" In your body, the gradually accumulating burden of reactive experiences is called allostatic load, which increases inflammation, weakens your immune system, and wears on your cardiovascular system. In your brain, allostatic load causes neurons to atrophy in the prefrontal cortex, the center of top-down executive control; in the hippocampus, the center of learning and memory; and in other regions. It impairs myelination, the insulating of neural fibers to speed along their signals, which can weaken the connectivity between different regions of your brain, so they don’t work together as well as they should. "

― Rick Hanson , Hardwiring Happiness: The New Brain Science of Contentment, Calm, and Confidence