Hasyim researched the subject of human sleep cycles for half a decade and compiles his findings in this work aimed at improving readers’ quality of restfulness. For those puzzled by why their bodies’ active and lethargic periods occur throughout the day, the author offers explanations and a practical follow-up plan to adjust readers’ circadian rhythm patterns to promote improved productivity and energy. He credits the Lean Six Sigma project, whose core goal is to streamline processes in business, with sparking an effort to maximize his own productivity by making adjustments in his personal awake and sleep routines. The book provides an illuminating overview of how a circadian clock functions and the detrimental effects it can have on the human body when it becomes disrupted. Personally, the writer recalls how much energy he’d had as a boy on a regular schedule living in Indonesia. But when he ventured to college in Singapore, disruptive late-night study assignments and coffee jags entered the picture. Graphs and charts outline the classic synchronous circadian process, including how levels of cortisol and melatonin regulate stress, darkness perception, and sleep drives and how an irregular rhythm can affect metabolism, disease susceptibility, and inflammation. According to one of the many studies Hasyim cites, these factors contribute to causing the sleep deprivation of 51% of American adults. Other chapters stress the integral importance of aerobic and strength training, the monitoring of caloric intake, and the problematic nature of an unregulated “random eating lifestyle.” The author describes this habitual diet in clear detail and in conjunction with healthier alternatives, such as intermittent fasting regimens and fat-loss programs (with particularly good advice for reducing dietary sugars). Finally, he delivers practical guidance on adopting the optimal routine for seeking homeostasis in everyday life. While compelling and encouraging for readers seeking personal improvement, sections of the volume veer away from the circadian subject matter and are overly repetitive. Other areas present facts that are arguably utilitarian and common-sensical (lack of sleep adversely affects mood and productivity; regular exercise promotes increased energy and output). These particulars affect the book’s overall impact but don’t detract from its core message of reminding readers about the importance of regularly reassessing their sleep, exercise, and dietary needs and schedules.