What controlled breathing does to your body

Breathing is unusual. It runs perfectly well without you, and yet you can take the controls whenever you like. That makes it the most accessible entry point into a system — the autonomic nervous system — that otherwise operates without your input.

This page explains the mechanism as it is generally understood, and is equally clear about the parts that are less settled than wellness writing usually admits.

Your heart rate already follows your breath

Put a finger on your pulse and breathe slowly. Your heart speeds up slightly as you breathe in and slows as you breathe out. This is a normal reflex with an unwieldy name — respiratory sinus arrhythmia — and it is present in everyone.

The vagus nerve acts as a brake on the heart. That brake eases off during the in-breath and applies during the out-breath. So a breath with a long out-breath spends proportionally more time with the brake on.

This is the whole mechanism behind the "longer exhale" advice. It is not mystical and it is not new; it is a description of a reflex you can watch happening.

Why five or six breaths a minute keeps coming up

Blood pressure, heart rate and breathing all oscillate, and those oscillations interact. For most adults they line up most strongly somewhere between five and six breaths a minute — a state usually described as cardiorespiratory resonance. Breathe at that pace and the natural swing in heart rate becomes large and smooth.

That is where the number on the Coherent Breathing page comes from. It is also, probably not coincidentally, close to the pace of a rosary, a chanted mantra and a slow lullaby — practices that developed independently in cultures with no contact with each other.

Individual resonance pace varies, roughly between four and a half and six and a half breaths a minute, and taller people tend to sit at the slower end. The right pace for you should feel unremarkable rather than challenging.

What the research supports

Reasonably consistent: slow paced breathing produces short-term increases in heart rate variability and reductions in self-reported stress and anxiety immediately after a session. Pursed-lip breathing has an established place in pulmonary rehabilitation for easing the sensation of breathlessness.

Less settled: whether any specific pattern is better than another. Where techniques have been compared head to head, what seems to matter is a slow rate and a long exhale rather than a particular ratio. The trials are typically small, cannot be blinded — you always know whether you are breathing slowly — and rely on people reporting how they feel.

Not supported: breathing exercises as a treatment for anxiety disorders, depression, insomnia, high blood pressure or chronic pain in place of established care. Some breathing work appears within evidence-based treatments, most clearly as one component of cognitive behavioural therapy for panic. That is a very different claim from the exercise being a treatment on its own.

What about faster breathing?

Deliberately fast breathing does roughly the opposite: it raises alertness by pushing the sympathetic side of the nervous system. It also lowers carbon dioxide, which narrows blood vessels in the brain and causes light-headedness, tingling and occasionally fainting.

That is why the one fast technique here is capped at ten quick breaths per round, carries a longer safety list than anything else on the site, and insists you sit down. People do faint doing this, and drownings have occurred when it was combined with being in water.

Where this comes from

Starting points for reading rather than a systematic review. None of these authors are connected with this site.

• Zaccaro A, Piarulli A, Laurino M, et al. (2018). How Breath-Control Can Change Your Life: A Systematic Review on Psycho-Physiological Correlates of Slow Breathing — Frontiers in Human Neuroscience. A systematic review of what slow breathing does to the body and to how people report feeling. Useful for seeing both the consistent findings and how varied and small the underlying studies are.
• Lehrer PM, Gevirtz R. (2014). Heart rate variability biofeedback: how and why does it work? — Frontiers in Psychology. Where the "resonance frequency" idea comes from — the observation that heart rate variability peaks at a particular slow breathing pace, around five to six breaths a minute for most adults. This is the reasoning behind Coherent Breathing on this site.
• Ma X, Yue ZQ, Gong ZQ, et al. (2017). The Effect of Diaphragmatic Breathing on Attention, Negative Affect and Stress in Healthy Adults — Frontiers in Psychology. A controlled trial of diaphragmatic (belly) breathing training in healthy adults, reporting improvements in sustained attention and self-reported negative affect. Small sample, and the training was more intensive than a few minutes on a website.