We’ve always known that getting enough sleep is important and can have a significant impact on one’s health, but scientists have just begun to unravel the genetics behind why some people are more prone to sleep problems. Insomnia is the most common sleep disorder. About 30 percent of adults report short term problems, while about 10 percent report chronic insomnia. It’s also the second most common mental disorder.
Recently, 23andMe collaborated with researchers from VU University Amsterdam and Netherlands Institute for Neuroscience on one of the largest genome-wide analysis studies to identify genes associated with insomnia. Published in the journal Nature Genetics, the study used data from more than 1.3 million consenting research volunteers from the 23andMe database and the UK Biobank.
“Our study shows that insomnia, like so many other neuropsychiatric disorders, is influenced by 100’s of genes, each of small effect,” said Guus Smit, a VU-University neurobiologist involved in the study. “These genes by themselves are not that interesting to look at. What counts is their combined effect on the risk of insomnia. We investigated that with a new method, which enabled us to identify specific types of brain cells, like the so-called medium spiny neurons.”
The sheer size of this research cohort enabled us to ask questions about genetics of insomnia and its relationships with other conditions and sleep-related problems individuals may face. With this large dataset, researchers were able to identify 202 genome-wide significant loci involved in insomnia. They were also able to show the involvement of specific cell type — striatal medium spiny neurons, hypothalamic neurons and clastrum pyramidal neurons — and specific cortical and subcortical tissues — some of which have been implicated previously in the regulation of reward processing, sleep and arousal in animal studies, but have never been genetically linked to insomnia in humans.
“This study is an immense step forward in understanding the genetic background of insomnia, made possible by the unprecedented increase in cohort size,” said Vladimir Vacic, Senior Scientist, Computational Biology at 23andMe and co-author on the paper. “Our results underline that insomnia is a serious condition, sharing genetics with psychiatric disorders and increasing the risk of metabolic syndrome phenotypes.”
What researchers found particularly interesting was the low genetic overlap between insomnia and other sleep-related traits. Findings show that insomnia is more genetically similar to psychiatric conditions, such as anxiety and major depressive disorder, and personality traits such as neuroticism. It has less in common with sleep traits like morningness, which describes the ease of getting up in the morning, and daytime dozing, snoring or excessive napping.
Finding key brain areas and cell types implicated in the neurobiology of insomnia and related disorders help us better understand how insomnia affects humans and may provide novel avenues for treatment.