Yahoo Lifestyle The perfect amount of stress
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Your company is making redundancies. You need dental work that’ll cost you hundreds. Your dad is admitted to the hospital again. And now that idiot driver on your left is swerving into your lane as he yaks on his mobile. You might just snap...
Stress, when it’s chronic or repeated, does more than unnerve us; it can make us physically sick. It dampens the immune system and dries out the digestive tract, setting the stage for disorders from irritable bowel syndrome to ulcerative colitis. It impairs memory and in extreme cases fuels anxiety. It can even gnaw away at the ends of chromosomes, pressing fast forward on cellular ageing.
It may come as a surprise, then, to learn this villain is also – paradoxically – a wellspring of life. Without stress, we’d be as good as dead. We wouldn’t have the gumption to slalom down Thredbo’s mountains, to ask for a pay-rise, or even to get out of bed. That’s because stress in appropriate amounts is the very stimulation that keeps us engaged with the world.
“Our goal isn’t a life without stress,” says neurobiologist Dr Robert Sapolsky. “The idea is to have the right amount of stress.” That is, stressors that are short-lived and manageable.
The stress 101
Good stress is when you feel a sense of control. No matter how your body responds in the moment, you know you’re going to come out fine the other side. A roller-coaster ride may send your stress-hormone levels soaring, but you know the ride will be over in minutes. In the words of Sapolsky, it’s “voluntarily relinquishing a degree of control and predictability in a setting that is benevolent overall.” Got that?
Duration is key, but so is your perception of the external event, says psychologist Wendy Berry Mendes. Do you frame the stressor as a challenge or a threat? Imagine you’re waiting in the wings before a presentation, flipping through your PowerPoint slides in your mind. Adrenaline shoots into your system; noradrenaline follows. Your heart rate increases, your hands get warm. Cortisol inches up. This is “challenge” stress.
“[Physiologically,] a challenge response looks a lot like aerobic activity,” says Mendes. Sex is a form of challenge stress. And good things come from challenge stress, including the growth of new brain cells. Resistance exercise also qualifies as challenge stress, when it’s not overdone.
But consider a scenario in which you’re so worried about the preso you can’t sleep the night before. The lack of sleep leaves your amygdala (an area of your brain that plays a role in memory and emotions) on high alert. Moments before the talk, you’re still mentally flipping those slides, but you can’t make out the images. Noradrenaline has beaten out adrenaline, causing more constriction than dilation of your blood vessels. Your heart rate increases, but less blood is pushed to the brain and body. Cortisol gushes. Your hands go cold and your mind goes blank. This is “threat” stress. Uh-oh.
The story worsens if the threat becomes chronic. Then you experience what neuroendocrinologist Dr Bruce McEwen calls “toxic” stress: you’re overwhelmed and feel out of control. “Things are coming at you left and right,” he says. “You can’t keep up with them. There’s the danger of developing a sort of ‘learned helplessness’” (ie, not even trying to cope anymore). “The more threatened you feel, the less capable you feel,” says McEwen, “and the worse your physiology is going to be.”
A tipping point? Is there an identifiable tipping point – a place where, through physiological cues, we know we’ve slipped past good stress and into the danger zone? When it comes to the performance of specific tasks, there is. In the first phase of the stress response, when just adrenaline and noradrenaline are flowing (see box “Your body on stress”), performance improves, whether the challenge is mental (taking a driving test) or physical (scuba diving). But once cortisol joins the party, everything changes.
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For years, stress researchers have noted a relationship between cortisol levels and the ability to remember things – in particular, those with an emotional component. Increased levels of cortisol affect memory in a hill-shaped curve: a boost in cortisol ramps up the ability to remember – up to the top of the hill. But after that point, memory decreases as cortisol levels continue to climb. Too much of a good thing becomes a bad thing. If you’re stressed and your memory starts to go, you know you’ve crossed the line.
But if the stressor continues, the memory-enhancing receptors fill up, so cortisol finds a different type of receptor to attach to – one that can disrupt memory long-term by causing dendrites in your hippocampus (the part of your brain involved in memory), to wither. So think of a dendrite as an old-fashioned phone line: it’s a fibre-like projection at the end of a brain cell that receives electrical messages from other brain cells. Retract that line and you mess up the message.
Hmm, so what’s a stressed-out woman to do?
There is no uniform right amount of stress. Each of us has a different stress threshold (ie, the degree of stress needed to benefit or harm us) depending on our history and even our genetic make-up. For sure, there are events that are universally rated high stress: you lose your job or a loved one, a tropical storm floods your house, you’re in the middle of a messy break-up.
But what matters most regarding health and even longevity is not the event itself but how you respond to it. And how you respond – emotionally and physiologically – depends on how you perceive it.
Consider the flood scenario: you come home and water is rising in your living room as high as your coffee tabletop. Your partner is pacing, his hands are clammy, his breath is shallow. He’s headed towards hypertension, or worse. You, on the other hand, feel your heart rate pick up. You know what to do. You jump back in your car and race to Bunnings, where you grab the last portable pump from the shelf. Home again, you feel a glow as water gushes out of the house.
Related: What it feels like to have a stroke at 27
Our perceptions spring from our disposition, which arises from our history and our genes. Whereas emotions and mood are fluid, dispositions are more fixed. Someone who’s generally anxious is likely to see a stressor as a threat, while someone who’s resilient will see that same stressor as a challenge. In the anxious person, the prefrontal cortex may be less well developed and so have less control over the amygdala and its access to fear memories.
“People prone to anxiety, post-traumatic stress disorder or depression have imbalances in those circuits and their underlying chemistry,” says McEwen. “And that makes them react to a situation in a more anxious way than another person. So, the idea of how much stress is too much is as much an internal or individual problem as anything else.”
Regardless of your upbringing or personality, there is good news: science has shown we can all alter our perceptions. We can, with training, transform a threat into a challenge. We can even stress-proof our brains, raising our overall stress threshold. And when stressors subside, most of the damage (eg, retracting dendrites or developing an overgrown amygdala) can be reversed. We can improve our overall health and add years to our lives.
A University of California, San Francisco, US, study led by Mendes shows one way to do this is by reappraising our own physiological responses. How we interpret a racing heart and quickened breathing can determine whether we’ll experience good or bad stress.
Mendes and her colleagues found that subjects who were prepped to interpret stress-related physiological responses as positive had increased cardiac efficiency and more blood vessel dilation than those who were either prepped to ignore a stressor or not prepped at all. In other words, whether the subjects experienced challenge stress (warm hands, alert brain) or threat stress (cold hands, mind blank) depended on their appraisal of their own physical state.
“In both cases, you’re experiencing increased arousal,” Mendes says. “But there’s a fork in the road: you can shift to a more positive response to the stressor. You activate which way you are going to go.”
So the next time you’re beside yourself about a big presentation – or any onerous task – consider how Mendes’ subjects handled a speech that was delivered to two scowling evaluators. One group of subjects read articles about how physiological responses to stressors aid performance, another read articles about how ignoring stressors was most helpful (they were told to look away from the frowning evaluators) and the third didn’t read any articles beforehand.
The benefits of the first group’s reappraisal extended beyond their ability to wow an audience. Those prepped to interpret racing hearts as positive adopted a “glass half full” frame of mind: in a test, they were less likely to latch onto negative words like “failure” or “fear”.
Mendes (fittingly) calls her paper Mind over matter and kicks it off with a prescient quote from US psychologist and philosopher William James: “The greatest weapon against stress is our ability to choose one thought over another.” Can you feel your blood pressure dropping already?
4 ways to instantly stress-proof your day
1 Reinterpret a neggy experience Say you leave your headphones in the car when you go to the gym. Interpret the return trip to the car not as irritating, but as a chance to warm up before you even get on the treadmill.
2 Share your troubles Brain scans show that the same circuitry fires up when we feel emotional pain as when we feel physical pain. But that circuitry is slower to react in those with greater social support in their daily lives. Have a vent sesh to a mate.
3 Remember the good stuff Even in the middle of a stress storm there’s at least one good thing you experience each day. Make it “real” by telling someone about it or writing it down. It can be as small as getting the “thanks wave” when you let someone into your lane.
4 Work out We can’t stress this enough (geddit?). Exercise works as a mild or “good” stressor: 150 minutes of moderate-intensity exercise a week is linked with both reduced stress levels and increased growth of new brain cells. As if you wouldn’t.
