I had a nightmare the night before last, which has stuck with me a little bit, because I finally understand something about it. It was one of those situations where there's some sort of mathematics exam, but with some really complicated not-quite-math-like problems like you'd find in puzzle hunt games.
(As a side theme, there was a bit of the old social anxiety going on for part of it, but it's changed somewhat. There was math exam for a while (presumably in the morning), and then lunch. And at lunch, we all got food and then sat down at medium-sized tables in groups. I was one of the last to get food, and the few tables with people I felt comfortable with were full, and all the rest would involve some sort of awkward interaction. It's been many years since I recall this sort of dream, so a lot has changed in my life, but previously I would have felt a lot of internal angst about how to deal with this. But now, the change was that my reaction was frustration that I'd have to deal with other people's awkwardness, when all I really wanted was to sit down and do my own thing and ignore everyone around me. Which is a nice change from feeling angst myself, if still not the courteous dream-behavior that I'd like myself to have.)
The main part, though, is that I figured out what the driving force behind that type of nightmare is for me. You know how "they say" that the human brain can hold 7 things in short term memory, plus or minus 2 things? In this dream, I could hold about 0.5 things in short term memory. I would be focused on a task, and would have a dim idea of why I was doing it or what I should do next, but never really both. Sometimes I would get done with the task and then I'd struggle to recreate the steps of what needed to happen next, from scratch. (But it's always hard because everything around me was filled with people doing stuff and moving things and if they'd all just be still and stop picking up the stuff I was using, I might have a chance at getting something done!) Other times, I'd be distracted by something while in the middle of the task, and would then forget something very important about the task, like why I was doing it or how it fit in to the bigger picture or how to actually do it in the first place. So I'd spend much of the dream panicking about not having any real comprehension of what was going on around me, and aware that any success I had was just blind luck, and possibly even something that only seemed to be success.
I've had these dreams before, but I never really understood the mechanic until now. And I can understand why I'd get one of these dreams, now, too: being sick really impairs my mental functioning, and one of the main ways is by making it much harder to concentrate on things. It's like my mental sharpness returns more quickly than my focus, and so there's this unsettling period of time where I feel up to tasks and yet am aware that I'm not making much progress on them because of the distractability.
So, knowing is half the battle, but what happens when you forget because oooh shiny! :)