In Brief

Grade-school children appear to fall asleep later as they grow older, leading to a problem of morning drowsiness in the later elementary school years, a recent study indicates.

The problem is that children increasingly delay sleep but still must wake up early for school, says the researcher who led the study, psychologist Avi Sadeh, PhD, of Tel Aviv University in Israel. As a result, they feel tired and their learning and attention skills suffer.

Why do they delay sleep? Sadeh says physiological and hormonal changes account for at least part of it. But there are psychosocial reasons as well.

"There are increased school demands, the need of children to feel more like adults [by having] a more active 'night life' and incentives like late-evening or late-night TV shows and Internet surfing," says Sadeh. "Also, as children grow older, their parents become more tolerant of letting them stay up late."

In the study, children lost a full hour of sleep between second and sixth grade, with boys showing particularly fitful sleep. Girls fared slightly better, sleeping longer and more restfully than their male peers, in the study of 140 Israeli second-, fourth- and sixth-graders.

Sadeh and his research colleagues, Amiram Raviv, PhD, and Reut Gruber, PhD, focused on grade-school children because they've been largely ignored in the sleep literature, which has focused on sleep deficits and disruption among infants and adolescents. Sadeh's study, published in the May Developmental Psychology (Vol. 36, No. 3), suggests that children between those stages suffer more sleep deprivation and disruption than previously thought.

To reach this conclusion, he and his research team used an actigraph--a wrist attachment that monitors body activity, sleep onset and waking--to measure the children's sleep patterns during five consecutive school nights. They also gave children and their parents self-report questionnaires on children's sleeping habits.

Besides discovering that older and male children slept less, the researchers found that children woke up twice nightly on average. Those with less educated parents and more stress in their families--death or illness, for example, or relocation--also slept less.

Sadeh says that an earlier bedtime is likely the best solution to the problem, based on preliminary findings from research he's conducting. When children go to bed earlier and get more sleep, their learning and attention skills improve, he says.

--B. MURRAY