Too much sun, smoking and a poor diet can make us look older. But additional forces are at work aging our cells. 

A growing body of research has pointed to chronic stress—and the hormones that come along with it—as hastening aging. That stress is particularly important for chromosomes. Unfortunately, our chromosomes suffer injuries over time. But to help guard them, chromosomes come with protective end buffers called telomeres.

New research finds that these caps are notably shorter in people with depression—which has been linked to irregular stress hormone levels. The findings are in the journal Biological Psychiatry. [Mikael Wikgren, et al., "Short Telomeres in Depression and the General Population Are Associated with a Hypocortisolemic State"]

Folks without depression who reported feeling the most stressed also had shorter telomeres. And abnormal levels of stress hormones have been found in people with post-traumatic stress disorder, chronic fatigue syndrome and irritable bowl syndrome. Which means that many more people might have chromosomes that are shortening in short order.

Those gray hairs might betray your chronological age. But the state of your chromosomes may be a better marker for how old you effectively really are.

—Katherine Harmon

[The above text is a transcript of this podcast.]