 Interscope Records serviced the song to US contemporary hit radio on May 8, 2007, as the album's third single; elsewhere it was released in June 2007.Described as one of her favorite songs on the album, Stefani began writing the song while pregnant and finished with Kanal, drawing inspiration from Roberta Flack and Billy Idol records.A 1980s-inspired mid-tempo synthpop ballad, "4 in the Morning" features a light keyboard during its intro through its break, a guitar, synthetic strings and a slick sheen.