alt Hacker NewsI've experienced it once or twice, and mine was the classic "can't move, malevolent presence just barely in the corner of your vision". Once, I think I was actually still half-asleep-ish, and trying to yell and my wife woke me up.
Definitely not pleasant, even when I'm rationally aware of what's going on.
I had it happen twice that I can remember. Once I hallucinated that I had a third arm that snaked around to my desk lamp, and just last night that someone whispered "hello" into my ear. Apparently that last one's pretty common.
I've never seen the shadow man or anything.