A new study has dived into the genetic roots of insomnia and discovered the complex mosaic of genes associated with the condition. The team then dug even deeper, employing a new method that managed to see how these genes help to code for specific cell types that make up different parts of the brain.
Insomnia is among the most common health complaints in the world, affecting over 770 million people across the planet. It’s previously been suggested that insomnia has a genetic component and runs strongly through families, but the hundreds of genes and brain cells behind it have never been clearly identified until now.
An international team of scientists has delved into the genetic data of over 1.3 million people and identified 956 gene variants that are associated with an increased risk of insomnia, as reported in the scientific journal Nature Genetics.
They also discovered that some of these genes play an important role in the functionality of axons, the long “wire” projections that conduct electrical “messages” away from the nerve cell body. Genes identified in the study appeared to exert an influence on specific cell types, including striatal, hypothalamic, and claustrum neurons. Other genes were associated with activity in certain parts of the brain previously suggested to be linked to chronic restless sleep – the frontal cortex and the subcortical nuclei.
Importantly, the research also highlights a strong genetic similarity with depression and anxiety.
“These findings are a breakthrough, since we can now for the first time start searching for underlying mechanisms in individual brain cells in the laboratory," Professor Guus Smit, study author and neurobiologist at the University of Amsterdam, said in a statement.
“Our study shows that insomnia, like so many other neuropsychiatric disorders, is influenced by 100’s of genes, each of small effect,” added Statistical Genetics professor Danielle Posthuma.
“These genes by themselves are not that interesting to look at,” Posthuma added. “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.”
To reach these findings, the team used vast banks of genetic data from the UKBiobank and 23andMe, the consumer genomics and biotechnology company. This approach has been used in a number of genome-wide studies as it provides scientists with an unprecedented amount of useful data to work with. For example, similar studies have also found some of the genetic underpinnings of depression and a variety of inherited conditions, such as cystic fibrosis.