[Album] Songs you love to loop

I've been looping songs over and over for hours recently while studying until the wee hours of the morning. I wouldn't be able to do this with just any kind of song, it has to be something that I can hum to, that sounds somewhat trance-inducing or ambient, so that I can easily push it to the back of my mind and concentrate on the notes. However, the music helps me study and it's always there for a listen when I feel like taken a momentary break.

Last night the song I used for this was Mad World by Gary Jules. Tonight it's Frozen by Madonna.

So, am I the only one that likes to loop songs for hours? Does looping drive you crazy, so much so that you MUST have a mix going, or at least, an album (from a single artist)? What tracks do you love to loop?

Jam it back in, in the dark.