Yoga can blunt harmful effects of stress, from the Harvard Mental Health Letter
Yoga has been studied since the 1970s as a possible treatment for depression and anxiety. How well it works has been hard to say, since until recently, many of the studies evaluating its therapeutic benefits have been small and poorly designed. Now, more rigorous research on yoga suggests that performing this ancient practice may be helpful for both anxiety and depression, reports the April 2009 issue of the Harvard Mental Health Letter.
Yoga appears to blunt the harmful effects of heightened stress by influencing the body's response to stress. This is reflected in slower heart and breathing rates and lower blood pressure, all of which are good for the body. There is also evidence that yoga helps increase heart rate variability, an indicator of the body's flexibility in responding to stress.
For example, in 2008, researchers presented preliminary results from a study of yoga and pain. Their subjects were 12 yoga practitioners, 14 people with fibromyalgia (a condition many researchers consider a stress-related illness that is characterized by hypersensitivity to pain), and 16 healthy volunteers. When the three groups were subjected to external pain (pressure on a thumbnail), the yoga practitioners had the highest pain tolerance and the lowest pain-related brain activity on a brain scan.