Chronic stress: a silent problem, a real cost
In France, nearly 9 out of 10 workers say they feel stress at work. More than half believe that this stress impacts their health. And yet, the vast majority do nothing, or don’t know what to do. Not because of a lack of will, but because the tools available seem either too complex or reserved for insiders.
What we do know is that chronic stress is not trivial. When the brain perceives a threat, real or imagined, it triggers a hormonal cascade: adrenaline, then cortisol, the stress hormone. In the short term, this answer is useful. In the long term, chronically high cortisol levels eventually disrupt the immune system, disrupt sleep, erode concentration, and contribute to cardiovascular disorders.
The problem is that chronic stress sets in gradually, often without a clear warning signal. You get used to it. We normalize it. Until the body no longer normalizes.
The vagus nerve: the little-known key to your balance
To understand how to act on stress, we need to understand a central player in the autonomic nervous system: the vagus nerve. This nerve, the longest in the human body, connects the brain to almost all the organs (heart, lungs, intestines). It is the backbone of the parasympathetic nervous system, the one that regulates rest, digestion and recovery.
When stress gets out of hand, the sympathetic nervous system, the “fight or flight” mode, takes over. The vagus nerve plays the opposite role: it acts as a natural brake, bringing the body back to a state of calm and balance.
The good news? The vagus nerve can be stimulated. And one of the most accessible, best scientifically researched means is the slow, deep breathing.
HRV, the barometer of your nervous system
There is a physiological indicator that directly reflects the state of this balance: the Heart rate variability, or HRV (HRV, Heart Rate Variability). Contrary to what its name might suggest, a high HRV is a sign of good health. It indicates that the heart adapts flexibly at every moment, a sign that the autonomic nervous system is functioning well and that the vagus nerve is active.
Conversely, a low and stable HRV is often associated with a state of chronic stress, overexertion or profound fatigue.
HRV has been measured by cardiologists for decades. It is now at the heart of much research in preventive medicine and health psychology. Its major interest: it is an objective marker, which does not depend on what we consciously feel.
Measuring Stress: Why PSS-10 Changes Everything
Telling yourself “I’m stressed” is one thing. Being able to quantify it, situate it in time, compare it from one week to the next is another. This is precisely what thePerceived Stress Scale PSS-10 (Perceived Stress Scale), one of the most widely used psychological assessment tools in the international scientific literature.
The PSS-10 is a ten-question questionnaire, validated in many countries and cultures, that assesses the extent to which a person has perceived their life as unpredictable, uncontrollable, or overloaded in the past month. It does not measure an isolated stressful event, but the overall perception of stress, which makes it a particularly relevant indicator for monitoring changes over time.
Taking the PSS regularly means having an objective benchmark. It is also to be able to observe, with supporting data, the effect of a change in lifestyle, a breathing practice or a period of rest.
Cardiac coherence: a simple practice, proven effects
Of all the stress management techniques, cardiac coherence is undoubtedly the one with the most favourable benefit/effort ratio. The principle is simple: breathe at a slow and steady pace, typically 5 seconds of inhalation and 5 seconds of exhalation, for a few minutes.
This particular rhythm resonates with the natural oscillations of the cardiovascular system. It directly stimulates the vagus nerve, reduces cortisol secretion, increases HRV and promotes a state of alert calm. Studies have shown that regular practice of cardiac coherence, three times a day, five minutes, can significantly reduce anxiety, improve sleep quality, and strengthen recovery capabilities.
The challenge, of course, is consistency. An isolated session has little lasting effect. It is a daily, progressive practice that ends up reshaping the nervous system’s response to stress.
Handflow: Assess, Understand, Act
It is with this in mind that the application was designed Handflow, a completely free French solution dedicated to stress management. Its approach is based on three pillars.
Evaluate. The application integrates the PSS-10 questionnaire, allowing the user to measure their perceived stress level at regular intervals and to follow its evolution over time thanks to a visual history. A summary report can be exported as a PDF, useful for sharing with a doctor, psychologist or any other health professional.
Understand. Handflow informs the user about how they feel: what does their PSS score mean? What lifestyle factors influence their stress? The app includes personalized advice, contextualized based on the results, to help everyone better interpret their own data.
Take action. The heart of the experience is the practice of guided breathing. Cardiac coherence (5/5), relaxation (4/6) or other customizable rhythms, with visual and sound guidance. The app follows practice over time (frequency, duration, regularity) to encourage consistency rather than performance.
What sets Handflow apart in a market saturated with wellness apps is a radically user-friendly philosophy: no account to create, no personal data collected. Just a tool, freely available on the App Store and Google Play, rated 5 stars by its users.
What’s Coming in 2026
Handflow is preparing for 2026 the launch of a new physical device: a Guided breathing tool, designed to enable dual-tasking cardiac coherence practice, without requiring user attention.
An innovation that responds to one of the main obstacles to regular practice: the need to keep your eyes glued to your phone.
This project is supported by BPI France and the Nouvelle-Aquitaine Region, and is accompanied by theUnitec incubator in Bordeaux, so many guarantees of seriousness for a startup that intends to be a long-term part of the French preventive health landscape.
Consistency, not perfection
Stress management is not a destination, it’s a practice. Like diet or sleep, it requires a minimum of daily attention, not hours, but a few minutes, on a regular basis.
What science teaches us today is that the body has remarkably effective natural regulatory mechanisms. The vagus nerve, the HRV, the cardiac coherence are not esoteric concepts: they are biological realities, measurable, on which it is possible to act.
The tools exist. They are free. And sometimes all you have to do is breathe, slowly, deeply, regularly, to start changing something.
