Why Sleep Is a Biological Powerhouse
Sleep is far from a passive state; it is a period of intense biological activity that keeps every major system running smoothly. During deep sleep, growth hormone peaks, tissues repair, and immune cells multiply, restoring the body after daytime demands. At the same time, the brain’s “glymphatic” network flushes out metabolic waste that can impair cognition if allowed to build up. Researchers note that these nightly maintenance jobs depend on entering the correct sleep stages at the right times, something erratic schedules can easily disrupt.
Large-scale analyses confirm the stakes. A 2017 meta-analysis covering more than 300,000 adults found that sleeping seven to nine hours on a regular schedule was linked to the lowest risk of major cardiovascular events, while both shorter and longer sleep raised that risk significantly. Recent reviews by the American College of Cardiology echo these findings, underscoring sleep’s role in heart, metabolic, and immune health.
