It’s common knowledge that too little sleep can increase our odds of getting sick, but a new study sheds light on just how direct the connection is. Researchers found that the body’s circadian clock controls an essential immune system gene in mice — a gene that helps the body ward off bacteria and viruses.

“People intuitively know that when their sleep patterns are disturbed, they are more likely to get sick,” study author Erol Fikrig, professor of epidemiology at the Yale School of Medicine, said in a press release. “It does appear that disruptions of the circadian clock influence our susceptibility to pathogens.”