We’ve all heard that stress isn’t good for us. It causes depression and anxiety, as well as sleepless nights. Medical experts have tied chronic stress to an increase in cardio vascular disease and even infectious diseases.

But how can something intangible like stress have such a tangible, negative effect on us?

Researchers at Carnegie Mellon believe they have found the answer.

“Chronic psychological stress is associated with the body losing its ability to regulate the inflammatory response. Published in the Proceedings of the National Academy of Sciences, the research shows for the first time that the effects of psychological stress on the body’s ability to regulate inflammation can promote the development and progression of disease,” according to Science Daily.

Inflammation is partly regulated by the hormone cortisol, which is directly affected by stress because it decreases tissue sensitivity to the hormone.

Without the hampering effects of cortisol, inflammation goes unchecked, which researchers believe pays a big role in making us sick.

The researcher responsible for the study, Sheldon Cohen, conducted a study prior to this, proving his hypothesis that people suffering under prolonged stress are more susceptible to catching the common cold.

To read more about stress and its causes, click here.