Do breathing exercises really work against stress?

Breathing exercises have become impossible to ignore. Apps, employers, and countless videos present them as a simple and inexpensive way to reduce stress. The promise is appealing: a few minutes of calm breathing and the body shifts into a more relaxed mode. One question, however, usually goes unaddressed, even though it touches on the very heart of the matter: how long does that calm last after you stop? After all, an effect that only exists while you're breathing says little about your stress levels for the rest of the day.

That question can be properly investigated, because the better studies distinguish between three moments: during the exercise, immediately after a single session, and after a period of repeated practice. It's precisely at that dividing line that much of the marketing falls apart.

Researchers use, among other things, heart rate variability, the variation in time between successive heartbeats. A relaxed body, with an active vagus nerve, generally shows more variation than a body under tension. It is therefore a commonly used, objective measure of the degree of physiological relaxation.

The most comprehensive overview to date pooled 223 studies (Laborde et al., 2022). The authors deliberately separated the three moments, and the outcome is consistent. The increase in vagally mediated heart rate variability was greatest during the breathing itself, clearly smaller in the measurement immediately after a session, and only modest after a training period of several weeks. The impressive figures that usually circulate, then, belong to the moment of the exercise itself and not to the hours that follow.

How quickly the after-effect fades is shown by a controlled experiment involving almost a hundred adults (Steffen et al., 2021). During slow breathing, heart rate variability rose. After a brief stress task and a rest period, however, it had returned to baseline. The peak, in other words, disappeared as soon as the exercise and its immediate context were over.

That comes with an important measurement caveat. Slow breathing increases respiratory sinus arrhythmia, the natural fluctuation of heart rate in step with breathing. Part of that increase is a mechanical consequence of the slow, deep breathing itself and is unrelated to any genuine change in tonic vagal activity. A higher heart rate variability during the exercise is therefore not evidence that the underlying stress burden has actually decreased.

Research among employees shows that breathing does have an effect in the acute moment. In a study with 75 full-time employees, the body recovered measurably better after a stress task when they did a brief breathing exercise, compared to a control group (Chelidoni et al., 2020). In precisely this kind of tense situation, then, breathing is useful. But here too, it was a matter of the minutes immediately afterward, not the rest of the day.

We see the same pattern with blood pressure. Slow breathing lowers blood pressure in the moment itself, but the evidence for a lasting reduction is thin. A recent meta-analysis explicitly stated that the long-term effect on the heart and blood vessels has not yet been established (Shao et al., 2024).

Does this mean breathing exercises offer little benefit? No, but the lasting gain lies in a different area than is often suggested. People who practice for weeks on end report, on average, less stress, low mood, and anxiety. The meta-analysis most directly addressing this found small to moderate effects on these self-reported outcomes, with the authors explicitly noting that most studies carried a moderate risk of bias and that a gap looms between hype and evidence (Fincham et al., 2023). This concerns subjective experience, and that is a legitimate and valuable outcome in its own right.

On the objective physiological markers, the picture is weaker. For cortisol, the best-known stress hormone, a meta-analysis of 58 studies showed that relaxation and attention-based techniques can somewhat lower cortisol levels. Body-oriented techniques, the category breathwork falls closest to, showed no demonstrable effect on it (Rogerson et al., 2023). And whether resting heart rate variability, measured independently of the exercise, structurally increases through repeated practice is uncertain. The evidence is mixed: some studies find a small improvement, others none. In a carefully designed twelve-week study, self-reported stress complaints decreased, while heart rate variability showed no measurable change (Birdee et al., 2023). The pattern that emerges from this is that training mainly improves the ability to raise variability during the exercise itself, much less so the baseline resting state.

In practice, this means breathing is best understood as a fast-acting tool for acute stress, while it's only a drop in the ocean against chronic stress. The claim that five minutes of breathing a day eliminates stress across the board or permanently reprograms the nervous system doesn't hold up against the best available evidence.

For anyone using breathing exercises, at work or at home, that's not a reason to stop, but it is a reason to position them honestly.

Sources

Laborde, S., e.a. (2022). Effects of voluntary slow breathing on heart rate and heart rate variability: A systematic review and a meta-analysis. Neuroscience and Biobehavioral Reviews.

Steffen, P. R., e.a. (2021). Integrating Breathing Techniques Into Psychotherapy to Improve HRV: Which Approach Is Best? Frontiers in Psychology.

Chelidoni, O., e.a. (2020). Exploring the Effects of a Brief Biofeedback Breathing Session Delivered Through the BioBase App in Facilitating Employee Stress Recovery: Randomized Experimental Study. JMIR mHealth and uHealth.

Shao, R., e.a. (2024). The Effect of Slow-Paced Breathing on Cardiovascular and Emotion Functions: A Meta-Analysis and Systematic Review. Mindfulness.

Fincham, G. W., e.a. (2023). Effect of breathwork on stress and mental health: A meta-analysis of randomised-controlled trials. Scientific Reports.

Rogerson, O., e.a. (2023). Effectiveness of stress management interventions to change cortisol levels: a systematic review and meta-analysis. Psychoneuroendocrinology.

Birdee, G., e.a. (2023). Slow breathing for reducing stress: The effect of extending exhale. Complementary Therapies in Medicine.