it wasn’t just food and sleep behaviors that followed natural patterns. It was everything. In their diet, their physical movements, and their social interactions, too, our ancestors (and modern-day primitive tribes) stayed in tune with the rhythms of nature—eating different foods in different seasons (and in different places), moving their bodies in different ways at different times based on the demands of their environment, and exploring their world freely at times and staying closer to the safety and familiarity of the tribe at other times. The whole arc of their lives followed a pattern that mirrored the seasons of a year: they were born; they budded into adolescence and bloomed into adulthood; they contributed to the tribe through physical labor and sharing wisdom; they shared their lifetime of accumulated wisdom with the rest of the tribe, planting seeds for a better next generation; and eventually they died, often at a very advanced age. Of course, many of our ancestors died prematurely due to infant mortality, accidents, infection, or acts of violence—I’m not trying to paint a romanticized picture. But in general, their lives were rhythmic and circular, even leisurely, not because they wished them so, but because that’s the way it was for people so immediately dependent on and immersed in nature. Research shows us that contemporary hunter-gatherers actually have considerably more leisure time than we do in our modern, convenience-laden, productivity-oriented society.4
My family, of course, didn’t have to live so close to nature. And in 1983, when I turned five, we pretty much stopped doing it. We closed up our cabin, sold our land, and moved closer to a small town called Brockville. Although we still lived in a rural setting (on an apple orchard outside of town), we adopted a more conventional way of life. Our new house had electricity and running water, and I attended a small school with other kids from town. By and large, I left behind my intimate connection with nature and those seasonal rhythms. I finished elementary and high school, attended university in the United States, earned a degree in anatomy and physiology and a graduate degree in physical therapy, and lived in a number of places in the country. I was always attentive to healthy living—I ate well (conventionally speaking), played competitive volleyball, climbed mountains, and rode mountain bikes. But I didn’t think much about natural living per se, and my own personal habits were as artificial and disconnected from natural rhythms as most people’s.
That began to change in 2007, when my father passed away prematurely of pancreatic cancer. Deeply impacted by his death, I began to look at my life in new ways, and to question many of my lifestyle choices. I was a healthy twentysomething, working in a profession that I enjoyed. I was lean and fit, eating in ways that most people would consider healthy, and blessed with a strong network of friends. Anybody who met me would have considered me the very picture of health. But the reality was more complicated. Deep down, I sensed that not all was right. I was working too hard and obviously not getting enough sleep. I had some adult acne, and chronic inflammation in my left shoulder. I felt stressed and overstimulated, and while I thought I was more or less “happy,” I also felt adrift, lacking a deeper sense of peace and rootedness. I had lots of friends, but still felt pretty isolated. What was I really doing with my life?
Always intellectually curious, I read a number of books and research papers that cued me in to our evolutionary past and its enormous relevance for our present-day health. I became especially fascinated with the idea of physiological rhythms and began chasing down anything I could find in the scientific literature on that topic. There was quite a lot of research out there—hundreds of published papers that I eventually read and analyzed. What I discovered fascinated me.
Biologically, we’re walking around in bodies that are well adapted to gathering seasonal plants and hunting ancient animals, sleeping deeply during the hours of darkness, and living and working together as a tight-knit tribe—bodies, in other words, that operate on nature’s clock and expect cyclical variations in our key lifestyle behaviors. All of our physiological systems and even individual cells have internal mechanisms that align us with nature’s oscillations between on and off, active and resting, open and closed, expansion and contraction. More tangibly, rhythmic patterns are encoded on the molecular level in the DNA of (almost) all living things, even single-cell organisms that lack a nervous system and the ability to communicate in complex ways.5 Rhythms are perceptible everywhere. We are not on/off creatures. We fluctuate and flow. We expand and contract.
As I came to realize, our bodies are at odds with everyday conditions and schedules in the modern world, which tend to be linear and binary rather than cyclical and gradual. Today, alarm clocks and artificial lights give us control over how we structure our days, so we can stay up far into the night and wake up long before (or long after) sunrise. Modern agriculture and global commerce allow us to eat whatever we want, no matter the time of year. Whereas our ancestors had to walk, run, climb, and carry things during the daylight hours in order to survive, we can live sedentary lives and still put food on the table and a roof over our heads. Nor are we dependent, as our ancestors were, on a close-knit tribe in order to thrive. Many of us live atomized lives, separated from our families and friends by large distances. Our days rarely echo the ancient patterns of social interaction—broad contact with others during the daytime, retreating into a smaller, more intimate circle at night. Instead, some of us feel socially isolated for much of the day and night. We keep ourselves so busy during our waking hours and distracted just before and after sleep that we don’t allow ourselves the kinds of opportunities our ancestors did to reconnect with the person who matters most—ourselves. The nonstop external stimulation displaces the quietude and openness necessary for us to know and deeply care for our own inner worlds.
The science I was reading during those early years suggested that modernity’s deviation from natural rhythms had exacted a huge, and largely unremarked upon, toll on human health. Since we don’t eat seasonally and locally, and we rely on shelf-stable processed foods, we don’t get the nutrition we need—a variable mix of protein, fat, carbohydrates, and micronutrients. We often wind up eating too little complete protein and too much refined carbohydrate and sugar. Over time, this unbalanced, nutrient-poor diet causes our stress-induced cravings for sugar and carbohydrates to intensify. We never feel that we have eaten enough, and no matter how much we eat, we still want more. We wind up sick with chronic illnesses like cancer, heart disease, and obesity.
The shift from traditional, whole-food diets to modern, processed foods is a central cause of these “diseases of civilization.” But it’s not the only cause. We also don’t get the sleep we need throughout the year, leaving ourselves vulnerable to addiction to caffeine or alcohol, which we consume in order to compensate—to wake us up or calm us down. Inadequate sleep also leaves us more vulnerable to insomnia, mental illness like anxiety and depression, heart disease, cancer, and other chronic diseases. And it’s not just the sleep itself. As I explain in the following pages, it’s also the amount of time we spend in darkness or near-darkness that directly impacts our health.
We also don’t move our bodies in tune with the rhythms of nature as they’re evolved to do, so we either stay sedentary and develop related chronic diseases, or we cajole ourselves into exercising in highly contrived ways, leaving us vulnerable to injuries or other stress-related problems. While the modern features of low-nutrient processed food, sedentary and overstimulating lifestyles, and chronically disrupted circadian rhythms are most certainly problematic, there is yet another direct influence on our overall health and quality of life that is emerging as massively impactful: loneliness and social isolation. We feel disconnected from others, so we turn to social media as a panacea for loneliness and as a facsimile for deep companionship—which makes us feel even more disconnected. We fall prey to depression, anxiety, substance abuse, and worse. We lose touch with our four primary lifestyle variables—sleep, eat, move, and connect—that are essential to living well. In contrast to our hunter-gatherer ancestors, who slept, ate, moved, and connected according to annual seasonal changes, today we sleep poorly and erratically, move infrequently or excessively, eat processed, nutrient-poor, and inflammatory foods, and connect artificially while remaining essentially isolated. This creates a closed loop, a self-perpetuating cycle, because the less we exercise or the more stress we experience or the more poorly we sleep, the more we turn to “comforting” processed foods and stimulating media that in turn further disrupt our sleep or contribute