47 pages • 1 hour read
Matthew WalkerWhy We Sleep
Nonfiction | Book | Adult | Published in 2017A modern alternative to SparkNotes and CliffsNotes, SuperSummary offers high-quality Study Guides with detailed chapter summaries and analysis of major themes, characters, and more.
Part 4, Chapters 12-14Chapter Summaries & Analyses
Part 4: “From Sleeping Pills to Society Transformed”
Chapter 12 Summary: “Things That Go Bump in the Night: Sleep Disorders and Death Caused by No Sleep”
Walker discusses four sleep disorders, which support his claim that “few other areas of medicine offer a more disturbing or astonishing array of disorders than those concerning sleep” (237).
One example is somnambulism, which refers to sleep disorders that involve movement (e.g., sleepwalking, sleep texting, sleep sex, sleep talking, sleep eating, and in rare cases sleep homicide). These events occur during NREM sleep, with one trigger being a sudden burst of nervous system activity. Somnambulism occurs in both child and adult populations. Episodes are typically harmless, although Walker provides one rare example where an episode led horrifyingly to homicide.
Another example is insomnia—the most common sleep disorder, which affects more women than men—where individuals cannot generate sleep despite allowing themselves opportunities to do so. Triggers include environmental, medical, physical, psychological, and physiological factors. Because individuals with insomnia have lower sleep quality, their cognitive and emotional states do not function as well during the day. As such, “insomnia is really a 24/7 disorder: as much a disorder of the day as of the night” (246).
Walker saves the most horrifying of the chronic sleep disorders for last: fatal familial insomnia, a genetically inherited disorder characterized by insomnia. This disorder “has taught us a shocking lesson: a lack of sleep will kill a human being” (255). Research studies conducted in animals have further supported that sleep deprivation alone, similar to food deprivation, will result in death. Prolonged sleep deprivation in rats led to serious metabolic, thermal, immune, and physiological consequences, including loss of body mass, an inability to regulate core body temperature and fight off basic infections, internal hemorrhaging, and fluid in the lungs. In the end, sleep deprivation led to septicemia, or blood poisoning, which scientists believed was the cause of death in the rats. Walker concludes this chapter by reaffirming the importance of sleep—especially eight hours of total sleep.
Chapter 13 Summary: “iPads, Factory Whistles, and Nightcaps: What’s Stopping You from Sleeping?”
Chapter 13 discusses factors—many of which are a product of our modern world—that impact sleep. Technology, particularly electric light, is one factor. Due to electric light, humans are the only species capable of controlling our environment light. This technology manages to “veto our natural timing and quality of sleep” (267) because it emits light wavelengths that signal to the brain that it is still daytime even when the sun has set. In fact, our internal time keeping, including the release of melatonin, is delayed by two to three hours each evening. The ubiquity of smartphones, tablets, and computers—all of which emit LED lights—has only made sleep quantity/quality worse. In turn, this impacts how alert we feel during the day. Walker provides several recommendations to minimize the impact of electric light on sleep, including: dimming lights in the room during the evening; wearing yellow-tinted glasses indoors from the afternoon onwards to filter out light that suppresses melatonin; installing software on phone, computer, and tablet devices that reduce harmful light wavelengths over the course of the evening; and using blackout curtains.
To Walker, “thermal environment, specifically the proximal temperature around your body and brain, is perhaps the most underappreciated factor determining the ease with which you will fall asleep tonight, and the quality of sleep you will obtain” (275). Core body temperature must decrease by several degrees Fahrenheit to initiate sleep. Walker argues this is one reason humans wash their faces at night. Splashing water on the face helps dissipate heat from the skin’s surface, which, in turn, decreases the core body temperature. Climate-controlled homes, pajamas, and warm bedding all disrupt the natural increase and decrease of environmental temperature by making it more difficult for the core body temperature to drop. This disruption impacts sleep quantity/quality.
Walker concludes noting that humans are the only animal known to “enforce awakening” (279). Alarm clocks cause an explosive fight-or-flight response. By hitting snooze, humans are causing this response to repeat itself, and thus alarming the heart over and over. To minimize this cardiovascular assault, Walker recommends maintaining a consistent sleep schedule and avoiding the snooze button.
Chapter 14 Summary: “Hurting and Helping Your Sleep: Pills vs. Therapy”
While millions of Americans use sleeping pills each night, Walker argues that they cause more harm than good. Despite their name, these pills do not cause natural sleep. Instead, they act as sedatives. They also include “unwanted side effects” (283), such as daytime grogginess, forgetfulness, increased chances of premature death or developing cancer, weakened immune system, and rebound insomnia (i.e., sleep challenges made worse by discontinuing sleeping pills). Sleeping pills create a vicious cycle: Daytime grogginess means individuals drink more caffeine throughout the day and evening, which makes it more challenging for them to fall asleep, worsening their insomnia. Because they think the sleeping pills are not working, many will take an extra half or whole pill. To Walker, “this only amplifies the next-day grogginess from the drug hangover” (283). Scientific studies show that sleeping pills also do not help individuals fall asleep faster, reiterating “that they may not be the answer to returning sound sleep to those struggling to generate it on their own” (284).
One promising non-pharmacological alternative to sleeping pill usage is cognitive behavioral therapy for insomnia (CBT-I). CBT-I is a structured program that helps individuals identify and replace behaviors and thoughts to break bad sleep habits (e.g., reducing caffeine and alcohol consumption, having a cooler temperature in the bedroom, and decreasing screen use before bedtime). This method also helps individuals “regain their psychological confidence in being able to self-generate and sustain healthy, rapid, and sound sleep, night after night” (291).
Part 4, Chapters 12-14 Analysis
In Chapters 12 through 14, Walker starts at the “bedside” (11), explaining several sleep disorders (Chapter 12), factors in our modern environment that impact sleep (Chapter 13), and raises concerns around sleeping pill usage (Chapter 14). Research studies in animals have shed light on the biological mysteries of sleep, including sleeping orders, and yet many of them are “dramatic, disturbing, and ethically provoking” (257). One vivid example is a study conducted by a research team at the University of Chicago, which prevented rats from sleeping for weeks to determine if sleep deprivation led to death. All of the rats suffered significant deteriorations in cognitive and bodily functions to the point that some were euthanized before death itself occurred. The results match earlier studies conducted on young dogs, which also found the lethal effects of total sleep deprivation. These findings—even for Walker—are hard to read. He raises the ethical dilemmas they present given the horrific lethal outcomes and notes researchers no longer conduct such studies. Both he and the reader grapple with whether science reached too far into the ethical realm in its quest to solve the mysteries of sleep.
Walker continues to expand on his claim that modern society divorces humans from the way nature/evolution intended sleep. Homo sapiens and modern sleep patterns evolved in east Africa, where there are large temperature differences between day and night in both summer and winter. To Walker, modern hunter-gatherer/pre-industrial peoples, such as the Hadza tribe in northern Tanzania, “have remained in thermic harmony with this day-night cycle” (277). They sleep with little clothing, minimal bedding, and huts with no central air conditioning or heat. This exposure to temperature fluctuations enables them to have naturally timed, healthy sleep quality. The reason for this sleep quality is that the natural drops in evening temperatures trigger their core body temperature to decrease, which initiates the release of melatonin. Industrialized cultures stand in stark contrast. Because of pajamas, bedding, and climate-controlled homes, our bodies have a more difficult time making the transition to sleep. Sleep clinicians treating individuals with insomnia will advise patients to drop their current thermostat temperatures as one intervention to aid with sleep.
In Chapter 14, Walker shifts his focus from factors that impact individual’s ability to sleep to solutions individuals can use to improve sleep. Due to the harmful health consequences associated with sleeping pills, Walker is against their use as a sleeping aid. Walker finds promise with non-pharmacological alternatives for insomnia patients, such as CBT-I, in part because they help patients regain their confidence in generating and sustaining sleep. He also provides 12 key tips from the National Institute of Health (also found in the appendix) that he calls “good ‘sleep hygiene’ practices” (292). He recommends individuals who are not suffering from insomnia or another sleep disorder try and follow these practices. While sleep deprivation is a serious epidemic, Walker uses these practices to illustrate steps to “ensure a far better night of sleep” (292).
