When I was growing up, our former neighbors, whom we'll call the Sloans, were the only couple on the block without kids. It wasn't that they couldn't have children; according to Mr. Sloan, they just chose not to. All the other parents, including mine, thought it was odd—even tragic. So any bad luck that befell the Sloans—the egging of their house one Halloween; the landslide that sent their pool careering to the street below—was somehow attributed to that fateful decision they'd made so many years before. "Well," the other adults would say, "you know they never did have kids." Each time I visited the Sloans, I'd search for signs of insanity, misery or even regret in their superclean home, yet I never seemed to find any. From what I could tell, the Sloans were happy, maybe even happier than my parents, despite the fact that they were (whisper) childless.

My impressions may have been swayed by the fact that their candy dish was always full, but several studies now show that the Sloans could well have been more content than most of the traditional families around them. In Daniel Gilbert's 2006 book "Stumbling on Happiness," the Harvard professor of psychology looks at several studies and concludes that marital satisfaction decreases dramatically after the birth of the first child—and increases only when the last child has left home. He also ascertains that parents are happier grocery shopping and even sleeping than spending time with their kids. Other data cited by 2008's "Gross National Happiness" author, Arthur C. Brooks, finds that parents are about 7 percentage points less likely to report being happy than the childless.

The most recent comprehensive study on the emotional state of those with kids shows us that the term "bundle of joy" may not be the most accurate way to describe our offspring. "Parents experience lower levels of emotional well-being, less frequent positive emotions and more frequent negative emotions than their childless peers," says Florida State University's Robin Simon, a sociology professor who's conducted several recent parenting studies, the most thorough of which came out in 2005 and looked at data gathered from 13,000 Americans by the National Survey of Families and Households. "In fact, no group of parents—married, single, step or even empty nest—reported significantly greater emotional well-being than people who never had children. It's such a counterintuitive finding because we have these cultural beliefs that children are the key to happiness and a healthy life, and they're not."

Simon received plenty of hate mail in response to her research ("Obviously Professor Simon hates her kids," read one), which isn't surprising. Her findings shake the very foundation of what we've been raised to believe is true. In a recent NEWSWEEK Poll, 50 percent of Americans said that adding new children to the family tends to increase happiness levels. Only one in six (16 percent) said that adding new children had a negative effect on the parents' happiness. But which parent is willing to admit that the greatest gift life has to offer has in fact made his or her life less enjoyable?

Parents may openly lament their lack of sleep, hectic schedules and difficulty in dealing with their surly teens, but rarely will they cop to feeling depressed due to the everyday rigors of child rearing. "If you admit that kids and parenthood aren't making you happy, it's basically blasphemy," says Jen Singer, a stay-at-home mother of two from New Jersey who runs the popular parenting blog MommaSaid.net. "From baby-lotion commercials that make motherhood look happy and well rested, to commercials for Disney World where you're supposed to feel like a kid because you're there with your kids, we've made parenthood out to be one blissful moment after another, and it's disappointing when you find out it's not."

Is it possible that American parents have always been this disillusioned? Anecdotal evidence says no. In pre-industrial America, parents certainly loved their children, but their offspring also served a purpose—to work the farm, contribute to the household. Children were a necessity. Today, we have kids more for emotional reasons, but an increasingly complicated work and social environment has made finding satisfaction far more difficult. A key study by University of Wisconsin-Madison's Sara McLanahan and Julia Adams, conducted some 20 years ago, found that parenthood was perceived as significantly more stressful in the 1970s than in the 1950s; the researchers attribute part of that change to major shifts in employment patterns. The majority of American parents now work outside the home, have less support from extended family and face a deteriorating education and health-care system, so raising children has not only become more complicated—it has become more expensive. Today the U.S. Department of Agriculture estimates that it costs anywhere from $134,370 to $237,520 to raise a child from birth to the age of 17—and that's not counting school or college tuition. No wonder parents are feeling a little blue.

Societal ills aside, perhaps we also expect too much from the promise of parenting. The National Marriage Project's 2006 "State of Our Unions" report says that parents have significantly lower marital satisfaction than nonparents because they experienced more single and child-free years than previous generations. Twenty-five years ago, women married around the age of 20, and men at 23. Today both sexes are marrying four to five years later. This means the experience of raising kids is now competing with highs in a parent's past, like career wins ("I got a raise!") or a carefree social life ("God, this is a great martini!"). Shuttling cranky kids to school or dashing to work with spit-up on your favorite sweater doesn't skew as romantic.

For the childless, all this research must certainly feel redeeming. As for those of us with kids, well, the news isn't all bad. Parents still report feeling a greater sense of purpose and meaning in their lives than those who've never had kids. And there are other rewarding aspects of parenting that are impossible to quantify. For example, I never thought it possible to love someone as deeply as I love my son. As for the Sloans, it's hard to say whether they had a less meaningful existence than my parents, or if my parents were 7 percent less happy than the Sloans. Perhaps it just comes down to how you see the candy dish—half empty or half full. Or at least as a parent, that's what I'll keep telling myself.