Yeah, stress tends to trigger it.
I woke up in my underwear sitting on a stool one day, thinking I was at my high school. I was pretty much still half asleep, so I was hearing voices all around me, it was really weird, lol. I was too scared to even move (thinking I was at school in my underwear), and I sat their half asleep, until the sun rose and I noticed I was in my bedroom.
I also woke up sitting at the top of the stairs once!