Cold water swimmers can seem almost evangelical about their post-swimming 'high’ and credit cold swims with curing depression, anxiety and PTSD (as well as cancer, pain and all manner of other afflictions). But what is the evidence to back this up? In fact, it seems that the key might be its effect on our stress responses. In brief, learning to cope with the extreme stress of cold water immersion may fast-track improvements in our ability to cope with all of life’s stresses,