Your Body Clock and Its Roles in Good Health and Sleep

From a Wall Street Journal review by A. Roger Ekirch of the book by Russell Foster titled “Life Time: Your Body Clock and Its Essential Roles in Good Health and Sleep”:

As Russell Foster, the director of the Sleep and Circadian Neuroscience Institute at Oxford, explains in “Life Time: Your Body Clock and Its Essential Roles in Good Health and Sleep,” we are “not able to do what we want at whatever time we choose. Our biology is governed by a 24-hour biological clock that advises us when it is the best time to sleep, eat, think, and undertake a myriad of other essential tasks.”

This “circadian pacemaker,” which controls the flow of hormones and other bodily processes with daily rhythms, is located in the suprachiasmatic nuclei, a tiny bundle of some 50,000 neurons—the size of a grain of rice—located in the hypothalamus at the base of the brain. To keep us in sync with the natural world, the pacemaker is reset, or “entrained,” daily, most importantly by the light received via photoreceptors in our eyes. “Without this precise regulation by an internal clock,” Mr. Foster writes, “our entire biology would be in chaos.”

If that bracing prospect does not grab one’s attention, there is no shortage of compelling insights in this astonishing book. More than a few of these take the medical profession to task. According to a study of high-risk cardiovascular surgery, the death of patients “was significantly reduced with afternoon versus morning surgery,” due to the extended shifts of weary surgeons. In the U.S., as many as 98,000 deaths annually are attributed to medical errors, of which a principal cause is insufficient sleep among practitioners. To make matters worse, the efficacy of more than 100 drugs depends, in part, on when they are ingested, yet few physicians and hospitals take timing into account. “In general,” the author laments, “patients receive anti-cancer drugs at times that are convenient for the staff administering the drugs. Clinical capacity and cost are key issues, and there are important logistical issues in the delivery of toxic drugs in busy hospitals.” Ignorance is a contributing factor, given that circadian neuroscience and sleep health are rarely taught in medical schools.

Mr. Foster also discusses optimal times for eating, sex, travel and work. But for all of its practical advice, to label “Life Time” a self-help guide would understate its far-reaching implications. What gives the book special force is the author’s prominence on the front lines of circadian neuroscience and sleep medicine, not to mention the breadth and depth of the research, which he is as excited to share as if he were recounting a gripping mystery. Inviting readers into his laboratory, he explains the status of fresh findings—those of other scientists as well as his own—in addition to past breakthroughs that are already having an impact. If at times the book’s subject matter is complex, particularly for anyone whose last exposure to biology was in high school, the clarity of Mr. Foster’s spirited prose is welcome, as are his wry humor and contagious sense of wonder.

The most critical circadian rhythm, and the book’s primary focus, is the sleep/wake cycle, which too often falls out of alignment in our high-wattage, 24/7 world. A week ago I saw a billboard: “It’s 6 a.m. What’s your realtor doing for you?” Contrary to the belief of an 18th-century Scottish scholar that “sleep can scarce be justly reckoned part of our life,” it occupies some 36% of our lives. It is during sleep that memories are consolidated in the brain, toxins removed and information processed. “Sleeping on a problem,” the author states, “really can help the human brain find new solutions to difficult problems.” Conversely, inadequate sleep has been directly connected to such maladies as heart disease, stroke, diabetes, mental disorders and cancer, as well as automobile accidents—between the hours of 4 a.m. and 6 a.m., our cognitive abilities are worse than if we were legally drunk.

Mr. Foster takes pains to probe the dangers of night-shift work, which disrupt the circadian rhythms of a large proportion of the population. Amid a slew of disquieting consequences, several different varieties of cancer have been linked to working nights. Significantly, he reports, the International Agency for Research on Cancer has classified night-shift work as “a probable carcinogen.” “I bet,” the author notes, “that wasn’t in the job description.”

Inspired by the past success of antismoking campaigns, he suggests that schools, with equal fervor, educate young people about the dangers of sleep deprivation. This would require dispelling boasts by public figures about the brevity of their own slumber. Thomas Edison famously disparaged sleep as a “heritage from our cave days,” yet in truth he kept a cot at his Menlo Park laboratory for napping during the day.

With education, Mr. Foster hopes, “the machismo culture of long hours and little sleep will go the way of the ashtray.” If the success of his proposal appears daunting, the message is disarmingly simple. “What we do when really matters.”

A. Roger Ekirch is a professor of history at Virginia Tech and the author of “At Day’s Close: Night in Times Past.”

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