Nature: January 2008 Archive Page

The idea that dreams are a dojo for perfecting waking activities fits well with what is already known about practice. Mental rehearsal through visualization improves skills, enhances learning, and changes the brain, polishing performance in almost any domain, from sports to piano playing.

The single most pervasive theme in dreaming is that of being chased or attacked. Just as athletes in training repeat parts of their performance, we may, in our nightmares, be attacked and chased over and over again, not to solve a particular problem but to actually practice efficient escape behavior.

Saber-toothed tigers no longer stalk our villages, but Stone Age themes still rule our dreams. "Nowadays, the evolutionary footprint is clearest in the dreams of children, who often dream about being chased by monsters, much the same way we were once chased by predators," says Revonsuo. As life has evolved, so have the threats we rehearse. "You insert a modern danger into that ancestral key and get a bizarre combination," says Revonsuo. "We dream of being chased, shot, or robbed, getting into traffic accidents, a burglar in our house, or perhaps smaller mishaps such as losing our wallets--and that prepares us for our waking life."