The category is a song that makes you fall asleep.
I chose Pink Floyd's Comfortably Numb, not because it's pleasant and relaxing but because it is BORING. I almost chose it as the song I hate the most, but there it is as the most boring.
So if you know the song, you don't have to listen, and if you don't just listen a little and if you feel the urge to stop ASAP, I won't blame you!!