Young children who have difficulty in breathing while asleep tend to develop hyperactivity and aggressiveness, as well as emotional symptoms and difficulty with peer relationships.
The study, conducted by researchers at Albert Einstein College of Medicine of Yeshiva University, is based on 11,000 children followed up over six years and is the largest and most comprehensive of its kind.
"This is the strongest evidence to date that snoring, mouth breathing and apnea (abnormally long pauses in breathing during sleep) can have serious behavioural and social-emotional consequences for children," said study leader Karen Bonuck, professor of obstetrics and gynaecology and women's health at Einstein.
"Parents and paediatricians alike should be paying closer attention to sleep-disordered breathing in young children, perhaps as early as the first year of life," added Bonouck, the journal Paediatrics reports.
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, according to an Einstein statement.
SDB reportedly peaks from two to six years of age, but also occurs in younger children. About one in 10 children snore regularly and two to four 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.
"Until now, we really didn't have strong evidence that SDB actually preceded problematic behaviour such as hyperactivity," said Ronald D. Chervin, study co-author and professor of sleep medicine and of neurology at the University of Michigan.