Hypothesis Predicts Major Failure Point in Chronic Fatigue Syndrome (ME/CFS) - Health Rising They proposed that two factors – sympathetic nervous system hyperactivity and ß2AdR receptor problems – are knocking the blood vessels of people with ME/CFS for a loop. As sympathetic nervous system hyperactivity is giving them a good squeeze, the ß2AdR receptors which are supposed to open them up are getting hammered by the immune system. That leaves the blood vessels unable to deliver the proper amounts of blood to the muscles, brain, organs, etc. The body, of course, can’t have that and so it attempts to fix the situation by releasing vasodilators like bradykinin and prostaglandins. The authors believe these vasodilators spill over into the bloodstream where they, alas, produce fatigue, pain, and flu-like symptoms as well as headaches, gut pain, cognitive and sleep problems.