Why breathing?
Breathing is one of the few parts of the body's stress response you can gently steer. Here is what that means — and what it doesn't. Each point is labelled by how sure we can be.
When we're stressed, breathing often becomes faster or less comfortable. Slowing the breath can be one way of deliberately shifting attention and supporting a calmer physiological state.
How sure can we be?
- Established consistent findings from many studies or standard physiology.
- Plausible a reasonable explanation that fits the evidence, but hasn't been directly proven.
- Preliminary early or limited research points this way.
- Unknown the question hasn't been answered yet.
Breathing and arousal
Established
Under stress the body prepares for action — the familiar 'fight-or-flight' response. Breathing often becomes quicker or less comfortable as part of this.
The opposite state, sometimes called the relaxation response, involves slower breathing, a slower heart rate and a feeling of calm.
Sources: National Center for Complementary and Integrative Health (NIH)
Respiratory rate: the part you can steer
Established
Most of the stress response happens automatically. Breathing is different: it runs on its own, but you can also choose to slow it down.
That makes the breath a practical handle — something concrete you can do when other things feel out of your hands.
Attention
Plausible
Following a slow rhythm gives your attention a simple, repeating job. For many people this offers a short break from following worries or busy thoughts.
Researchers think this attentional part matters, but it is hard to separate from the effects of the breathing itself.
Autonomic regulation and heart rhythms
Established
While people breathe slowly, their heart-rate rhythm changes in a consistent way (an increase in what is called heart rate variability). A large review of over 200 studies found this during practice, shortly after, and after weeks of practice.
What these changes mean for everyday wellbeing, and exactly how they come about, is still being studied. We do not claim breathing 'resets' or 'fixes' the nervous system.
Sources: Laborde S, Allen MS, Borges U, et al; Sevoz-Couche C, Laborde S
Subjective stress: how people feel
Preliminary
When results from randomised trials are combined, breathing practices are linked with modestly lower self-reported stress, anxiety and low mood compared with not practising.
The trials are mostly small and some have design weaknesses, so the authors themselves advise caution. Breathing seems to help some people, some of the time — which is worth having, but is not a treatment.
Is there a perfect rhythm?
Unknown
Probably not one that suits everyone. A large placebo-controlled trial found that breathing at about 5.5 breaths a minute helped no more than a well-designed comparison at 12 breaths a minute — both groups improved.
Early research suggests patterns with a longer out-breath may be particularly pleasant for mood, but that comes from a single trial. So we offer a few comfortable rhythms rather than one 'correct' one.
Sources: Fincham GW, Strauss C, Cavanagh K; Balban MY, Neri E, Kogon MM, et al
Why we never ask for bigger breaths
Established
Breathing faster or more deeply than you need lowers carbon dioxide in the blood, which can cause light-headedness, dizziness or tingling.
Slow breathing works with ordinary-sized breaths. If you ever feel dizzy, just stop and breathe normally.
Sources: MedlinePlus Medical Encyclopedia (US National Library of Medicine)
Where breathing fits
Established
Breathing and relaxation exercises are generally safe, and the World Health Organization includes simple self-help skills like these in its stress guide.
They are one tool among many — sleep, movement, connection with people, and professional help when things are hard. They do not replace care from a doctor or psychologist.
Sources: National Center for Complementary and Integrative Health (NIH); World Health Organization
Sources
- National Center for Complementary and Integrative Health (NIH). 5 Things To Know About Relaxation Techniques for Stress. https://www.nccih.nih.gov/health/tips/things-to-know-about-relaxation-techniques-for-stress (opens in a new tab) Relaxation techniques are generally safe but evidence of usefulness for specific health conditions is limited. They should not replace conventional care or delay seeing a health professional.
- Zaccaro A, Piarulli A, Laurino M, et al. How breath-control can change your life: a systematic review on psycho-physiological correlates of slow breathing. Frontiers in Human Neuroscience. 2018;12:353. doi:10.3389/fnhum.2018.00353 (opens in a new tab) 15 studies in healthy people. Slow breathing (<10 breaths/min) was associated with autonomic, brain-activity and psychological changes. The authors state the mechanisms are still under debate, and distinguish slow breathing from simple breath awareness or counting.
- Laborde S, Allen MS, Borges U, et al. Effects of voluntary slow breathing on heart rate and heart rate variability: a systematic review and a meta-analysis. Neuroscience & Biobehavioral Reviews. 2022;138:104711. doi:10.1016/j.neubiorev.2022.104711 (opens in a new tab) 223 studies. Voluntary slow breathing increased vagally-mediated heart rate variability during practice, immediately after a session and after multi-session interventions; few adverse effects expected. This concerns physiological measures, not mental-health outcomes.
- Sevoz-Couche C, Laborde S. Heart rate variability and slow-paced breathing: when coherence meets resonance. Neuroscience & Biobehavioral Reviews. 2022;135:104576. doi:10.1016/j.neubiorev.2022.104576 (opens in a new tab) Reviews proposed mechanisms of breathing near ~0.1 Hz (about 6 breaths/min). Describes the mechanisms as multiple and complex; mechanistic proposals here are hypotheses, not established facts.
- Fincham GW, Strauss C, Montero-Marin J, Cavanagh K. Effect of breathwork on stress and mental health: a meta-analysis of randomised-controlled trials. Scientific Reports. 2023;13:432. doi:10.1038/s41598-022-27247-y (opens in a new tab) Across 12 RCTs (785 adults), breathwork was associated with lower self-reported stress than non-breathwork controls, with a small-to-medium effect; anxiety and depressive-symptom outcomes showed similar small effects. The authors note small samples and moderate risk of bias, and advise cautious interpretation.
- Fincham GW, Strauss C, Cavanagh K. Effect of coherent breathing on mental health and wellbeing: a randomised placebo-controlled trial. Scientific Reports. 2023;13. doi:10.1038/s41598-023-49279-8 (opens in a new tab) 400 participants practised paced breathing about 10 minutes a day for 4 weeks at ~5.5 breaths/min or at 12 breaths/min (attention placebo). Stress, anxiety, depression and wellbeing improved over time in both groups, with no difference between them.
- Balban MY, Neri E, Kogon MM, et al. Brief structured respiration practices enhance mood and reduce physiological arousal. Cell Reports Medicine. 2023;4(1):100895. doi:10.1016/j.xcrm.2022.100895 (opens in a new tab) Daily 5-minute practices for a month: an exhale-focused breathing pattern (cyclic sighing), box breathing, cyclic hyperventilation with retention, or mindfulness meditation. The exhale-focused pattern produced greater improvement in positive mood and lower respiratory rate than mindfulness meditation. Single trial; healthy adults.
- MedlinePlus Medical Encyclopedia (US National Library of Medicine). Hyperventilation. https://medlineplus.gov/ency/article/003071.htm (opens in a new tab) Over-breathing lowers carbon dioxide in the blood, which causes many of the symptoms of hyperventilation, including light-headedness, dizziness, and numbness or tingling around the mouth or in the arms. Basis for this app's 'no bigger breaths' and 'stop if dizzy' guidance.
- World Health Organization. Doing What Matters in Times of Stress: An Illustrated Guide. Geneva: WHO; 2020. ISBN 9789240003927. https://www.who.int/publications/i/item/9789240003927 (opens in a new tab) A brief, illustrated stress-management guide with audio exercises, intended for anyone experiencing stress. Includes grounding and noticing skills practised for a few minutes a day. Used here as a design reference for accessible, low-burden self-help.