Recently, I came across a stress relief method through breathing, based on respiratory sinus arrhythmia (RSA) theory.
There are 2 apps which are applying this idea.
I realize Stress Doctor doesn't mention about breath holding, whereas HeartRate+ does mention about breath holding.
I was wondering, which is a more appropriated method? Will breath holding help in stress relief? Or, breath holding will make stress relief worst? Any good reference which talks about this?