At a recent scientific meeting, Harvard psychologist Deirdre Barrett explained why dreams are useful, and how they evolved. Unlike Sigmund Freud, who famously observed that dreams are wish-fulfillments, Barrett thinks dreams serve a useful purpose in the real world. They are a realm where humans solve problems - especially visual problems.

Live Science reports:

A theory to explain dreams, or any human behavior for that matter, needs to take into account evolution, Barrett said . . . "My opinion is that, evolution just isn't wasteful, that when things evolve for one purpose, that generally they don't continue throughout time to have only that purpose, but anything else that may be useful about them gets refined," she said in a telephone interview with LiveScience prior to the convention.

She also noted that REM sleep has been around for quite some time, since mammals evolved some 220 million years ago. "The longer something has existed during evolutionary history, the likelier it is to have other functions overlaid on it," she said . . . [In her research,] she found examples of almost every type of problem being solved in a dream, from the mathematical to the artistic. But many were related to problems that required individuals to visualize something in his or her mind, such as an inventor picturing a new device.

The other major category of problems solved in dreams included "ones where the conventional wisdom is just wrong about how to approach the problem," Barrett said.

Dreams might have evolved to be particularly good at allowing us to work out puzzles that fall into those two categories, she said.

"I think that dreams and REM sleep have probably further evolved to be useful for really as many of the things that our thinking is useful for," Barrett said. "It's just extra thinking time, so potentially any problem can get solved during it, but it's thinking time in the state that's very visual and looser in associations, so we've evolved to use it especially to work on those kinds of problems."

via Live Science