"Why do we dream? As a chronic insomniac, I like to pretend that our dreams are meaningless narratives, a series of bad B-movies invented by the mind. I find solace in the theory that all those inexplicable plot twists are just random noise from the brain stem, an arbitrary montage of images and characters and anxieties. This suggests that I'm not missing anything when I lie awake at night -- there are no insights to be wrung from our R.E.M. reveries.
While we're fast asleep, the mind is sifting through the helter-skelter of the day, trying to figure out what we need to remember and what we can afford to forget.
Unfortunately for me, there's increasing evidence that our dreams are not neural babble, but are instead layered with significance and substance. The narratives that seem so incomprehensible why was I running through the airport in my underwear? -- are actually careful distillations of experience, a regurgitation of all the new ideas and insights we encounter during the day."
--Jonah Lehrer, from his blog The Frontal Cortex