SAN FRANCISCO (FRONTLINE MEDICAL NEWS)Externalizing problems appear to interfere long term with sleep, whereas sleeping difficulties appear to play a role in children’s development of internalizing problems several years later, new research showed.

“Interventions addressing externalizing difficulties may lead to improvements in sleep, but addressing internalizing difficulties are unlikely to lead to benefits for children’s sleep,” concluded Jon Quach, PhD, of the University of Melbourne and Murdoch Children’s Research Institute, Victoria, Australia, and his colleagues.

Although they also conclude that “addressing sleep problems at earlier time points may reduce both internalizing and externalizing difficulties,” the researchers said the data are inconsistent, only weakly suggesting that sleep influences later externalizing problems at only two different age points, Dr. Quach said when presenting the findings at the Pediatric Academic Societies meeting.

The researchers analyzed long-term data from 4,983 children, tracked from ages 4-5 years in 2004 through 12-13 years in 2012 in the Longitudinal Study of Australian Children – Kindergarten Cohort. The average age of the children’s primary caregivers was 35 years, and 86% of the households had English as the main language. Most of the households were two-parent (86%), and more than half the parents (58.2%) had completed high school. Study retention at last follow-up was 79%.

Data collection every 2 years included parent-reported sleep problems and child behavior. Behavior assessment came from the parent-reported Strengths and Difficulties Questionnaire for externalizing and internalizing difficulties. Parents reported severity of sleep difficulties and presence of specific problems at least 4 nights a week: difficulty falling asleep, night waking, sleep restlessness, and not wanting to sleep alone.

The researchers investigated the direction of influence – potential but unproven causation – between sleep problems and internalizing and externalizing problems. The analysis also assessed the extent of the associations. The first pair of analyses examined the relationship between sleeping and either externalizing or internalizing problems, independently assessed.

The findings revealed that sleeping problems were primarily associated with later internalizing difficulties, strongly suggesting that sleeping issues may cause or contribute to internalizing issues 2 years later.

With externalizing problems, however, the effect of poor sleep was inconsistent: Only at one point did it appear that sleeping difficulties contributed to externalizing difficulties. Instead, externalizing problems appeared to contribute to sleeping difficulties at three out of four time points. (The exception was that externalizing problems at ages 8-9 years did not appear to affect sleep at ages 10-11 years.) Though inconsistent, the results suggest that externalizing problems likely affect difficulty sleeping much more so than the other way around.

Then the researchers assessed the interacting associations between all three factors together. At all ages, poor sleep appeared to lead to internalizing difficulties 2 years later. Only once – at ages 6-7 years – did internalizing problems appear to influence sleep 2 years later.

The relationship between sleeping problems and externalizing problems was more complex and less consistent. Externalizing problems often, but not always, were positively associated with sleeping problems 2 years later. And only at ages 4-5 years did difficulty sleeping appear to lead to externalizing problems at ages 6-7 years.

In addition, independent of any interaction with sleeping problems, externalizing difficulties appeared to lead to internalizing problems at all time points.

Although this type of analysis can strongly suggest a direction of causality, Dr. Quach noted, the associations remain subject to the limitations of any observational data, where clearly determining causation or its direction is not possible.

The Australian Research Council and the National Health Medical Research Council in Australia funded the research. The authors did not report any conflicts of interest.