Scientists identify genes and brain cells involved in insomnia

We all sometimes have a bad night's sleep, but about one in ten people chronically suffer from poor sleep. People suffering from insomnia will have a hard time falling asleep or staying asleep, which will lead to symptoms such as fatigue, lack of energy, difficulty concentrating, mood disorders. and decreased performance at work or at school.

The biological mechanisms of insomnia are poorly understood, but studies have suggested that there may be a genetic link, as lack of sleep seems to work in the family. Although studies on genes related to insomnia have already been identified, an international team of researchers have recently brought it to the next level. Researchers led by Danielle Posthuma, Professor of Statistical Genetics at the Vrije University in Amsterdam, analyzed a genetic database involving 1.3 million people, including those from UKBiobank, who have undergone a genetic test with the private company 23andMe.

By associating genes common to sleep patterns, the researchers were able to identify 956 new genes whose variants contribute to the risk of insomnia. They then went further and examined what types of cells and which regions of the brain use these genes.

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Some genes play an important role in the functionality of axons – the long, thin projections of a nerve cell, or neurons, that transmit electrical impulses. Others were active in the frontal cortex neurons and subcortical nuclei of the brain, which had previously been identified in brain imaging studies in people with insomnia.

"Our study shows that insomnia, like so many other neuropsychiatric disorders, is influenced by a hundred genes, each of which has a minor effect. These genes in themselves are not so interesting to look at. What matters is their combined effect on the risk of insomnia. We studied this with a new method, which allowed us to identify specific types of brain cells, such as the so-called medium-prone neurons, "Posthuma said in a statement.

What was particularly surprising was that there was little overlap between the newly identified genes and those known to be involved in other sleep traits, such as morning or evening. Instead, there was a lot of overlap with the genes involved in depression and anxiety. This suggests that brain circuits regulating emotions, stress and tension could be potentially promising targets for insomnia treatments.

The study published in Nature Genetics highlights the power of recording huge datasets, revealing slight variations that together produce a significant effect and would otherwise go unnoticed.

"This study is a huge step forward in understanding the genetic background of insomnia. The findings point out that insomnia is a serious illness, due to the shared genetic risk of psychiatric disorders related to metabolic disorders involved in obesity and diabetes, says Vladimir Vacic, senior scientist in computational biology at 23andMe .

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