Every time that I'm in the dark, I imagine what might be lurking in the shadows. It's kind of like a drug in that way - darkness seems to change the way I think - making me way more prone to fear.

We take it for granted that we can see at all times of day and night. But there was a time, not all that long ago, in the age before electricity, when night brought total darkness - and with it, a not-so-small amount of terror. We get a sense of this when we go camping or when there's a power outage, and our fear of the darkness is primal.