Challenging behaviours are frequently associated with serious childhood developmental disabilities such as ADHD and Asperger disorder, with one of the most common being severe and intractable sleep disturbance. This is associated with daytime behaviour problems, poor developmental and academic progress, and problems for the family which also suffers from sleep deprivation. A dose of 3 mg of melatonin significantly reduced the time required to fall asleep to 15-64 minutes in ADHD children who were being treated with methylphenidate. Benefits occurred within one week of starting therapy. No side effects were reported. Melatonin also improves health status and advances the sleep-wake rhythm in children with idiopathic chronic sleep-onset insomnia. Although one study showed that melatonin improved quality of life in children with pediatric epilepsy who take sodium valproate to control seizures, another study showed an increase in seizure activity in children with severe neurological deficits during treatment with melatonin, so caution should be used.