According to a study published in the the journal SLEEP, sleep-disturbed children are more severely depressed and have more depressive symptoms and comorbid anxiety disorders compared with children without sleep disturbance.

To ensure the most effective care, parents of sleep-disturbed children are advised to first consult with the child's pediatrician, who may issue a referral to a sleep specialist for comprehensive testing and treatment.

The study, authored by Xianchen Liu, MD, PhD, and colleagues of the University of Pittsburgh, was conducted on 553 children with a depressive disorder. Out of this study group, 72.7 percent had sleep disturbance, of which 53.5 percent had insomnia alone, nine percent had hypersomnia alone and 10.1 percent had both disturbances. Depressed girls were more likely to have sleep disturbance than boys, but age had no significant effects.

Furthermore, the study found that across sleep-disturbed children, those with both insomnia and hypersomnia had a longer history of illness, were more severely depressed and were more likely to have anhedonia, weight loss, psychomotor retardation and fatigue than those with either insomnia or hypersomnia.

"We know that depression is associated with sleep problems. But what this study shows is that, in depressed youths, not all sleep problems are the same," said Liu. "Insomnia is the most common problem, but having a combination of insomnia and sleepiness is 'double trouble'. Youths having both of these had more severe depression than youths with just one sleep problem. This means that we should carefully ask depressed youths about the specific type of sleep problem they're having. It may also mean that we should think about different treatments to specifically target an individual's sleep problem."

Experts recommend that grammar school-aged children get between 10-11 hours of sleep a night to achieve good health and optimum performance, while children in pre-school should sleep between 11-13 hours a night.