Sudarshan Kriya Yoga is a structured sequence of breathing patterns, slow to fast, taught in a multi-day course. It is not the book's method, and the book does not teach fast breathing to beginners. But the PTSD trials are among the most serious tests any breathing practice has been given, so they belong here.
The first was tiny: 21 male veterans of Iraq or Afghanistan, 11 trained and 10 on a waitlist. The trained group's PTSD scores fell with a large effect (d = 1.16), along with anxiety, respiration rate and the eye-blink startle response, and the gains held at one year. The second was the real test: 85 veterans randomized to either the breathing course or cognitive processing therapy, a standard trauma treatment, at a VA center. At six weeks both groups improved by similar amounts (about six points on the PTSD checklist), and the breathing arm was judged non-inferior at six weeks, one month, and one year on PTSD symptoms. On depression and mood it was non-inferior early but fell behind the therapy at one year. Dropout was similar in both arms.
Honest reading: a breathing course can do about what a first-line therapy does for PTSD symptoms in veterans who choose it, in one trial, with a non-inferiority margin of ten points that some clinicians would call generous. That is encouraging, not settled. If you have PTSD, this is a conversation to have with whoever treats you, not a substitute for them. The book's Borrowed Weather room and the note at the front say the same.
The studies
Seppälä EM, Nitschke JB, Tudorascu DL, et al. Breathing-based meditation decreases posttraumatic stress disorder symptoms in U.S. military veterans: a randomized controlled longitudinal study. Journal of Traumatic Stress 27(4), 2014, 397–405. Read the abstract
- Sample
- 21 (11 active, 10 waitlist)
- Design
- Randomized waitlist-controlled trial with one-month and one-year follow-up.
- Found
- PTSD scores fell in the active group (d = 1.16) along with anxiety, respiration rate and startle; startle reductions tracked hyperarousal at one year.
- Limits
- Very small; male veterans only; waitlist control.
Bayley PJ, Schulz-Heik RJ, Tang JS, et al. Randomised clinical non-inferiority trial of breathing-based meditation and cognitive processing therapy for symptoms of post-traumatic stress disorder in military veterans. BMJ Open 12(8), 2022, e056609. Read the abstract
- Sample
- 85 (41 SKY, 44 CPT)
- Design
- Parallel randomized non-inferiority trial at an outpatient VA center.
- Found
- PTSD checklist fell 5.6 points with SKY and 6.8 with CPT at six weeks; SKY non-inferior at six weeks, one month and one year. On depression and mood, SKY was non-inferior early but inferior at one year.
- Limits
- Ten-point non-inferiority margin; 27–34 percent dropout; single site.
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.