Personally i believe your mood affects the music you listen to. For instance if you have just broken up with your boyfriend you wont want to listen to happy up-beat music because you wont feel like dancing around. Just the same if you were happy you want want to listen to sad depressing music. But there are some one sided affects on the whole situation. Because if you are happy and you listen to sad depressing music you might become sad but if you are sad and you listen to up beat music your mood wont change and you end up grumpy and snapping at people because somebody is happy and you become jealous of everybody elses happiness. So ultimately i believe that mood is first in determining your music choices and behavior.!!!!!!