Tayo suffered from post traumatic stress disorder which is a mental disorder that causes flashbacks and paranoia from a traumatic event, in his situation he was suffering from the effects of the war. His condition now days is treated with medication. Due to him not being treated outside of the hospital when he was released he didn't have many strategies for coping with the effects from the disorder. His strategies where staying coped up and reliving the event over in his head. Once he embarked on his journey of the ceremony he was helped with the nontraditional medicine of the native American ways.
At first he turned to alcohol, and then with the help of the Navajo shaman he learned to accept and deal with his problems.