14th June 2017
Insomnia genes identified
Researchers from the Netherlands and Germany have identified seven risk genes for insomnia.
An international team of researchers has found, for the first time, seven risk genes for insomnia. This discovery is an important step forward in understanding the biological mechanisms of sleep. In addition, it proves that insomnia is not, as is often claimed, a purely psychological condition.
Insomnia is among the most common health complaints – affecting between 10% and 30% of adults worldwide at any given point in time and up to half in a given year. Even after treatment, poor sleep can remain a persistent vulnerability for many people. Professor Van Someren, a sleep specialist from the Vrije Universiteit Amsterdam (VU), believes his team's findings could lead to an understanding of insomnia at the level of communication within and between neurons, providing new ways of treating the condition. He also hopes this breakthrough will improve the recognition of insomnia.
"Compared to the severity, prevalence and risks of insomnia, only few studies targeted its causes," he says. "Insomnia is all too often dismissed as being 'all in your head'. Our research brings a new perspective: insomnia is also in the genes."
From a sample of 113,000 individuals, the researchers found seven genes for insomnia. These play a role in the regulation of transcription, the process where DNA is read in order to make an RNA copy of it, and exocytosis, the release of molecules by cells in order to communicate with their environment. One of the identified genes, MEIS1, has previously been related to two other sleep disorders: Periodic Limb Movements of Sleep (PLMS) and Restless Legs Syndrome (RLS). By collaborating with Konrad Oexle and colleagues from the Institute of Neurogenomics in Munich, Germany, they concluded that variants in the gene seem to contribute to all three disorders. Strikingly, PLMS and RLS are characterised by restless movement and sensation, respectively, whereas insomnia is characterised mainly by a restless stream of consciousness.
The researchers also found a strong genetic overlap with other traits – such as anxiety disorders, depression, neuroticism, and low subjective wellbeing: "This is an interesting finding, because these characteristics tend to go hand in hand with insomnia. We now know that this is partly due to the shared genetic basis," says neuroscientist Anke Hammerschlag (VU), PhD student and first author of the study.
The team also studied whether the same genetic variants were important for men and women. "Part of the genetic variants turned out to be different," says Professor Danielle Posthuma, a statistical geneticist at VU Amsterdam. "This suggests that, for some part, different biological mechanisms may lead to insomnia in men and women. We also found a difference between men and women in terms of prevalence: in the sample we studied, including mainly people older than 50, 33% of the women reported to suffer from insomnia. For men, this was 24%."
The study is published this week in Nature Genetics.
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