Scientists have found that anxiety, depression, and insomnia are genetically linked.

Dr. Phillip Gehrman, assistant professor in the department of psychiatry at the University of Pennsylvania School Of Medicine, says that the genes that play a role in adolescent insomnia are he same as those involved in depression and anxiety

He says that the results of the study show that insomnia as a diagnosis has a moderate heritability in 8 to 16 year olds, which is consistent with past studies of insomnia symptoms in adults.

The researcher says that significant genetic effects shared between insomnia, depression and anxiety suggests that overlapping genetic mechanisms exist to link the disorders.

According to Dr. Gehrman, researchers involved in the study were surprised that they did not find sleep-specific genetic effects.

"Monozygotic twins did not have higher rates of insomnia. However, if one monozygotic twin had insomnia, their twin was more likely to have insomnia than if they were dizygotic twins," he said.

The sequential cohort study included data from 749 monozygotic twin pairs and 687 dizygotic twin pairs between the age of 8 and 17 and their parents.

Mean age was 11.9. Twins and their parents completed the Child and Adolescent Psychiatric Assessment (CAPA), and DSM-III-R criteria was used to assess insomnia, depression and anxiety.

Criteria for insomnia were met by 19.5 percent of the sample.

Analysing their observations, the researchers came to the conclusion that adolescents suffering from anxiety and depression should also be screened for insomnia.