interesting…im not too sure but i would predict that things that make us happy like music make our bodies release things called endophins which make us happy. the opposite is for things that make us sad.
what makes our bodies release this for different people- ie rock for me or classical for someone else….im afraid i dont know! 🙁
Biologically I’m not sure for the reason of this effect, but I think the speed (tempo) of the music is important – slow songs tend to be quite sad. The notes that make up the music are quite important too, notes that make up the “minor chords” that you often hear in sad pieces make us sad.
Using Green Day as the example (good choice @Adelle and @kiwib99) The notes/chords for Wake me up when September ends are mainly minor chords and it is very slow, this is quite a sad song. But the notes/chords in American Idiot are all major chords and the music is pretty quick so you get a much different feeling from it.