When people are chronically angry or scared, constant muscle tension ultimately leads to spasms, back pain, migraine, fibromyalgia, and other forms of chronic pain. They may visit multiple specialists, undergo extensive diagnostic tests, and be prescribed multiple medications, some of which may provide temporary relief but all of which fail to address the underlying issues. Their diagnosis will come to define their reality without ever being identified as a symptom of their attempt to cope with trauma.

— The Body Keeps the Score by Bessel van der Kolk, Bessel A. Van Der Kolk (Page 266)