From the book, "Why We Sleep" by Matthew Walker, a professor of neuroscience and psychology. Comprehensively explores the critical importance of sleep for both physical and mental well-being, arguing that it is the "foundation" of health, surpassing diet and exercise. The author details the detrimental consequences of sleep deprivation on virtually every major system, including the immune system, cardiovascular health, emotional regulation, and cognitive functions like memory and learning. Furthermore, the book addresses various aspects of sleep science, explaining the circadian rhythm and different stages of sleep (NREM and REM), and critiques modern societal habits—such as early school start times and the use of alcohol and caffeine—that impede healthy rest. Finally, the book concludes with a discussion of solutions, including the effectiveness of Cognitive Behavioral Therapy for Insomnia (CBT-I) and a call for organizational changes in workplaces and healthcare to prioritize sufficient sleep.