Not directly about hypnosis but related as Danny Glover Talks about Epilepsy on the Rosie O’Donnell Show and discusses how when he was a teenager he developed epilepsy.  As a young actor, he was always at risk of having a seizure on stage but "he developed a way of concentrating so that seizures wouldn’t happen. In one case he felt he had kept the seizure at bay until he was safely off the stage" . . . in essence, he taught himself a way of thinking that allowed him to recognize the onset of a possible seizure and then keep it at bay until he was in a safe place.  This is a form of self-induced focused trance or autohypnosis.  Hypnosis can be used to teach the skill to others.