We all know that too much stress isn't healthy. Now, intriguing scientific evidence shows that chronic stress may accelerate aging in our immune cells.

Prof. Elissa Epel of University of California, San Francisco, may have found new evidence of how stress wears us down by making the immune cells in our bodies age prematurely.

Epel's team followed 58 mothers, 39 of whom were caring for a chronically ill child. Most of them reported higher stress levels than mothers with healthy children.

But when researchers looked at the DNA in their immune cells, they noticed a stunning finding. The telomeres, or biological clocks, in the cells of the chronically stressed women were much shorter, indicating they had aged prematurely.

"We were flabbergasted. It was something you couldn't have expected to find," Epel says.

"We found that in women with the highest stress, they were so short that the cells had aged 10 years more than in the other women. That's not a matter of normal aging but from stress."

The authors say "the exact mechanism that connect the mind and the cell are unknown.'' But they will now begin work to see if other types of cells are affected by stress.

The study is published in the Annals of Internal Medicine.

Karyl Jones-Whittey knows all about living with daily stress. She says that every day is difficult caring for her autistic son, Ian.

"It is exhausting. It is the feeling of being absolutely weighed down with the weight of the world," she says.

Now, Karyl has her own problems, suffering from high blood pressure and arthritis.

"It makes me wonder about how many of my medical conditions -- many of them have only cropped up since Ian was born -- how many are them are related to living under chronic stress?"

Dr. David Posen writes and lectures about the dangers of stress. He hopes the research will be an eye-opener that stress is more than an annoyance; it can be harmful to our health.

"We all have stress in our lives and learning how to handle it is a life skill. And it's neglected and now it's bubbling to the top, you can't put it off much longer," he says.

This new link between stress and cell aging may trigger a flood of new research on how to reverse stress, says Dr. Doug Saunders of the Ontario Psychological Association.

"To look at stress reduction techniques, like cognitive behaviour therapy, meditation, to see if this can impact biological markers like telomeres."

The research may also lead to new medications that protect these telomeres from stress. But for now, it's an intriguing finding that suggests just how toxic chronic stress may be.