Asheville – Why We Sleep: Unlocking the Power of Sleep and Dreams, by Matthew Walker, Ph.D., seems an odd choice for review, given that, historically, other books critiqued in this space have only been about public policy or economics. A relevant angle is not difficult to produce, however. One could use the bulk of the book to argue that it is foolish for the Asheville City Council, or Congress for that matter, to hold marathon meetings wherein controversial, high-impact issues are debated past the witching hour. Then again, maybe it was just the boss’ way of complaining that one contributor can’t assume the privilege of working 22-hour shifts if the consequence is making six editors pull their hair out trying to figure out what in tarnation she was trying to type. Either way, the book is a must-read for anybody who believes they, or those around them, don’t need more than six hours of sleep.
The book begins by telling the reader what his mom probably already did. “Within the brain, sleep enriches a diversity of functions, including our ability to learn, memorize, and make logical decisions and choices. Benevolently servicing our physiological health, sleep recalibrates our emotional brain circuits, allowing us to navigate next-day social and psychological challenges with cool-headed composure. We are even beginning to understand the most impervious and controversial of all conscious experiences: the dream. Dreaming provides a unique suite of benefits to all species fortunate enough to experience it, humans included. Among these gifts are a consoling neurochemical bath that mollifies painful memories and a virtual reality space in which the brain melds past and present knowledge, inspiring creativity. ”
He continues, “Downstairs in the body, sleep restocks the armory of our immune system, preventing infection and warding off all manner of sickness. Sleep reforms the body’s metabolic state by fine-tuning the balance of insulin and circulating glucose. Sleep further regulates our appetite, helping control body weight through healthy food selection rather than rash impulsivity. Plentiful sleep maintains a flourishing microbiome within your gut, from which we know so much of our nutritional health begins. Adequate sleep is intimately tied to the fitness of our cardiovascular system, lowering blood pressure while helping keep our hearts in fine condition.”Walker, a sleep scientist, then proceeds to reference studies, with evolutionary commentary interspersed, that led to awe-inspiring discoveries of what happens during sleep. Much of the book discusses non-REM, or NREM sleep, a time when scientists once believed the brain, like the body, was dormant. Usually with references to replicated studies, each testing large populations, Walker shows how the findings advocate getting eight hours of uninterrupted sleep nightly.
Knowing when to sleep and when to wake up is a function of both the circadian cycle, dictated by levels of melatonin in the body, and sleep pressure, which is dependent on the buildup of adenosine, which is depleted during sleep. That said, Walker is not an advocate of using over-the-counter melatonin pills, except for maybe one-time jetlag relief. For one reason, concentrations are usually not close to what is quoted on the bottles. Actually, he believes an acceptable medical treatment for insomnia is not yet known. He says major prescription drugs, like trazodone, may knock a person out, but they’re more like anesthesia. They don’t provide the same nourishing and replenishing services to the mind and body as real sleep does. As far as stimulants go, Walker, who relishes his eight hours a day, is definitely not a fan of caffeine, for a number of reasons interspersed throughout the book.
It all started when scientists wired electrodes to the brains of rats and observed changes and patterns in the traces as they learned to navigate a maze. Astonishingly, when the rats went to sleep, the scientists saw the navigation patterns replaying slowly during REM sleep. It seems the rat brains were somehow reinforcing the day’s lessons as they slept. From there, Walker spoke about the less-famous “other” part of sleep, NREM. Using electrodes again, scientists discovered the brain cycles through REM and four stages of NREM sleep three or four times during eight hours of sleep. It is as if the brain is iteratively evaluating the day’s memories and transferring those it wants for sustained, long-term reference out of the hippocampus’ short-term storage and into the prefrontal cortex. Cutting sleep short by a cycle or two could leave the process, and the memories, incomplete. It’s erroneous to believe that if one gets his eight hours in a series of naps, the cycle will just pick up where it left off. Walker is also of the belief that there is no making up for lost sleep.
Walker recalls in detail meeting a pianist who told him how odd it was that he could practice and practice and not get a song right. Then, he would go to sleep, and the next day, he’d play it perfectly. Continuing to get a full night’s sleep for a week after facts or skills are learned will help reinforce the memories. In addition to processing information better, getting a full night’s sleep before either a test or an athletic competition will, statistically, improve performance. Depriving oneself of sleep, as it turns out, has the same effect as getting drunk before a test or performance – or getting behind the wheel.
Emotional IQs also suffer from sleep deprivation. In one study, the amygdalas in the brains of the voluntarily sleep-deprived group demonstrated a 60% “amplification” over those in the control group. The amygdala triggers emotional responses associated with fight-or-flight, so its amplification makes people “revert to a primitive pattern of uncontrolled reactivity.” The amygdalas in the control group continued their normal function by interacting with the prefrontal cortex, which Walker describes as being somewhat of the parent in the house, the seat of rationality. When Walker replicated the experiments, he observed remarkable mood swings in the subjects.
For those not interested in learning or being athletic, sleep remains important. The brain chemistry, physiology, and study results pertaining to all those health issues listed above are covered in some detail in the text. Perhaps most importantly, Walker wrote, “It was a saddening confirmation of my theory: the parts of our brain that ignite healthy deep sleep at night are the very same areas that degenerate, or atrophy, earliest and most severely as we age.” On the bright side, sleep has been discovered to figuratively clean the streets of the brain at night, removing even beta-amyloids, the buildup of which is highly correlated with Alzheimer’s disease.