The conventional wisdom is that infants are hard on a marriage because parents’ sleeping habits are disrupted by babies. But a new study that appears in the journal Child Development finds that marital instability when a child is nine months old can affect child sleep problems at 18 months.
“This study suggests that regardless of the cause of marital instability, marital instability affects the babies and interferes with babies’ sleep,” said Laura Scaramella, a University of New Orleans psychology professor and one of the study’s investigators.
Researchers interviewed more than 350 families with adopted infants in order to eliminate the possibility that these shared genes influence the relationship between marital stability and child sleep problems.
“What’s critical about our study is that we were able to rule out genetic effects,” Scaramella said. “So it’s not that both parents and babies share a predisposition toward negative emotional arousal or poor sleep. The other important thing was that infant sleep problems did not predict marital instability, which is the common belief.”
Researchers found that marital instability when children were nine months old predicted increases in sleep problems when they were 18 months old. The findings held even after taking into account factors such as birth order, parents’ anxiety and difficult infant temperament.
“Sleep during infancy is critical because of all the brain growth that occurs during the first few years of life,” Scaramella said. “Interrupted sleep can have lasting effects on infant development.”
The study, which was funded by National Institute of Child Health and Human Development, was conducted by researchers at UNO, the Oregon Social Learning Center, University of Leicester, Cardiff University, University of Pittsburgh, University of California at Davis, Pennsylvania State University and the Yale Child Study Center. It will appear in the May/June 2011 edition of Child Development.
Researchers are now investigating whether the relationship between marital instability and child sleep problems persists after age two. Since the original study was funded, the researchers received additional funding to follow up on the original sample from age three through five, to recruit an additional 200 families and to collect DNA from the entire sample.