ANN ARBOR, Mich. - A study of more than 11,000 children followed for over six years has found that young children with sleep-disordered breathing are prone to developing behavioral difficulties such as hyperactivity and aggressiveness, as well as emotional symptoms and difficulty with peer relationships, according to researchers at the University of Michigan and the Albert Einstein College of Medicine of Yeshiva University.
Their study, the largest and most comprehensive of its kind, published online today in the journalPediatrics.
“This is the strongest evidence to date that snoring, mouth breathing, and apnea [abnormally long pauses in breathing during sleep] can have serious behavioral and social-emotional consequences for children,” said study leader Karen Bonuck, Ph.D., professor of family and social medicine and of obstetrics and gynecology and women’s health at Einstein. “Parents and pediatricians alike should be paying closer attention to sleep-disordered breathing in young children, perhaps as early as the first year of life.”
Sleep-disordered breathing (SDB) is a general term for breathing difficulties that occur during sleep. Its hallmarks are snoring (which is usually accompanied by mouth breathing) and sleep apnea. SDB reportedly peaks from two to six years of years of age, but also occurs in younger children. About 1 in 10 children snore regularly and 2 to 4 percent have sleep apnea, according to the American Academy of Otolaryngology–Health and Neck Surgery (AAO-HNS). Common causes of SDB are enlarged tonsils or adenoids.
“The importance of these new findings,” noted University of Michigan co-author Ronald D. Chervin, M.D., M.S., “is that most previous large, epidemiological studies showed only showed associations between SDB and disruptive behavior at the same point in time when the survey was done.
"We really did not have strong evidence that SDB actually comes before problematic behavior such as hyperactivity. Our new study now shows that SDB symptoms clearly do precede behavioral problems, in a robust manner that suggests any underlying causal effect could be quite strong,” says Chervin, who is the Michael S. Aldrich Collegiate Professor of Sleep Medicine, Professor of Neurology, and Director, Sleep Disorders Center.
Prior studies suggesting a possible connection between SDB symptoms and subsequent behavioral and social-emotional problems, was less definitive because they included only small numbers of patients, short follow-ups of a single SDB symptom, or limited control of variables such as low birth weight that could skew the results.
The new study analyzed the combined effects of snoring, apnea and mouth-breathing patterns on the behavior of children enrolled in the Avon Longitudinal Study of Parents and Children, a project based in the United Kingdom.
Children whose symptoms peaked early—at 6 or 18 months—were 40 percent and 50 percent more likely, respectively, to experience behavioral problems at age 7 compared with normally-breathing children. Children with the most serious behavioral problems were those with SDB symptoms that persisted throughout the evaluation period and became most severe at 30 months.
Researchers believe that SDB could cause behavioral problems by affecting the brain in several ways: decreasing oxygen levels and increasing carbon dioxide levels in the prefrontal cortex; interrupting the restorative processes of sleep; and disrupting the balance of various cellular and chemical systems. Behavioral problems resulting from these adverse effects on the brain include impairments in executive functioning (i.e., being able to to pay attention, plan ahead, and organize), the ability to suppress behavior, and the ability to self-regulate emotion and arousal.