Children's sleep and cognitive functioning

It is obvious that young children who have difficulties sleeping are likely to have problems in school. A new study shows that African-American children and children from lower socioeconomic backgrounds fare worse than their counterparts when their sleep is disrupted.

The study offers one of the first demonstrations that the relationship between children's performance and sleep may differ among children of different backgrounds. Conducted by researchers at Auburn University and Notre Dame University, it is published in the January/February 2007 issue of the journal Child Development.

The study looked at 166 8- and 9-year-old African-American and European-American children from varying socioeconomic backgrounds. The children's sleep habits were measured through wristwatch-sized activity monitors they wore during sleep for one week, sleep diaries of bedtimes and wake-up times, and reports of sleep quality and sleep-related problems such as sleepiness during the day. The children also were given individual cognitive tests measuring a range of mental functions related to school achievement.

When children's socioeconomic status was taken into consideration, African-American and European-American children's performance on cognitive tests was similar when they slept well, the study found. But when sleep was disrupted, African-American children's performance was worse. Similarly, children from lower and higher socioeconomic backgrounds performed similarly on tests when they slept well and their sleep schedules were consistent. But when their sleep was disrupted, children from higher-income homes did better than children from lower-income homes. The study did not address why African-American children and youngsters from lower-income homes may be more vulnerable to the effects of sleep disruption.

"The results build on a small but growing literature demonstrating that poorer sleep in children is associated with lower performance on school-related tests," says Joseph A. Buckhalt, lead author of the study and Wayne T. Smith Distinguished Professor at Auburn University. "The findings are consistent with the idea that health-related disparities between different groups of American children have important consequences. In the context of these disparities, children are not at equal risk for cognitive difficulties when sleep is disrupted."