A very large genetic study of insomnia has identified hundreds of genes associated with the condition that is also linked to such things as depression, anxiety, schizophrenia, as well as metabolic disorders.
The scientists who worked on the study suggest that the breadth of those links likely indicates that there are different genetic subtypes for the condition. It’s estimated that as many as 30 percent of adults have insomnia, which is defined as an inability to fall asleep at least three times a week over several months.
Large Study
Published in the journal Nature Genetics the study included data from more than 2.3 million people, more than half a million of whom reported having insomnia and the remaining 1.8 million without the condition who were used in this research as controls.
This study almost doubled the size of the previous largest genome-wide association study on insomnia that was conducted by some of the same scientists. Danielle Posthuma, a professor at Vrije University in Amsterdam, again led it at Vrije University in Amsterdam.
Posthuma and her co-authors explained in this paper that the current work suggests that “for extremely polygenic traits such as insomnia, increasing sample size does lead to an increase in detected (single nucleotide polymorphisms), loci, genes, and pathways, providing more confidence in existing and novel mechanisms.”
Many Genes Involved
At the same time, the additional data in this study did not improve the predictive power for insomnia. This is in part due to the highly polygenic nature of insomnia, meaning that there are many, many genetic variants associated with the condition that have yet to be identified. Insomnia is estimated to be the third most polygenic trait behind major depressive disorder and educational attainment, according to the researchers for this study.
The study identified 289 genes involved in insomnia, but that total still only explains about 10 percent of the heritability of the condition. Some of the genes associated with insomnia appeared linked to metabolic or psychiatric conditions.
Other studies indicate that about three-quarters of adults with depression suffer from insomnia.
23andMe does not have a genetic health report on insomnia, but it does have a collection of reports on such things as Deep Sleep, Sleep Movement, and Wake Time in a “sleep hub” meant to look at how your genetics may play a role in the quality of your sleep.
You can read the full insomnia study in Nature Genetics.