This is a reprint – the link is below.
http://www.sciencedaily.com/releases/2007/02/070207090939.htm#
ScienceDaily (2007-02-08) — Although it is known that children with sleep difficulties are likely to have school difficulties, new research reveals that this connection between sleep and school performance is related to a child’s socioeconomic and ethnic/racial background. The study observed 166 8- and 9-year-old African-American and [...]