Most breathing studies recruit undergraduates, which is a problem for a book whose rooms include the empty chair and the paper gown. One French study did the comparison directly.
Twenty-two older adults and twenty-five younger ones did a single session of deep, slow breathing with a longer exhale than inhale. In both groups, high-frequency heart-rate variability (the vagal signal) rose and state anxiety fell. The rise in vagal activity was significantly larger in the older group. The authors suggest that slow breathing may be more useful, not less, for restoring vagal tone later in life.
One session, 47 people, a lab. But it is the right direction, and it agrees with the blood-pressure trials, whose participants skew older. Nothing here changes the safety list in Before you begin; slow breathing can make anyone light-headed on standing, and more so with age.
The studies
Magnon V, Dutheil F, Vallet GT. Benefits from one session of deep and slow breathing on vagal tone and anxiety in young and older adults. Scientific Reports 11, 2021, 19267. Read the abstract
- Sample
- 47 (22 older, 25 younger)
- Design
- Single-session pre–post comparison by age group, low inhale/exhale ratio.
- Found
- High-frequency HRV increased and state anxiety decreased in both groups; the HRV increase was larger in older adults.
- Limits
- Single session; no control condition; RMSSD did not change, which the authors attribute to the unequal ratio.
Where this lands in the book
Techniques
Rooms
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.
Verdict scale: Science means trials or meta-analyses with consistent findings; Promising means real trials that are small, few, or unreplicated; Mixed means the studies point both ways; Mechanism means it shows how something works in the body, not that it helps in life. Checked against the published abstracts in October 2026. Not medical advice.