The science of the sigh: what controlled breathing actually does to the body

Sighing is a built-in biological function, not just an emotional response. The psychological sigh — two inhales, one long exhale — deliberately activates the parasympathetic nervous system. A 2023 RCT found cyclic sighing outperformed mindfulness meditation for mood improvement. The exhale-to-inhale ratio is the critical mechanism. Evidence is promising but still developing; individual responses vary.