Andy Sandness pulled the trigger, and immediately knew he had made a terrible mistake.

It was two days before Christmas in 2006 and Mr Sandness, then 21, had been drinking too much in his rural Wyoming home, and battling depression. He took a rifle out of the cupboard, placed the barrel under his chin, and fired.

Against all odds he survived, telling the arriving police officer, as he cradled him in his arms: “Please, please don’t let me die! I don’t want to die!”