A wandering mind often stumbles downhill emotionally. People spend nearly half their waking lives thinking about stuff other than what they’re actually doing, and these imaginary rambles frequently feel bad, according to a new study that surveyed volunteers at random times via their iPhones.

People’s minds wander at least 30 percent of the time during all activities except sex, say graduate student Matthew Killingsworth and psychologist Daniel Gilbert, both of Harvard University. Individuals feel considerably worse when their minds wander to unpleasant or neutral topics, as opposed to focusing on current pursuits, Killingsworth and Gilbert report in the Nov. 12 Science.

These new findings jibe with philosophical and religious teachings that assert happiness is found by living in the moment and learning to resist mind wandering, Killingsworth says.

Mind wandering serves useful purposes, he acknowledges, such as providing a way to reflect on past actions, plan for the future and imagine possible consequences of important decisions. “We may tend to reflect on things that went poorly or are a cause for worry,” Killingsworth proposes. “That’s not a recipe for happiness, even if it’s necessary.”

In his new study, people’s minds actually wandered more often to pleasant topics than to unpleasant or neutral topics. But those reveries offered no measurable mood boost over thinking about tasks at hand, the researchers found.

It’s important to note that the new data apply only in the short run, comments psychologist Jonathan Schooler of the University of California, Santa Barbara. “Positive flights of fancy may lead to creative problem solving and planning that makes people happier down the road,” he speculates…