The truth about stress: from the benefits of the ‘good kind' to the exercise that only makes it worse

The Guardian

18-04-2025

True (up to a point)The way stress manifests is very much bodily, centred around hormones such as cortisol and their effect on us. But this process is triggered by the brain (notably the amygdala and the hypothalamus) and the way our brains react to stress is often set in early childhood, even in the womb. Pregnant women who experience extreme stress can give birth to infants who react more strongly to stress hormones – with increasing evidence suggesting that this causes modifications to the baby's DNA. Self-actualising your way out of stress is difficult – not least because the causes might be serious and inescapable – but not always impossible. Some studies have shown that if you tell people they are the sort of person who doesn't feel stress, they experience fewer symptoms. One US study found that teenagers growing up with worries about violent crime in a deprived part of Chicago tended to fare better if they simply tried to not think about it.
FalseStress is central to the human existence, and its most obvious and visceral manifestation – our fight-or-flight response to immediate threat – has evolved to protect us from danger. There is also evidence that it can help us concentrate. A study of video game players taking part in a tournament found that those who showed barely any rise in cortisol levels fared the worst, and those with the highest increase performed moderately. Winners tended to have some extra cortisol, but not too much. This hormonal and psychological balancing act is different for everyone, so gauging the 'right' amount of stress is difficult. But as a broad guide, stress is less likely to be harmful if it is predictable, and particularly if it is voluntary. Studies have shown that conducting an orchestra makes the body show multiple signs of apparent stress. But this is the stress of exhilaration, which is less likely to cause ill effects.
FalseFor decades the study of stress was based entirely around men, and often centred on the better-off. The breakthrough came with a pioneering Swedish study which found that people who had high demands on their time but little control over their lives tended to be the most stressed. Subsequent research has shown how unavoidable demands, whether through caring responsibilities or having multiple jobs, are especially stressful. These findings are central to much of the understanding about modern stress, particularly that connected to work. Sir Michael Marmot, the pioneering researcher into health inequalities, has argued that jobs like those in an Amazon-type warehouse, where the pace is relentless and every movement is tracked, are 'as if we took everything we knew about psychosocial work hazards, put it in a syringe and injected people with it'.
FalseMuch of our modern understanding of stress is based on experiments with laboratory rats carried out in the 1930s by Hans Selye, an Austrian–Hungarian doctor and researcher who discovered that repeated and chronic triggering of the body's hormonal alarm system can harm health. But even the Victorians worried that innovations like rail travel and the telegraph were too much for humans to deal with. George Miller Beard, the highly creative populariser of the disorder he called neurasthenia, used his evocatively titled 1881 book, American Nervousness, to blame stress on everything from science to civil liberties and 'the phenomenal beauty of the American girl of the highest type'. Is modern stress any worse? It is certainly different. Compared to a Victorian, a 21st-century Briton has a state-provided safety net, decades' more life expectancy and a child mortality rate about 60 times lower. There is, however, much focus on whether information overload from things like phones is a new type of stress. It is a reasonable concern, particularly for children – but it's far from new. The term 'information overload' was coined by Alvin Toffler, a US author whose bestselling book Future Shock argued that the pace of change in society caused by things like modern technology was simply too much for people's brains – in 1970.
Mainly falseIn his 1972 poem The Shoelace, Charles Bukowski noted that while humans can generally cope with major upheavals, what eventually proves too much is the 'continuing series of small tragedies' – everything from the 'shoelace that snaps with no time left' to an unexpected bill. He was right; repeated studies have shown that stress tends to affect people most when it is chronic. But it's also important to note that the scale of a worry is relative. What qualifies as a 'minor' stress is entirely personal and subjective, and dependent on everything from personal circumstances and background to income – a single larger-than-expected bill can be catastrophic if you're poor. There are some ways that stress, or at least its effects, can be mitigated. But don't let anyone tell you that a particular cause of stress is minor. That is entirely a matter for you and your body.
FalseThere are endless studies showing that physical activity can alleviate stress symptoms. But other research has shown that very high-intensity exercise can worsen matters. One study put volunteers through either a gruelling mock job interview process or a physical test using a stationary bike. While post-test questionnaires showed those in the latter group perceived themselves to be less stressed, their cortisol levels were higher, and stayed so for hours after. Cortisol itself is not a problem for the body. It plays a central role in maintaining things like blood glucose levels, and also acts as a hormonal alarm clock, rising gradually during the night to a morning peak to help get us out of bed. The problem comes with the chronic triggering of the body's stress response. So, how to avoid this with exercise? One tip is to make sure it doesn't feel like a chore – research has shown this can be particularly stressful. Another is to see if less intensive exercise, perhaps even something like yoga, helps. But as ever, there are no firm rules. Everyone is different.
True and falseSome people lose weight under chronic stress. But around two-thirds of people are more likely to put it on. There are two different factors at work, and one is hormonal. Studies have linked consistently high levels of hormones like cortisol with a propensity to store fat around the stomach. Also, research has consistently shown that stress tends to push people towards less healthy eating choices. There is an entire sub-genre of studies in which volunteers are placed under artificial stress, presented with a table of various foods, and told to snack as they please. Each time, those exposed to stress gravitate towards fatty, sweet or salty choices, and eat more overall than the control group who were not stressed.
True
The same fight-or-flight hormonal alarm system exists in mammals, birds, fish, amphibians and reptiles. And this is not just about existential threats. Studies of baboons have shown that lower‑ranked animals in a troop display higher levels of stress hormones. But what is unique about humans is the idea of chronic anticipatory stress. As Robert Sapolsky, a US biologist who spent two decades studying Kenyan baboons, once joked: 'It is startling to realise that a vast length of time ago, while evading a predator or pursuing a prey, a dinosaur secreted glucocorticoids … [But] no dinosaur ever worried itself sick from perseverating on the absurd idea that an asteroid might strike Earth.' For humans, anticipatory stress serves a purpose. For example, if you were blithely unworried about taking an exam, your study regime might be a bit relaxed. Simply telling people not to worry about future events is pointless, and you should never feel guilty about worrying.
Very, very falseThere are two immediate and very obvious reasons why this is wrong. Stress is often imposed by inescapable external factors, and people's bodily response to it can often be exacerbated by their backgrounds, notably their childhood and infancy. But there is more to it: stress acts in such a way as to make it even harder to escape the circumstances which cause it, like poverty. One US study found that when poorer people were asked to think about an entirely hypothetical car repair bill, they performed less well in a subsequent cognitive test. Other studies have quantified this effect variously as being about the same as losing an entire night of sleep or shedding close to 15 IQ points. This is not a minor impact.
True (and yet not)This is correct in the sense that stress can often be imposed by your life circumstances and the preset way your body reacts. But the physical manifestations of stress are more possible to address. For example, while chronic stress can make you more likely to develop metabolic ailments such as type 2 diabetes, being more physically active can reduce this risk again. Some diets can have a similar effect, with studies showing that ones including a lot of green vegetables and foods rich in polyphenols, known for their anti-inflammatory properties, can reduce cortisol levels. Psychotherapy can also help with our in-built responses to stress. And research has shown the stress-reducing benefits of everything from more sleep and better-quality social relations to certain music, aromas and, at least in the short term, simple human touch. What works for one person might not for another, but one of the curiosities of stress is that its very slipperiness, the way it presents such a broad front in its impact on humans, also gives lots of ingress points when fighting back.
Stress Tested: How the New Science of Stress Hormones Can Transform Your Health by Dr Richard Mackenzie and Peter Walker is published on 24 April (Bluebird, £22). To support the Guardian and Observer, order your copy at guardianbookshop.com. Delivery charges may apply.