Just after seven in the morning
The alarm goes off. Cortisol floods the body, a chemical wake-up call that pulls us out of sleep. Later, on the way to work, we sprint after the tram. The heart pounds, adrenaline shoots through the veins. Made it. Back at the office, the body winds the stress hormones down again. Everything is going to plan. This is what healthy stress looks like: an ebb and flow, a dance between tension and release.
But what if the race never stops? If the body runs constantly at full throttle, driven by an invisible engine that knows no pause? According to the current Sanitas Health Forecast Study 2025, a quarter of the Swiss population feels frequently stressed. Among those under 30, the figure rises to 40 percent. Chronic stress is no longer a fringe phenomenon. It sits in offices, kitchens, and children's bedrooms. The question is no longer whether we have stress. It is: how do we deal with it?
Resilience is not a personality trait
Many people think of resilience as a kind of armour for the soul. A character trait that some people have and others simply do not. Or, better still, a gene that shields us from life's storms. That is not the case, says Birgit Kleim, psychologist at the University of Zurich. Together with neurobiologist Isabelle Mansuy, she leads the flagship research project STRESS. "We tend to think of resilience as the ability to adapt flexibly in moments of stress."
Christian Ruff, neuroscientist on the same project, puts it this way: "Resilient people are characterised by cognitive and emotional flexibility. They can adapt optimally to a given situation and then return to equilibrium as quickly as possible." Like tightrope walkers who keep their balance without falling. Not because they never wobble. But because they know how to catch themselves.
"Resilient people are characterised by cognitive and emotional flexibility, by the capacity to adapt optimally in moments of stress and to regain their footing swiftly afterwards."
This flexibility is measurable. Kleim and Ruff, together with neuroeconomist Marcus Grüschow, studied medical students at the University of Zurich. The students spent two years working through theory, then found themselves suddenly standing in the emergency ward. A massive stress test. The researchers wanted to know: who copes? And why?
A system in the brainstem plays a decisive role
Before the placement, the students underwent a stress test in the laboratory. While lying in a magnetic resonance tomograph, they were confronted with contradictory emotional information. The researchers were particularly interested in one region: the locus coeruleus-norepinephrine system (LC-NE) in the brainstem.
"When we are under pressure, this system releases noradrenaline," explains Ruff. "It is, so to speak, the body's own caffeine." It dilates the pupils, raises blood pressure and heart rate, and sharpens perception and attention. From an evolutionary perspective, it puts the body on a war footing.
The key finding: students whose LC-NE system responded more intensely and for longer to conflicts in the laboratory reported anxiety and depression symptoms more frequently after the emergency placement. By contrast, their peers with a more flexible response had fewer difficulties. "Where the brain was able to adapt more flexibly, resilience was more pronounced," says Ruff.
Training via the pupil
What initially sounds like pure basic research has practical consequences. Because the pupils reveal, from the outside, how strongly the arousal system is activated. "We can use that for neurofeedback training," says Kleim. People learn, in a playful way, to regulate their own stress arousal system.
Two start-ups have already emerged from the research project, developing exactly these kinds of training tools. The idea: anyone who can see their own stress level in real time can learn to control it consciously. Not through willpower alone. But through feedback that shows what actually works.
When stress is inherited
Isabelle Mansuy, neuroepigeneticist on the STRESS project, investigates the long-term consequences of chronic stress. Her research with mice shows: sustained stress alters the epigenetic signature. That is, the biological "control software" of our genes, which determines which genes are activated or suppressed.
"Chronic stress can negatively affect our entire body," says Mansuy. "The brain, the immune system, the cardiovascular system, the blood count, bone quality, and the microbiome." The consequences of stress in early childhood are particularly severe: unstable relationships, abuse, neglect, physical and verbal violence. "The health consequences often only appear much later in life," says Mansuy. "Many children therefore go undiagnosed."
More remarkable still: the negative consequences can be inherited, at least in mice. The stress-related epigenetic changes are passed on to the next generation, along with the risk for certain diseases. But, and this matters, resilience may also be epigenetically inherited. Because by no means all people who have been exposed to chronic stress go on to develop illness.
Learning from real life
Objective stress does not exist. How burdens are perceived depends strongly on the individual: on their biology, their biography, their environment. The Zurich researchers therefore study not only in the laboratory, but also in everyday life, together with George Bonanno of Columbia University, one of the world's leading resilience researchers.
"Many people think resilience is a specific trait of a person, or that there is even a resilience gene. But that is unlikely."
"With the help of smartphones, we can participate in the lives of our study participants," says Kleim. "We ask them regularly about stressful situations and how they responded." The researchers track how participants are doing later in the day. What works? What does not? This data is intended to feed into behavioural training programmes in which people can practise new strategies tailored to them individually.
Bonanno has shown across three decades of research that most people, around two thirds, are naturally resilient, even after traumatic events. This contradicts the common assumption that trauma inevitably leads to long-term psychological damage. His message: we are wired for resilience. Not because we are invulnerable. But because we can adapt.
Every tightrope walker must learn for themselves
The Swiss researchers are working on diagnostic blood tests designed to detect risks for stress-related illness at an early stage. They are developing apps and therapy concepts tailored to individuals. Because what helps one person can burden another. Not everyone takes to breathing exercises. Not everyone finds relaxation in meditation.
"We want to enable interventions before problems arise in the first place," says Ruff. "To strengthen joie de vivre, vitality, and energy."
The question is whether we can wind down again afterwards. Whether we are flexible enough to move between tension and release. Whether we can reappraise a negative situation. Psychology calls this "positive reappraisal." When the tram pulls away, we can get annoyed. Or we can use the time to breathe. To gather ideas. To recognise that the world does not end because of a delay.
In the end, resilience is not a question of character. It is the ability to keep your balance, even when the ground shifts beneath you. And that can be learned.
