Review by James Odell, OMD, ND, L.AC
Why We Sleep by the neuroscientist Dr. Matthew Walker deeply explores one of the least understood processes of our life – sleep. Until very recently, science had few answers to the question of why we sleep, what good it serves, or why we suffer such devastating health consequences when we do not sleep. For most of the populous, the purpose of sleep has remained mysterious. Dr. Walker illuminates the path to understanding several of the vital qualities of sleep and dreaming.
We know that sleep is essential to all animals, including humans. Insufficient sleep reduces our learning, memory, and cognitive abilities cause brain impairment, and increases the risks of numerous diseases from cancer to diabetes, coronary heart diseases, and even early death. Walker explains that within the brain, sleep enriches our ability to learn, memorize, and make logical decisions. It recalibrates our emotions, reprograms our immune system, fine-tunes our metabolism, and regulates our appetite. Dreaming pacifies painful, traumatic memories and creates a virtual reality space in which the brain blends past and present knowledge to inspire creativity.
Unfortunately, most people in modern societies are sleep-deprived, and we do not even realize it because we are so used to operating at sub-optimal levels. We must understand and unlock the transformative power of sleep Walker also explores what happens during rapid eye movement (REM) sleep and how common sleep meds affect us and whether can they do long-term damage. Sleep?
REM and NREM Sleep
Every night, our brain switches between 2 types of sleep: REM and NREM sleep.
Non-rapid eye movement (NREM) sleep is characterized by deep, slow brainwaves that are 10x slower than when we are awake. During deep NREM sleep, we experience a sensory blackout, and our cortex (the logical center of the brain) is relaxed. The entire brain is now fully aligned to distill and transfer selected memories from your short-term memory (in your frontal lobes) to your long-term memory (at the back of your brain).
Rapid eye movement (REM) sleep is characterized by faster brainwave activity that is like when you are awake. The brain’s visual, motor, memory, and emotional centers are activated, and pockets of feelings, info, memories, motivations, etc. are combined into a giant movie screen, i.e., your dreams. Your eyes may move rapidly as you dream.
When we are awake, we constantly receive new sensory inputs from the external environment. NREM sleep reinforces and stores those raw data and skills. REM sleep integrates these ingredients by connecting them with one another and with our past experiences and knowledge, to improve our mental model of how the world works, develop new insights, and solve problems innovatively.
In terms of our natural sleeping tendencies, Dr. Walker divides people into two broad groups, or “chronotypes”: morning larks and night owls. Each group operates along different circadian lines, and there is pretty much nothing owls can do to become larks – which is tough luck, because work and school scheduling overwhelmingly favor early risers. Owls are often forced, he writes, “to burn the proverbial candle at both ends. Greater ill health caused by a lack of sleep, therefore, befalls owls, including higher rates of depression, anxiety, diabetes, cancer, heart attack, and stroke.”
The book bears a sobering and vital message, too, about the centrality of sleep to the proper development of young minds. Early school starting times – particularly in the US, where barbarically, almost half of the public high schools start before 7.20 am – are disastrous for the mental health of teenagers. There is serious evidence, Dr. Walker suggests, for viewing lack of sleep as a factor in the onset of depression and anxiety.
Charting cutting-edge scientific breakthroughs, and synthesizing decades of research and clinical practice, Dr. Walker explains how we can harness sleep to improve learning, mood, and energy levels; regulate hormones; prevent cancer, Alzheimer’s, and diabetes; slow the effects of aging; increase longevity; enhance the education and lifespan of our children, and boost the efficiency, success, and productivity of our businesses. He leaves us with an Appendix on the Twelve Tips for Healthy Sleep. Easy to read, informative and a real page-turner, Why We Sleep is a crucial and illuminating book.