From what I’ve read, sleep paralysis usually takes place while the person is awake, or at least trying to wake up, but can’t move. I’m pretty sure that the whole incident that I’m about to relate was a dream, though.
Last night, I went to sleep and had some weird and very vivid dreams. (Some of them involved insects, a huge phobia of mine–I was convinced that I was awake, and even wished/hoped I was dreaming.) Later on, I was in bed, sleeping (in the dream). I vaguely remember hearing the doorbell ring and trying to get up, but being unable to speak/open my eyes/anything. I started feeling panicky, and I think eventually I was able to break out of it.
I also vaguely remember it happening a second time, but I’m not sure.
I also took a sleeping aid before going to bed (NyQuil). I’ve done so in the past with no ill effects.
I did read that a lucid dreaming episode can precipitate sleep paralysis, which makes sense considering the order of dream-events for me.