There is an interesting study published in the May issue of Pediatrics by a Finnish group who found that short sleep duration (less than 7.7 hours/night) in children age 7-8 correlates with increased risk for attention deficit/hyperactivity disorder (ADHD). It certainly adds further evidence to the connection between sleep, behavior, and daytime function in kids, something which should not be news to any parent.
I discussed this connection in a posting last month on obstructive sleep apnea (pauses in breathing while asleep caused by choking on the back of the throat) and ADHD. What remains unclear to me after reading this study, is the question of causality. Do the increased inattention, impulsivity, and other behavioral disturbances reflect an underlying neurological problem which also manifests as a reduced sleep requirement (because the kids are "all wound up"), or is the insufficient sleep causing the behavioral disturbances?
At least with regards to obstructive sleep apnea, the latter seems to be the case, and this has been demonstrated repeatedly in multiple studies over the last few years (one of which is cited and discussed in my posting from March 16).