Box breathing

Box breathing is a paced breathing technique using equal-length phases of inhale, hold, exhale, and hold (commonly four seconds each). Slowing respiration well below the typical 12–16 breaths per minute is associated with increased vagal tone and heart-rate variability in slow- and resonance-breathing studies. It is widely taught in military, clinical, and performance settings for acute stress regulation. Direct RCT evidence for box breathing as a distinct protocol is limited; most support is extrapolated from broader paced/slow-breathing research.