Random note, the work of
QRI, the consciousness-researching institute that I am big fan of, predicts that listening to white noise will move your current level of valence (i.e., how pleasant the current moment is) toward neutrality. So if you feel really bad, it will make it less bad, whereas if you feel good, it will make it less good. This is not a hard law because it's confounded by how your brain reacts to white noise, but it should be a good approximation.
I've tried this once using
mynoise.net and it seemed to work.
In general, music should be inherently pleasant if the sounds are consonant, which explains a pretty major evolutionary riddle. But this is confounded more than noise because emotional effects and boredom both play major roles.