I think I finally figured out what triggers my sleep paralysis attacks [1]—naps.
I ended up taking a nap this evening (combination of a really screwed up sleeping schedule and sleep depravation since I had to get up early today since P. is out of town), and I intended to only sleep for maybe an hour or so, but I slept longer than I expected. Durring the nap, I experienced an attack of sleep paralysis [2]. It wasn't as bad as some of my previous attacks (now that I know what's going on, the process isn't nearly as frightening) but it still quite annoying and it seemingly takes forever to snap out of it.
But in thinking over my past attacks, they have all (to my recollection) happened when napping, or rather, napping longer than I wanted to nap.