Breathing Problems during Sleep May Affect Mental Development in Infants and Young Children
Children who have problems breathing during sleep tend to score
lower on tests of mental development and intelligence than do other
children their age, according to two studies funded by the National
Institutes of Health (NIH). Both studies appear in the October issue
of Journal of Pediatrics.
The first study, funded by the National Institute of Child Health
and Human Development (NICHD), found that at one year of age, infants
who have multiple, brief breathing pauses (apnea) or slow heart
rates during sleep scored lower on mental development tests than
did other infants of the same age. The second study was funded primarily
by the National Heart, Lung, and Blood Institute (NHLBI). Results
show that 5-year-old children who had frequent snoring, loud or
noisy breathing during sleep, or sleep apneas observed by parents
scored lower on intelligence, memory, and other standard cognitive
tests than other children their age. They were also more likely
to have behavioral problems.
“The findings from these studies support other research that
has shown that breathing problems during sleep are associated with
serious health consequences in children,” said Carl E. Hunt,
M.D., director of the NIH National Center on Sleep Disorders Research
(NCSDR). “However, at this point we don’t know if the
sleep problems during these episodes cause the decline in test scores
or if the sleep episodes and the lower test scores are both related
to some common underlying mechanism.”
More than 10 percent of young children have habitual snoring, the
mildest form of sleep-disordered breathing (SDB). One to three percent
of children have obstructive sleep apnea, a more severe form of
SDB in which breathing stops briefly and repeatedly during sleep.
SDB is thought to be more common in toddlers and younger children
than in older children because the younger ones are more likely
to have large tonsils and adenoids, which can briefly block the
airways in the back of the throat during sleep. African American
children are twice as likely to develop SDB compared to white children.
Children who are overweight or obese are also more likely to develop
In the first study, researchers evaluated 256 full-term and preterm
infants at one year of age with a standardized test that measured
physical and mental development. The infants were part of the multi-center
Collaborative Home Infant Monitoring Evaluation (CHIME) study. The
CHIME study sought to identify factors that could put infants at
risk for sudden infant death syndrome (SIDS). Participants included
healthy infants as well as those at increased risk of SIDS because
they had a history of prematurity, a life-threatening event during
sleep, or a sibling who had died from SIDS. The infants’ breathing,
heart rates, and blood oxygen levels were monitored electronically
at home for the first 4-6 months of age.
The researchers found that infants who totaled more than five episodes
of abnormally slowed heart rate or apnea during the period they
were monitored scored lower on the mental development test at one
year of age than did infants who experienced fewer or no such episodes.
The episodes were often associated with drops in oxygen levels.
The lower mental development scores persisted even after data were
adjusted to correct for other factors known to affect mental development
in preterm infants. The study also found that full-term infants
who experienced the abnormal episodes scored lower on the tests
than did other full term infants, according to Hunt, the lead author,
who conducted the research while at the Medical College of Ohio
The second study involved 205 children at 5 years of age. Researchers
at Boston University School of Medicine compared neurocognitive
function and behavior of 61 children with SDB symptoms to 144 children
without symptoms. Symptoms of SDB, as reported by parents, included
frequent snoring; heavy, loud, or noisy breathing during sleep;
or observed apneas during sleep. An overnight sleep test (polysomnogram)
was also performed to objectively measure the severity of SDB.
The study found that children with SDB symptoms scored lower on
standard tests measuring executive function (attention and planning),
memory, and general intelligence. These children also had significantly
more behavioral problems than children without SDB symptoms, based
on parental survey scores.
“One of the more remarkable findings in this study was that
the neurocognitive effects were significant even among the children
who had mild symptoms of sleep-disordered breathing but no actual
sleep apneas,” said Daniel Gottlieb, M.D., M.P.H., lead author
of the study. “Parents need to be aware that their child’s
snoring could signal serious problems.”
The mild SDB symptoms associated primarily with snoring in these
children result in frequent arousals and fragmented sleep, leading
to poor sleep quality and hence to sleep deprivation. Today’s
findings are similar to other studies of children and adults that
link poor sleep or sleep deprivation to problems with school (or
job) performance, difficulties with memory and concentration, increased
risk of injuries, and trouble controlling impulses, emotions, and
behavior, especially in children.
“Unfortunately, the effects of poor sleep are often overlooked
or misinterpreted in children. Rather than appearing sleepy like
adults who are sleep deprived, children may in fact seem to be more
active or even hyperactive,” comments Hunt.
In an accompanying editorial, Hunt notes that brain development
is not complete until at least late childhood, and hence children
may be uniquely vulnerable to SDB symptoms and their consequences,
especially if such symptoms begin during infancy or early childhood.
Brain areas, such as the prefrontal cortex, which regulate executive
function, might be particularly susceptible to damage from SDB,
In addition, other researchers have reported that the effects of
SDB appear to have long-term consequences for children. For example,
a University of Louisville study found that young children who snored
loudly and frequently were more likely to have lower grades in middle
school even several years after the breathing problem was
treated or resolved.
“These two new studies point to the need for parents and
pediatricians to be on the watch for what might appear to be less
serious breathing problems in their babies and young children when
they sleep,” notes Hunt. “If we can identify these children
before the effects on mental development have occurred, the challenge
then will be to identify possible ways to intervene and prevent
any reduced potential for doing their best in school.”
Scientists have not yet determined safe and effective ways to reduce
cardiorespiratory episodes in infants. In children, however, treatment
for SDB typically involves having the tonsils and adenoids surgically
removed. In more severe cases, or for children who cannot have surgery,
a machine known as continuous positive airway pressure (CPAP), which
forces air into the air passages while the patient is sleeping,
can be as effective in children as it is in adults with sleep apnea.
The health consequences associated with SDB in children are gaining
increasing recognition. In April 2002, the American Academy of Pediatrics
established clinical practice guidelines on obstructive sleep apnea
in children. The guidelines call for all children to be screened
for snoring and for children diagnosed with obstructive sleep apnea
to be treated.
For more information about sleep and sleep research, visit www.nhlbi.nih.gov/sleep.
“Sleep Well. Do Well. Star Sleeper Campaign,” featuring
Garfield the cat, http://starsleep.nhlbi.nih.gov.
SIDS and the Back to Sleep campaign, http://www.nichd.nih.gov/sids/sids.cfm.
AAP Clinical Practice Guideline on the Diagnosis and Management
of Childhood Obstructive Sleep Apnea Syndrome, www.aap.org/policy/re0118.html.
NICHD and NHLBI are part of the National Institutes of Health
(NIH), the biomedical research arm of the federal government. NIH
is an agency of the U.S. Department of Health and Human Services.
NICHD publications, as well as information about the Institute,
are available at http://www.nichd.nih.gov,
or from the NICHD Information Resource Center, 1-800-370-2943; e-mail
NHLBI resources are available at www.nhlbi.nih.gov,
or from the NHLBI Health Information Center, (301) 592-8573; email