Help! Need Help ID'ing a popular dance/techno song!
 

I think this is a very popular dance/techno song. I need to know what the name of the song is and who sings it. I'm not sure of the chorus but it's sung by a woman and the chorus ends with the words "without you". Something along the lines of "at night when I sleep, I'm alone...without you". Can anyone help me id this song...they play it on all the dance radio stations and all the chick clothing stores like Abercrombie and Fitch and Holister, etc.