Gargantuan studies show links between sleep difficulties and cardiovascular and psychiatric illnesses, reports Scientific American.

Now, two studies published Monday in Nature Genetics provide first peeks at the biological basis of insomnia, implicating specific brain regions and biological processes, and revealing links with heart disease and psychiatric disorders like depression. Both are genome-wide association studies (GWASs), which examine DNA from many thousands of individuals to determine where genetic markers related to health, disease or a particular trait reside.