Need title of this catchy pop/dance song by female, possibly british, possibly 2000's

I hear this sometimes on the radio and I just love it. I remember when it was popular I always turned the radio up, but I never really caught the name, artist, or very many lyrics. The melody just grabbed me. The artist sounds like she could be british, but maybe not, and the song sounds 2000-ish, MAYBE late 90's. Some of the lyrics are:

Oh when the lights do down......

I'll be calling, calling, calling....I'll be calling, calling, calling...


AND, it could be "Oh when the lights go out", not "go down".

AND it could be "I'll be falling, falling, falling....", not "calling".

Help!

Thank you!
Darrien

Ellie Goulding

Lights