YOU know that person. The one who uses a delayed train as an excuse to get stuck into a good book. The one who can make a joke 10 seconds after breaking their ankle. The one who loves giving presentations and never falters under pressure. They seem to float through life unfazed by the stress that can overwhelm the rest of us. What’s their secret?
Are they blessed with stress-resistant genes? Did their upbringing make them exceptionally resilient? Have they learned specific ways of coping with life’s challenges? Or do they just know how to avoid stress altogether? To answer these questions, researchers have been examining how humans and animals react and adapt to adversity, identifying those who are particularly resilient to stress and teasing apart the factors that contribute to this ability. It is a journey that has taken them from and interrogation chambers in North Carolina to fire stations in Indianapolis and humour classes in Austria.
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This work is helping the military recruit candidates for high-stress jobs. It has also led to the first human trial of a “stress vaccine”, with the potential to inoculate us against its devastating effects, from post-traumatic stress disorder (PTSD) to depression. But there is a bigger pay-off to understanding the secret of stress-free living. Knowing why some people handle stress better than others, and the things we might all do to improve our resilience, won’t just help all of us manage life’s daily struggles better, it might also teach us how to use stress to our advantage.
One thing is for certain: whether you are running late for an interview or coping with a personal loss, stress is unavoidable. In 2018, the largest known study of showed that three-quarters of people had been so stressed in the past year that they had felt overwhelmed or unable to cope. It can be so damaging to our well-being that one in three of these people had been left feeling suicidal, and one in six had self-harmed.
Yet, stress is also an essential physiological response that allows us to quickly adapt to the world around us. What we call stress is actually a chemical reaction that begins in our brain, specifically the amygdala, which is on constant surveillance for any potential threat. The amygdala combines sensory information with memories of similar situations to judge whether an emergency response is required. If alarm bells ring, a distress signal is sent to the hypothalamus – a small nodule near the base of the brain – which activates two major pathways. The first triggers our ancient fight-or-flight system, which pumps out adrenaline, making us more alert by increasing our heartbeat and the efficiency of our breathing and forcing more blood into our muscles. The second prompts the release of other hormones, including cortisol. This keeps the stress response active and releases stored glucose to give us more energy. It also suppresses our digestion, immune system and inflammation, to focus resources on the immediate threat. When the threat has passed, cortisol levels drop, helping to bring all these chemicals back to their original levels.
Runaway response
This is all very handy when you are facing a poisonous snake or an oncoming vehicle because it enables you to start taking evasive action before you have even registered the threat. It also allows you to concentrate on your work as a deadline looms, and focuses your thoughts when speaking in front of an audience. But sometimes the stress response kicks in unnecessarily or is so powerful it overwhelms us. Sudden or severe stress can result in PTSD and depression. And low-level, chronic stress creates a slew of health problems. With no let up, raised levels of adrenaline can damage blood vessels and increase the risk of heart attack and stroke. Cortisol can cause digestive problems, weight gain and diabetes. And constant modulation of the immune system can lead to fatigue and physical and mental health issues.
Whether stress has positive or negative consequences often depends on how we deal with it. Your reaction to stress and how quickly you return to normal when the stressor has passed is called resilience. This is what varies significantly between individuals. But what makes some of us so resilient while others struggle to cope?
There is no doubt that upbringing plays a part. Animal experiments demonstrate that early trauma affects an individual’s response to stress as an adult. Testing this link in humans is difficult, though, given the diversity, frequency and severity of events that can negatively impact a child. One of the few studies to give an insight is the , a one-of-a-kind study of children raised in Romanian orphanages. In total, 136 children were randomly chosen from six institutions, half of whom were fostered between the ages of 6 months and 30 months. When the children were around 12 years old, a team led by at the University of Washington, Seattle, assessed their response to stress-inducing tasks. Analysis of their saliva revealed that those who had been fostered had similar cortisol levels to a control group of children living in nearby families – but only if they had been placed in foster care before the age of 2. Those fostered later or who remained in orphanages had a blunted stress response, producing less cortisol.
Sensitive period
This might seem like a good thing because it suggests that these children were less easily stressed. In fact, it seems to be a manifestation of underlying damage to the normal stress response, and is associated with long-term behavioural problems and an increased risk of depression. Other research hints at what is going on, revealing that the first two years of life are a sensitive period in which our environment is particularly likely to cause that influence the stress response. The mechanisms are probably numerous, but research led by Linda Chao at the University of California, San Francisco, suggests that in the brain’s grey matter, where the cell bodies of neurons are found. Myelin normally forms an insulating sheath around nerve fibres, but in grey matter it prevents new connections forming between neurons, and is linked with PTSD and depression.
As for which aspects of the early environment are key to healthy development, experiments point to social interaction, stimulation and parental support. Developmental psychologist Suniya Luthar at Arizona State University identifies the single most important factor in developing stress resilience as a strong, supportive, dependable relationship with your primary caregivers. “But adults who did not have a good childhood experience are by no means doomed,” she says. “If they are able to find the same ingredients – dependable, supportive, close relationships – the ill effects of childhood adversity can certainly be reduced.”
Moreover, an individual’s ability to cope with stress isn’t purely down to early life experiences. Genes also play a role, especially those involved in the production of a chemical called neuropeptide Y (NPY). Exactly how this works is unknown, but animal experiments suggest that NPY acts as a kind of . Faced with a threat, production soars, helping to instigate a rapid response, but levels quickly return to normal once the danger is over.
To assess NPY’s role in humans, studies often focus on members of elite military forces who perform well under extreme stress. For example, researchers at the US National Center for PTSD in Connecticut compared blood samples from US special forces and regular soldiers during a training exercise at Fort Bragg in North Carolina, where they were deprived of food and sleep, pursued by the “enemy” and interrogated when caught. This revealed that the special forces soldiers sustained higher levels of NPY for longer during the exercise. Their NPY also returned to its original level more quickly afterwards, showing that they were better able to recover from the stress they had experienced. In addition, the more NPY an individual released, the they reported during the training.
“Human studies often focus on members of elite military forces who perform well under stress”
We all inherit different variations of NPY genes. Some protect against stress, while others increase the risk of an impaired stress response and the . So perhaps these special forces soldiers hit the genetic jackpot. However, there are tantalising hints that we aren’t stuck with the NPY that our genes dictate. For instance, after a surprise simulated ambush, the NPY levels of marines who had previously completed an eight-week course on mindfulness than those of soldiers without such training.
Another common thread that links chilled-out people is to do with their personality, particularly their sense of humour. Research shows that people who see the funny side of life’s mishaps are likely to interpret and react to stress more positively, buffering themselves against some of the negative effects. For instance, in a study of firefighters, Michael Sliter at Indiana University–Purdue University Indianapolis, found that, in general, the number of symptoms of PTSD and burnout they reported correlated with the number of stressful situations they had been in over the past month. But firefighters who used humour more often as a coping mechanism were .
How to make a stress vaccine
We all produce a chemical called neuropeptide Y (NPY) that acts like an on-off switch to modulate our body’s stress response. Intriguingly, a single injection of NPY before a stressful experience seems to protect animals from some of the negative consequences of stress. This discovery inspired and Dennis Charney at Mount Sinai Hospital in New York to try a similar approach for people with post-traumatic stress disorder (PTSD). Their team gave each volunteer an intranasal dose of NPY before they read a story designed to elicit their PTSD. Although only a small pilot study, it hinted that NPY might offer relief from some PTSD symptoms. There was a problem though: it took an hour of inhalation and a specially designed gadget to get enough of the chemical into people’s brains.
Ketamine surprise
For this reason, Murrough and his colleagues have turned their attention to another chemical. Infamous as a party drug, ketamine may sound like an unlikely stress buster, but it is actually a mainstay of modern medicine, commonly used as an anaesthetic. It has also been found to have antidepressant properties. While testing these in mice, Rebecca Brachman, then at Columbia University in New York, made a surprise discovery. As with NPY, a single dose of ketamine can protect mice from the negative effects of chronic stress. It seems to work by increasing the brain’s ability to grow new neurons and form new connections.
Recently, Murrough’s colleague Sara Costi began the first human study to see if ketamine has potential as a human “stress vaccine”. Her healthy volunteers receive one dose of ketamine – less than people tend to take for recreational purposes – or a placebo. A week later, the volunteers give a presentation to a stern-looking panel, who provide negative feedback.
“We’re looking at whether pretreating people with ketamine has an effect on their stress response,” says Murrough. The team is also closely monitoring for side effects. But, he says, there are few of these with this low, one-off dose, and even if ketamine is needed several times in a year, the available evidence suggest that the benefits outweigh the risk.
Results are expected within the year. “It’s very exciting,” says Murrough. “We wouldn’t be advocating putting it in our drinking water, but perhaps we could give it to soldiers about to deploy on a mission, or to firefighters or police.” He acknowledges that using the stress vaccine in a non-combat scenario would be harder because stress is usually unexpected. “But there might be a window of time after the stress in which the drug might still be useful,” he says.
Laughing releases feel-good hormones thought to make us less likely to ruminate on or re-experience stressful events. It also helps us build relationships, providing the social support that is a key to resilience. But there is good news for anyone who struggles to find their funny bone. A pilot study in Austria put 35 people who were experiencing stress, exhaustion or depressive symptoms through a seven-week “humour training” course, including role play, finding humour in everyday life, cultivating playfulness and learning how to make others laugh. The training seemed to and increase cheerfulness, although it was limited by not having a control group.
An additional factor influencing your stress resilience is more surprising. Growing evidence points to an intimate relationship between gut bacteria and our mood and behaviour. What’s more, several studies have highlighted differences between the gut bacteria in people with stress-related conditions, such as depression and PTSD, and in people without these. Stress can also make your gut more leaky, allowing bacteria to escape into your bloodstream, which triggers inflammation that can lead to physical and mental health problems. One study, for example, found that couples experiencing the chronic stress of a bad marriage had But the relationship works in the other direction too. Mice given “good” bacteria called Lactobacillus rhamnosus for 28 days before facing chronic social stress were .
Although there are still major gaps in our understanding of the complex dialogue between gut and brain, there is substantial evidence that therapies aimed at changing the balance of microbes in the gut, and also what we eat, could have an exciting role in protecting us against – even reversing – the negative consequences of stress.
Cool profile
All this makes it clear that people who seem immune to stress are blessed with a combination of attributes. We still don’t have a scientific way to identify the ideal stress-resilient profile, but In one study, they randomly subjected half their wannabe recruits to a highly stressful prisoner of war exercise, while the others undertook mundane weapons training. Researchers wanted to compare their hormone profiles and any deterioration of cognitive functions in later tests to gauge the effects of stress. The aim is to use these markers in future selection exercises to identify candidates likely to struggle in stressful situations. They could also be used to monitor soldiers in the field and measure the impact of training on stress resilience.
Such a resilience profile would be useful for any employer needing to recruit people for stressful jobs. But what about the rest of us just wanting to cope better when we miss a train or attend an interview? Of course, there are plenty of ways to de-stress. Regularly listening to music seems to , and lowers blood glucose, making challenges seem less stressful. Exercise also boosts hormones that can act to lower perceived stress. Meditation, meanwhile, has a long history as a stress reliever, and research shows that can trigger brain changes related to better emotional control and stress resilience that are similar to those seen in long-term meditators.
In future, we may even be able to inoculate ourselves against stress (see “How to make a stress vaccine”). For now, James Murrough at the Mount Sinai Hospital in New York, who is working on this, recommends good mental hygiene. “This is about making sure you have the right resources in place to help you cope,” he says. Alongside regular exercise, sufficient sleep and time out to relax, you should also cultivate your social networks. “You have to put the work in to make sure your social ties are healthy so that when stress occurs you can rely on them,” says Murrough. “Data suggests that is your best bet for building resilience against daily stress.”
But don’t forget that a little stress isn’t a bad thing. In fact, it might just boost your cognition, if research on rats is anything to go by. A team led by Daniela Kaufer at the University of California, Berkeley, exposed rats to a stressful environment for 3 hours while tracking the development of new neurons in their hippocampus, a brain region responsible for memory. Intriguingly, in the stressed animals than in a control group. But the real surprise was the long-term effect. Rats that had been stressed did better in cognitive tests, even weeks later, specifically engaging their new neurons to help with these tasks. It isn’t yet possible to do this kind of study in humans, but we do know that new neurons allow us to learn better. “We think there are many similarities between animals and humans, but we’re not quite there yet,” says Kaufer.
Nevertheless, she is often asked what the perfect amount of stress is. “It’s impossible to give you an exact figure,” she says. “The ideal amount is going to be different from one person to another.” What someone finds invigorating, another may find daunting. On top of that, what feels stressful one day might not feel so another. “But if there is beneficial stress, then it’s likely to be something you can pinpoint yourself,” says Kaufer. “It’s probably the difference between the stress that paralyses you and the stress that you can push through, that makes you feel really great afterwards.”
The difference between stress and anxiety
Stress and anxiety are often intertwined in our minds, but they refer to different things. Stress is a biological process that results in a series of chemical reactions within our body and brain that help us focus on a challenging situation and adapt our behaviour (see main story).
Stress can be a positive or negative experience and although you may feel stressed for a few seconds, or a few weeks, it normally occurs within a discrete time frame.
Anxiety can be triggered by stress, but it is a feeling that tends to hang around after the initial threat or challenge disappears.
If anxiety occurs most days for longer than six months, it is known as This condition .
Find out how to eat healthily, lose weight, and sort the fads from science facts:
Article amended on 27 February 2020
We clarified when people suffered negative effects of stress.
