NEW YORK (Reuters Health) - Children with attention deficit/hyperactivity disorder (ADHD) who are not receiving medication often have sleep disturbances characterized by difficulty falling asleep and short duration of sleep and of REM sleep, Canadian investigators have found.

"Clinicians have reported sleep problems in an estimated 25 to 50 percent of children with ADHD, and treatment of sleep problems has been shown to improve behavior and decrease the need for stimulant medication in children with ADHD," lead author Dr. Reut Gruber at McGill University told Reuters Health.

"My work is geared toward exploring new avenues of examination to help understand the basic mechanisms associated with ADHD, optimizing treatment, and minimizing unnecessary use of medication," she added.

To compare sleep architecture in children with and without ADHD, the researchers conducted standard overnight multichannel polysomnography evaluations performed at each child's home using a portable polysomnography device. The 15 children with ADHD and 23 normal comparison children without ADHD (controls), between 7 and 11 years, were not taking medications and had not consumed caffeine for at least a week prior to the test.

According to results published in the journal Sleep, those with ADHD averaged significantly less total sleep time (499 min) compared with the control group (533 min). They also had reduced REM sleep (84 min vs 100 min), and a smaller percentage of REM sleep out of total sleep time (17 percent vs 19 percent).

Parental questionnaire responses indicated significantly more problems with sleep onset delay, sleep anxiety, and insufficient sleep as indicated by daytime sleepiness.

These findings suggest the children with ADHD have a delay in their circadian rhythm, or "internal time clock" that keeps them from being on a regular sleep cycle, Gruber's team maintains.

Currently, Gruber is evaluating the benefits of light therapy or sleep extension for children with ADHD.

"Over the next 5 years," she continued, "I plan to study the mechanisms underlying the interplay between sleep, behavior and attention in children with ADHD, and to develop sleep-based therapeutic interventions for ADHD."

To that end, she has "obtained specialized equipment for measuring sleep and activity in the child's natural environment, instruments for measuring circadian parameters, as well as specialized software to measure neurobehavioral processes, neurophysiological functioning and to integrate observational and physiological methods."

Until such research is completed, she strongly advises physicians "to assess sleep and signs of daytime fatigue in children with ADHD. If this is the case, depending on the clinical picture, a thorough investigation should be made and recommendations should be tailored to each individual child."

SOURCE: Sleep, March 1, 2009.

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