Autonomic and endocrine functions and music
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Music has been used for therapeutic purposes for many years. However, the precise mechanisms by which music may imporve human well being (especially in terms of stress)still remain unclear. There has been no definition of stress that everyone accepts. The most common one defines stress as "physical, mental, or emotional strain or tension". But stress is not always harmful. In contrast it can also result in increased productivity. This kind of good stress is also called eustress. In general the hypothalamic-pituitary-adrenal axis and the stimulation of the sympathetic nervous system and epinephrine secretion play an important role in the physiological and biochemical factors of negative stress. The sympathetic system becomes more active during times of stress. It mediates the neuronal and hormonal stress response commonly known as the fight-or-flight response. Furthermore it accelerates activity of the heart and is involvoled in the secretion of epinephrine and norepinephrine from the kidneys. In a study by Conrad et al. (2007) 10 critically ill patients were studied to identify mechanisms of music-induced relaxation using slow movement of Mozart's piano sonatas. The results showed that blood pressure increased in the control group, but decreased in the music group. Additionally patients of the music group didn't require any further sedations by propofal. Moreover, levels of growth hormone remained unchanged in controls, but rose after music therpay by 60%. IL-6 remained unchanged in contrals, but decreased significantly after music therapy by 83%. Furthermore, epinephrine remained unchanged in controls, but decreased significantly after music therapy by 55%. Interleukin-6 stimulates the immune response to burns or other tissue damage leading to inflammation. In the serum of healthy subjects the sIL-6-receptor occurs in a concentration of 25-35 ng/ml. For instance, this level increases significantly with various illnesses like HIV and leukemia. IL-6 also increases the secretion of cortisone and epinephrine. This study demonstates that the effect of music on pituitary growth hormone release may be central to the sedative actions of music. Furthermore there is an inverse correlation between growth hormone releasing factor availability and IL-6 release from peripheral blood cells. That implies that music implication on IL-6 availability may then be the crucial pathway of stress reduction. In another study by Bernardi et al. (2005) the effect of 2 minute periods presentation of different kinds of music on cardivascular, cerebrovascular, and respiratory systems were studied. They observed that the faster the tempi the higher ventilation, breathing rate, blood flow velocity, systolic and diastolic blood pressures and heart rate. It is worth mentioning that these effects appeared to depend on the speed of the music rather than on the style. But the most interesting finding ist that "listening" to a 2 minute rest was characterized by the lowest rates of these factors. Hence, passive listening to music accelerates breathing and increases blood pressure and heart rate proportional to the tempo and perhaps to the complexity of the rhythm. In general, an arousal effect proportional to the speed of music was observed, where slower rhythm induced relaxation. Especially a pause may be crucially important in determining some of the relaxing effects of music. Thise findings imply an alternative technique of relaxation without the active participation of the subject, that in turn could be very helpful in comatose patients. An appropriate selection of music and pauses can be used to induce relaxation and reduce sympathetic activity that may be potentially useful in the management of cardiovascular diseases.