You've probably heard that stress can seriously up your risk of high blood pressure, heart attacks and other heart problems.
While researchers aren't sure exactly why, the research is unanimously in favor of relaxation for your heart's sake. "There are studies to show that stress is comparable to other risk factors that we traditionally think of as major, like hypertension, poor diet and lack of exercise," Kathi Heffner, Ph.D., assistant professor of psychiatry at the Rochester Center for Mind-Body Research at the University of Rochester Medical Center in New York, told Health.com.
Intense, sudden periods of stress or shock, like a breakup or even winning the lottery, can trigger such a rush of adrenaline that the heart can't function properly, resulting in heart failure or heart attack-like symptoms. In the case of a breakup or death of a loved one, this has become known as broken heart syndrome.
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Sheldon Cohen, Ph.D., a psychology professor at Carnegie Mellon University, has been at the forefront of stress research since the 1990s. Early on, he showed that chronic stress lasting more than a month but less than six months doubled a person's risk of catching a cold.
His more recent research has tried to figure out why, and results seem to point to inflammation. It appears that stress hampers the body's ability to fight inflammation, by making immune cells less sensitive to the hormone that "turns off" inflammation, HealthyDay reported.
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A March study found that, at least in mice, chronic stress impaired the prefrontal cortex, the part of the brain involved in abstract thought, cognitive analysis and detecting the appropriate behavior for a given situation. Previous research in mice also showed that shorter bursts of stress impaired the centers of the brain involved in memory and learning, and left the mice struggling to remember how to find their way through a maze.
A number of studies have also found that stress increases the amount of certain proteins in the brain that have been linked to Alzheimer's, possibly accelerating the development of the disease.
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A 2007 University of Cambridge study found that people who coped the best with stressful life events had a 24 percent lower risk of stroke. It may be partly due to the fact that people who handle stress well often are healthy in other ways, like exercising regularly and not smoking.
A 2011 study examined the specific effects of work-related stress, and found that among middle- and upper-class men, psychological stress caused about 10 percent of strokes.
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Studies have shown that chronic stress can kill brain cells, and even prevent the creation of new ones, in the hippocampus, a part of the brain involved in a healthy response to stress, according to Time.com. In 2011, a study in mice illustrated these findings and began to explain one possible way antidepressants work. The mice exposed to a stressful situation didn't want to eat, gave up during a swimming task much faster and exhibited "pleasurelessness" -- similar to human depression symptoms like loss of appetite, sadness and hopelessness.
In humans, the prolonged presence of stress hormone cortisol can reduce levels of serotonin and dopamine, which are linked to depression.
Stress is also likely to exacerbate mood problems in people with a history of depression or bipolar disorder, and could trigger relapse.
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It's no surprise that when you're under stress, you might not always be thinking so clearly. But a 2012 study found that stress seems to actually change how we weigh risks and rewards, and can cloud our judgment when we are faced with important decisions.
Counterintuitively, stressed-out people actually tend to focus on the positive, and may ignore the cons of the decision they're about to make, one of the study's authors, Mara Mather Ph.D., a professor of gerontology and psychology at the University of Southern California, said in a statement.
That may also help explain why alcoholics crave a drink more when they're under pressure. "The compulsion to get that reward comes stronger and they're less able to resist it," Mather said.
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We love a good comfort food every once in a while, but reaching for foods high in fat and sugar too often can pack on the pounds, and stress makes it harder to resist. Cortisol increases appetite, and may even specifically encourage junk food cravings.
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It's a vicious cycle: You're stressed about that presentation at work, so you break out, and then you're stressed about the breakout! Researchers aren't exactly sure why, but stress seems to up the amount of oil produced by the skin, clogging pores and causing acne, according to WebMD.
Flare-ups of other skin problems, like psoriasis, have also been linked to stress, and can be equally stressful themselves. But relaxing really helps: A 1998 study found that psoriasis plaques cleared up more quickly in people who regularly meditated.
One of the big reasons that women lose that lovin' feeling is stress, but men aren't immune either. In fact, Kinsey Institute researchers found that stress zaps the libido of around 30 percent of men (although another 21 percent said it actually increased their sex drive.). "Men are more likely to see sex as a stress reliever, whereas for many busy women, their husband's desire is just another demand on their time and energy," Alice Domar, Ph.D., director of the Mind/Body Center for Women's Health at Boston IVF told Ladies Home Journal.
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While research on the effects of stress on cancer growth are largely inconclusive, there is some evidence pointing toward a link between stress and breast cancer aggressiveness.
Relaxing not only seems to delay the progression of the disease, but may also speed recovery.
And if you're currently cancer free, relaxing now can keep you healthy later. A 2003 study found that stress may double a woman's risk of developing breast cancer down the line.