Aggressive schoolchildren appear to be more likely to have sleep-disordered breathing than their more mild-mannered counterparts, a cross-sectional study showed.



Conduct problems, parent-reported bullying, and school disciplinary problems were all associated with higher scores on a measure of sleep-related breathing disorders, according to Louise O'Brien, PhD, of the University of Michigan in Ann Arbor, and colleagues.



"Our study was cross-sectional and cannot prove causality," they wrote online in Sleep Medicine, "but dose-response findings were consistent with the hypothesis that sleep-disordered breathing, and sleepiness in particular, could contribute to conduct problems in schoolchildren."

As for a possible mechanism, the researchers pointed to previous reports linking sleepiness with impaired emotional regulation.

Action Points Note that this study indicates that urban schoolchildren with aggressive behavior (including bullying and disciplinary problems) are more likely to have symptoms suggestive of sleep-disordered breathing.

Point out that the study cannot prove cause and effect but raises the possibility that investigating sleep disorders in these children may have a beneficial effect upon aggressiveness.

The findings "raise the possibility that addressing the underpinnings of childhood sleepiness may offer a largely untapped opportunity to reduce the common problem of aggressive behavior in schoolchildren."

Bullying has potential negative consequences for both the aggressor and the victim.

Bullies are at risk for psychiatric problems, delinquency, substance abuse, antisocial behavior, violence, and criminal activity, whereas victims are at risk for damaged self-image, depression, and decreased quality of life, according to the researchers.

One possible biological contributor to aggressive behavior is sleep-disordered breathing, they noted.

To explore the issue, O'Brien and her colleagues looked at children in grades 2 and 5 (mean age 9) in the urban Ypsilanti (Mich.) Public School System. In that city of some 24,000 people, about 30% of the children live below the poverty line.

Parents of 341 children completed validated screening assessments for conduct problems, bullying behavior, and sleep-disordered breathing. Teachers provided assessments of conduct problems, behavior, and disciplinary problems in school.

Overall, 32% of the children were classified by a parent or teacher as having a conduct problem, 12% were classified as demonstrating bullying behavior, and 17% received at least two disciplinary referrals from teachers.

Nearly a quarter (23%) snored more than half the time -- which is suggestive of sleep-disordered breathing -- and were sleepier than those who did not habitually snore.

Children with conduct problems according to parent or teacher reports were significantly more likely than nonaggressive children to screen positive for sleep-disordered breathing (30% versus 14%, P<0.001).

Although they were also significantly more likely to snore habitually, it was a sleepiness subscale and not a snoring subscale (which is more specific to sleep-disordered breathing) that predicted conduct problems in a multivariate analysis.

"Although previous literature has reported aggressive behavior as a possible symptom of sleep-disordered breathing, we now suggest more broadly that common and frequently unrecognized daytime sleepiness, related perhaps in some but not all cases to sleep-disordered breathing, could underlie a sizable portion of aggressive behaviors within urban public schools," O'Brien and her colleagues wrote.

Children classified as having bullying behavior according to their parents -- but not when they were so classified by teachers -- were more likely to have high sleep-disordered breathing risk (42% versus 17.5%, P=0.007), with increasingly severe bullying associated with higher scores on the sleep-related breathing disorder scale.

In addition, children with at least two discipline referrals in school were more likely to screen positive for sleep-disordered breathing, although the difference did not reach statistical significance (27% versus 16%, P=0.14).

Nevertheless, in a multivariate analysis, the sleep-related breathing disorders score did independently predict disruptive behavior in school (OR 10.8, P=0.033).

The authors acknowledged some limitations, including possible selection bias stemming from the low recruitment rate, the use of a questionnaire to assess sleep-disordered breathing, and the inconsistency between parent and teacher reports of behavior.