Nightmare - Disco / modern

Hey guys,
I'm looking for a song I heard in disco this weekend in London! Actually I didn't hear it for the first time, should be kinda known!
Sounds like the singer/singers is/are female, I can't remember all of the lyrics, but the word "nightmare" appears very often in this song! It's hard to understand more than this word.
The right categories should be dance, house, mainstream
I don't think that this song is older than one year.
Hope you can help me :-)

Please help me! Need to know the name of this song!!