"Brunch" was created to cure hangovers, in 1895 by an English writer named Frank Beringer.
English writer Guy Beringer is credited with first proposing the idea for the meal in his 1895 essay "Brunch: A Plea." In the piece, which was published in Hunter's Weekly, he argues that brunch would serve as the perfect remedy for Sunday morning hangovers and it could be the perfect social gathering at which to share stories of Saturday night's debauchery.
The term brunch has a second origin in the U.S.: many credited it to reporter Frank Ward O'Malley who wrote for the NY newspaper The Sun from 1906 until 1919. It was reportedly based on the typical mid-day eating habits of a newspaper reporter. It seems O'Malley, whom H.L. Mencken called "one of the best reporters America has ever known," had a reputation for phrasemaking, with such gems as, "Life is just one damned thing after another."
Brunch finally took off in America in the 1930s in Chicago; according to Evan Jones, author of "American Food: The Gastronomic Story," it became popular because movie stars, celebrities, and the wealthy would stop for late morning meals while taking transcontinental train rides. After a decline in American churchgoers post-WWII, Jones explained to the NY Times why brunch gripped the nation like a fever: "We like to sleep on Sundays, read the newspapers and loll in bed. After the World War II generation went away from church altogether, Sunday became a day to enjoy doing nothing and brunch just grew like topsy".