A large–scale international study has investigated the influence of genes on sleep behavior. Within the framework of this collaboration, scientists of Helmholtz Zentrum München report in the journal Nature Genetics that several genes play an important role in sleep disorders – including one that is also associated with the restless legs syndrome (RLS).

According to estimates, around seven percent of EU citizens are affected by this sleep disorder. “This is a cause for concern, especially with regard to possible sequelae,” said Professor Konrad Oexle, a scientist at the Institute of Neurogenomics of Helmholtz Zentrum München.” Insomnia not only leads to impaired performance, but it is also a long–term risk factor for depression, cardiovascular disease, diabetes and obesity.”

Previous research has shown that stress during the day is not the only cause for not being able to sleep at night. Genetic causes also contribute to the pathogenesis of chronic insomnia. In women, the proportion of genetic causes (i.e., the heritability) appears to be 60 percent; in men it is around 40 percent. To find out which genes are specifically responsible for insomnia, scientists led by Oexle, together with colleagues from the Netherlands and Iceland, have undertaken a large–scale study.

They performed a genome–wide association study (GWAS) and a genome–wide gene association study (GWGAS) of 113,006 subjects of the UK Biobank and looked for common variants among those who suffered from sleep disorders. The authors found seven genes and three other genes in the genome. They then included another sample of 7,565 subjects in their analysis which allowed to confirm a total of five genomic regions as relevant.

One gene turned out to be particularly interesting. “Our top candidate MEIS1 most likely plays a key role in insomnia,” said Professor Juliane Winkelmann, director of the Institute of Neurogenomics and one of the authors of the study. "This is also interesting because the gene MEIS1 is also associated with the restless legs syndrome, which we have been investigating for years.”

Konrad Oexle looks to the future: "Our study can serve as a concrete starting point for new molecular biology studies on the development and treatment of insomnia." In the long term, the scientists want to open up new therapeutic options for the growing proportion of the population suffering from sleep disorders. In their opinion, too few studies have been carried out on the causes of the disease, especially in view of the accompanying and secondary diseases. Oexle: "The problem is too often attributed to the psychological state of those affected, but our study shows that it is also genetic.”