Chronic stress ages the body and can make cells appear up to 17 years older than they really are, according to a recent study reported in the Proceedings of the National Academy of Sciences. While researchers and healthcare practitioners have long thought as much, this study reveals exactly how stress takes its biological toll on the body.

The researchers compared 39 healthy mothers who were raising chronically ill children to 19 mothers of the same age whose children were healthy. The mothers’ ages ranged from 20 to 50. Through blood and urine samples, researchers found that women with the highest stress levels had weaker immune cell function, higher oxidative stress, and a shorter life span of cells, significantly increasing risk of age-related diseases. This was the case even after adjusting for lifestyle factors such as obesity, smoking, and age.

Researchers note it is the perceived stress that matters. When two people are given the same stressor and one discerns it as manageable while the other is overwhelmed, it is the latter who suffers more on a biological level. Consequently, stress management techniques such as massage, yoga, meditation, breath work, exercise, and counseling are key to health.