Daydreams may solve complex problems

People spend one third of their waking lives daydreaming. But letting your mind wander is not a waste of time, according to a new study. It's a chance for the brain to stop focusing on immediate tasks, and subconsciously resolve important life problems.

The study, published yesterday in the Proceedings of the National Academy of Sciences, shows that brain areas associated with complex problem solving, previously thought to go dormant during daydreaming, are in fact highly active.

"A lot of people reject daydreaming as a wasteful activity," says Kalina Christoff, the study's lead author and a University of British Columbia psychology professor. "But our study suggests that if you daydream, you might be able to advance some of your current concerns."

The study put 15 research subjects through a functional MRI for 90 minutes, to examine the metabolic processes of their brains. They completed a simple, routine task of pushing a button when numbers appeared on a screen. Prof. Christoff tracked the research subjects' attentiveness through brain scans, subjective reports and by monitoring their performance of the task.

She found that two key regions of the brain were active during daydreaming: the "default network," associated with easy, routine mental activity, and the brain's "executive network," associated with high-level, complex problem-solving.

Usually when one network is working, the other isn't. It is rare to see them working in tandem, the paper concludes. As well, the brain activity was most active when the research subjects weren't aware they were daydreaming.

"When your mind wanders, a different kind of thinking occurs," said Prof. Christoff. "When you aren't trying to solve problems deliberately, it provides more mental space, you make connections and let your mind go wherever it wants."

She has long been interested in spontaneous thought - but it is difficult to study because it doesn't occur on cue. But now studies are being designed that permit scientists to look at the quantity and quality of brain activity during "mind wandering."

Prof. Christoff says that many of her best research ideas have come to her when she is in the car, daydreaming.

"Driving is the perfect activity for letting your mind wander because it is highly automatized and requires only a small part of our attention," she said. "When you daydream, you may not achieve your immediate goal, say reading a book or paying attention in class. But your mind may be taking that time to address more important questions in your life."

She compares it to mulling over a life decision and letting it circulate in your brain, as opposed to deliberately weighing the pros and cons.

Prof. Christoff runs UBC's Cognitive Neuroscience of Thought Laboratory, which studies neural and cognitive mechanisms of human thought, reasoning and problem solving. Her research team for the study included members who are now at Stanford University and the University of California at Santa Barbara.