Benson developed the idea of the response, which counters the fight-or-flight response described during the 1920s by Walter Bradford Cannon at the Harvard Medical School.[10] According to Benson more than 60 percent of all visits to healthcare providers are related to stress. Stress causes the "fight or flight" hormones, epinephrine and norepinephrine, to secrete into the bloodstream. This incites or exacerbates a number of conditions. They include hypertension, headaches, insomnia, irritable bowel syndrome and chronic low back pain, as well as heart disease, stroke and cancer.[11]