Sleep is one of the most fundamental pillars of human health — yet it is also one of the least understood. Most people know they need sleep, but far fewer realize that how much sleep they need, and the type of sleep they get, changes dramatically over the course of a lifetime. From the 16-hour slumbers of newborns to the fragmented, early-rising sleep patterns of older adults, the biology of sleep is in constant evolution. Understanding these changes has real implications for physical health, cognitive function, emotional wellbeing, and longevity. In this comprehensive guide, we explore how sleep needs change at every stage of life, why these changes happen, and what you can do to optimize your sleep no matter your age. Key Insight: Sleep needs are not fixed. They shift throughout life in response to brain development, hormonal changes, lifestyle factors, and the natural aging process. Why Sleep Needs Change With Age Sleep is regulated by two primary biological systems: the...