The inner clock Living in sync with our circadian rhythms

The importance of circadian rhythms has been significantly underappreciated, according to this edifying debut examination. Science journalist Peeples explains that these rhythms are generated by the suprachiasmatic nucleus in the brain, which coordinates a cyclical system of biological processes that, among other functions, decrease body temperature and appetite at night while priming the body to digest and metabolize food during the day. Exploring the surprisingly far-reaching effects of circadian rhythms, Peeples discusses research showing that premature infants "who get daily cycles of light and dark" in the neonatal intensive care unit gain weight faster than those "kept under near constant light or dark," and that an athlete's performance has been found to "vary by 26 percent over the course of the day" due to circadian fluctuations in energy levels. Peeples enlivens the research discussions with original reporting, recounting the discombobulation she felt after spending 10 days in an underground bunker with no awareness of the time, as well as her sleepless nights camping out in Denali, Alaska, where the summer sun barely sets. Peeples includes a few tips on practicing "circadian hygiene" (avoid screens at night and restrict food intake to narrower windows of time that close a few hours before bed), but the focus is largely on the stimulating research showing how circadian rhythms rule people's lives. This enlightens. Agent: Suzanne Gluck, WME. (Sept.)This review has been updated for clarity.

A study of how understanding the natural cycles of time could open up new pathways of health and well-being. One of the most interesting fields attracting new scientific inquiry is chronobiology, which examines timing processes, including periodic cycles, in organisms. Aside from animals and plants, writes science journalist Peeples, there is evidence that the deep-seated natural rhythms of the human body are crucial to our physical and mental health. Unfortunately, as the author shows, they have been severely disrupted by modern lifestyles. Peeples is willing to dive wholeheartedly into her subject, and her research even included a period in an underground bunker to see how it affected her. She tracks through the history of clocks and artificial lighting, which pushed people into unnatural schedules, and she presents new research that has revealed how the parts of the light spectrum have different effects on the human body and mind. Blue light, especially early in the day, can provide an extra burst of energy, while orange is good for winding down after activity. Peeples ranges widely, delving into jet lag, the problems for astronauts and polar scientists in dark environments, and the damaging impact of excessive artificial light on the ecosystem. She also looks at experiments suggesting that the right lighting conditions can help to treat dementia, depression, and other mental illnesses. The importance of circadian rhythms is slowly being recognized, Peeples notes, although the current research needs better systemization. She hopes that chronobiology will eventually become part of the standard health tool kit, but until that time, she offers useful advice. Throw away the alarm clock, get some sunshine every day, and listen to what your body is telling you. Peeples writes with infectious enthusiasm, and the result is an engaging look at a field with huge potential. Copyright (c) Kirkus Reviews, used with permission.