The book does not treat depression and says so; it points readers to care. These two trials are here because they are the clearest tests of a breathing-based practice in people with a diagnosis.
In the first, 25 adults with major depressive disorder who were still depressed after at least eight weeks on an antidepressant were randomized to eight weeks of Sudarshan Kriya Yoga or a waitlist. On the clinician-rated Hamilton scale, the breathing group fell nearly ten points while the waitlist did not move. In the second, thirty adults with major depression took twelve weeks of Iyengar yoga plus "coherent breathing" at five breaths a minute, at a high or low weekly dose; depression scores fell substantially in both groups, with no non-yoga control arm. The HRV-biofeedback meta-analysis above (14 trials, medium effect) is the broader evidence that slow breathing with feedback moves depressive symptoms.
Small numbers, waitlist or no control, and in the second case a package of yoga and breathing that cannot be separated. The honest summary is "worth studying properly," not "proven," and in either case alongside treatment. The book's Three A.M. room has the 988 line for a reason.
The studies
Sharma A, Barrett MS, Cucchiara AJ, Gooneratne NS, Thase ME. A breathing-based meditation intervention for patients with major depressive disorder following inadequate response to antidepressants: a randomized pilot study. Journal of Clinical Psychiatry 78(1), 2017, e59–e63. Read the abstract
- Sample
- 25 (13 SKY, 12 waitlist)
- Design
- Randomized pilot, eight weeks, in patients non-responsive to at least eight weeks of antidepressant treatment.
- Found
- Hamilton depression scores fell 9.77 points with SKY versus a 0.50 rise on the waitlist (p = .003); Beck depression scores also improved more.
- Limits
- Pilot size; waitlist control; single site.
Streeter CC, Gerbarg PL, Whitfield TH, et al. Treatment of major depressive disorder with Iyengar yoga and coherent breathing: a randomized controlled dosing study. Alternative and Complementary Therapies 23(6), 2017, 236–243. Read the abstract
- Sample
- 30 completers
- Design
- Randomized to high-dose (three classes a week) or low-dose (two) yoga plus coherent breathing at five breaths a minute for twelve weeks.
- Found
- Depression scores fell significantly in both groups.
- Limits
- No non-yoga control; yoga and breathing cannot be separated; small.
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.