The short version
In for about 3, out for about 6, through the nose or softly pursed lips. Six of them takes about a minute. If counting annoys you, keep only the rule: out longer than in. For a slow burn rather than a sudden jolt.
What the research says
Slow, exhale-emphasized breathing is the common thread in the breathwork trials: a 2023 meta-analysis of twelve randomized trials found a small-to-medium reduction in stress, with the authors warning against “a miscalibration between hype and evidence.” Cited under Chapter 2.
Rooms where it does the work
Two rules, no exceptions
Never practice any technique on this site while you are driving, operating machinery, or doing anything that needs your full attention. The slow ones can make you drowsy, faster than you’d expect. And never practice a breath-hold, bellows breath, or any vigorous breathing in or near water. Read Before you begin for the doctor’s list and the rest.
The short version is a reminder, not a lesson. The chapter has the story, the steps, the mistakes, and the limits.