"You Light Up My Life" is a ballad written by Joseph "Joe" Brooks, and originally recorded by Kasey Cisyk for the soundtrack album to the 1977 film of the same name. The song was lip synched in the film by its lead actress, Didi Conn. The best-known version of the song is a cover by Debby Boone, the daughter of singer Pat Boone, which held the #1 position on the Billboard Hot 100 chart for ten consecutive weeks in 1977, setting a new record for that time.