In a genetic study of unprecedented size, scientists have searched for inherited causes of insomnia in the DNA 1,310,010 people.

They found 956 different genes linked to the sleep disorder, drawing closer to an explanation of what causes it and, perhaps, to new ways to treat it.

The study appears to be the first gene search to involve DNA collected from more than one million people.

“It’s amazingly massive,” says Stuart Ritchie, a psychologist involved with genetics research at the University of Edinburgh. On Twitter, scientists let loose with superlatives: “Holy cr*p,” “mammoth,” and “Wow!”

Danielle Posthuma organized a record-breaking genetic study involving 1.3 million people to search for the causes of insomnia. Yvonne Compier

The project involved crunching genetic and medical information collected from the UK Biobank and the consumer DNA testing company 23andMe. It was led by Danielle Posthuma, a neuroscientist specializing in statistical genetics at Vrije University, in Amsterdam.

Termed a “genome-wide association,” this type of study involves comparing the DNA of people with and without a disease. Doing so can unveil which DNA differences are responsible for it.