Living Longer: Balance

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You're crawling along in bumper-to-bumper traffic, late for a doctor's appointment. You misplaced your cell phone—the one with all the important numbers you haven't backed up—so you can't call to say you've been delayed. Worst of all, you hear that the stock market is in a steady nosedive, which is bound to affect your retirement fund. Everyday stress? Or can these blood pressure-elevating events cause lasting harm?

It depends—both on how long you're experiencing stress and, equally important, on how you perceive it, according to scientists who have studied the link between stress and aging. Short-term stress can actually be a good thing. "Stress is a positive experience if there is a feeling of control and satisfaction. You need challenges," says Bruce McEwen, Ph.D., head of the neuroendocrinology laboratory at Rockefeller University and author of The End of Stress as We Know It (The National Academies Press, 2002). In fact, stress drives evolutionary change because it improves our memory of important events and helps us adapt. "If something emotionally arousing occurs, you want to remember that," says James McGaugh, Ph.D., professor of neuroscience at the University of California, Irvine. Stress is nature's way of making sure you do.

Long-term stress, the kind you can't control or resolve, however, can have far-reaching, harmful consequences. Recent research at the University of California, San Francisco, has shown that chronic stress appears to shorten telomeres, the caps at the end of our chromosomes; this leads to the premature aging of our cells. (For more on telomeres, see "3 Key Aging Concepts.") Says Elissa Epel, Ph.D., a psychologist and leading stress researcher at UC, San Francisco: "We know that stress plays a role in health and aging."

Epel's landmark study of mothers caring for chronically ill children made headlines in 2004 for providing a definitive link between stress and the aging of our cells. In that study, Epel and her colleagues compared the telomeres of mothers of healthy children with those of mothers who were caring for children with chronic conditions, such as cerebral palsy and autism. Both the length of time the mothers spent caring for an ill child and their own perception of how much stress they were under played a profound role in shortening their telomeres. In fact, the white blood cells of the mothers who perceived they were under a high level of stress aged the equivalent of 9 to 17 years more than those of the mothers who felt their stress was manageable.

Scientists are unsure exactly how stress shortens telomeres, but one theory is that the stress hormones cortisol and adrenaline play a crucial role. During a stressful event, your body releases adrenaline from the adrenal glands, which accelerates the heart rate, increases blood pressure and breathing, and prepares your body for emergency action—in combination, this is known as the fight-or-flight response. Next, as a sort of chaser, the adrenal glands release cortisol, which rushes to your brain to keep that response going through the crisis and help lodge the event in your memory. Once the emergency passes, your body returns to normal.

But during chronic stress, the system remains in the "on" position too long, overexposing your body to cortisol, adrenaline, and other chemicals. The results of this overloaded system can be devastating: repeated blood pressure surges speed up atherosclerosis (clogging of the arteries), and too much cortisol damages brain cells. "There is evidence that elevated levels of stress hormones cause the hippocampus, which is a crucial moderator of memory, to atrophy," says Marilyn Albert, Ph.D., a neurology professor at Johns Hopkins University and codirector of the Johns Hopkins Alzheimer's Disease Research Center.

So how long can you live with stress before it starts shortening your life? Most scientists won't hazard a guess. But Epel, who ran the study on the mothers of sick children, speculates that stress may turn harmful after about six months. "Anything less is just adjusting to life's events," says Epel. Those lucky ducks who let trouble roll off their backs fare better: studies of centenarians show that people who live a long time tend to let go of their stress easily.

Some people also produce more stress hormones than others, and some take longer to eliminate the hormones from their bodies, says McEwen, who adds that genetics as well as early exposure to stressful events (such as physical or emotional trauma as a child) may influence the amount of cortisol and adrenaline your body pumps out. In other words, it appears we can be programmed from an early age to respond to stress in a certain way. Finally, as some people age, they produce stress hormones longer and don't shut them off as efficiently, McEwen says. While these last factors are out of your control, there are things you can do to manage stress—and even reverse the damage it causes.

Break a sweat Besides keeping your weight under control, regular physical activity can promote the growth of neurons in the brain that are affected by chronic stress, studies in animals have shown. Exercise "stimulates certain factors in the brain that help to repair it and protect it," says Albert.

Sleep more Research has shown that poor sleep habits or interrupted sleep disrupts the balance of hormones in your body, specifically cortisol and the sleep hormone melatonin. Getting enough rest at night—six to eight hours—may help reduce cortisol levels, says McEwen. If you're so stressed out that you can't sleep, Jonathan Smith, Ph.D., director of the Roosevelt University Stress Institute in Chicago, recommends progressive muscle relaxation. "Tense up your shoulders and then let go," he says. "For every part of your body, you tense up for 10 seconds or so and then go limp for 20 seconds." Deep-breathing exercises may also help, he adds.

Learn to meditate Researchers have shown that a regular practice of meditation adds to the thickness of the cortex—a region of the brain, associated with attention and sensory processing, that tends to thin with age. The theory is that people with a thicker cortex may deal better with stress. One study of people who had been meditating for one to three years found that younger and older participants had equal cortical thickness in certain areas, suggesting that the practice of meditation can prevent the natural thinning of the cortex due to age, says Sara Lazar, Ph.D., a research scientist at Massachusetts General Hospital and lead author of the study.

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Make new friends Studies have long shown a link between a strong social-support network and reduced levels of stress. But maintaining friendships may be particularly effective for women. A landmark University of California, Los Angeles, study found that when women are under stress they release the hormone oxytocin, which is often called the cuddle hormone because it encourages women to "tend and befriend." The more they tend to their children and befriend other women, the more oxytocin they release, further producing a calming effect. Men don't get the same effect because the testosterone they produce when under stress counters the effects of the oxytocin.

Indulge in activities you enjoy Baking a cake, reading a book, walking the dog, climbing a hill and making it all the way to the summit—all can reduce stress if you enjoy them. "Any pleasurable, fun activity is going to lower your blood pressure and reduce your stress," says Smith. "Studies have also shown that owning a cat or dog can reduce blood pressure."

Rent a Marx Brothers movie A 2005 study at the University of Maryland School of Medicine found that laughter causes the tissue that forms the inner lining of blood vessels to expand, increasing blood flow to the heart and other organs. (Stress causes blood vessels to contract.) "There's nothing like a good laugh to break the intensity of a situation and give you some much-needed perspective," says Stephanie Marston, a marriage and family therapist and a frequent guest on the Today show. "When you laugh, your brain releases endorphins that create feelings of joy and euphoria. Having a sense of humor is a key facet in creating greater balance in your life."

Reassess your stress When you're particularly stressed, Marston recommends taking a few minutes at the end of your day to remember what you're grateful for. "Research indicates that people who focus on what they have are far more satisfied and fulfilled," she says. "By being specific about things for which you are grateful—your home, your family, your friends—you shift your attitude."

Just let go! In a memorable 1960s Anacin commercial, a housewife with a bad headache screams, "Mother, please! I'd rather do it myself!" She might have added years to her life by letting Mom pitch in. Making a conscious effort to eliminate stressors will help you feel in control, Smith says.

Karen Cheney is a health writer in Jenkintown, Pennsylvania. Not long after writing this story, she signed up for a meditation class.

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