We know that a little stress can be inevitable in life, and not particularly detrimental to your health. However, when you’re constantly feeling under pressure — overwhelmed, anxious, completely frazzled — the effects can actually add up to something dangerous. As if a clear, peaceful mind wasn’t incentive enough to de-stress, we rounded up some of the scariest ways stress can wreak havoc on our bodies — from fueling cancer to raising the risk of heart attacks.

1. Fuels Cancer In Animal Studies

A recent animal study conducted by Wake Forest University researchers showed that stress could help cancer cells survive against anti-cancer drugs. The study, published in the Journal of Clinical Investigation, was done on mice induced to experience stress by being exposed to the scent of a predator. When experiencing this stress, an anti-cancer drug administered to the mice was less effective at killing cancer cells, and the cancer cells were actually kept from dying because of the adrenaline produced by the mice, Everyday Health reported.

2. Shrinks The Brain

Even for healthy people, stressful moments can take a toll on the brain, a new study from Yale University suggests.
Researchers reported in the journal Biological Psychiatry that stressful occasions — like going through a divorce or being laid off — can actually shrink the brain by reducing gray matter in regions tied to emotion and physiological functions. This is important because these changes in brain gray matter could signal future psychiatric problems, researchers warned.

3. Spurs Depressive Symptoms

A study in mice suggests stress could play a role in the development of depression. Researchers at the U.S. National Institute on Mental Health conducted several experiments on mice, where they noted how stress affected their behavior. They found that stress was linked with depression-like behaviors, such as giving up swimming in a plastic cylinder and lengthening the response time it took to eat food, TIME reported. “I think the findings fit well with the idea that stress can cause depression or that stressful situations can precipitate depression,” study researcher Heather Cameron, chief of neuroplasticity at the NIMH, told TIME.

4. Increases Risk Of Chronic Diseases

It’s not just the stress, but how you react to it, that could have an impact on your health down the road, according to a new study from Pennsylvania State University researchers. Published in the journal Annals of Behavioral Medicine, the study found that people who were more stressed out and anxious about the stresses of everyday life were, in turn, more likely to have chronic health conditions (such as heart problems or arthritis) 10 years later, compared with people who viewed things through a more relaxed lens.

5. Does A Number On Your Heart

Feeling anxious and stressed is linked with a 27 percent higher risk of heart attack — the same effect smoking five cigarettes a day has on the heart, the New York Daily News reported. “These findings are significant because they are applicable to nearly everyone,” study researcher Safiya Richardson, of Columbia University Medical Center, told the Daily News. “The key takeaway is that how people feel is important for their heart health, so anything they can do to reduce stress may improve their heart health in the future.” And not only could chronic stress raise a person’s heart attack risk, but it might also affect how well he or she survives after a heart attack. Reuters reported on another study, conducted by researchers at St. Luke’s Mid America Heart Institute, that showed that stress is linked with a 42 percent higher risk of dying in the two years after being hospitalized for a heart attack.

5. Makes Colds Worse

If you always suspected that stress was making you sick, you might be on to something. Research shows that stress has an impact on our immune systems, with one recent study in the Proceedings of the National Academy of Sciences even showing it can make colds worse. That’s because when you are stressed, your body produces more cortisol, which can then wreak havoc on your body’s inflammatory processes. The researcher of the study, Carnegie Mellon University’s Sheldon Cohen, explained to ABC News:

“You have people whose immune cells are not responding to cortisol and, at the same time, they’re exposed to a virus system creating an inflammatory response. But the body doesn’t have the mechanism that allows it to turn off the inflammatory response, which manifests as cold symptoms,” said Cohen.

6. Could Affect Cancer Outcomes

Cancer — the diagnosis, treatment, and even the time after it’s been “beaten” — is a stressful process, and research shows that managing that stress could improve outcomes of the disease. Researchers at the University of Miami found that undergoing a Cognitive-Behavioral Stress Management program seemed to have a positive effect on breast cancer patients’ immune system cells. “For the women in the CBSM groups, there was better psychological adaptation to the whole process of going through treatment for breast cancer and there were physiological changes that indicated that the women were recovering better,” study researcher Michael H. Antoni, a professor of psychology and psychiatry and behavioral sciences at the university, as well as program leader of biobehavioral oncology at the Sylvester Comprehensive Cancer Center, said in a statement. “The results suggest that the stress management intervention mitigates the influence of the stress of cancer treatment and promotes recovery over the first year.”

7. Could Affect Your Offspring’s Genes

The effects of stress on a person’s genes may be passed on from generation to generation, according to a recent Science study — suggesting stress’s effects may not just take a toll on the person itself, but the person’s progeny, too. New Scientist reported on the research, which was conducted in mouse germ cells (before they become eggs or sperm) by University of Cambridge researchers. They reported that certain markings to the genes, influenced by outside factors like stress, are generally thought to be erased in the next generation. But the new study shows that some of these markings to the genes still exist in the next generation.

“What we’ve found is a potential way things can get through, whereas before, everything was considered to be erased,” study researcher Jamie Hackett told New Scientist.

For easy and effective ways to deal with stress in your life, and reduce its impact on your health, read more here and here.