by Jennifer B. PhD, Baltimore, MD.
Biofeedback is a form of alternative medicine that involves measuring a subject's bodily processes such as blood pressure, heart rate, skin temperature, galvanic skin response (sweating), and muscle tension and conveying such information to him or her in real-time in order to raise his or her awareness and conscious control of the related physiological activities.
Types of biofeedback instrumentation
An Electromyogram is the most common form of biofeedback measurement. An EMG uses electrodes or other types of sensors to measure muscle tension. By the EMG alerting you to muscle tension, you can learn to recognize the feeling early on and try to control the tension right away. EMG is mainly used as a relaxation technique to help ease tension in those muscles involved in backaches, headaches, neck pain and grinding your teeth (bruxism). An EMG may be used to treat some illnesses in which the symptoms tend to worsen under stress, such as asthma and ulcers.
Peripheral skin temperature
Sensors attached to your fingers or feet measure your skin temperature. Because body temperature often drops when a person experiences stress, a low reading can prompt you to begin relaxation techniques. Temperature biofeedback can help treat certain circulatory disorders, such as Raynaud's disease, or reduce the frequency of migraines. The physiological process behind the temperature drop associated with the stress response is quite simply vasoconstriction (blood vessels narrowed by the smooth musculature in their walls)
Galvanic skin response training
With Galvanic skin response training, sensors measure the activity of your sweat glands and the amount of perspiration on your skin alerting you to anxiety. This information can be useful in treating emotional disorders such as phobias, anxiety and stuttering. This is the method most commonly used by lie detector machines. It is the most popular form of biofeedback, with over 500,000 hand-held GSR2 units having been purchased by consumers since the early '70s; it is also one of the biofeedback methods used by Calmlink and the video game series Journey to Wild Divine. Galvanic Skin Response meters are also now gaining popularity in hypnotherapy and psychotherapy practice where subtle physiological changes indicating emotional arousal can be more easily detected than by observation alone.
An EEG monitors the activity of brain waves linked to different mental states, such as wakefulness, relaxation, calmness, light sleep and deep sleep. This is the least common of the methods, mostly due to the cost and availability of an EEG machine.
Voluntary control of the autonomic nervous system had been considered impossible, only controlled by conditioning. Other threads of inquiry leading to "biofeedback" emerged from clinical attempts to use mind/body self-regulation techniques in healthcare.
Clinicians reply on complicated biofeedback machines in somewhat the same way that you rely on your scale or thermometer. Their machines can detect a person's internal bodily functions with far greater sensitivity and precision than a person can alone. This information may be valuable. Both patients and therapists use it to gauge and direct the progress of treatment.
For patients, the biofeedback machine acts as a kind of sixth sense which allows them to "see" or "hear" activity inside their bodies. One commonly used type of machine, for example, picks up electrical signals in the muscles. It translates these signals into a form that patients can detect: It triggers a flashing light bulb, perhaps, or activates a beeper every time muscles grow more tense. If patients want to relax tense muscles, they try to slow down the flashing or beeping.
Like a pitcher learning to throw a ball across a home plate, the biofeedback trainee, in an attempt to improve a skill, monitors the performance. When a pitch is off the mark, the ballplayer adjusts the delivery so that he performs better the next time he tries. When the light flashes or the beeper beeps too often, the biofeedback trainee makes internal adjustments which alter the signals. The biofeedback therapist acts as a coach, standing at the sidelines setting goals and limits on what to expect and giving hints on how to improve performance.
People with HIV sometimes combine visualization with biofeedback to get in touch with their bodies, a way to treat themselves positively, and meditation.