My take on this is that there's a little part of my brain that wants (nay, needs) to be distracted so that I can actually get on with working. It can be a TV in the next room, a movie or video game soundtrack pumping in my headphones, or a coffee shop full of people and white noise. If that part of my brain isn't distracted by these things, it interrupts the main thread and I find myself lost in HN, my feeds, the BBC website… anywhere but my work.