In the dreamscape of nightmares, clues to why we dream at all

The sleeper thinks the nightmare is over, only to step into Your Nested Nightmare, Chapter II. Whatever the particulars of the plot, researchers say, nightmares and dreadful dreams offer potentially telling clues into the larger mystery of why we dream in the first place, how our dreaming and waking lives may intersect and cross-infect each other, and, most baffling of all, how we manage to construct a virtual reality in our skull, a seemingly life-size, multidimensional, sensorily rich nocturnal roundhouse staffed with characters so persuasive you want to ... strangle them, before they can strangle you.

A big reason bad dreams offer insight into the architecture of dreams generally is that, as a host of studies have shown, most of our dreams are bad. Whether research subjects keep dream journals at home or sleep in research labs and are periodically awoken out of rapid eye movement, or REM, sleep -- the stage most often associated with dreaming -- the results are the same: about three-quarters of the emotions described are negative.

Read full story in The New York Times