In the post-war period, Hemingway suffered from many illnesses: diabetes, severe headaches, high blood pressure and overweight problems. He also abused alcohol.
The deaths of several of his friends, including Gertrude Stein, James Joyce and Scott Fitzgerald, led to depression. He also suffered from other ailments due to several car accidents in which he was involved. His mental state eventually manifested as bipolar disorder. As a result, he was inactive for three years, returning to writing only in 1946. He wrote a novel, “The Garden of Eden,” and began work on a three-part novel describing the fate of various people from three perspectives during World War II (on land, at sea and in the air), but abandoned the project. Eventually, the “sea part” turned into the novel “Islands in the Stream” and the short story “The Old Man and the Sea.”