vertigo

I don't know if this is like vertigo, but it's a weird thing and I'm guessing it has a name.

I was leaning over a railing yesterday, looking down three floors and my imagination went wild. I pictured myself falling over the railing and landing on the floor below. Of course, my brain worked it over for awhile. Maybe the railing would collapse, maybe I would just pitch myself over the side like in an action movie, or maybe someone would push me over and I'd flip over the side. And, not trusting my inner imagination to imagine without acting, I slowly backed away from the railing and met my friend for lunch.

I've had a similar feeling sitting in an exit row on an airplane. Especially if I'm stuck sitting next to the emergency door. I imagine myself opening the door while the plane is in mid-air, just to see what happens. I think about everyone getting sucked out of the plane and then ask to switch seats with someone, just in case I can't control my hand.

What's really strange, is that I've never done anything like that, ever. I've never jumped out of an open window in a highrise. I've never thrown myself off the roof of my house. I've never opened the window while in a swinging gondola. But I've imagined it. And I can't figure out if it means I have an overactive imagination or a low threshhold for risk. What do you think?