Gretchen Reynolds, Phys Ed: Why Exercise Makes You Less Anxious, New York Times, November 18, 2009; available at http://well.blogs.nytimes.com/2009/11/18/phys-ed-why-exercise-makes-you-less-anxious/
A recent experiment presented its results at the annual meeting of the Society for Neuroscience in Chicago. The scientists found that running causes neurons to respond differently to stress, which has the effect of decreasing anxiety. The scientists allowed one group of rats to run and another set was not allowed to. Afterward, they put the rats into cold water -which they typically do not like – and then took them out to examine their brains. The scientists found that the cells in the running rats were buffered from exposure to the stressful experience and seemed, at least biochemically, calm. There have been several studies that have begun to research the positive effects of exercise on the brain, but overall it has been found to have a calming and possibly even euphoric effect on the brain. However, scientists agree that such affects take time and cannot be observed overnight.