Parents often think that snoring babies are deeply sleeping ones. But perhaps not, a new study suggests, finding that snoring, along with mouth-breathing and sleep apnea, are signs of disordered sleep that may predict long-term problems in children’s behavior and emotional well-being.
In a study published in the journal Pediatrics, researchers say that babies who have these sleep problems at 6 months may be anywhere from 20% to 100% more likely to have problem behaviors such as hyperactivity by age 7.
The study analyzed sleep habits of more than 11,000 children born in 1991-92 in the former county of Avon in England. The children’s parents were enrolled during pregnancy, and filled out questionnaires about once a year, starting when their children were 6 months old, about whether they snored, breathed through their mouth, or stopped breathing for a few seconds at a time (sleep apnea) while they slept. Parents also completed a screening test for their children at ages 4 and 7 that assessed emotional and behavioral symptoms in five different areas — hyperactivity, emotional problems (such as anxiety and depression), difficulty in getting along with their peers, conduct disorders (such as aggressiveness) and sharing and helpful tendencies.
The children who had the worst sleep disorder symptoms — those that peaked at age 2.5 and persisted — showed scores consistent with clinical diagnoses of behavioral disorders like ADHD at both age 4 and age 7.
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The study’s lead author, Karen Bonuck of Albert Einstein College of Medicine, says she and her team also controlled for 15 factors that could contribute to either snoring or apnea, as well as behavioral difficulties, including mother’s education, family adversity, mother’s smoking or alcohol use while pregnant, and the nature of father’s employment (manual or professional job). None of these factors seemed to affect the consistent relationship between sleep disorders and later behavioral problems.
Why might snoring associated with these problems? “Sleep is a time to restore the brain’s cellular and chemical homeostasis,” says Bonuck. “When sleep is disordered, the brain receives less oxygen than it needs, and may get more carbon dioxide than it needs.” That may lead to developmental disruptions in the prefrontal cortex, the region responsible for regulating higher-level functions such as planning and organization. Interruptions in oxygen at younger ages may be even more damaging than at later ages, says Bonuck, since the brain is still developing and forming the neural connections it needs to establish complex behaviors like emotional regulation and social conduct.
While the findings suggest that disordered breathing could be a major risk factor for behavioral problems, it’s not clear what parents can do about their children’s snoring or apnea. For the youngest infants, interventions may not be necessary, but Bonuck suggests that parents who are concerned about their children’s consistent snoring — a problem that often arises from enlarged tonsils or adenoids — should discuss it with their pediatrician. Treatment may help reduce social and emotional problems later on — and lead to quieter nights’ sleep.
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Alice Park is a writer at TIME. Find her on Twitter at @aliceparkny. You can also continue the discussion on TIME’s Facebook page and on Twitter at @TIME.