DURHAM, N.C. -- Touch a hot stove, and your fingers will recoil in pain because your skin carries tiny temperature sensors that detect heat and send a message to your brain saying, "Ouch! That's hot! Let go!"
The pain is real and it serves a purpose, otherwise we'd suffer greater injury. But for many people with chronic pain, that signal keeps getting sent for months or years, even when there is no clear cause.