one-sided presentation of his own theory of dreams. Walker believes that “the process of REM-sleep dreaming accomplishes two critical goals: (1) sleeping to remember the details of those valuable, salient experiences, integrating them with existing knowledge and putting them into autobiographical perspective, yet (2) sleeping to forget, or dissolve, the visceral, painful emotional charge that had previously been wrapped around those memories”. However, other theories of dreams, with arguably much higher explanatory power, are available, such as the threat simulation theory, the neurocognitive theory of dreams, or the more recent emotion assimilation theory of sleep and dreaming… For a more exhaustive discussion of what and why we dream, you can check my essay on dreams due to be published in The Psychologist (Petrov & Robinson, in press) which is partly based on my research on dreams.
All in all, despite minor limitations, the Matthew Walker’s Why We Sleep is one of those rare books that contains the sine qua non of good writing – it changes the way you view the world.
