Stress makes the common cold more miserable and harder to kick by letting inflammation linger, a new study found.

Men and women who had chronic stress caused by work woes or marital strife were more likely to develop persistent cold symptoms after inhaling the cold virus than their stress-free counterparts. The culprit: cortisol, a stress hormone that serves as the off switch for the body's inflammatory response.

"The symptoms of a cold are not caused directly by the virus, they're caused by the inflammatory response to the infection," said Sheldon Cohen, a professor of psychology at Carnegie Mellon University in Pittsburgh and lead author of the study published today in the Proceedings of the National Academy of Sciences. "You want to produce enough of inflammation to fight off the infection, but not so much that you experience cold symptoms."

With chronic stress, cortisol is overproduced, and the immune system becomes resistant. In the absence of the off switch, inflammation lingers long after the cold virus is gone.

Read more from ABC News.