That happens to me occasionally when I work really hard on something. A couple of years ago I was doing math almost constantly for a few weeks, and by the end I

That happens to me occasionally when I work really hard on something. A couple of years ago I was doing math almost constantly for a few weeks, and by the end I was dreaming about problems every night. I felt like I was going insane, since after I started having those dreams I was thinking about math almost continually. Dreaming about something usually indicates that I'm about to get a lot better at it, though, so it's kind of nice.