Pity the beleaguered 21st-century brain. What we put it through. Once upon a time there was an off-switch. It went by various names: night, closing time, sabbath, vacation. An ad jingle popular in the late 1980s - so popular we'd say today it "went viral," though "viral" then had a meaning as remote from popularity as now is from then - was uncannily prescient. It went, "Can you fight 24 hours? Businessman, businessman, Japanese businessman!" The featured product was an energy drink claiming to be fuel for endless, happy, profitable, restless, insatiable struggle.

The fitness magazine Tarzan (Aug 28) lays this snippet of folk history before us in its feature on rest. The ad, amusing and fantastic then, sounds all too grimly real now. Tarzan's feature is titled "Rest Techniques." Can't we rest without "techniques"? We can't, it seems. Once we could. When the ad appeared the virtual revolution was just beneath the surface, unseen, soon to burst forth. The 24-hour work-and-play day it gave us, or imposed on us, was already solidly entrenched when the smartphone went viral, circa 2010. That sealed the last escape hatches. Rest was sacrificed on the altar of... what? Ceaselessness, perhaps. Was it worth it?

Maybe it was. But the brain is not ceaseless. Nor is the rest of the body, as we're learning the hard way. Eighty-two percent of Japanese feel chronically tired, says the Japan Recovery Association (JRA) based on a nationwide survey of 10,000 respondents. Tarzan's "techniques," then, are timely. We'd better consider them, before we exhaust ourselves into nervous and physical wreckage.

Our basic physical needs are three-fold, but only two get their due, writes JRA director Dr Hideki Katano. Nourishment, exercise and rest. The slighted one, of course, is rest. Japanese culture has made a disgrace of succumbing to fatigue. "Fight on! Fight on!" Or play on. Play has dignity, rest none.

The health and labor ministry has acknowledged the problem - halfheartedly, says Katano. Its two solutions - shorter working hours and more sleep - are fine as far as they go but go almost nowhere: "Even if we rest longer, if we rest wrongly we won't get rested."

Resting rightly requires knowledge of such arcana as, for example: "Medically speaking," writes somnologist (sleep specialist) Osami Kajimoto, "fatigue, like fever or pain, is a warning. Whatever you're doing - work, exercise - stop," on pain of potential bodily and mental harm.

The subject under discussion is "brain fatigue," rarely recognized as such. Other organs too get tired - the stomach, for instance, but the symptoms it delivers are clear, though too often unheeded. When the stomach cries out to us, "No more! Please!" it's not failure to understand that keeps us eating regardless. Did you know - as internist Kotaro Nakada explains - that aging dries the digestive juices? Without, apparently, diminishing the appetite, so the fact must be kept in mind and a measure of discipline imposed, a bitter but important truth. Meat, Nakada warns, poses particular problems for the aging digestive system.

The body's relationship with food is an ambiguous one. You'd think what tastes good would be good. Why should it be otherwise? But everyone knows it is otherwise, little good though the knowledge does us if the pleasures of the festal board overwhelm it. The brain, though, is an organ in a class by itself. It's the one organ we have what we might call a personal relationship with. It talks to us, we talk to it. It listens to us, we listen to it. Other organs poke and prod us. The brain reasons with us.

Kajimoto raises a familiar example: you're driving along a straight, flat road, or performing a repetitive office task. Concentration sags, the mind numbs. That's the brain saying, "I'm bored, my cells are oxidizing, pull over, take a break." But at the end of that long straight road is an appointment that can't wait. The repetitive task is to meet an urgent deadline. What then, when society's needs conflict with the brain's? It's a problem.

Here's another: The world is overheating, whether the brain likes it or not. It doesn't. The brain, writes Kajimoto, consumes 20 percent of the body's energy and is ultra-sensitive to heat. Its ideal temperature is 22 to 24 degrees. Well, breathe rhythmically through the nose. It helps a little, like an air conditioner turned down low. The brain will reward you with heightened performance. How much heightened, one wonders, with outside temperatures soaring into the upper 30s and beyond? It's the brain that gave us the capacity to wreck the climate. Maybe it'll give us the capacity to cope with the consequences, even (a long shot) reverse them. It's something to hope for, and hope, we know, is medicinal in its own right.

In the meantime, being a knowing organ, our brain knows everything we know about all the pressures we labor under - social, economic, climatological, psychological too no doubt. It understands. It'll compromise -- up to a point. Learn that point and respect it is what Tarzan's "techniques" amount to.

The brain, broadly speaking, has two regions, the cerebrum and the cerebellum, the former the seat of consciousness, thought and feeling, the latter of motor functions. The cerebrum is similarly roughly divisible, into two parts: neocortex (thought) and limbic system (feeling). Mammals, whose brains somewhat resemble ours, have it easy. Their neocortex was spared the hyper-development that puts ours in perpetual and jarring conflict with the limbic system, causing us so much distress and weariness. The beasts are free to act on their feelings as they occur. They can't write constitutions but their freedom of expression far exceeds ours. It's our neocortex that keeps us in check.

Imagine the office otherwise, writes neurologist Satoshi Yoshino - angry, frustrated, balked employees roaring, wailing, gnashing their teeth and throwing things. The neocortex got us out of the jungle, so much the better as far as that goes, but the self-stifling it demands of us in return takes is toll - whose name is mental fatigue. Can't I throw just one ashtray, vent one howl? No, and that's that.

But there are alternatives, Yoshino reassures us. He proposes a few. One is so delightfully Zen-like it tops our list, though not his: "Make time for not thinking." Turn the brain off. Easier said than done. The modern hyper stimulated brain is like an child refusing to be put to bed. Yoshino's prescription: a run, a swim, anything physically vigorous enough to short-circuit logical thinking. Walking, which sounds good, does not seem to qualify, being too relaxed. (On the other hand, what great thoughts come to one as one walks!)

Ditch, he says, "cost performance." His case in point seems strange. He cites with approval the lavish expenditures of fans in support and pursuit of their celebrity idols. What's good about that? Its brash defiance of common sense and, it may be argued, every other kind of sense as well. Just the temporary short-circuiting the cerebral cortex needs from time to time.

Space permits perhaps one final item from Yoshino's list. "Escape," he says, "the rigors of 'compliance.' Nowadays," he explains, "when every careless utterance spoken in the workplace is potential 'harassment' of some kind, you need to watch every word."

Harassment is brutal, compliance with anti-harassment norms, often hastily composed and still in their experimental stage, constricting. Yield to them during the day, fling them off the day's work done. Spend the evening - as many evenings as possible - with an old friend, a new friend, a lover, someone who means nothing to you and to whom you mean nothing, anybody at all with whom you can let your guard down and just - that rarest of luxuries - be your unconstricted, uncensored, unedited, warty, blundering, gaff-prone self for a few hours.

May you find rest, weary soul.