Stressed to Death
If an infectious virus doesn’t get you, a stressed-out lifestyle and high-fat diet probably will. Cortisol, the hormone your body releases when under stress, is the strongest immunosuppressant known. In other words, nothing weakens our defenses against disease quite like stress.
Even something as seemingly unimportant as not getting enough sleep can have a dramatic effect on immunity. Sheldon Cohen and his colleagues studied the sleep habits of 153 healthy men and women for two weeks before putting them in quarantine and exposing them to rhinovirus, which causes the common cold. The less an individual slept, the more likely he or she was to come down with a cold. Those who slept less than seven hours per night were three times as likely to get sick.19
If you want to live long, sleep more and eat less. To date, the only demonstrably effective method for prolonging mammalian life is severe caloric reduction. When pathologist Roy Walford fed mice about half of what they wanted to eat, they lived about twice as long—the equivalent of 160 human years. They not only lived longer, but stayed fitter and smarter as well (as judged by—you guessed it—running through mazes). Follow-up studies on insects, dogs, monkeys, and humans have confirmed the benefits of going through life hungry. Intermittent fasting was associated with more than a 40 percent reduction in heart disease risk in a study of 448 people published in the American Journal of Cardiology reporting that “most diseases, including cancer, diabetes and even neurodegenerative illnesses, are forestalled” by caloric reduction.20
These studies lead to the slacker-friendly conclusion that in the ancestral environment, where our predecessors lived hand-to-mouth, a certain amount of dietary inconsistency—perhaps exacerbated by sheer laziness interrupted by regular aerobic exercise—would have been adaptive, even healthy. To put it another way, if you hunt or gather just enough low-fat food to forestall serious hunger pangs, and spend the rest of your time in low-stress activities such as telling stories by the fire, taking extended hammock-embraced naps, and playing with children, you’d be engaged in the optimal lifestyle for human longevity.21
Which brings us back to the eternal question asked by foragers offered the chance to join the “civilized” world and adopt farming: Why? Why work so hard when there are so many mongongo nuts in the world? Why stress over weeding the garden when there are “plenty fish, plenty fruits, and plenty birdies”?
We are here on Earth to fart around, and don’t let anybody tell you any different.
KURT VONNEGUT, JR.
In 1902 the New York Times carried a report headlined “Laziness Germ Discovered.” It seems one Dr. Stiles, a zoologist at the Department of Agriculture, had discovered the germ responsible for “degenerates known as crackers or poor whites” in the “Southern States.” But in fact, our laziness seems less in need of explanation than our frenzied industry.
How many beavers die in dam-construction accidents? Are birds subject to sudden spells of vertigo that send them falling from the sky? How many fish drown to death? Such events are all rather infrequent we’d wager, but the toll exacted upon humans by the chronic stress many consider a normal part of human life is massive.
In Japan, there’s a word for it, 
: death from overwork. Japanese police records indicate that as many as 2,200 Japanese workers committed suicide in 2008 due to overwhelming work conditions, and five times that number died from stress-induced strokes and heart attacks, according to Rengo, a labor union federation. But whether our language contains a handy term for it or not, the devastating effects of chronic stress are not limited to Japan. Heart disease, circulatory problems, digestive disorders, insomnia, depression, sexual dysfunction, and obesity—behind every one of them lurks chronic stress.
If we really did evolve in a Hobbesian ordeal of constant terror and anxiety, if our ancestors’ lives truly were solitary, poor, nasty, brutish, and short, why, then, are we still so vulnerable to stress?22