Researchers at Albert Einstein College of Medicine of Yeshiva University studied more than 11,000 children and published their findings in today's (5th March 2012) Pediatrics. They have shown that younger children that have sleep disordered breathing have a tendency to develop behavioral difficulties, such as hyperactivity and aggressiveness, as well as emotional symptoms and difficulty with peer relationships.

Study leader, Karen Bonuck, Ph.D., professor of family and social medicine and of obstetrics & gynecology and women's health at Einstein said:

"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 ... 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 an umbrella term for various breathing difficulties that can affect a person during sleep, snoring (which is usually associated with mouth breathing) being the most common, as well as sleep apnea, where breathing is disrupted periodically.

SDB reportedly peaks from two to six 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.

Ronald D. Chervin, M.D., M.S., a co-author of the study and professor of sleep medicine and of neurology at the University of Michigan clarifies:

"Until now, we really didn't have strong evidence that SDB actually preceded problematic behavior such as hyperactivity ... Previous studies suggesting a possible connection between SDB symptoms and subsequent behavioral problems weren't definitive, since 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. But this study shows clearly that SDB symptoms do precede behavioral problems and strongly suggests that SDB symptoms are causing those problems."

The Yeshiva University study used data from the UK program, known as the Avon Longitudinal Study of Parents and Children. Parents were asked to fill in questionnaires about their children's sleeping and breathing habits at various stages of their development from 6 to 69 months of age. Dr. Bonuck assessed that parents were particularly accurate at describing their children's habits.

At between four and seven years old, parents filled out an additional report called the Strengths and Difficulties Questionnaire (SDQ), which is widely used to assess behavior.

The SDQ has scales for describing a child's behavioral patterns including:
  • Inattention/hyperactivity
  • Emotional symptoms (anxiety and depression)
  • Peer problems
  • Conduct problems (aggressiveness and rule-breaking)
  • Prosocial behavior (sharing, helpfulness, etc.)
The researchers also controlled for 15 potential confounding variables that included issues such as socioeconomic status, maternal smoking during the first trimester of pregnancy, and low birth weight.

The results were clear in that:
  • Children with symptoms that peaked earlier at 6 or 18 months were 40 percent and 50 percent more likely, respectively, to experience behavioral problems at age 7, when 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
  • Disrupting the balance of various cellular and chemical
Behavioral problems resulting from these adverse effects on the brain include impairments in executive functioning (i.e., being able to pay attention, plan ahead, and organize), the ability to suppress behavior, and the ability to self-regulate emotion and arousal.

Dr. Bonuck continued that :

"We found that children with sleep-disordered breathing were from 40 to 100 percent more likely to develop neurobehavioral problems by age 7, compared with children without breathing problems ... The biggest increase was in hyperactivity, but we saw significant increases across all five behavioral measures ...

Although snoring and apnea are relatively common in children, pediatricians and family physicians do not routinely check for sleep-disordered breathing ... In many cases, the doctor will simply ask parents, 'How is your child sleeping?' Instead, physicians need to specifically ask parents whether their children are experiencing one or more of the symptoms: snoring, mouth breathing or apnea of SDB."

Dr. Bonuck also clarified that parents should be aware that their child's snoring might be an indication of future or current behavioral problems, and could consider the possibility of asking their family doctor for an assessment by a otolaryngologist (ear, nose and throat physician) or sleep specialist. Surgery is usually the first and most effective treatment, as SDB is usually considered to be a mechanical problem, although weight loss can also help in cases where a child is obese.

What Dr. Bonuck's research doesn't make clear is if there might be a possible relationship the other way around, i.e. that a child's behavioral problems in the day might be a part of the cause of their restless or poor sleep breathing patterns in the night.

Dr. Bonuck's paper is titled "Sleep Disordered Breathing in a Population-Based Cohort: Behavioral Outcomes at 4 and 7 Years."

In addition to Dr. Bonuck, other Einstein contributors were Katherine Freeman, Dr.P.H., and Linzhi Xu, Ph.D. The study was supported by grants from the National Heart, Lung, and Blood Institute, part of the National Institutes of Health.

Written by Rupert Shepherd