The short version: Diaphragmatic breathing (slow, deep breathing from the belly) is a concrete, learnable skill for psychedelic preparation, in-session grounding, and integration. It activates the parasympathetic nervous system, which counters the stress response. This post introduces a course teaching the technique for ketamine-assisted psychotherapy and Oregon Psilocybin Services; it supports preparation, it doesn’t replace medical screening.
A client heading into her first ketamine session once told me she was less worried about the medicine than about “losing it” in front of her provider if she got overwhelmed.
What she needed wasn’t reassurance. She needed something to do. If you’re preparing for a ketamine or psilocybin session, stress and anticipatory anxiety are common, and they affect how a session goes. I built a course teaching diaphragmatic breathing as a practical tool for the full arc of a psychedelic experience: preparation, the session itself, and integration afterward.
Why Breath Matters in Psychedelic Preparation
Diaphragmatic breathing, also called deep or belly breathing, is slow, deep breathing that engages the diaphragm rather than the chest. It stimulates the vagus nerve and activates the parasympathetic nervous system, which counters the physiological stress response. Slow breathing is associated with improved heart rate variability and greater parasympathetic activity, and diaphragmatic breathing specifically has been linked to reduced negative affect and lower cortisol (Zaccaro et al., 2018; Ma et al., 2017). The course covers the physiology in enough depth that you understand why the technique works, not just that it does.
One Skill, Three Phases
The rest of the course applies this to each phase of the experience.
Preparation. Before a session, diaphragmatic breathing gives you a reliable way to work with anticipatory anxiety. Practicing in the days beforehand also means the skill is already familiar when you need it most.
The session itself. During a ketamine or psilocybin session, breath becomes a grounding tool: something to return to during difficult moments without pulling you out of the experience. Many people also find that slow, nasal breathing helps settle nausea, one of the more common side effects of ketamine sessions.
Integration. Afterward, the course shows you how to pair breathwork with practices like journaling and art-making to process what came up.
What You’ll Take Away
By the end of the course, you’ll have a working understanding of how diaphragmatic breathing affects your nervous system and a practiced routine for using it before, during, and after a session. It’s a skill that outlasts any single psychedelic experience; the same technique works for everyday stress.
This course gives you a concrete skill to bring into ketamine-assisted psychotherapy or Oregon Psilocybin Services: something to do with your hands and your attention when a session gets difficult, grounded in why it works.
Frequently Asked Questions
What is diaphragmatic breathing?
It’s slow, deep breathing that engages the diaphragm, the muscle beneath your lungs, rather than the chest. Your belly expands on the inhale instead of your shoulders rising. This pattern stimulates the vagus nerve and shifts your nervous system toward its calmer parasympathetic state.
How does breathing help during a ketamine or psilocybin session?
It gives you an anchor. When a session gets intense, slow diaphragmatic breathing calms the body’s stress response without requiring you to think your way out of the moment. Because the skill is physical and well-practiced, it stays available even when ordinary problem-solving doesn’t.
Can I use this technique if I get nauseated during a session?
Yes. Slow, nasal diaphragmatic breathing is a common first-line tool for managing nausea during ketamine sessions, and many people find it helps. If nausea is a significant concern for you, raise it with your prescriber too; there are also medical options.
Do I need to take the full course to benefit from this?
No. The basic technique is simple, and you can start practicing it today: breathe in slowly through your nose so your belly expands, then exhale even more slowly. The course adds the physiology, guided practice, and the specific applications to preparation, sessions, and integration.
Not sure where to start? Get in touch.
Peter H. Addy, PhD, LPC, LMHC is a Portland-based licensed psychotherapist specializing in psychedelic-informed and harm-reduction psychotherapy, ketamine-assisted psychotherapy, and chronic pain. His research background includes postdoctoral work at Yale School of Medicine on psychedelic substances. Learn more about my practice →
