Scientists have identified 44 genes associated with major depression in a large study involving more than 135,000 people, The Huffington Post reports.

They said the genomic variants, or “loci”, have a statistically significant association with the condition and found the genetic basis of the condition overlaps with other psychiatric disorders such as bipolar disorder and schizophrenia.

More interestingly researchers discovered depression is also linked to genes for obesity and multiple measures of sleep quality, including daytime sleepiness, insomnia and tiredness.

Professor Patrick Sullivan, from the University of North Carolina School of Medicine, hailed the research a “game-changer” and said the findings could help inform better depression treatments in the future.

“Figuring out the genetic basis of major depression has been really hard,” he said. “A huge number of researchers across the world collaborated to make this paper, and we now have a deeper look than ever before into the basis of this awful and impairing human malady.

“With more work, we should be able to develop tools important for treatment and even prevention of major depression.”

The study was an unprecedented global effort by over 200 scientists who work with the Psychiatric Genomics Consortium. Of the 44 loci identified, 30 are newly discovered while 14 have shown up in previous studies.