The same breathing serves different jobs at different times. Early on it may be there to help you sleep and stay contained. Later it may be there to help you feel more, not less.
This is worth knowing so you do not judge yourself for finding a practice useful now that was useless six months ago, or the other way round. In the early stretch after something hard, use breath for steadiness and rest. Once the ground is firmer, the same slow breathing can be what lets you stay with a feeling for long enough to know what it is.
Qur’an and Sunnah
once you are safe, keep up regular prayer (Quran 4:103). The verse adjusts the practice to the circumstances, a shortened form under threat and the fuller one when things are steady again.
فَإِذَا قَضَيۡتُمُ ٱلصَّلَوٰةَ فَٱذۡكُرُواْ ٱللَّهَ قِيَٰمࣰ ا وَقُعُودࣰ ا وَعَلَىٰ جُنُوبِكُمۡۚ فَإِذَا ٱطۡمَأۡنَنتُمۡ فَأَقِيمُواْ ٱلصَّلَوٰةَۚ إِنَّ ٱلصَّلَوٰةَ كَانَتۡ عَلَى ٱلۡمُؤۡمِنِينَ كِتَٰبࣰ ا مَّوۡقُوتࣰ ا
After performing the ritual prayer, continue to remember God- standing, sitting, and lying on your sides- and once you are safe, keep up regular prayer, for prayer is obligatory for the believers at prescribed times
Qur’an 4:103read it in the library
Translation: M.A.S. Abdel Haleem, The Qur'an, Oxford University Press, 2004.
What the research says
The trauma evidence here is early. A single session of heart rate variability biofeedback lowered post-traumatic stress symptoms in veterans in a small uncontrolled pilot, and in 38 people in residential treatment this kind of breathing training produced gains much like progressive muscle relaxation, with both groups improving. Neither study tested the timing question. They suggest slow breathing has a place in trauma work without telling you where in the work it belongs.
Schuman DL, Killian MO. (2019). Pilot Study of a Single Session Heart Rate Variability Biofeedback Intervention on Veterans' Posttraumatic Stress Symptoms.. Applied psychophysiology and biofeedback doi
Zucker TL, Samuelson KW, Muench F, Greenberg MA, Gevirtz RN. (2009). The effects of respiratory sinus arrhythmia biofeedback on heart rate variability and posttraumatic stress disorder symptoms: a pilot study.. Applied psychophysiology and biofeedback doi
Strength of evidence: one line of research. A single study, or a theoretical account.
Why it works
The technique does not change, but what you need from it does, and matching the two is most of the skill.
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
Any breathing instruction that reaches you through a screen or a book comes from someone who cannot see you. Keep the final say over what your body does.
Let the in breath come however it comes, then breathe out through pursed lips as though through a straw for a count of eight, finishing with two more counts through the nose. Three ordinary breaths, then go again.
How often you actually do it matters more than which version you chose. The people who keep turning up tend to get more out of it, and those who carry on at home get more again.