Sudarshan Kriya
Sudarshan Kriya is a "breathing-based technique" that is a core component of the Art of Living courses and "the cornerstone of ... Art of Living Foundation's trauma relief programs".
A number of medical studies on its preparatory practices have been published in international peer-reviewed journals. A range of mental and physical benefits are reported in these studies, including reduced levels of stress (reduced cortisol—the "stress" hormone), improved immune system, relief from anxiety & depression (mild, moderate & severe), increased antioxidant protection, and enhanced brain function (increased mental focus, calmness and recovery from stressful stimuli), among other findings. Persons enrolling for the courses sign a non-disclosure agreement with an undertaking not to teach the learned techniques (including Sudarshan Kriya) to other people without taking Teacher's Training.
According to Bharti Verma, M.D., in The Way of Grace, by David Lucas Burge and Gary Boucherle, "Sudarshan Kriya is not hyperventilation. The process is unlike hyperventilation and seems much more complex in its nature. A person hyperventilating will often experience lightheadedness, blurred vision, muscle spasms of hands and feet, a general feeling of being unwell, fainting and loss of consciousness. In contrast, course participants learning Sudarshan Kriya report a state of deep relaxation while feeling rejuvenated and re-energized. Clearly the experiences of persons practicing Sudarshan Kriya are exactly the opposite of what a hyperventilating exercise would be expected to produce."
Read more about this topic: Ravi Shankar (spiritual Leader)