Washington, Mar 2 : Intrinsic sleep problem might be an underlying cause of attention-deficit hyperactivity disorder (ADHD) in children, a new study has found.

Dr. Reut Gruber, Director of the Attention, Behaviour and Sleep Lab at the Douglas Mental Health University Institute, found during a study that children with ADHD had a total sleep time that was significantly shorter than that of controls.

The findings suggested that children in the ADHD group had an average total sleep time of eight hours, 19 minutes, which was 33 minutes less than the average sleep time of eight hours, 52 minutes in controls

"I do not believe that sleep per se is the cause of ADHD, but it may make the symptoms worse in children with sleep problems. There are reports in the literature in which treating sleep problems led to improvement in ADHD symptoms but I suspect that these results were seen in children with sleep apnea," said Gruber.

"More research needs to be done in order to determine if sleep affects ADHD children with no primary sleep disorder," Gruber added.

Lack of sleep on regular basis accumulates to become a sleep debt, which can produce significant daytime sleepiness and neurobehavioral impairment.

Previous studies have shown that disrupted sleep can affect daytime learning and attention in childhood and can lead to ADHD-like symptoms.

According to the authors, this study may suggest that ADHD children suffer from an intrinsic sleep problem that could be related to the underlying pathophysiology of the disorder.

They report that the impact of sleep duration on neuropsychological functioning in children with ADHD should be investigated further.

The study appears in journal Sleep. (ANI)