Stress has measurable and significant physical and mental health impacts (a Yale study found chronic stress can actually shrink your brain), and we hear quite a bit about it, as researchers continue examining its long and short-term influence. They've even determined that stress is contagious.

We know that chocolate has very real anti-stress properties, and that eating a diet high in greens and veggies helps mitigate some of the negative physical effects of stress.

But what's not often talked about is that some stress is beneficial. This is not the chronic stress that can hurt you, but the heightened emotional state one feels before speaking in public or writing an important paper. Scientists have found that our abilities peak under moderate levels of stress. And as long as it doesn't go on too long, that short-duration stress isn't unhealthy.

Stress and anxiety are unavoidable elements of our lives and sometimes can have benefits.

"Moderate levels of stress can have an inoculating function, which leads to higher than average resilience when we are faced with new difficulties,” says psychologist Lisa Damour, Ph.D. who spoke at the American Psychological Association’s annual conference in Chicago

Thinking of stress and anxiety as sometimes helpful and protective lets people benefit from it, Damour says. They alert you that there's something in your environment that might need to change. If you're worried about a test or presentation, then the anxiety tells you that you need to study. If you are anxious while driving, the stress tells you to pay attention.

But the key is not to worry if you are stressed sometimes.

"We want to support well-being, but don’t set the bar at being happy nearly all of the time. That is a dangerous idea because it is unnecessary and unachievable,” Damour says. “If you are under the impression that you should always be joyful, your day-to-day experience may ultimately turn out to be pretty miserable.”

Keeps the brain alert

hands on steering wheel in traffic Stress plays the job of keeping you alert and telling you to pay attention. (Photo: MvanCaspel/Shutterstock)

A study at the University of California, Berkeley, found that “Some amounts of stress are good to push you just to the level of optimal alertness, behavioral and cognitive performance,” said Daniela Kaufer, associate professor of integrative biology at the UC Berkeley, in a news release.

Those stress hormones can help animals (and people) adapt to changing environments. For example, we are more likely to remember something if it was accompanied by some level of stress.

“I think intermittent stressful events are probably what keeps the brain more alert, and you perform better when you are alert,” post-doc Elizabeth Kirby told Forbes magazine.

However, when those stressful events are continuous, the opposite occurs and the memory is impaired, she said.

The key is keeping stress limited to a few moments. When we do, there can be multiple benefits, including longevity, as another study revealed.

Researchers found a newly described form of stress called chromatin stress triggers a response in cells that leads to a longer life. Although the research was done in yeast, if it has the same response in humans, it could lead to new treatments in the aging process.

Understanding stress

So how do you know when stress is healthy or not? There isn't an exact answer, and on top of that, individual people vary in their response to stress. But one way to mitigate stress is to actively address it. Ignoring it by vegging out in front of the TV or drinking wine doesn't address the deeper levels (or causes) of stress. And those people who do manage stress — people who are generally skilled at managing their emotions — are more likely to perform at higher levels.

So minimizing stress is tactic A, but tactic B is actively managing the stress and emotions you have in response. Getting quality sleep, meditating, exercising, banishing negative self-talk and engaging in positive thinking, deep breathing, spending time with friends, taking time off, and disconnecting from work are all active ways to deal with stress.

Editor's note: This story has been updated with new information since it was published in August 2014.

Starre Vartan ( @ecochickie ) covers conscious consumption, health and science as she travels the world exploring new cultures and ideas.

Why some stress is actually good for you
We often hear about the negative impacts of stress, but some stress is necessary — and even healthy.