Homeostasis refers to bringing balance or equilibrium to a system; it’s in charge of bringing rest to a system that is not at rest. The longer you go without sleep, the more powerful the drive to sleep and get your system back in balance. In the same way, the longer you read this compelling chapter and ignore the urge you have to urinate, the stronger the drive to pee will be until it’s overwhelming and you can’t concentrate on anything you’re reading—again, the drive to balance. A chemical called adenosine mediates the homeostatic system of sleep.
