A study by two Harvard University researchers suggests that people's minds are wandering nearly half the time and this wandering causes them a lot more grief than happiness.

Images of people daydreaming with big, goofy grins on their faces notwithstanding, the researchers found that a wandering mind is usually an unhappy mind.

The volunteers' minds were on something other than their current activity 46.9% of the time. And those whose minds were elsewhere were decidedly unhappy.

Anyone who supervises people at work or has children knows that people's minds are constantly wandering. It wanders to events in the past, events in the future or events that never happened at all. It drifts to other times, other places, other worlds. The researchers set out to track just how focused people's minds were on the present, using an Internet-based cell phone application.

They contacted 2,250 volunteers at random intervals, collecting 250,000 data points in all. They asked what people were currently doing and whether they were thinking about their current activity or about something else. If someone's mind was not on the task at hand, they were also asked whether it was dwelling on something pleasant, unpleasant or neutral.

The volunteers' minds were on something other than their current activity 46.9% of the time. And those whose minds were elsewhere were decidedly unhappy. Time-lag analyses conducted by the researchers suggest that all this mind wandering was usually the cause, not the consequence, of people's unhappiness.

The volunteers were given a choice of 22 different general activities to describe what they were doing at the time they were called. The happiest people were those who were making love, exercising or engaged in conversation. The unhappiest people were those who were working, using a home computer or resting.

The researchers estimate that only 4.6% of a person's degree of happiness was due to the activity they were engaged in, but 10.8% of their happiness could be attributed to whether or not their mind was wandering.

For every activity on the list except one, people reported wandering minds at least 30% of the time. The exception was people who were making love.

The researchers interpret these findings to mean that people who live in the moment are much happier than those who don't. While dreaming of the past or the future may be part of the human condition, those most focused on the present are happiest.

They point to the wide range of occupations, socioeconomic backgrounds and ages (18-88) of the volunteers under study as evidence of the generality of their findings.

A paper detailing the study appears in the November 12, 2010 issue of Science.

People interested in tracking their own happiness can do so at www.trackyourhappiness.org. An iPhone is required for participation.