Washington: Children suffering from excessive daytime sleepiness (EDS) may have learning, attention and behaviour problems even though clinical tests show they are sleeping long enough at night.

Penn State University researchers studied 508 children and found that those whose parents reported EDS despite little indication of short sleep, were more likely to experience learning, attention/hyperactivity and conduct problems than children without EDS.

"Impairment due to EDS in cognitive and behavioral functioning can have a serious impact on a child's development," said Susan Calhoun, who led the study, according to a Penn State statement.

"When children are referred for neurobehavioral problems, they should be assessed for potential risk factors for EDS. Recognising and treating EDS can offer new strategies to address some of the most common neurobehavioral challenges in young school age children," added Calhoun.

Calhoun said researchers were surprised that most of the children studied showed few signs of short sleep when tested, nor was short sleep associated with any of the learning, attention and behaviour problems. Previous research found EDS prevalent in 15 percent of children from a general population sample.