By Richard Gray, Science Correspondent
Children with Attention Deficit Hyperactivity Disorder have problems processing emotional memories while they are sleeping, according to research by scientists.
The findings help to shed light on some of the underlying causes of the disorder, which leaves children unable to focus and more prone to impulsive behaviour.
The researchers found that children with ADHD suffered disruptive brainwave patterns in areas of the brain related to memory as they slept when compared to healthy children.
They were poorer at recalling images with emotional connotations, such as a picture of a scary animal, the day after they had been shown them.
The scientists say these problems in processing emotional memories could exacerbate the emotional and behavioural problems that occur in children with ADHD.
“Due to a lack of reorganisation of emotional content in children with ADHD, one can assume that emotional problems during the daytime are amplified by dysfunctional sleep,” said Dr Alexander Prehn-Kristensen, who led the study at the department of child and adolescent psychiatry at the Christian Albrechts University in Keil, Germany.
She added that the inability to process memories with emotions attached to them properly may help to explain why patients with ADHD are more prone to risky behaviour.
She said: “Epidemiological reports have revealed that patients with ADHD are more likely to display risky behaviour and are less affected in their behaviour by negative experiences.”
The researchers, whose work is published in the journal Public Library of Science One, studied assessed the brain patterns and memories of 16 healthy children and 16 children with ADHD and 20 healthy adults for the study.
Sleep disorders are often associated with ADHD and could explain some of the problems forming memories, but the scientists said they found little difference in the quality of sleep in the patients compared to healthy children in their study.
It is estimated that around two to five per cent of school aged children suffer from ADHD and it is the most common behavioural disorder in the UK.
There is currently no treatment for ADHD but patients are given mediation such as the stimulant Ritalin to control their behaviour. The drug is also used to treat narcolepysy, an uncontrollable desire to sleep.