Researchers at the University of Michigan Medical School in the US found that there was a two-fold higher risk for symptoms of sleep-disordered breathing, particularly daytime sleepiness among the students who bully or have conduct problems.
"What this study does is raise the possibility that poorsleep, from whatever cause, can indeed play into bullying or other aggressive behaviours -- a major problem that many schools are trying to address," said lead researcher Louise O`Brien, assistant professor at UM`s Sleep Disorders Center.
"Our schools do push the importance of healthy eating andexercise, but this study highlights that good sleep is just as essential to a healthy lifestyle."
For their study, published in the journal Sleep Medicine, the researchers looked at elementary school students in the Ypsilanti, Michigan public schools who had exhibited conduct problems like bullying or discipline referrals.
It was found bully students were twice as likely to havesymptoms of sleep-disordered breathing, particularly daytime sleepiness among these students.
O`Brien said the study showed that sleepiness seemed to be the biggest driver of the behaviour problems, not the snoring, which is often a more obvious symptom associated with sleep-disordered breathing.
Sleep-disordered breathing is an umbrella term for a spectrum of breathing problems during sleep, which range from habitual snoring to obstructive sleep apnea, where the airway collapses at night.
According to the researchers, the sleepiness experienced by the kids the study could be caused by sleep-disordered breathing, but also by many other factors like chaotic home environments, fragmented sleep or not enough sleep because of too much electronic stimulus from televisions, cell phones or computers in the bedroom.
Although there are other reasons for these behaviours, if sleepiness does contribute to aggressive behaviour as this study suggests, a significant proportion of bullying in kids might be eliminated by efforts to reduce children`s daytime sleepiness, they said.
O`Brien said: "We know that the pre-frontal cortex area of the brain is sensitive to sleep deprivation, and this area is also related to emotional control, decision making and social behaviour.
"So impairment in the prefrontal cortex may lead to aggression or disruptive behaviour, delinquency or even substance abuse.
"But the good news is that some of these behaviours can be improved. Sleep-disordered breathing can be treated, and schools or parents can encourage kids to get more sleep."