4-7-8 breathing (inhale 4, hold 7, exhale 8 through the mouth) can genuinely help when your mind is racing — but nothing shows this exact rhythm beats plain slow breathing.

noli's read

Slow breathing in general has a well-documented calming effect (Zaccaro et al.'s 2018 review), and that's likely what a 4-7-8 practitioner is feeling. But once you isolate this specific ratio — popularized by Dr. Andrew Weil — the literature turns contradictory: a 2022 study (Vierra et al., n=21) actually found decreased heart-rate variability (HRV) after a 4-7-8 session, the opposite of the intended effect; a more recent head-to-head comparison (Marchant et al. 2025, n=84) found 4-7-8 produced the smallest HRV increase of three tested protocols (versus box breathing and a simple 6-breaths-per-minute pace); conversely, a 2022 study in sleep-deprived young adults (Bourdillon et al.) found this same protocol lowered heart rate and raised HRV. A 2025 scoping review covering 15 studies concludes the evidence base is still small and inconsistent. The felt effects the video describes (easier sleep onset, clearer head, looser jaw and shoulders) are plausible as a generic slow-breathing effect, but nothing shows 4-7-8 specifically outperforms plain slow breathing. Verdict: mixed — the relaxing experience is real, the 'this exact ratio works better' framing isn't.

the sources

1. 1Zaccaro A et al. 2018