Sometimes a bout of insomnia can be linked to a specific stressful event or circumstance, but for many, it’s simply the way their brains and bodies work.
Now, new research has identified for the first time eight specific genes that are linked to insomnia or excessive daytime sleepiness, which refers to when someone feels tired for an unusually high percentage of their waking hours. (This can be a symptom caused by not getting enough sleep, other sleep disorders, a side effect from taking another medication or an underlying medical condition.)
What’s more, the data showed that some of the genes associated with disturbed sleep identified in this study seemed to be linked to certain metabolic and neuropsychiatric diseases, too, like restless legs syndrome, schizophrenia and obesity.
“It was [previously] known that sleep disturbances may co-occur with many diseases in humans, but it was not known that there are shared genetic components that contribute both to sleep problems and these conditions,” Richa Saxena, study co-author and assistant professor of anaesthesia at the Massachusetts General Hospital and Harvard Medical School, told The Huffington Post.
Estimates suggest as many as 30 percent of people around the world have some type of trouble sleeping. And approximately 10 percent of people in the U.S. have symptoms that could be clinically diagnosed as insomnia.
And while environmental factors ― like how noisy your neighborhood is, whether kids or work is waking you up during the night, or stress over a traumatic experience ― undoubtedly affect sleep, so do the traits that you inherit from your family.
Studies have previously identified genes linked to some sleep disorders like narcolepsy and sleep apnea, but these are the first genes specifically linked to insomnia.
Disturbed sleep genes also linked to other diseases
The new study looked at the prevalence of insomnia, sleep problems and excessive daytime sleepiness in 112,586 European adults who had participated in a UK Biobank study. Everyone also had their genes mapped for the study ― and additional information about weight and other diseases or chronic conditions was collected.
The discovery also revealed that some of the genes most strongly linked to sleep disturbances were also linked to restless legs syndrome, insulin resistance, depression, schizophrenia and obesity.
Specifically, the genes linked to insomnia were most strongly related to those associated with restless legs syndrome, insulin resistance and depression. The genes linked to individuals sleeping longer on average were linked to schizophrenia risk. And the genes associated with excessive daytime sleepiness were also linked to obesity.
Previous epidemiological studies that looked at incidence of sleep trouble and incidence of some of these diseases suggested there was a connection, Saxena said. “But it was not known [until this study] that there are shared genetic components ― shared underlying biological pathways ― that contribute to both sleep problems and these shared conditions,” she said.
It’s likely that many more genes are involved, too
Do the new findings mean that everyone who has trouble sleeping is at higher risk for restless legs syndrome, schizophrenia and obesity? Not necessarily ― and most likely no, Saxena said.
“This research is not yet able to determine if disturbed sleep causes these disorders or vice versa,” she explained.
In reality, it is likely that many different genes contribute to both sleep problems and these medical problems, Saxena said. But this new study does suggest that these problems share genes and underlying pathways.
Practically speaking, the research is a long way off from actually helping anyone sleep better or better manage these various conditions, Saxena added. But the hope is that researchers could design and test various drugs to target these genes.
For now, it’s big news that there may be a genetic reason people with these disorders are more likely to have troubled sleep.
Sarah DiGiulio is The Huffington Post’s sleep reporter. You can contact her at firstname.lastname@example.org.