The quality of sleep a child gets, including how much they snore as a baby, may affect his or her risk of growing into a hyperactive schoolchild down the line, suggests a new study.
The findings, published today in the journal Pediatrics, could resonate with parents of the more than 5 million American children who currently hold the diagnosis of attention deficit hyperactivity disorder, or ADHD.
Conducted in England as part of the Avon Longitudinal Study of Parents and Children, investigators looked at more than 11,000 children from birth to age 7. Sleep questionnaires were distributed to parents at six different time points. In particular, the researchers looked for evidence of sleep-disordered breathing, which is characterized by snoring, mouth-breathing or not breathing at all for a few seconds, a condition known as apnea. To assess the behavior of these children, the researchers administered a test known as the Strengths and Difficulties Questionnaire (SDQ) at ages 4 and 7 years.
Those with higher sleep-disordered breathing scores in infancy and/or early childhood displayed significantly more behavior problems at ages 4 and 7. By age 7, the high scorers were more than 1.5 times as likely as their soundly sleeping peers to show hyperactivity. Other issues linked to troublesome breathing during sleep were emotional disturbance (depression and anxiety) and aggressive, combative conduct.
Pediatricians contacted by ABC News see these results borne out by their clinical experience.
"As a general pediatrician, I come across problems related to sleep-disordered breathing every day," said Dr. Stephen Lauer, vice chairman and associate professor of pediatrics at Kansas University Medical Center. "When there are issues of behavioral problems, school performance and especially ADHD concerns, the first question I ask has to do with sleep and snoring."
This study alone, however, cannot prove that sleep-related breathing problems are the root cause of the behavioral issues: Lead author Karen Bonuck, researcher at Albert Einstein College of Medicine in New York, said that despite the "strong and persistent association between the symptoms and the outcome... [t]here is always the potential in epidemiologic research that there are characteristics that aren't accounted for." Even factors the researchers accounted for in their work may have exerted an unseen influence. Prematurity, smoking during pregnancy and lower socioeconomic status – each individually associated with childhood behavioral troubles – were seen more among the problem sleepers, which brings up the possibility of an as-yet-unknown uniting cause.
So if we can't be sure of a cause-and-effect relationship, how do we know if better sleep will lead to better behavior? Study co-author and University of Michigan neurologist and sleep specialist Dr. Ronald Chervin is currently involved in a large multicenter trial comparing sleep-disordered breathing children who do and don't undergo tonsillectomy-adenoidectomy in order to see if these surgeries cure not only sleep problems, but the behavior problems too. "That will give us another level of evidence," he said.
While we await those results, what are sleep-disordered children, and their sleep-deprived parents, to do?
"Just be aware of your child's sleep," Bonuck said. "Don't be alarmed. Be aware. Raise the issue, and keep raising the issue, with your child's doctor."