When I clicked on this article about one song that reduces anxiety and saw that it was not one song but a list I had two thoughts: 1, that I would know, or at least have heard of, two or three and 2, that none of them would be classical. I was wrong on both counts. I hadn't even heard the one by Mozart. So here's that one. As for these being the most anxiety reducing songs... well, I'm sure they didn't test every song that's ever been written so the list is invalid. ;-)
And, yeah, I'll listen to the others on the list sometime.