People who perpetually allow their thoughts to go back and forth from the past to the future without being in the present, are likely to be dissatisfied and unhappy, a US study has revealed.
"A human mind is a wandering mind, and a wandering mind is an unhappy mind," wrote psychologists Matthew Killingsworth and Daniel Gilbert of Harvard University in the journal Science.
"The ability to think about what is not happening is a cognitive achievement that comes at an emotional cost."
The study tracked 2,250 people via the trendy iPhone gadgets using an application, or app, that contacted volunteers at "random intervals to ask how happy they were, what they were currently doing, and whether they were thinking about their current activity or something else that was pleasant, neutral or unpleasant."
When the results were tallied, people had answered that their minds were wandering 46.9 percent of the time.
Subjects reported being happiest while having sex, exercising or having a conversation. They reported being least happy while using a home computer, resting or working.
By examining the mind-wandering responses, researchers found that "only 4.6 percent of a person's happiness in a given moment was attributable to the specific activity he or she was doing, whereas a person's mind-wandering status accounted for about 10.8 percent of his or her happiness."
The study said "time-lag analyses" suggested that "subjects' mind-wandering was generally the cause, not the consequence, of their unhappiness."
Subjects tended to be most focused on the present, and least prone to mind-wandering, during sex, the study noted. During every other activity, minds were wandering no less than 30 percent of the time.
Seventy-four percent of those followed in the study were American, the researchers said, adding that the subjects came from a "wide range of socioeconomic backgrounds and occupations."
"Mind-wandering is an excellent predictor of people's happiness," said Killingsworth.
"This study shows that our mental lives are pervaded, to a remarkable degree, by the non-present."
The application is available at www.trackyourhappiness.org.