Everybody knows new parents have it rough. You wake up fifteen times in a single night to the tune of your baby's wailing. You dedicate your days to feeding and changing diapers. You can't leave the child alone for a single moment. In some ways, it sounds an awful lot like servitude, doesn't it?

However, there is one very special reward for all that unpaid labor: the sight of your baby's smile. Now, research has proven what every parent already knows - that your infant's grin is just as addictive as any drug (chocolate and coffee included).

Scientists at the Baylor College of Medicine recently performed a study to see just what went on inside the brains of first-time moms when their babies smiled at them. The researchers showed 28 new mothers a series of photographs of their own child and other babies, with happy, neutral, and sad expressions on their faces. Using functional magnetic resonance imaging, the team scanned the mothers' brain activity in response to each photograph.

They discovered that all images of crying babies would light up an area of the brain associated with conflict - but only the image of their own beaming infants could send a rush of blood to the brain's pleasure center, similar to the sense of elation that sex, drugs, and other addictive behaviors often bring on.

"It may be that seeing your own baby's face is like a ‘natural high," one of the researchers, Lane Stathearn, assistant professor of pediatrics at Baylor and Texas Children's Hospital, told MSNBC.

The rush of pleasure new mothers feel at the sight of a smile could serve as an important biological factor in helping them to take great care of their kids, despite all the challenges of parenting. The research could also help us to understand what happens in the brains of abusive mothers, and result in possible support systems or interventions to make sure their children receive proper care.

The researchers' findings should come as no surprise to most parents, such as one of the study's subjects, Katrina Lyons, who can't get enough of the sight of her two son's beaming faces, and has photos of her children all over the house. "It's got to be like crack," she says. "I just have to see them everywhere."

By Kathryn Hawkins