Grades slipping? Check for snoring.

Children who snore frequently are more likely to struggle with their schoolwork than are children who rarely snore, researchers in Germany report in the August American Journal of Respiratory and Critical Care Medicine.

The scientists asked parents of 1,129 third-graders to rate their children's snoring as occurring always, frequently, occasionally, or never. The researchers then compared each child's snoring frequency with his or her academic performance.

Children who always snored were roughly four times as likely to perform poorly at math, science, and spelling as were children who never snored. Poor math and spelling grades also plagued children who snored frequently. Those who snored occasionally didn't have any more academic problems on average than did kids who never snored.

Most likely, snoring causes "repeated arousal" during the night and leaves some children fired in the morning, says pediatrician Christian F. Poets of the University Hospital of Tiibingen in Germany.

He and his colleagues tested for another common sleep disorder--intermittent hypoxia, or low blood oxygen-by having the children wear a sensor on a finger overnight. Children showing evidence of nighttime hypoxia, which can accompany snoring, didn't fare worse in school than their fellow students did. That result suggests that the academic problems of heavy snorers in the study arose from sleepiness at school, not oxygen deprivation during the night, Poets says.

One message of the study, he adds, is that parents should mention habitual snoring in their children to doctors. In some eases, surgical removal of tonsils or adenoids can relieve the problem.--N.S.