Via Andrew Sullivan's blog, we get this report on the dreams of small children:

Preschoolers’ dreams are often static and plain, such as seeing an animal or thinking about eating. There are no characters that move, no social interactions, little feeling, and they do not include the dreamer as an active character...Preschoolers do not report fear in dreams, and there are few aggressions, misfortunes and negative emotions. Children who have night terrors, in which they awaken early during the night from SWS [slow-wave sleep] and display intense fear and agitation, are probably terrorized by disorientation owing to incomplete awakening rather than by a dream. Thus, although children of age 2–5 years can see and speak of everyday people, objects and events, they apparently cannot dream of them.

When I read this I thought back on the sorts of dreams I'd had as a pre-schooler. They certainly didn't seem static or plain. Often, these dreams were filled with the anxieties common to children trying to make sense of an unfamiliar world. Of course, it's difficult to judge the age at which your childhood nightmares occurred. So, I thought, maybe I've got it wrong. Maybe children really do have very static, very plain dreams.

A few hours later my five-year-old daughter told me of a nightmare she'd had the previous evening. In the dream, she said, a bad man had taken over the world. He had filled all the holes in the world with snakes, and had covered all the oceans with plastic, so that the fish couldn't breathe.

Okay, I thought. That's pretty intense, for a five year old. Or for anybody, really.