"You Light Up My Life" is a ballad written by Joseph Brooks, and originally recorded by Kasey Cisyk for the soundtrack album to the 1977 film of the same title. The song was lip synced in the film by its lead actress, Didi Conn. The best-known cover version of the song is a cover by Debby Boone, the daughter of singer Pat Boone. It held the No. 1 position on the Billboard Hot 100 chart for ten consecutive weeks in 1977 and topped Record World magazine's Top 100 Singles Chart for a record 13 weeks.