We have clear evidence from heart rate variability studies that people with chronic pain are in the fight, flight or freeze autonomic nervous system state (sympathetic state) and have a hard time activating and staying in the rest, digest and relax autonomic nervous system state (parasympathetic). This is one the big keys to getting out of chronic pain- the ability to relax and stay relaxed as your resting state.
So many people are living in the fight or flight or freeze state throughout the day and this contributes to a whole host of issues, some of which as the study mentions are diabetes and rheumatoid arthritis. One of the best ways I teach to stay in the parasympathetic state is to learn to mindfully relax both the body and mind so that the body softens (less bracing and muscle guarding) and to slow the brain wave activity so that we are not constantly living in our heads all time consumed by thoughts. Learning to relax mind and body is a conscious practice, but one that I have seen very effective in relieving chronic pain. This review study supports this approach.
“Pooled results from the meta-analyses reflected a consistent, moderate-to-large effect of decreased high-frequency HRV in chronic pain, implicating a decrease in parasympathetic activation.”