I have tried other breath training patterns (box breathing, resonance breathing - I even used an HRV monitor to find the right pacing for me) - they did not do as much for me as a single session of 4-7-8.
Dr Andrew Weil came up with 4-7-8 and explains its use here; appropriate dosing is apparently quite important:
I think the reason why I had such a great effect just from one session may have to do with all the purple foods I consume. Purple (and magenta, red, and black) foods contain anthocyanins which have interesting effects on microcirculation and oxygen delivery to the brain and other tissues. Foods that seem to really work well in this regard are blueberries, acai, maqui, and hibiscus tea. But there's also purple sweet potatoes (very tasty, but high in oxalates), strawberries, cranberries, red cabbage, black beans, and even eggplant.
For the curious, here are some articles on related topics:
Study shows how slow breathing induces tranquility - med.stanford.edu/news/all-n...
Real-world stress resilience is associated with the responsivity of the locus coeruleus - nature.com/articles/s41467-...
Locus Coeruleus Modulates Neuroinflammation in Parkinsonism and Dementia - pubmed.ncbi.nlm.nih.gov/332...
Editorial: The Anatomical Basis of the Cross Talk Between Immune System and Brain - frontiersin.org/articles/10...
Enhanced task-related brain activation and resting perfusion in healthy older adults after chronic blueberry supplementation - pubmed.ncbi.nlm.nih.gov/282...
Locus Coeruleus Stimulation Recruits a Broad Cortical Neuronal Network and Increases Cortical Perfusion - jneurosci.org/content/33/8/...