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.”