Few words in the English language conjure up more negative emotions than stress. The mere mention of those six letters might elicit mental images of looming work deadlines, unpaid bills, the pressure of exams or tense family Christmases, to list just a few scenarios.
But what if I told you that stress can also be positive? That just as it can harm us, it also plays a key role in strengthening our immune system, forging connections in our brain that improve mental performance and building the resilience we need to navigate our way through the vagaries of life.
This first came to light through the work of an American psychiatrist called Firdaus Dhabhar, then a researcher at the Rockefeller University, New York, who was studying the connection between short-term stress and the immune system as part of the fight-or-flight response. In the mid-1990s, stress was viewed as almost unanimously bad for us, but to Dhabhar this was illogical. From a Darwinian perspective, the survival instincts of our animal ancestors would have been honed through repeated brushes with danger.
“It does not make sense that stress should always be a bad, harmful, negative entity,” he says. “The fight-or-flight stress response is essential for survival. A gazelle needs this response to escape the jaws and claws of a lion, just as a lion needs it to catch its meal. Mother Nature gave us this response to help us survive and thrive, not to kill us.”
For example, the tension of an upcoming race helps prime the cardiovascular and musculoskeletal systems of athletes for optimum performance, while surveys have even found that the stress of needing to get work done alongside childcare means that parents are likely to be more productive home workers than singletons.
Both mild-to-moderate physical and mental stress stimulate the production of chemicals in the blood called interleukins, activating the immune system and making it more able to fight off infections, while stress can even affect the development of children before they are born. Babies born to mothers who experienced mild everyday stress during pregnancy had more advanced developmental skills by the age of two, compared with the children of mothers who had enjoyed a relatively relaxed, unstressful pregnancy.
There are also various ways to think about stress. As well as the pressure and tension inflicted by life events, different forms of exercise can be viewed as stress for the muscles, while various types of cognitive challenges can be considered as stress for the mind.
Over the past 20 years, Dhabhar and others have shown that bouts of short-term stress can aid us in the modern world. A Ted Talk by Dhabhar, now a professor at the University of Miami, on the positive effects of stress has garnered 30,000 views on YouTube.
Exercise physiologists found that Marchand, who had begun serious competitive cycling in retirement at the age of 68, had an aerobic capacity for exercise – the gold standard means of measuring cardiovascular fitness – comparable to men aged 42 to 61, half a century younger than him.
Scientists researching healthy ageing now regard him as an indicator of what can be possible if we continue to apply manageable stress to our muscles, blood vessels and heart as we age. But most humans are not like Marchand. Many of us become progressively inactive as the years tick by, which exacerbates any age-related changes already taking place. As a result, if our muscles are not being stressed, their fibres slowly atrophy and we grow progressively weaker. The interaction between the nervous system and the muscles also becomes less efficient without regular use, slowing our reaction times and making us more vulnerable to falls
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