Parents aren’t the only ones losing sleep from marital issues.

Couples having marital difficulties may have infants who are losing sleep, according to a new study – and that may have a continuing impact on the children.

Specifically, researchers found that marital instability when the child was nine months old was related to child sleep problems at 18 months, including difficulties falling asleep and staying asleep, according to Anne Mannering, an Oregon State University faculty member in the Department of Human Development and Family Sciences.

“If sleep problems persist, this can correlate with problems in school, inattention and behavioral issues,” Mannering said. “Parents should be aware that stress in the marriage can potentially impact their child even at a very young age.”

The findings of the research, which was funded by the National Institutes of Health, appear in the journal Child Development. Mannering was at the Oregon Social Learning Center when she and her collaborators conducted the research.

According to Mannering, this is the first study done on the link between marital issues and infant sleep that unambiguously eliminated the role of shared genes between parents and children. Researchers interviewed more than 350 families with adopted infants in order to eliminate the possibility that these shared genes influence the relationship between marital instability and child sleep problems.

“Our findings suggest that the association between marital instability and children’s subsequent sleep problems emerges earlier in development than has been demonstrated previously,” she said.

The researchers found that marital instability when children were nine months old predicted increases in sleep problems when they were 18 months old. Even after taking into account factors such as birth order, parents’ anxiety and difficult infant temperament, the findings still held.

Interestingly, the researchers did not find the reverse to be true: children’s sleep problems did not predict marital instability.

Marital instability was ranked using a standard four-point research measure, with couples independently answering questions such as “Has the thought of separating or getting a divorce crossed your mind?”

Mannering said the couples were predominately middle class, white and fairly educated and all had adopted their child within the first three months of birth.

The research team is now investigating whether the relationship between marital instability and child sleep problems persists after age two, and the role that the parent-child relationship might play in these associations.

Researchers from the Oregon Social Learning Center, University of Leicester, Cardiff University, University of Pittsburgh, University of California at Davis, The Pennsylvania State University, University of New Orleans and Yale Child Study Center contributed to this study.

The study was funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development, the National Institute on Drug Abuse, and the Office of the Director of the National Institutes of Health.

The Huffington Post also interviewed Anne Mannering on May 23, 2011.