Biofeedback utilizes electro-dermal sensors to measure Galvanic Skin Resistance (GSR), also referred to as Electro-Dermal Response (EDR). GSR measures mild electrical impulses on the surface of our skin, which change due to moisture. The moisture of the skin changes according to the body’s degree of stress and/or relaxation. There is a direct relationship between sympathetic nervous activity and emotional arousal. GSR is so sensitive it can even measure fluctuations in emotional states; think about the lie detector, for example. Biofeedback instruments measure muscle activity, skin temperature, electrodermal activity (sweat gland activity), respiration, heart rate, heart rate variability, blood pressure, brain electrical activity and blood flow. There are many types of biofeedback: GSR, EEG, CAT scan, MRI, etc. These technologies are able to capture the bodies’ analog electrical signals and translate those signals into meaningful information through complex algorithmic software that a technician can then decipher. Research shows that biofeedback, alone and in combination with other behavioral therapies, is effective for treating a variety of medical and psychological disorders. Biofeedback is currently used by physicians, nurses, psychologists, counselors, physical therapists, occupational therapists, a host of other professionals and laypeople alike.In 1987, Schneider found that biofeedback is effective in reducing physician visits, medication usage, duration and frequency of hospital stays, as well as reducing mortality and enhancing quality of life.