If you’re going to walk up to the edge of life and look over into the precipice, you’d better know how to find your way back.
Many of you know about my lifelong passion for fasting and have read my books and research. I’ve long credited fasting for all the flourishing aspects of my life; from my deeply erotic nature to my vast mystical and ecstatic experiences.
I have never shared the details of the extent of my fasting – until now. For several decades I have routinely completed 14-day water-only fasts multiple times per year. I have done one 21-day water-only fast and suffice it to say I won’t be doing that again lol. (But damn—what a ride.)
My fasts have always been life altering, consciousness bending and explosively spiritual. But not until recently did I discover the depths to which it could draw on my deepest life sources. During my last 14 day water fast I described the feeling that my body, mind and very soul were a building that was taken down to the studs. I didn’t understand the full ramifications of this until after the fast was over and I was in the refeeding stage. Then I realized then that had I not been in absolute peak physical, psychological and spiritual condition I would have faced very dire consequences. And so this is meant to be a cautionary tale, not meant to be discouraging, but instead to encourage careful consideration when undergoing a spiritual practice that has the potential to take you to the very edge.
Extreme spiritual practices
There are places human beings have always gone to meet something larger than themselves. The desert fast held for forty days. The shamanic initiatory ordeal that lasts without sleep for a week. The solitary retreat in darkness. The vision quest at the edge of survival. The ingestion of sacred plant medicines in doses that dissolve the known world. These are not peripheral experiments or modern wellness trends. They are among the most ancient technologies our species possesses — preserved across cultures and millennia because they work, because they reliably open something in human consciousness that ordinary life cannot reach.
But there is a truth at the center of these practices that is rarely named plainly, and almost never examined with the seriousness it deserves. Every one of these practices, at its depth, is an engineered near-death experience.
Not a metaphor for dying. Not a symbolic death in the ceremonial sense alone. A genuine, measurable, neurologically and physiologically documented approach to the threshold between existence and dissolution — between the self that entered the practice and the possibility that the self does not return intact. And in the twenty-first century, with these practices more accessible than at any prior moment in human history, the people entering them most often have no idea that this is what they are doing.
That gap — between the profundity of what is actually occurring and the understanding the practitioner brings to it — is not merely an inconvenience. It is a genuine danger. And it is a danger that compounds quietly, invisibly, across years and decades of sincere practice. Understanding why requires looking at what these states actually are, what the traditions that carried them knew that we have largely forgotten, and what happens to a person who crosses this threshold repeatedly without the architecture that was always meant to hold such crossings.
This article is going to get a tad technical and scholarly because I want to illustrate the points on how dangerous spiritual practices can become. I believe these practices are the most beautiful and powerful forms of discipline. They can prepare you for brave and brilliant love. But I also believe that they must be practiced with caution and with guardrails in place to protect your sacred self.
What these states actually are
The neurological and physiological research of the past three decades has begun to map, with increasing precision, what happens inside the body and brain during the kinds of states produced by deep fasting, prolonged meditation, and high-dose psychedelic compounds.
The picture that emerges is not subtle.
Extended fasting — particularly water-only or dry fasting beyond the three-to-five-day threshold — initiates a cascade of metabolic changes that reach deep into the functioning of the central nervous system. Glucose depletion triggers ketogenesis and, eventually, shifts in blood-brain barrier permeability. Cortisol levels rise significantly before eventually crashing. Electrolyte disruption can precipitate altered states of consciousness that are difficult to distinguish, from the inside, from mystical experience, from psychotic break, or from the early stages of multi-organ compromise. Physiologically, the body in a deep fast is making a series of increasingly critical decisions about what to sustain and what to cannibalize, and the brain — the organ the practitioner is attempting to use to navigate the experience — is itself being metabolized.
This is not an argument against fasting in fact I would argue that it is – in many ways – an argument for fasting. It is a description of what fasting, at depth, actually is and how close it can take you to the edge.
The neuroscience of psychedelic states has clarified a parallel picture. High-dose psilocybin, DMT, ketamine, and related compounds produce a measurable suppression of the Default Mode Network (DMN) — the brain system associated with self-referential processing, narrative identity, and the maintenance of the subjective sense of self as a bounded, continuous entity (Carhart-Harris et al., 2012). The dissolution of the DMN is not a side effect of these compounds. It is the mechanism. The experience of ego dissolution — the sense that the boundary between self and world has ceased to exist, that the “I” who entered the ceremony cannot be located — is the direct neural correlate of DMN suppression, and at sufficient doses it is as total and as terrifying as its name implies.
Willoughby Britton and her colleagues at Brown University’s Contemplative Studies Department have documented, in rigorous clinical research, the range of experiences that can arise from intensive meditation practice — including experiences that meet diagnostic criteria for depersonalization disorder, psychosis, mania, and severe depression (Lindahl et al., 2017). Her Cheetah House project has provided support to hundreds of meditators who encountered what she terms “difficult, challenging, or distressing” meditation experiences — and a significant portion of those came from experienced practitioners with years or decades of committed practice behind them.
The point, in each of these cases, is the same: these practices, at depth, do not merely alter consciousness in comfortable or productive ways. They take the practitioner to genuine boundaries of psychological and physiological coherence. They approach, and sometimes cross, thresholds that the human system was not designed to sustain indefinitely without support.
The psychiatrist Stanislav Grof, who worked with LSD in clinical settings for decades before its prohibition and subsequently developed holotropic breathwork as a non-pharmacological method of accessing similar states, named what can emerge from this territory spiritual emergency — a phrase chosen precisely because it communicates both dimensions simultaneously (Grof & Grof, 1989). It is spiritual in the sense that the content and the transformative potential are genuinely transpersonal. It is emergency in the sense that the structure holding the experience has failed, and the person is in real crisis. The two things are not separate. They are the same thing, seen from two angles.
The knowledge that the ancient traditions held
The traditions that preserved and transmitted these practices across generations understood what was at stake with a clarity that our culture has largely abandoned.
Mircea Eliade, in his foundational study of shamanism across world cultures, documented the structure of shamanic initiation with anthropological precision (Eliade, 1964). In virtually every tradition he examined, the initiatory ordeal — which characteristically involved prolonged isolation, fasting, exposure to physical extremity, and visionary encounters — was not undertaken spontaneously or privately. It was held within an elaborate structure of preparation, guidance, and communal reception. The novice was prepared for years before the initiatory ordeal. A guide who had themselves survived the passage was present throughout or immediately available. And critically, the community waited on the other side — the return was as ritualized, as carefully held, as the descent itself.
The reason for this was not ceremonial conservatism. It was epistemological clarity. These traditions understood that genuine transformation requires a genuine death of the ordinary self, and that death — even symbolic, even temporary — is dangerous. The membrane between initiated and uninitialized awareness is not a metaphor. It is a real discontinuity, and crossing it in either direction requires both preparation and a receiving structure.
The Christian mystical tradition understood the same terrain through a different vocabulary. John of the Cross, writing in sixteenth-century Spain, described the noche oscura del alma — the dark night of the soul — not as a poetic metaphor for sadness but as a precise phenomenological account of what occurs when the ordinary supports of the psyche are systematically stripped away in the approach to mystical union (John of the Cross, 1578/1959). His writing is remarkably clinical: the individual loses access to the spiritual consolations that previously oriented them, the ordinary structures of meaning collapse, and they are left in a darkness that is, from the inside, indistinguishable from complete spiritual desolation and psychological disintegration. John was not frightened by this process — he had traversed it — but he was entirely clear that it was not to be entered lightly, and that discernment, guidance, and a sustaining tradition were essential to survival.
The Sufi concept of fana — the annihilation of the ego-self in the divine — is understood within that tradition to be the most exalted station of the mystic path, and the most dangerous (Chittick, 1989). The Sufi masters who wrote about fana were not describing a pleasant dissolution. They were describing a total extinction of the self that, without the proper ground, without the holding of the shaykh and the community, could leave the traveler permanently unmoored.
The Tibetan Buddhist tradition developed, over centuries, the most elaborate cartography of dissolution-states in any spiritual system — the Bardo Thodol, or Tibetan Book of the Dead, being only the most well-known example (Fremantle & Trungpa, 1975). These texts exist precisely because the tradition recognized that encounters with the luminous ground of awareness — whether in death, in deep meditation, or in visionary practice — were encounters that required navigation. The whole of the Vajrayana system can be understood as a set of technologies for navigating extreme states of consciousness without being destroyed by them. This is why transmission from a qualified teacher was considered non-negotiable rather than optional.
What these traditions share — across their enormous cultural and theological differences — is a consensus that approaches the unanimous: genuine dissolution is genuine transformation and genuine danger, simultaneously, and the structures that surround it are not incidental. They are load-bearing.
Victor Turner’s anthropological concept of liminality — the threshold state between social structures and identities — illuminates why the container matters so fundamentally (Turner, 1969). The liminal state is, by definition, the dissolution of category. The liminal individual has left behind the social structures that defined them and not yet entered the ones that will define them on the other side. They are in between — structurally invisible, symbolically dangerous, genuinely vulnerable. In traditional societies, the liminal period was always bounded. There was a beginning, a middle, and an end. There were guides and there were rules. There was always a door back.
What we have largely inherited in the twenty-first century is liminality without limits. Dissolution without containers. Death without a plan for resurrection.
The particular danger of long term ascetic practices: complacency
There is a dimension to this discussion that is almost never named, and it may be the most important one. Most of the existing literature — where it acknowledges risk at all — focuses on the risks of first exposure. The novice fasting for the first time. The first psychedelic ceremony. The first intensive meditation retreat. These risks are real, and they are well worth addressing. But they are not the deepest risk.
Fasting: my personal all-time favorite
Fasting, because of its potential power, poses one of the largest risks. The deepest risk belongs to the experienced practitioner who may tend to become complacent and assume they have mastered something than in fact is bigger and more powerful than they are. They may think, “I’ve done this hundreds of times before. I’ve got this.” Then only to discover that it’s this one particular fast that takes them right up the edge – so very close that they can’t entirely see it. It has nothing to do with age, physical conditioning or will. Sometimes the stronger the person is the more they underestimate what’s happening. As the days of the fast go on – and once the fast is over – coming back may require a particular skill set and expertise they had not anticipated needing.
Here is what decades of practice actually builds: not immunity to dissolution, but expertise at dissolving. Every deep fast, every extended retreat, every ceremony that took the practitioner to genuine threshold — each of these crossings was also a thinning. A thinning of the membrane between ordinary consciousness and whatever lies beyond it. This phenomenon can be highly destabilizing psychologically and spiritually and can require balls of steel to come back from gracefully and intact.
But in addition to this another well-documented phenomenon occurs: autophagy so deep it literally reboots and changes the body’s stem cells. Actions like these have unpredictable and unexpected biological and psychological consequence. The brutal physical nature of it is what takes the person to the very edge of life.
Refeeding after a fast: Calculated risks
The danger doesn’t end when the fast does. In fact, the refeeding stage is where the most dire risks—including heart failure and death—reside. Refeeding Syndrome is a well-documented medical phenomenon where sudden shifts in electrolytes can overwhelm a body that has been ‘taken down to the studs.’ This is why an expertise at dissolving must be matched by an equal expertise in rebuilding. You cannot rush the return to the world of the living.
Psychological consequences
The human psyche is, among its many functions, a homeostatic system. It learns. It adapts. It accommodates repeated experience. The novice who required days of fasting or a threshold dose of psilocybin to touch genuine ego dissolution may, after twenty years of consistent practice, approach the same territory with a three-day fast, or at a much lower dose, or with nothing more than a focused meditation session in a charged environment.
This is experienced from the inside as deepening. As refinement. As evidence that the practice is maturing and that the practitioner is becoming more capable of sustaining what the tradition offers. And in many real ways, that assessment is correct. The practitioner is more capable. Their navigation of these states has become more sophisticated. Their vocabulary for describing and integrating the experiences has expanded enormously.
But capability is not the same as safety. And sophistication is not the same as protection.
Willoughby Britton’s research found, counter-intuitively, that more intensive practice was associated with more frequent and more severe adverse effects — not the reverse (Lindahl et al., 2017). The assumption that experience confers protection turned out to be largely incorrect. The data suggests that experience confers, at least in part, the ability to go further — which means more frequent contact with the most difficult terrain.
The physiological dimension reinforces this. The body at sixty is not the body at thirty. Adrenal reserves are different. Cardiovascular tolerance for the extremes of fasting or physical ordeal is different. The brain’s capacity to buffer the metabolic disruptions of prolonged altered states changes across the decades. A fasting protocol that was well within the experienced practitioner’s adaptive range at forty-five may carry genuinely different risks at sixty-five — but the practitioner, accustomed to trusting their body’s responses and the practice’s guidance, may not have recalibrated their sense of the edge.
And then there is grief. There is chronic illness. There is the ordinary accumulation of unmourned losses. These are not spiritual irrelevancies — they are load-bearing elements of the psychological structure. A practice entered in one psychological context carries different risks when entered in another. The practitioner who always came home from the edge may find, one day, that the edge has moved, that home is further away than it used to be, or that something in them, for the first time, does not want to make the return trip.
This is not failure. It is not weakness. It is the honest territory of a practice that has been genuinely traversed over many years. And it is precisely why the architecture of return — which many experienced practitioners have long since stopped attending to — matters more, not less, as the years accumulate.
Spiritual Emergency: The Clinical Reality
The clinical literature on what happens when these thresholds are crossed without adequate support describes a coherent and serious picture.
Grof and Grof’s foundational work on spiritual emergency delineated the spectrum from spiritual emergence — the gradual, generally integrable opening of transpersonal experience — to spiritual emergency, in which the opening is so rapid, so total, or so structurally unsupported that the individual cannot maintain ordinary functioning (Grof & Grof, 1989). The clinical presentations they describe overlap substantially with psychosis — the dissolution of self-other boundaries, the intrusion of numinous or terrifying visions, the loss of the ability to function in ordinary social reality. The critical distinction Grof proposed is not phenomenological — the content of the experience does not reliably distinguish spiritual emergency from acute psychosis — but contextual and longitudinal. How did this begin? What is the person’s relationship to the experience? Is there movement through the territory, or is the person stuck?
This distinction is not merely theoretical. It has direct implications for treatment. Pharmacological suppression of a genuine spiritual emergency may interrupt a process that, given appropriate support and containment, would resolve toward integration and genuine transformation. Conversely, treating an acute psychotic episode as a spiritual emergency to be honored rather than medically addressed can be catastrophic. The clinical sophistication required to hold this distinction is considerable — and it is rarely present in either conventional psychiatric settings or in many of the spiritual and ceremonial contexts in which these states arise.
The MAPS (Multidisciplinary Association for Psychedelic Studies) clinical trials for MDMA-assisted psychotherapy — some of the most rigorously designed studies in this space — found that even in highly controlled settings, with extensively trained therapists, standardized protocols, and careful participant screening, approximately one-third of participants experienced what were classified as serious adverse events during or following their sessions (Mitchell et al., 2021). These were not naive individuals in recreational contexts. These were carefully screened therapeutic participants with dedicated clinical support. The data is not an argument against the practice. It is a statement of what the practice actually is.
David Lukoff, whose diagnostic category “Religious or Spiritual Problem” was included in the DSM-IV after an extensive lobbying effort, argued that the mental health system had systematically pathologized experiences that, given appropriate support, were not only survivable but potentially transformative (Lukoff, 1985). His clinical work documented case after case in which the determining factor between breakdown and breakthrough was not the intensity of the experience itself, but the quality of the container in which it occurred — the presence or absence of someone who knew the territory.
The architecture of return
The question of how a person finds their way back from the edge is, at root, a question of what they were anchored to before they left. And the single most consistent finding across traditions, clinical research, and phenomenological accounts is this: the return path must be built prior to the crossing.
This is not a casual observation. It is a structural requirement.
Embodied preparation. The body is the anchor when the mind goes somewhere it cannot explain. Somatic practices — conscious breathwork, movement, sensory grounding — that are established prior to and maintained within altered-state practices provide a thread of return when the cognitive and narrative layers of the self have dissolved (Levine, 1997; van der Kolk, 2014). Peter Levine’s foundational research on trauma and the nervous system demonstrated that the body holds coherence at a biological level that precedes psychological meaning-making — and that this somatic coherence is recoverable even when the cognitive self is temporarily unavailable. This is why body-based orientation is not a supplement to deep practice but a prerequisite.
A qualified guide. Not someone who has read about this territory. Not someone with a certificate earned in a weekend training. Someone whose nervous system has been to these depths and returned — and who has the relational capacity and the integrity to tell the practitioner the truth about what they see, even when the practitioner cannot see it themselves. The research on therapeutic outcomes in both psychedelic-assisted therapy and intensive retreat contexts consistently identifies the quality of the relational container as the primary predictor of positive integration (Johnson et al., 2008; Carhart-Harris & Goodwin, 2017). The guide is not incidental. In the architecture of return, the guide is structural.
Honest intention. The practices most prone to producing uncontained emergencies are those entered without honest examination of what the practitioner actually wants from them. The language of spiritual seeking can obscure motivations that, if examined directly, would reveal grief that hasn’t been fully metabolized, a wish for annihilation that is more literal than the language of ego-death suggests, or a hunger for the intensity of these states that has its own dissociative logic. This is not a judgment on those motivations — they are deeply human. But entering dissolution without honesty about what is actually propelling the descent creates conditions in which the return path is genuinely unclear, because the destination was genuinely unclear.
A stake in ordinary life. The mystical traditions would not have described this as they did, but the clinical and phenomenological literature is consistent: people return from the edge, in part, because something specific calls them back. A relationship. An unfinished task. A love that is not yet complete. These ordinary tethers are not spiritual limitations — they are lifelines. The practitioner who has progressively divested from ordinary engagement, whose identity is increasingly organized around their spiritual practice and their capacity to go deep, has often quietly removed the very anchors that made previous returns navigable.
Integration as practice. Return from a genuine threshold state is not a single event. It is a process that unfolds over months and, sometimes, years. The clinical research on psychedelic-assisted therapy found that the most significant psychological movement often occurred not during the session itself but in the weeks and months following — and that this movement was directly dependent on the quality of integration support available (Carhart-Harris & Goodwin, 2017). The same is true of intensive fasting and retreat. The crossing is one thing; the incorporation of what was encountered into an ordinary life is another, and arguably more demanding, work entirely.
The most experienced are the most exposed
There is a certain irony at the heart of this territory. The people most likely to be navigating these edges — the practitioners with decades of commitment, the clinicians who have guided hundreds of others through threshold experiences, the teachers whose reputation rests partly on their capacity to go deep — are often the least likely to recognize when they have entered genuine danger.
This is not a character failing. It is a structural consequence of what experience confers. Experience confers familiarity with the terrain. Familiarity reduces the alarm response. The veteran practitioner who has visited genuine ego dissolution forty times has a nervous system that no longer treats it as an emergency — which means the warning systems that protect the less experienced are calibrated differently. The person who has always returned trusts that they will return again. And that trust, which is earned and legitimate, can become the last thing that needs to be examined.
William James, whose Varieties of Religious Experience remains one of the most searching accounts of the phenomenology of mystical states, identified four marks of the mystical: noetic quality, transiency, passivity, and ineffability (James, 1902/1985). The third of these — passivity — is the one most relevant here. The mystic in the genuine state does not feel themselves to be in control. They feel themselves to be carried. The entire structure of traditional guidance, ritual container, and community reception existed, in part, to provide the external architecture that the internal architecture could not provide when passivity was complete.
The practitioner who has learned, over decades, to navigate apparent passivity — who has developed cognitive strategies for orienting within dissolution — has acquired a genuine and valuable capacity. But it can also function as a concealment. The appearance of navigation does not always indicate that navigation is actually occurring.
Evelyn Underhill, whose 1911 study Mysticism remains among the most rigorous accounts of the mystical path in the Christian tradition, described the later stages of mystical development with a precision that contemporary clinicians have largely confirmed: the deepening of practice brings not increasing stability but increasing vulnerability to states that earlier stages had not accessed, and the mystic who has arrived at genuine contemplative depth is in some ways more, not less, dependent on the holding structures of tradition and community than the novice (Underhill, 1911/1990). The tradition understood that the destination was not self-sufficiency. It was a deeper and more transparent dependence on what could hold the mystic when the mystic could no longer hold themselves.
A note on the present moment
We are living through a period of unprecedented democratization of access to threshold experiences. The psychedelic renaissance has made high-dose psilocybin, MDMA, ketamine, and ayahuasca available to more people, in more contexts, with less preparation, than at any prior moment in history. Social media has distributed fasting protocols with instructions but without epistemology. Meditation apps offer silent retreat content without the lineage structures that were always their context. The technology is everywhere. The cosmology is largely absent.
This is not an argument for prohibition or restriction. It is an observation about what has been lost in the distribution, and what the costs of that loss appear to be.
The clinical literature is beginning to document those costs. Studies of psychedelic-related emergency presentations to psychiatric facilities have increased significantly in recent years (Simonsson et al., 2021). Willoughby Britton’s ongoing research continues to document meditation-related adverse effects across a population that is growing in size without growing in the quality of support available to it. The retreat centers, clinical practitioners, and spiritual teachers who are doing this work responsibly are overwhelmed. The ecosystem of holding — the return architecture that every tradition that understood these practices built around them — has not scaled at anything approaching the rate at which the practices themselves have spread.
The people entering these experiences deserve better than the silence of a culture that has forgotten what it once knew about how to hold them.
The edge has always been where transformation lives
None of this is a case against the practices. The human encounter with genuine dissolution — with the place where the ordinary self stops and something else becomes perceptible — is one of the most profound experiences available to us. Across cultures and across millennia, it has been the beginning of actual healing rather than managed survival, of genuine wisdom rather than accumulated information, of the kind of love that knows what it costs.
The traditions were right to carry these practices. The people who enter them sincerely are not wrong to do so. The transformation on the other side is real.
But the edge demands honesty. It demands preparation. It demands — and this is the thing most easily lost in a culture that prizes individual autonomy — a humility about the limits of what any one person can navigate alone.
If you are going to walk up to the edge of life and look over into the precipice, you had better know how to find your way back.
You had better know what you are anchored to before you leave. You had better have someone who knows this terrain and who will come looking for you if you don’t return on time. You had better have examined, with as much honesty as you can bring, why you are going — and what you are coming back for.
And if you have been practicing for thirty years, and the threshold is lower now than it used to be, and the crossings come more easily than they once did — that is not evidence that you no longer need the architecture of return. That is evidence, if anything, that you need it more.
The edge has always been where transformation lives. The question is not whether to approach it. The question is whether you have built, before you need it, the structure that will hold you while you are there — and the path that will bring you home when it is time.
For those of us dedicated to intense spiritual practices we sometimes forget we have a choice. I know I do. Every time I do a 14-day water-only fast I’m choosing to sharpen my mystic discipline, hone my mind and rebuild my body. But even with all the experience I have I lose perspective and can tend to abandon myself to the process. I now always remember that coming back from the journey is equally as important as getting there.
Randi Fredricks, Ph.D.
Author Bio
Randi Fredricks, Ph.D. is a leading expert in the field of mental health counseling and psychotherapy, with over three decades of experience in both research and practice. She holds a PhD from The Institute of Transpersonal Psychology and has published ground-breaking research on communication, mental health, and complementary and alternative medicine. Dr. Fredricks is a best-selling author of books on the treatment of mental health conditions with complementary and alternative medicine. Her work has been featured in leading academic journals and is recognized worldwide. She currently is actively involved in developing innovative solutions for treating mental health. To learn more about her work, visit her website: https://drrandifredricks.com
References
Carhart-Harris, R. L., Leech, R., Hellyer, P. J., Shanahan, M., Feilding, A., Tagliazucchi, E., Chialvo, D. R., & Nutt, D. (2012). The default mode, ego functions and free energy: A neurobiological account of Freudian ideas. Brain, 135(5), 1320–1340. https://doi.org/10.1093/brain/aws010
Carhart-Harris, R., & Goodwin, G. M. (2017). The therapeutic potential of psychedelic drugs: Past, present, and future. Neuropsychopharmacology, 42(11), 2105–2113. https://doi.org/10.1038/npp.2017.84
Chittick, W. C. (1989). The Sufi path of knowledge: Ibn al-Arabi’s metaphysics of imagination. State University of New York Press.
Eliade, M. (1964). Shamanism: Archaic techniques of ecstasy (W. R. Trask, Trans.). Princeton University Press. (Original work published 1951)
Fremantle, F., & Trungpa, C. (1975). The Tibetan book of the dead: The great liberation through hearing in the bardo. Shambhala.
Grof, S., & Grof, C. (Eds.). (1989). Spiritual emergency: When personal transformation becomes a crisis. Tarcher/Putnam.
James, W. (1985). The varieties of religious experience: A study in human nature. Harvard University Press. (Original work published 1902)
John of the Cross. (1959). Dark night of the soul (E. A. Peers, Trans.). Doubleday. (Original work written c. 1578)
Johnson, M. W., Richards, W. A., & Griffiths, R. R. (2008). Human hallucinogen research: Guidelines for safety. Journal of Psychopharmacology, 22(6), 603–620. https://doi.org/10.1177/0269881108093587
Fredricks, Randi. (2011). An exploratory study of the effects of water fasting for depression (Doctoral dissertation). ProQuest database. (UMI No. 3453555)
Fredricks, Randi. (2012). Fasting: An Exceptional Human Experience. Bloomington, IN: AuthorHouse.
Levine, P. A. (1997). Waking the tiger: Healing trauma. North Atlantic Books.
Lindahl, J. R., Fisher, N. E., Cooper, D. J., Rosen, R. K., & Britton, W. B. (2017). The varieties of contemplative experience: A mixed-methods study of meditation-related challenges in Western Buddhists. PLOS ONE, 12(5), e0176239. https://doi.org/10.1371/journal.pone.0176239
Lukoff, D. (1985). The diagnosis of mystical experiences with psychotic features. Journal of Transpersonal Psychology, 17(2), 155–181.
Mitchell, J. M., Bogenschutz, M., Lilienstein, A., Harrison, C., Kleiman, S., Parker-Guilbert, K., Ot’alora G., M., Garas, W., Paleos, C., Gorman, I., Nicholas, C., Mithoefer, M., Carlin, S., Poulter, B., Mithoefer, A., Quevedo, S., & Doblin, R. (2021). MDMA-assisted therapy for severe PTSD: A randomized, double-blind, placebo-controlled phase 3 study. Nature Medicine, 27, 1025–1033. https://doi.org/10.1038/s41591-021-01336-3
Simonsson, O., Hendricks, P. S., Carhart-Harris, R., Kettner, H., Osika, W., & Goldin, P. R. (2021). Prevalence and associations of challenging, difficult, or distressing experiences using classic psychedelics. Journal of Affective Disorders, 289, 226–235. https://doi.org/10.1016/j.jad.2021.04.039
Turner, V. (1969). The ritual process: Structure and anti-structure. Aldine de Gruyter.
Underhill, E. (1990). Mysticism: A study in the nature and development of spiritual consciousness. Doubleday. (Original work published 1911)
van der Kolk, B. A. (2014). The body keeps the score: Brain, mind, and body in the healing of trauma. Viking.
