Nunn was born in Los Angeles, California. She joined Berlin in 1978 and temporarily left the group the following year to pursue an acting career. In 1981, she rejoined the group as the lead vocalist and soon forged her recording career in the band. Her greatest success in Berlin was the top-selling 1986 single "Take My Breath Away", the theme song for the film Top Gun. It reached the no. 1 spot on the Billboard Hot 100. She sang other popular songs with Berlin, including "Sex (I'm A...)", "The Metro", "You Don't Know", "No More Words" and "Masquerade".