Pain is our body's alarm system—but what happens when that alarm keeps ringing long after the danger has passed? For decades, pain has been understood as a symptom of physical injury or structural damage. But recent advances in neuroscience are challenging this long-held belief, especially when it comes to chronic pain—pain that lingers for months or even years.

The nervous system is the control center for your body. It interprets the things your body senses, and it sends information to the...