CHICAGO — Would I be happier if I spent less time at work?
Surely we have all asked ourselves this at one time or another. Perhaps during a fit of pique about a ridiculous deadline or the idiot who works in the next cubicle over. But even when things are going well, you might still wonder: Would I be happier if I worked less? After all, there are other things in life one might want to do during the daytime hours — hang out with the children, climb Mount Everest, sit in a cafe and read a book — all of which seem, in theory, more pleasurable than racking up more hours at the office.
Before my daughter arrived it hardly ever occurred to me to work less, but since she came along, I've given it more thought. I'm pretty happy now, but could I be happier with fewer hours at work? After all, I really enjoy playing with dinosaur stickers and reading Knuffle Bunny.
If you asked me which gives me more joy, my work or my family, there is no question that it's my family. Hands down. If I had to give one up, it wouldn't even be a contest.
And, yet, in a typical workday I spend at least eight hours at my job, sometimes more, and only about three with my family. And, ultimately, I think that's the time split that makes me happiest.
How can this make sense? Isn't it obvious that the activity that gives you the most happiness should be the one you do the most? It turns out that happiness doesn't work that simply because of what economists call "diminishing marginal utility."
When I teach this, it's usually in the context of consuming things — say, oranges. The first orange you really enjoy, the second is slightly less good, the third you are pretty bored, and by the 10th you are quite sick. The same logic works with time.
Each hour of your day— sleeping, eating, working, playing with those dinosaur stickers — delivers some amount of happiness. And usually the second hour of the same activity makes you less happy than the first one. The first hour of dinosaur stickers, amazing. The second hour, okay. The third hour? Even the best parent may wonder if it's time for a glass of wine. In the language of economics, the marginal utility of time with your kids — the happiness you get from the last hour you spend with them — is declining as you spend more hours.
Work is the same way for two reasons. The enjoyment of work — to the extent that you have any — is likely highest in the first hours of the day when you are fresh, not tired, working on the most important things. By the eighth, 10th, 12th hour of the day, it's a lot less fun.
Of course, work also provides you with income. But the value of this also declines as you add more work. Think about it like this: The first hour of work buys you food, the second buys you housing, and so on, but the 12th hour might be buying you a nicer espresso maker. Everyone likes nice espresso, but the value of the income decreases as you get more of it. (This is called "decreasing marginal utility of consumption.") How quickly your enjoyment of any activity declines is pretty personal. But, in general, for nearly everyone, there seems to be at least some decrease in enjoyment as you continue an activity. In short, humans are programmed to get bored.
So how do you divide your time to make yourself happiest? It's simple: The last hour of your time doing each activity should contain equal amounts of happiness. If I spend eight hours at work and three with my daughter, then this is ideal if the eighth hour at work has the same amount of happiness as the third hour with her.
The key here is understanding that I may value my daughter much more than my job and still want to spend more time at work. Because it may be that the first hour of time with her gives me incredible joy — far outstripping even a whole week of work happiness — but the enjoyment diminishes fairly quickly. If it decreases much faster than the enjoyment of work, then it's easy to see why I might want to spend more hours at work.
Emily Oster is an associate professor of economics at the University of Chicago. Her forthcoming book is "Expecting Better: How To Fight the Pregnancy Establishment With Facts." © 2013 Slate