EBD Blog

As many people who monitor the Web for terms such as “behavior” and “disorder” know, sleep disorders are among the more widely discussed topics one finds when searching with those and similar terms. Mostly, that’s because of a lot of discussion about restless leg syndrome and related behavior associated with sleep disorders. However, colleagues here are at the University of Virginia (U.Va.) have some relatively new—and pretty alarming—scientific findings on sleep disorders in children, so I’m passing the information along to readers of EBD Blog.

Paul Suratt, M.D., and colleagues at the U.Va. Sleep Disorders Center studied 114 six- to twelve-year-olds to examine the relationships among various measures of sleep disorders and cognitive performance.

There were important significant relationships between snore group (snored every night versus less often), sleep efficiency, and race and 2 of 3 general cognitive tests (vocabulary and similarities). Significant but weaker relationships were observed between sleep latency and 2 memory indices (verbal memory and general memory) and between sleep efficiency and 2 behavior indices (attention-deficit/hyperactivity disorder summary and hyperactive-impulsive summary). The number of episodes of apnea and hypopnea per 1 hour of sleep predicted the vocabulary score as well as did the snore group, but it did not predict other tests as well as other variables. Tonsil size did not predict any cognitive or behavior score. Confidence intervals for group means were small, whereas prediction intervals for individual children were large.

In short, children who snore nightly and have other indicators of sleep problems were likely to have vocabulary scores (and other measures of cognitive performance) that were substantially lower than the scores of their peers who did not snore and have other indicators of sleep problems. The size of this effect is substantial (1.3 standard deviations difference). In the coverage of the story by a science press site, Dr. Surrat characterized the difference as approximating the effect of lead ingestion on IQ.

“Vocabulary scores are known to be the best single predictor of a child’s IQ and the strongest predictor of academic success,” explains Dr. Paul M. Suratt, a pulmonologist who directs the UVa Sleep Laboratory.

According to Dr. Suratt, the vocabulary differences associated with nightly snoring are equivalent to the IQ dissimilarities attributed to lead exposure. “Studies show that, even at nontoxic levels, lead exposure can reduce a child’s IQ by more than seven points,” he notes.

Suratt, P. M., Peruggia, M., D’Andrea, L., Diamond, R., Barth, J. T., Nikova, M., Perriello, V. A. Jr., & Johnson, M. L. (2006). Cognitive function and behavior of children with adenotonsillar hypertrophy suspected of having obstructive sleep-disordered breathing. Pediatrics, 118, 771-781.

Here’s the U.Va. press release, from whence came the quote of Dr. Surrat, and here’s a link to Science Daily’s coverage Here’s a link to the U.Va. Health Science Center Sleep Disorders Center’s info on childhood problems (warning: not Safari-friendly; try Firefox); I had a sleep study there years ago and have benefitted from use of a cpap device for sleep apnea, but parents concerned about their children probably should contact the sleep clinic at a good local hospital, upon referral from the child’s physician. And, here’s a link to the PubMed abstract.