Holding your breath for a moment makes the next one deeper, which sounds backwards until you know why. The urge to breathe is driven by carbon dioxide, not by a shortage of air.
Sensors in the brainstem watch the level of carbon dioxide in your blood, and a pause, especially after breathing out, lets it rise a little. The body answers with a fuller breath, sometimes a yawn, and things rebalance. Knowing this is useful twice over: you can explain to someone why a pause makes them breathe better, and you can put a practice together yourself rather than only copying one.
Qur’an and Sunnah
When I have fashioned him and breathed My spirit into him (Quran 15:29). Breath is placed right at the beginning of what a person is, which sits well with how much a small change to it can do.
فَإِذَا سَوَّيۡتُهُۥ وَنَفَخۡتُ فِيهِ مِن رُّوحِي فَقَعُواْ لَهُۥ سَٰجِدِينَ
When I have fashioned him and breathed My spirit into him, bow down before him,’
Qur’an 15:29read it in the library
Translation: M.A.S. Abdel Haleem, The Qur'an, Oxford University Press, 2004.
What the research says
A widely used methods paper in this field explains that heart rate variability indexes cardiac vagal tone, the calming branch of the nervous system acting on the heart, and that it tracks with how well people regulate emotion and attention. That gives a measurable handle on what breathing practices are moving. It describes the plumbing rather than proving that any one exercise works.
Laborde S, Mosley E, Thayer JF. (2017). Heart Rate Variability and Cardiac Vagal Tone in Psychophysiological Research - Recommendations for Experiment Planning, Data Analysis, and Data Reporting.. Frontiers in psychology doi
Strength of evidence: one line of research. A single study, or a theoretical account.
Why it works
The pause gives the body a reason to take a proper breath, so the breath comes from the body rather than from your instructions.
This one is still a draft. It is waiting on a scholar and a clinician to read it before it is published.
Near this one
Close your right nostril with your thumb and breathe in through the left. Swap fingers at the top, breathe out through the right, in through the right, then out through the left. That is one round.
The soft sound and the feel of this breath in your throat give your attention somewhere to sit. When the mind is loud, something you can hear holds better than something silent.
Breath work goes straight into the body, and for some people that is the problem. If your panic has ever been about not getting enough air, putting your attention on your breathing can set it off rather than settle it.