Homeostasis
The body's thermostat. Many dials, each held in a narrow range, each pushed back when it drifts.
Your body keeps a lot of things inside a narrow range: temperature, blood sugar, blood pressure, how much water you carry. When one drifts, nerves and hormones push it back, the way a thermostat turns the heating on when the room cools. Evidence: solid That's homeostasis, and it's textbook physiology. Evidence: solid
The brain runs its own version. Hit the same receptors, the docking points a brain messenger binds to, often enough and the brain turns them down: fewer of them, or less sensitive. The same dose then does less. That's one route to tolerance. Evidence: decent Sleep pressure is another case: the longer you're awake, the harder the body pushes for sleep, and sleep resets it. Evidence: solid
You'll read that homeostasis is the brain balancing dopamine. That's one small corner of it, not what the word means. Evidence: decent
Why it matters
It's why some things you take every day do less than they used to: the body has adjusted to meet them. Evidence: decent If that's a prescribed medicine, talk to your doctor before changing the dose. Push a system hard for long enough and the setting itself can move. That's allostasis. Evidence: decent