My pet theory is a bit similar to the article but in a more computer-architecture way. I tend to think that sleep is our brain performing "GC" our experiences, i.e. choosing what information to retain and what to discard. Since we don't have a separate circuit to do that, we basically reuse the same one (processor and its "bus") for a different purpose, by redirecting its output to /dev/null, and that's a dream. This kinda explains why we don't remember much of it because the result is meant to be discarded. There's no scientific evidence to this but it's quite fun to think this way.<p>edit: the GC theory also explains why we have a better memory after sleep!