I'll share here a quote from Cal Newport's Digital Minimalism, which I mentioned in another comment. Our brain's so-called default network, the one that fires "when thinking about nothing, […] seems to be connected to social cognition."

> Because the subject wasn’t engaged in a specific task, it was easy for researchers to think of the default network as something that comes on when you’re thinking about nothing. A little self-reflection, however, makes clear that our brains are hardly ever actually thinking about nothing. Even without a specific task, they tend to remain highly active, with thoughts and ideas flitting by in an ongoing noisy chatter. On further self-reflection, Lieberman realized that this background hum of activity tends to focus on a small number of targets: thoughts about “other people, yourself, or both.” The default network, in other words, seems to be connected to social cognition.