Neil Hall / Reuters

Up and down the economic ladder, many Americans who work—and especially those raising kids—are pressed for time, wishing they had more of it to devote to leisure activities (or even just sleeping). At the same time, research has indicated that people who are busy tend to be happier than those who are idle, whether their busyness is purposeful or not.

A research paper released late last year investigated this trade-off, attempting to pinpoint how much leisure time is best. Its authors examined the relationship between the amount of “discretionary time” people had—basically, how much time people spend awake and doing what they want—and how pleased they were with their lives. (Some examples of “discretionary” activities were watching TV, socializing, going to the movies, spending time with family, and doing nothing.)

The paper, which analyzed data covering about 35,000 Americans, found that employed people’s ratings of their satisfaction with life peaked when they had in the neighborhood of two and a half hours of free time a day. For people who didn’t work, the optimal amount was four hours and 45 minutes.

The research traced a correlation between free time and life satisfaction, but didn’t provide any definitive insight into what underlies that correlation—“which is exciting, because this is a work in progress,” says Cassie Mogilner Holmes, a professor at UCLA’s Anderson School of Management and a co-author of the paper, which hasn’t yet been peer-reviewed or published in an academic journal. Holmes’s co-authors are her UCLA colleague Hal Hershfield and Marissa Sharif, a professor at Wharton, the University of Pennsylvania’s business school.

The correlation that Holmes and her collaborators hit upon persisted even after they controlled for people’s age, gender, race, parental status, and other demographic variables (though they did not calculate how the optimal amount of free time varied depending on these factors). The researchers write that their finding is a “small” effect, but still significant, considering that “there are a slew of other variables that play into people’s overall assessment of their satisfaction in life.”

An experiment that the researchers arranged hinted at a possible explanation of the correlation they found. They asked participants to picture and describe what it would be like to have a certain amount of daily free time, and then report how they’d feel about that allotment. “What we find is that having too little time makes people feel stressed, and maybe that’s obvious,” says Holmes. “But interestingly, that effect goes away—the role of stress goes away—once you approach the optimal point.” After that point, Holmes says, the subjects started to say they felt less productive overall, which could explain why having a lot of free time can feel like having too much free time.

It’s not clear what an individual is to do with these findings, since the amount of free time people have usually has to do with a variety of factors, such as having children or a degree of control over work schedules. That said, Holmes told me that she shared her research with the MBA students in her class on happiness, and some of the most time-crunched among them were comforted by the findings: “I think that two and a half hours creates a nice goal that, even if you increase a little bit more of your discretionary time use, you [can expect] that it will translate into greater life satisfaction.”

Daniel Hamermesh, an economist at the University of Texas at Austin who studies time use, said it can be difficult to suss out the relationship between free time and life satisfaction. For one thing, some of the data analyzed in the paper was obtained by asking people to estimate how much free time they have, and those estimates can be unreliable. For another, it’s difficult to systematically say what qualifies as “discretionary” time and what doesn’t. “Every minute we have is subject to choice one way or the other, consciously or not,” he notes.

While Hamermesh didn’t inspect the underlying data in the paper, he offered a couple of possible (but, he notes, hard-to-test) explanations for the findings. “Let’s say everybody around me has two hours of discretionary time, and for some reason I have four,” he says. “I have no friends to play with”—his point being that people’s free time might be less fulfilling if they can’t spend it with others.

Another theory: Having too much free time might challenge a person’s self-image. For a man who provides for his family, Hamermesh says, “if I have so much time that I can spend it on, I don’t know, watching television, maybe I feel I’m not a real man.” (This feeling could be related to the pressure many people feel to appear useful and in demand as they vie for work in a competitive labor market.)

While overall life satisfaction is a metric shaped by many variables, Hamermesh said there’s some research specifically on how stressed people are feeling about time. “Perhaps not surprisingly,” he writes in his forthcoming book, Spending Time: The Most Valuable Resource, “any switch that increases time away from work reduces stress.” Some of the biggest reductions in feeling stressed about time, he notes, come from substituting an hour of sleep or TV-watching for an hour of work.

Another thing that studies show would likely affect people’s well-being is, for those who can afford it, spending money to buy free time—for example, getting takeout instead of cooking, or hiring someone to clean the house instead of doing it yourself.

Figuring out how time use affects people’s well-being can be difficult because getting experimental evidence would require people to upend their usual rhythms for the sake of research. Still, Holmes said she’s interested in studying how the sequence and structure of free time might affect the pleasure it brings. For instance, is it better to cluster it at the beginning or end of one’s day, or disperse it throughout the day? And on a larger scale, would people be happier with the standard five-day workweek or a week with four longer workdays and a three-day weekend? What about the best time to go on vacation? Maybe, Holmes wonders, happiness is not just about how much free time people have, but also when they have it.

We want to hear what you think about this article. Submit a letter to the editor or write to