In a genetic study of unprecedented scale, scientists have searched for inherited causes of insomnia by examining the DNA of 1,310,010 people.
They identified 956 distinct genes linked to the sleep disorder, bringing them closer to understanding its origins and, potentially, to developing new treatments.
This investigation appears to be the first gene search to incorporate DNA from more than one million participants.
“It’s amazingly massive,” says Stuart Ritchie, a psychologist involved with genetics research at the University of Edinburgh. On Twitter, researchers unleashed a torrent of superlatives: “Holy cr*p,” “mammoth,” and “Wow!”
The project required processing genetic and medical data from the UK Biobank and the consumer DNA testing company 23andMe. It was spearheaded by Danielle Posthuma, a neuroscientist specializing in statistical genetics at Vrije University in Amsterdam.
Known as a “genome-wide association,” this type of study compares the DNA of individuals with and without a condition. Doing so can reveal which genetic variations are responsible for it.
Danielle Posthuma organized a record-breaking genetic study involving 1.3 million people to search for the causes of insomnia. Yvonne Compier
“I know of several that are breaking a million people. It’s going to become very frequent,” says Guillaume Lettre, a geneticist at the Montreal Heart Institute who helped set an earlier record, a study of height that examined DNA samples from 700,000 individuals. “I think two million is within reach.”
Just a decade ago, scientists still hoped a relatively short list of key genes would explain, for instance, who develops diabetes. But early genome association efforts didn’t yield much. “We realized the easiest way to make discoveries is to increase the sample size. The genes we are finding have small effects,” Lettre says.
It’s no surprise that the million-person milestone was first reached with insomnia. The complaint is widespread, affecting 30 percent of the population. By one definition, you have insomnia if your tossing and turning disrupts your day at least three times a week over several months.
Insomnia is partly heritable, meaning you are more likely to suffer from it if your parents did.
In a preview of their findings posted online, the researchers reported that the genetic causes they pinpointed bore some resemblance to those implicated in depression and anxiety. While some insomniacs say they at least have more time to get things done, the scientists found the condition tied to a lower chance of progressing in school and correlated with a shorter life span.
They believe their gene list may include “novel targets for treatments,” although developing a new drug won’t be easy, because most genes have only a minuscule effect on whether you have insomnia.
Furthermore, the genes the team linked to the condition still explain less than 10 percent of the overall likelihood that a person has it. Posthuma called that outcome “a little bit disappointing” given the immense scope of the gene hunt.
That can mean only one thing. Even bigger studies lie ahead.
