NEW DELHI: Does your child suffer from regular disturbed sleep? Beware, he or she could grow up to be depressed and suffer from various 'co morbid anxiety disorders'.

According to a study published in the January 1 issue of journal SLEEP, sleep-disturbed children have been found to be more severely depressed and suffering from co morbid anxiety disorders compared with children without sleep disturbance.

The study, authored by Xianchen Liu and colleagues from the University of Pittsburgh, was conducted on 553 children with a depressive disorder in Hungary. Out of this study group, 72.7% had suffered from some kind of sleep disturbance, of which 53.5% had insomnia, 9% hypersomnia (prolonged night time sleep and daytime sleepiness) and 10.1% had both disturbances.

Researchers said depressed girls were more likely to have sleep disturbance than boys, but age had no significant effects. In an e-mail interview with TOI, Liu said the study also 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 (a key symptom of depression associated with lack of pleasure in everyday pleasurable activities), weight loss, psychomotor retardation and fatigue than those with either insomnia or hypersomnia.

Liu is an assistant professor of psychiatry and has been conducting sleep studies for more than 10 years with a focus on sleep in children and adolescents for 5 years and on sleep and depression and suicidality for about 3 years.

"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. 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," he stated.

The study, conducted in 23 mental health facilities in Hungary, also pointed out that 90% of depressed adults had sleep complaints and over two-third of depressed children had significant sleep onset problems. "The surprising finding of the study was the relationship between sleep disturbances and depressive symptoms. Insomniacs suffered from depressed mood, diurnal variation and agitation, hypersomnia caused weight loss and worthlessness," Liu said.

Said Dr Anupam Sibal, paediatrician at Delhi's Apollo Hospital,"Sleep deprivation leading to health complications is a common problem in adolescence. School children should get between 10-11 hours of sleep a night to achieve good health and optimum performance. We see the hours reduce to 8 in adolescence due to late night television and internet chatting. This impacts their health, attention span, reaction time, memory and motivation, ultimately affecting their academic performance."

To ensure the most effective care, researchers in the study have advised parents of sleep-disturbed children to first consult a paediatrician, who may issue a referral to a sleep specialist for comprehensive testing and treatment.