John Mayer has launched The Heart and Armor Foundation, a new charity helping war veterans suffering from post-traumatic stress disorder using scientific research.

The American singer/songwriter has been working on the organisation since 2012, and said 'It was going to the wounded warrior barracks that I think changed me forever. It immediately showed me that my notion of what I think (are) the wounds of war are completely wrong. The way in which I was proven wrong was so compelling and fascinating and nuanced'.