Five-year-old children who snore or have sleep apnea - the more serious disorder in which breathing stops intermittently while they sleep- score worse on tests of memory and intelligence than unaffected kids, investigators report.

Dr. Daniel J. Gottlieb, at Boston University School of Medicine, and colleagues studied a population-based sample of 205 five-year-old children. According to questionnaires filled out by parents, 30 percent of the children experienced sleep-disordered breathing, defined as habitual snoring, loud or noisy breathing when asleep or witnessed sleep apnea.

When the children were tested, general intellectual ability appeared to be significantly worse in those with sleep-disordered breathing.

The difference in IQ seen with the condition was “more than twice that associated with ... modest childhood lead exposure,” Gottlieb’s team points out in the Journal of Pediatrics.

Other measures that were significantly worse included scores on memory tests, attention/executive functioning and behavioral control.

SOURCE: Journal of Pediatrics, October 2004.