Sudden Dream Recall

[darkangel13]

Why is it that if you forget a dream upon awakening, you tend to have a hard time remembering it, even though you know you remembered the dream before getting up?  And if/when you do remember it, why does it tend to be at a completely random time? Like, sometimes I'll think of something relative to the dream and it'll suddenly pop up all at once in my head (the dream), but other times I'll be doing something completely random, like making a sandwich, for example, and it'll pop up in my mind all at once.

What happens in one's mind to recall a forgotten dream, and why do you recall it all at once, rather than piece by piece?

If anyone knows that'd be great, I've been wondering all of this for a while.

-Kristina