Phenomenology and content of the inhaled N, N-dimethyltryptamine (N, N-DMT) experience

Understanding the phenomenology and content of the inhaled N, N, dimethyltryptamine (N, N-DMT) experience is critical to facilitate and support ongoing research and therapeutic models targeting mental health conditions and central nervous system pathology. A qualitative analysis was conducted of all N, N-DMT experiences posted to the r/DMT Reddit community over a 10-year period from 2009 to 2018. A total of 3778 experiences from 3305 posts were included in this study. A median dose of N, N-DMT of 40.0 mg [interquartile range (IQR), 27.5 to 50.0] and a median experience duration of 10 min (IQR, 5.0 to 15.0) were identified. The most common somatic effects were somaesthesias (n = 1415, 37.5%) and an auditory ringing (n = 583, 15.4%). Visualizations predominantly consisted of fractals, shapes, patterns (n = 1231, 32.6%) and vivid colours (n = 953, 25.2%). Entity encounters were reported in 45.5% (n = 1719) of the experiences and involved predominantly a feminine phenotype (n = 416, 24.2%); deities (n = 293, 17.0%); aliens (n = 281, 16.3%); creature-based entities (n = 158, 9.2%, including reptilian and insectoid beings); mythological beings (n = 144, 8.4%, including machine elves); and jesters (n = 112, 6.5%). Entity interactions were predominantly positive (n = 600, 34.9% of encounters) involving benevolent, comforting, protecting, or outwardly caring interactions. A companion-type, pedagogical, or guide-type interaction was identified 32.4% of encounters (n = 557). Common typology, architecture, and structural features of the “DMT world” included descriptions of alternate or higher dimensions (n = 952, 25.2%); rooms [n = 582, 15.4%, including the “waiting room” (n = 105, 2.8%)], and a tunnel (n = 390, 10.3%). Features of mystical and ego-dissolution experiences were common. Additional rewarding aspects were identified, including a sense of familiarity and the acceptance/removal of the fear of death. Challenging and difficult responses were less frequent but also documented. Statements of profundity were identified in 232 experiences (6.1%), including pronouncing the experience or an aspect of the experience as the most “beautiful” or feeling the most “beautiful” of their life (n = 47, 1.2%). This study identified common phenomenological themes and content of naturalistic inhaled N, N-DMT experiences. Major thematic domains included (1) physical and somatic experiences; (2) visualizations and imagery; (3) entity encounters including entity phenotype, descriptors, attributes, disposition, and characteristics of the interaction; (4) typology, architectural features, structural characteristics, and scenery of the “DMT world”; (5) alerations in consciousness (including mystical experiences, out-of-body experiences, and ego-dissolution); (6) emotional responses (including positive, rewarding, difficult, and challenging); and (7) statements of profundity.

www.nature.com/scientificreports/ N, N-Dimethyltryptamine (N, N-DMT) is a naturally occurring classic psychedelic with psychoactive properties that are mediated primarily via the serotonergic pathway and serotonin 2A (5-HT 2A ) receptor agonism 1 . Plantbased DMT has been used for centuries for ritual healing ceremonies and spiritual practices [2][3][4][5] . Early reports of DMT-use derive from indigenous communities in the Amazon-basin and involve the oral consumption of Ayahuasca 3,4,6-8 , which is a Quechua term translated to "vine of the souls" or "vine of the dead" 9 . N, N-Dimethyltryptamine is typically orally inactive due to a deamination process facilitated by visceral monoamine oxidase enzymes 8 . The technology of the Ayahuasca brew orally activates the plant DMT alkaloids by combining them with plants containing beta (β)-carboline alkaloids, a reversible monoamine oxidase inhibitor (MAOI) 3,8 . Alternate routes of DMT administration, such as inhaled [10][11][12] , intravenous 13,14 , intramuscular 15 , intra-nasal, and per-rectum reduce the first pass effect resulting in an increase in bioavailability, a more rapid onset, and shorter duration of effect compared to oral administration 10 . Using data from the Global Drug Survey (an anonymous online global survey; n = 22,289), Winstock et al. observed that overall lifetime use of DMT was relatively low (8.9%) and the predominant reported route of administration amongst individuals who used DMT was inhaled (92.2%) 11 .
In one of the earliest peer-reviewed studies on the subjective effects of DMT, Strassman et al. conducted a unblinded followed by a double-blind randomized controlled trial of intravenous DMT-fumarate in twelve volunteers 16 . A significant dose-response effect of DMT was observed in all six domains of the Hallucinogen Rating Scale (HRS) including: somaesthesia, affect, perception, cognition, volition, and intensity 16,33,38 . To note, the HRS was developed through interviews with individuals experienced with inhaled DMT 16 .
Benny Shanon explored the subjective and perceptual effects of 245 Ayahuasca experiences, including 67 of his own experiences 2 . Shanon identified common patterns and attempted to "draw a map" of the Ayahuasca experience incorporating themes including, but not limited to, general effects; open-eye visuals; structural typology; the contents and themes of visions; non-visual perceptions; and consciousness 2 . Cott and Rock conducted a survey-based method in 19 DMT users and documented 9 themes that captured the essential aspects of the DMT-induced state following "ingestion", including hallucinations; entering other realms and contacting other sentient beings; lucidity; affective distortions; ineffability; intensity; spirituality and learning about truths; distortions in sense of time, space, and self; and familiarity 19 .
In a retrospective survey-based study, Griffiths et al. examined the single most memorable "God encounter experience" in individuals who used N, N-DMT (n = 606) and Ayahuasca (n = 435) 21 . A total of 73% and 65% of the N, N-DMT and Ayahuasca experiences, respectively, fulfilled criteria of a complete mystical experience and a large proportion of both cohorts rated the experience as among the most personally meaningful and spiritually significant lifetime experiences 21 .
Davis et al. systematically studied the account of the single most memorable entity encounter after inhaled N, N-DMT use in 2561 individuals 27 . Almost all of the individuals in this study reported an emotional response to the encounter to which profound and enduring ontological changes in worldview were attributed 27 . Timmermann et al. conducted a fixed-order, placebo controlled, single blind intravenous DMT administration study in 13 participants and established that DMT induced consistent visual, somatic, emotional, and 'higher-level' metacognitive effects 14 ; and noted similarities between DMT experiences and near-death experiences (NDE) 17 . More recently, Michael et al. performed a thematic analysis from semi-structured interviews of 36 inhaled naturalistic DMT experiences (dose 40-75 mg) 30 . The most prominent theme from this study involved an encounter with "sentient entities that were experienced as beyond", occurring in 94% of the experiences 30 .
The shared qualities amongst DMT and certain non-drug induced altered states of consciousness 17,18,21,27 , in concurrence with the growing evidence of an endogenous mammalian source of DMT 39,40 , has led to the increasingly accepted hypothesis that endogenous DMT may be responsible for particular alternate states of consciousness 17,21,27 . However, it is not clear that endogenous DMT release occurs in sufficient concentrations or with sufficient selectivity to produce pharmacological effects 41,42 .
There currently exists a paucity of knowledge describing how psychedelics are used in naturalistic settings in Western societies 43 . A greater understanding of the patterns of use of inhaled N, N-DMT in naturalistic settings and the broader user population will aid in the explication of the expanding research findings 43 . Inhaled N, N-DMT sometimes occasions profound "ontological shock" experiences prompting a reconsideration of the very nature of reality, and such experiences are associated with enduring positive changes in attitudes, moods and behavior 5,27 . Given the unusual and consequential nature of these experiences, the current study sought to provide new information about the phenomenology and content of inhaled N, N-DMT experiences by systematically analyzing thousands of N, N-DMT experience reports from online postings over a 10-year period. A greater understanding of the inhaled N, N-DMT experience is critical to further our understanding of the properties and potential of this compound. Such learnings could inform current and future research and therapeutic applications in the management of central nervous system and mental health conditions, and, potentially, catalyze interest in and insights into broader ontological questions pertaining to consciousness and the human psyche 21

Materials and methods
Data source and collection. All posts to the "DMT" community page ("r/DMT") on Reddit from database inception in 2009 through to 2018 inclusive (10 years), were screened for inclusion in this study. Reddit is an online social network, news aggregator, and host of forums for communities with common interests to share, discuss, and comment on a topic 45,46 . Data from Reddit has been aggregated previously to inform peer-reviewed research [46][47][48] . The r/DMT community is a public forum for the discussion and sharing of information pertaining to DMT and is a rich community-based open-access resource, which includes individuals reporting and describing DMT experiences. Archived posts to the r/DMT community were accessed via Pushshift: a big-data storage project, comprehensive search engine, and real-time analytics tracker for the website Reddit 49 . At the time of this study, Pushshift met the standards for the terms of use of the Reddit application programming interface (API).
The title of all posts to the r/DMT community within the study period were manually screened and included for full post review if the post had the potential to include a self-reported N, N-DMT experience (see Fig. 1). All relevant posts that were identified after the initial screen underwent full independent manual review to assess candidacy for final study inclusion.
Posts were included within the final study cohort if the post included a firsthand description of any aspect of an inhaled N, N-DMT experience. Posts were excluded based on the following criteria: (1) the route of administration was not inhaled (i.e., oral, intravenous, intramuscular, rectal, or intra-nasal); (2) the reported DMT alkaloid was not "DMT", "N, N-DMT, or "freebase DMT" (i.e., 5-MeO-DMT and 4-ACO DMT were excluded); (3) the post solely referenced or linked to an external website, video, audio file, or image; (4) the post failed to describe any experience or subjective response to N, N-DMT; (5) the post was non-English; or (6) the post was a duplicate or deleted. Non-English posts were identified but all contained enough information to be excluded based on alternate criteria (i.e., only included a link, image, and/or video). Therefore, zero experiences were excluded for being non-English. All plant-based accompaniments (i.e., Changa, enhanced leaf, and joints or spliffs) were included in this study. Plant-based accompaniments are largely used to improve to vaporization yield and reduce burning the crystalline N, N-DMT, although it is recognized that Changa also includes

Content analysis, statistics, and research ethics. All included posts and experiences underwent
independent full manual review. The following data were systematically collected for all posts: month and year of posting, Reddit author username, title, and word count. The following data were systematically collected if available for all experiences: age at time of experience, author gender, previous inhaled N, N-DMT use, previous psychedelic use, data pertaining to the setting of the experience, plant source used for DMT extraction, the device used for administration, the reported N, N-DMT dose and number of inhalations, the duration of experience, and concomitant psychoactive substance use. A grounded theory inductive qualitative analytic coding approach was used for all included experiences using NVivo 12 (12.6.0) 50 . Independent meaningful units (MU) were coded and organized into categorical themes 50,51 . Opportunity for code review, MU development, and thematic development were afforded to four authors (DWL, RCH, CT, and RG) after the completion of the coding of 50, 300, and 1000 experiences. The following thematic categories were developed: (1) physical and somatic experiences; (2) content of visualizations and imagery; (3) entity encounters including entity phenotype, descriptors, attributes, disposition, and characteristics of the interaction; (4) typology, architectural features, structural characteristics, and scenery of the "DMT world"; (5) alerations in consciousness; (6) emotional responses (including positive, rewarding, difficult, and challenging); and (7) statements of profundity.
Additionally, four validated scales for documenting cardinal aspects of the psychedelic experience were completed, including the Mystical Experience Questionnaire (MEQ) 52,53 , Challenging Experience Questionnaire (CEQ) 54 , God Encounter Questionnaire (GEQ) 21 , and Ego-Dissolution Inventory (EDI) 55,56 . The MEQ, CEQ, and EDI were completed for all experiences while the GEQ was completed for all reported entity encounters 27 . To note, the included questionnaires are validated for self-report and not for third-party assessment. However, due to the relative novelty of this field of study and the paucity of validated scales, we felt the application of these questionnaires in this study was still appropriate to facilitate and structure the analysis of the respective features occasioned by DMT. As such, items within the questionnaires were not completed as a rank or scale, but merely as a binary outcome identifying the presence or absence of the questionnaire items within a particular experience.
Statements of profundity were coded and defined as endorsements pronouncing the experience or an aspect of the experience as "the most [X] experience of my life" or "…the most [X] I have felt in my life…"; where [X] was coded as the descriptor. For statements that include multiple descriptors, the order in which the descriptor appeared within a statement was also coded.
Research ethics board approval. Institutional research ethics board (REB) approval for human research protocols (University of Toronto REB protocol number 39101) was obtained for the collection, analysis, and dissemination of the data and content included within this study.

Results
A total of 30,652 r/DMT reddit posts were identified and screened over the 10-year period from 2009 to 2018, of which 3305 posts containing 3778 unique inhaled N, N-DMT experiences were included in this study (see Fig. 1). Two-thousand nine-hundred and thirty-four posts (88.8%) included a report of a single experience, 297 posts (9.0%) included two experiences, and 74 posts (2.2%) included 3 or more experiences.
The included 3305 posts were created by 2277 Reddit authors, with a median age at the time of the N, N-DMT experience of 23.0 years [interquartile range (IQR), 20.0 to 29.8; reported in 118 experiences (3.1%)], and a median word count of 311 (IQR, 160.0 to 568.0; see Table 1). The gender of the author was identified in 237 experiences (6.3%), including 189 males (5.0%) and 48 females (1.3%). The location in which the experience occurred was reported in 1138 experiences (30.1%), of which the location was most frequently inside (n = 969, 25.6%) within a bedroom or living room (n = 492, 13.0%); while 169 experiences (4.5%) were reported as occurring outside. Music was reportedly used in 408 experiences (10.8%) and the presence or absence of a sitter was identified in 948 experiences (25.1%); of which 157 experiences (4.2%) were completed alone. Identified plant-based material accompaniments included the "sandwich method" (containing the DMT between other plants to avoid losing intake due to vaporization produced by directly burning the substance; n = 259, 6.8%); Changa (n = 165, 4.4%); and enhanced-leaf, joints, or blunts (n = 21, 0.6%). The median experience duration, estimated from 538 experiences (14.2%) was 10 min (IQR 5.0-15.0).
Amnestic events were identified in in 582 experiences (15.4%). Partial amnesia of the experience was reported in 513 experiences (13.6%) while full amnesia and "blackouts" were reported in 69 (1.8%) and 46 (1.2%) experiences, respectively. A loss of awareness to being under the influence of N, N-DMT during the actual experience was identified in 46 experiences (1.2%).
Ancient and/or cultural-associated imagery (i.e., ancient Egyptian or indigenous Meso-/South American) was reported in 80 experiences (2.1%). Visions of relatives (dead or alive) and visions of "previous lives" were described in 75 (2.0%) and 31 (0.8%) experiences, respectively. Additional content of visualizations and imagery are listed in Table 3.
Entity attributes, disposition, and characteristics of the interaction. The attributes, disposition, and characteristics of the entities and the encounters were identified and coded (see Table 4). Positive interactions occurred in 600 encounters (34.9%) and most frequently involved a benevolent (i.e., kind, compassionate, altruistic, etc.) interaction (n = 527; 30.7%); followed by an interaction characterized as comforting, protecting, Table 4. Entity attributes, disposition, and characteristics of the entity interaction. a In addition to entity attributes identified in the God Encounter Questionnaire (see Table 5).   5%). An interaction involving the Reddit author being provided nourishment occurred in 13 experiences (0.8%). An affusion-type or aspersion-type action or the entity pouring liquid on the Reddit author was described in 10 experiences (0.6%).

Coded units and themes
A companion-type, pedagogical, or guide-type interaction was identified in 557 encounters (32.4%). An entity guiding, touring, or showing occurred in 457 experiences (26.6%), while an entity beckoning or summoning occurred in 47 experiences (2.7%). The entity tested or offered a choice (including option to live or die) to the Reddit author in 77 experiences (4.5%). An entity controlled or altered the visuals of the experience in 58 encounters (3.4%), transferred knowledge in 52 encounters (3.0%), and was encouraging in 24 (1.4%). Gifts or information were offered by entities in 18 experiences (1.0%).
A negative or difficult entity interaction was described in 196 of the 1719 entity encounters (11.4%), most frequently involving a description of an entity being menacing, maliciousness, evil, threatening, violent, attacking, intimidating, or bullying in 92 experiences (5.4%). An angry, frustrated, unfriendly, unhappy, disappointed, or sad entity disposition was reported in 57 encounters (3.3%). A rejecting, denying, or unwelcoming encounter was reported in 45 experiences (2.6%). A description of being tortured or raped by an entity occurred in 14 experiences (0.8%), while being teared apart or eaten/consumed by an entity occurred in 11 encounters (0.6%).
A medical-type interaction was coded in 154 encounters (9.0%), most frequently involving the description of an entity examining, observing, scanning, or analyzing the Reddit author (n = 141, 8.2%). The implantation of a device was described in 59 encounters (3.4%); a surgery, procedure, operation, injection, or experimentation in 56 encounters (3.3%); and bodily exploration or probing in 34 encounters (2.0%).
The description of a novel or alien language was described in 152 experiences (8.8%), while communication via emotions, colours, or vibrations was reported 11 experiences (0.6%).
The majority of the Reddit authors had an emotional response during the encounter (n = 1583, 92.1%) and that which was encountered had an emotional response during the encounter in 394 experiences (22.9%). The Reddit author ascertained a message, task, mission, or insight from the encounter in 792 experiences (46.1%) and very few acquired predictions about the future (n = 6, 0.3%).
That which was encountered existed, at least in part, in some other dimension or reality in 1504 experiences (87.5%) and continued to exist after the encounter in 1117 experiences (65.0%). The Reddit author felt they were completely the same as that which was encountered in 48 experiences (2.8%).
Typology, architectural features, structural characteristics, scenery, and objects of the "DMT world". Common typological, structural, architectural features were identified and catalogued (see Table 6).

Coded units and themes
Documented in experience, n (%)

Experiences with no reported concomitant psychoactive substance use (n = 3242)
Helices, DNA, spirals, or hourglass shapes 22   www.nature.com/scientificreports/ hyperspace (n = 646, 17.1%); and alternate-, hyper-, or multi-dimensions NOS (n = 220, 5.8%). To note, it is recognized that an interaction with an entity that existed, at least in part, in some other dimension or reality occurred in 1504 experiences (39.8%); however, authors frequently reported interacting with entities from a different dimension/reality whilst not being present in that dimension/reality themselves. The description of being inside a room was identified in 582 experiences (15.4%); including 105 (2.8%) that identified being in the "waiting room, " specifically.
Reports of a sterile, clean, or functional room (including a medical, operating, or examination rooms) occurred in 88 experiences (2.3%). A geometric, fractal, or multi-coloured room was reported in 79 experiences (2.1%), while a white or bright room was described in 39 experiences (1.0%). See Table 6 for additional descriptions of rooms encountered.
A tunnel-type structure was reported in 390 experiences (10.3%). A void (including a white, golden, black, and void NOS) was described in 233 experiences (6.2%).

Rewarding emotional responses.
A sense of familiarity to the experience was identified in 482 experiences (12.8%), of which 55 experiences (1.5%) reporting a sense of "home" or belonging (see Table 7).
Becoming tearful or reporting tears of joy were reported in 111 experiences (2.9%) and euphoria was reported in 93 experiences (2.5%). Despite 236 reports (6.2%) indicating a "feeling as if dead or dying" or a "profound experience of death" (see Table 9), 59 experiences (1.6% of all experiences or 25.0% experiences including the theme of death) endorsed an acceptance of death or the removal of fear of death.
Fifty-three experiences (1.4%) described rebirth; 33 experiences (0.9%) incorporated a sexual, intimate, or erotic tone; and 22 reports (0.6%) stated the experience felt more real than everyday reality.   Table 7) containing at least one item within the "mystical" subsection of the MEQ, most frequently a "gain of insightful knowledge experienced at an intuitive level" (n = 717, 19.0%). A total of 2984 experiences (79.0%) included reports coded within at least one item within the "positive mood" subsection of the MEQ, most frequently an "experience of amazement" (n = 2715, 71.9%). A total of 2746 experiences (72.7%) included at least one item within the "transcendence of space or time" subsection of the MEQ, most frequently a "loss of your usual sense of space" (n = 2710, 71.7%). A total of 543 experiences (14.4%) reported at least one item within the "ineffability" subsection of the MEQ, most frequently a "sense that the experience cannot be described adequately in words" (n = 534, 14.1%).

Difficult emotional responses and the Challenging Experience Questionnaire (CEQ).
Difficult emotional responses to the experience included sense of being stuck in a time loop (n = 31, 0.8%), claustrophobia or feeling trapped/lost (n = 17, 0.4%), thoughts or mind racing (n = 9, 0.2%), and suicidality (n = 9, 0.2%; see Table 9). www.nature.com/scientificreports/ A total of 1019 experiences (27.0%) included a minimum of one emotional item from the CEQ (see Table 9). A total of 840 experiences (22.2%) included at least one component of the "fear" section from the CEQ, most frequently an "experience of fear" (n = 693, 18.3%). A total of 416 experiences (11.0%) included at least one component of the "grief " section from the CEQ, most frequently "emotional and/or physical suffering" (n = 386, 10.2%). A total of 107 experiences (2.8%) reported at least one component of the "insanity" section, most frequently "afraid that the state would last forever" (n = 92, 2.4%). Forty-five experiences (1.2%) reported a minimum of one item within the "isolation" subsection, most frequently "feel isolated from people and things" and "experience of isolation and loneliness" (n = 44, 1.2%, each). A total of 236 experiences (6.2%) reported at least one component of the "death" section, most frequently "feel as if dead or dying" (n = 227, 6.0%). A total of 17 experiences (0.4%) reported at least one component of the "paranoia" section.

Figure 2.
Frequency and distribution of reported entity phenotypes, characteristics, and attributes. Prevalence rates reflect the frequency in relation to experiences that reported an entity encounter (n = 1719) and do not summate to 100% due to instances whereby multiple entity phenotypes, characteristics, and/or descriptors were included within a single experience and/or were used to describe a particular entity. a Including Ganesh, Shiva, Kali, Indra, Naga, or Shakti; b including Tara; c including Ra, Anubis, and pharaohs; d including Minerva, Zeus, and Thor. www.nature.com/scientificreports/ Dual descriptors within a statement of profundity were identified in 43 experiences, of which the most common descriptors reported concurrently were "beautiful" and "intense or extreme" (n = 6); and "terrifying, terrified, scary, or scared" and "amazing" (n = 6).

Discussion
This study conducted a qualitative analysis of naturalistic inhaled N, N-DMT experiences and documented consistent phenomenological thematic patterns, particularly within the domains of (1) physical and somatic experiences; (2) visualizations and imagery; (3) entity encounters including entity phenotype, descriptors, attributes, disposition, and characteristics of the interaction; (4) typology, architectural features, structural characteristics, and scenery of the "DMT world"; (5) alterations in consciousness (including mystical experiences, out-of-body experiences, and ego-dissolution); (6) emotional responses (including positive, rewarding, difficult, and challenging); and (7) statements of profundity.
The results of this study contribute to the limited descriptive information about inhaled N, N-DMT use and the resultant experience 11,30,43 . This study identified a reported median dose of inhaled N, N-DMT of 40 mg and duration of experience of 10 min. This is consistent with a previous study conducted in a natural setting that documented an average inhaled N, N-DMT dosage of 40 mg which induced changes in subjective and neural markers that returned to baseline after approximately 7 min 37 . Additionally, the naturalistic study conducted by Michael et al. reported a similar mean dose of inhaled DMT of 54.5 mg 30 . Somatic and physical responses to N, N-DMT administration were commonly observed in this study, most frequently the perception of somaesthesias, or kinesthetic hallucinations, and an auditory ringing sound; both of which have been previously ascribed to Be au tif ul In te ns e or ex tre m e Pr of ou nd or po w er fu l Te rr ify in g, sc ar y, or sc ar ed Am az in g R ea l St ra ng es t, w ei rd es t, cr az ie st , sh oc ki ng , or un be lie va bl e Pe ac ef ul , ca lm in g, bl is sf ul , re lie vi ng , or re as su rin g M in d-sh at te rin g, m in d -b lo w in g, co nf us in g, in sa ne Be st or gr ea te st H ap py , jo y, pr id e Im po rta nt , im pa ct fu l, in si gh tfu l, in flu en tia l, or life ch an gi ng Lo ve M ag ic al , su rr ea l, or su bl im e En lig ht en in g, or sp iri tu al , gr ac ef ul , or pu rit y In cr ed ib le , or ex tra or di na ry Po si tiv e, w on de rfu l, ph en om en al , or m ira cu lo us Aw e-in sp iri ng or aw es om e C om pl ex , el ab or at e, or da zz lin g Eu ph or ic W ar m in g R eg re t, w or ry , or ho pe le ss D is tu rb in g, de bi lita tin g, or ap pa llin g C la rit y or br ig ht ne ss H ar de st , ha rr ow in g, or he ct ic Ex hi la ra tin g, ec st at ic , or m es m er iz in g U nc om fo rta bl e or pa in fu l H om el y, in vi tin g, ch er is he d, or gr at itu de N ig ht m ar e or w or st Fu n or en jo ya bl e Ex qu is ite , pe rfe ct , or sp ec ia l H ea lin g or w el lb ei ng Li be ra tin g or op en in g Incredible, or extraordinary 7 4 Positive, wonderful, phenomenal, or miraculous 6 2 2 Awe-inspiring or awesome  is a descriptor theme or themes). The total column represents the total coded frequency of a theme. For statements that included multiple descriptors, the order in which the themes appeared within a statement is indicated: first order column (i.e., the descriptor appeared first within the statement or alone), second order row (i.e., the descriptor appeared second within the statement), and third or fourth order column. The frequency in which first order and second order descriptors appeared jointly is highlighted at the intersection of those themes.  16,19,20,26 . Gouzoulis-Mayfrank et al. documented auditory hallucinations (including "telephone rings") in 2 out of 12 subjects (16.7%) who completed a high dose intravenous DMT session, which is a comparable incidence rate identified within this study (15.4%) 26 . Strassman et al. documented a high-pitched "whining/whirring", "chattering, " "crinkling" sound in approximately half of the subjects at the onset of intravenous DMT administration 16 . The features of the N, N-DMT-induced visualizations identified in this study most frequently involved the description of fractals, geometric shapes, and patterns (including descriptions of kaleidoscopes, a chrysanthemum, sacred geometry, and mandalas) and vivid, brilliant, and novel colours. Previous observations of DMToccasioned visualizations include similar descriptions 16,19,23,26 . Strassman et al. reported that following intravenous administration of DMT "many subjects described kaleidoscopic geometric patterns that were not obviously representational" 16 , while Cott and Rock concluded that "colours, patterns, and lights were one of two common visual hallucinations" 19 . Gouzoulis-Mayfrank et al. observed that visual hallucinations consisting of "complex geometric patterns" occurred in all volunteers after receiving a high dose of intravenous DMT, although these phenomena were recorded in only a subset of volunteers following a low dose 26 . Additionally, Meyer relies on "vivid, brilliantly colored, geometric visual hallucinations" as a qualifying criterium when defining a particular "level" of DMT experience 23 .
Various theories have been proposed to explain the predictable DMT occasioned visual experience from a neurophysiologic perspective. Entoptic phenomena, defined as visual effects whose source is within the eye or visual system, can include grids or lattice patterns, parallel lines, dots or flakes, zigzags or undulating lines, nested curves, and spirals 57,58 . Entoptic phenomena featured prominently in some prehistoric art 58 and were shown to be increased after repeated Ayahuasca ingestion in naturalistic settings 57 . The prevalent geometric-type visualizations identified in this study are consistent with descriptions of entoptic phenomena. Based on phenomenological studies 59 , Bressloff and colleagues developed a mathematic model suggesting that the geometrical visual hallucinations are determined by the patterns of connection between the retina, the striate cortex, and the neuronal network within the striate cortex 60 . Furthermore, results from recent electroencephalography (EEG) studies and a broader understanding of the hierarchical nature of the visual system support the empirically informed hypothesis that (1) DMT reverses the inherently top-down hierarchy of visual system and (2) DMT-visions are interpretations of propagating activity up the visual hierarchy in a bottom-up manner 14,61 . Dimethyltryptamine reproducibly (1) decreases top-down alpha-band oscillations in the cortical regions involved in visual-sensory processing, resulting in cortical excitation in these regions 14,36,[61][62][63] , and (2) increases bottom-up forward travelling waves from occipital to frontal regions 36,61 ; both of which correlate with the intensity of the DMT-induced visualizations 36,61 .
One of the most salient and discussed features of the DMT experience is encounters with seemingly autonomous entities, consistent with previous DMT studies 2,27,30 . In the current study, the most frequently reported encounters involved a feminine archetype; followed by deities, divine beings, and demi-gods; aliens, celestial beings; and extra-terrestrials; animal-based or creature-based entities (including reptilian and insectoid beings); mythological beings (including machine elves); and the jester archetype. Shanon 2 , Davis et al. 27 , and Michael et al. 30 identified analogous entity phenotypes in their studies examining Ayahuasca and inhaled N, N-DMT, respectively. In the present study, communication with entities was common (75%) and comparable to rates of communication documented by Davis et al. (84%) 27 . Positive, benevolent, comforting, caring, and welcoming entity attributes and interactions were most frequently described consistent with previous reports 27 . This study provides further recognition of a "companion-type, pedagogical, or guide-type interaction" and a "medical-type" interaction 27 . Timmermann et al. predicts that the dissolution of top-down cortical control over medial temporal lobe activity may explain the content of the DMT experience, including entity encounters 17,61,[64][65][66][67] .
The psychedelic disruption of top-down dynamics 17,61,64-67 and examining psychedelic entity experiences from the perspective of evolutionary psychology and neurophenomenology has led to the theory that psychedelics may partially liberate innate modules facilitating the experience of entity encounters 5,68 . Entity encounters cannot be dismissed as irrelevant hallucinations without substance or meaning, nor accepted as transcendent realities 5 . Winkelman has identified patterns in DMT entity experiences that reflect innate operators and modules fundamental to mental processes including, but not limited to, social role inferences, agency attribution, intentionality, causality, and animacy detection 5 . These patterns suggest that DMT is, in part, exposing innate human tendencies; however, further evidence is required to substantiate any ontological claims for these entity experiences 5,69 .
Pervasive and consistent themes were reported during N, N-DMT experiences included within this study and those in other studies of the DMT-state 2 . These themes may be explained by the cultural experience and background of the authors or priming of the authors prior to the experience. Another theory to account for the pervasive themes revealed by the DMT-state is that the DMT-state is in part a probe into a collective unconscious. The collective unconscious, a term introduced by Carl Jung, consists of a repository of knowledge and imagery shared by all human beings due to a common ancestral experience 68 . It is populated with archetypes, symbols, and instincts, which greatly influence individual unconsciousness, states of mind, and behaviours 68 . Jung, however, did not provide a clear ontological account for the archetypes and the collective unconscious 70,71 . With advancements in neurophysiology and quantum physics, a theoretical approach called "biogenic structuralism" has been developed to ground Jung's archetypal psychology within a neurophysiologic and quantum framework 70,71 . Particular attention has been placed on the relationship between the archetypes and "neurognosis", or the understanding of how the brain develops knowledge 70 . It has been suggested that neurognosis and Jung's archetypes are related, both, to the structural organization of the brain during development and the pattern of total quantum neural network activity 70 . Future approaches to study the DMT experience should attempt to understanding the ontological origin of prevalent themes from a neurophysiologic basis 14,61,64,65,67 .
Similarities between near death experiences (NDE) and the psychedelic experience have been described, including transcendence of physical form, themes of death and dying, OBEs, tunnels, descriptions of bright www.nature.com/scientificreports/ lights, familiarity, sense of belonging, religiosity, experience with a void or unearthly realm, and interaction with presences or entities 2,16,17,19,21 . These themes featured prominently within this study congruent with other studies describing the phenomenology and content of the DMT experience 2,16,17,21,27,33 . Timmermann et al. directly investigated the relatable features of the DMT experience to NDE in a within-subject placebo-controlled study of 13 healthy volunteers 17 . Significant correlations were observed between features of NDE following DMT administration compared to placebo. Moreover, a separate analysis was performed on volunteers who underwent an 'actual' NDE and demonstrated comparable NDE scores between an 'actual' NDE and the DMT state 17 . The discovery of an endogenous mammalian source of DMT 39,40 and the similarities between the DMT state and non-druginduced states, like NDE 17,21 , support the hypothesis that DMT is responsible for inducing certain non-ordinary states of consciousness. However, to date, it has yet to be established that endogenous DMT concentrations and selectivity are commensurate with levels required to induce effects seen during the exogenous DMT state 41,42 .
Poor recall of a DMT experience is widely reported in anecdotal sources and N, N-DMT has been described to have "a self-erasing mechanism" 72 ; however, there are limited data documenting the frequency of this occurrence. The results of this study support these reports by documenting the prevalence of reported partial experienceamnesia, full experience-amnesia, and "black outs." The amnestic mechanism of an N, N-DMT is unknown, however, may be similar to sleep dream amnesia and hypoactivation of the prefrontal cortex 73 . Alternatively, the inherent highly unusual and overwhelming nature of the DMT experience and frequent resultant ontological shock may hinder the ability of the cortex to reconstruct the experience further contributing to the reported amnestic properties of N, N-DMT.
Although many features of the DMT experience identified in this study can be labelled as positive, the presence of negative or challenging responses to DMT inhalation were also documented and important to recognize. Approximately 30% of the DMT experiences reported a minimum of one item from the CEQ; predominantly items from the "fear" subsection, followed by "grief " and "emotional and/or physical suffering" subsections. Moreover, approximately 7% of authors reported features of ego-dissolution. Ego-dissolution, defined as a compromised sense of self, can induce meaningful (i.e., a sense of unity or "oceanic boundlessness") but also negative outcomes (i.e., "dread of ego dissolution"), with potentially psychological destabilizing effects resulting from depersonalization and derealization 55,74,75 . Overall, the negative and challenging responses to DMT ingestion should not be overlooked or underestimated. Further studies should attempt to identify individualized variables associated with a deleterious response to DMT-use. For example, this study did not capture information on concomitant mental health diagnoses, which is a critical confounder to examine in future prospective studies.
The methods within the confines of this study attempted to limit the variability of the DMT product ingested within the included experiences. Only experiences reporting N, N-DMT, as defined above, were included and experiences from other forms of DMT, including synthetic DMT and 5-MeO-DMT, were excluded. Moreover, a secondary analysis was conducted excluding experiences with reported concomitant psychoactive substance use. However, self-extraction of N, N-DMT from plant sources, such as Mimosa hostilis root bark and Acacia confusa root bark, is one of the predominant methods for obtaining N, N-DMT for naturalistic inhaled use 76 . It should be noted that the different plant sources, in addition to variable methods of extraction, can lead to variability in the concentration of the N, N-DMT and profile of other plant alkaloids in the consumed product, which may modulate the effects of the DMT 76,77 .
There are several limitations to this study. First, the naturalistic nature of not only the experience but the reporting in this study limited the ability to systematically collect data for all experience reports. This methodology allowed for the induction of novel themes and codes; however, this limits the ability to provide true incidence rates for the included variables and instead relies on rates of reported variables as a proxy for incidence. Next, Reddit users are likely nonrepresentative of DMT-users at-large and may have introduced a selection bias not controlled for in the results. Moreover, previous reports on the Reddit platform may influence the experiences and reporting of fellow Reddit users. This is evident through the recurrent invocation of specific terminology and labels for otherwise novel phenomena (i.e., "machine elves"). Reddit users are also potentially more likely to post experiences that were interesting, meaningful, consequential, and/or positive which would bias the results of this study towards the inclusion of experiences that were more notable and/or favourable. Furthermore, this bias may be especially relevant for N, N-DMT due to the reported cases of amnesic episodes identified in this study and elsewhere 27 . Adequate characterization of psychological experiences associated with N, N-DMT would require controlling for dosage and other elements that are known to influence the experience, including the set, setting, and concurrent uses of other substances. Next, the scope of the study was limited to experiences that occurred while under the influence of N, N-DMT and did not capture information pertaining to enduring effects (i.e., continuing or long-lasting). Enduring effects are valuable and can be positive or negative and should be systematically collected in future inhaled N, N-DMT studies 27 . Although this study provides insight into the naturalistic inhaled DMT-use, detailed examination in a controlled setting is required to substantiate the themes and patterns identified here.
Overall, this study contributes to the limited understanding the patterns of naturalistic inhaled N, N-DMT use and the descriptive phenomenological features of the N, N-DMT experience at-large.

Data availability
All requests for raw and analyzed data and materials are promptly reviewed by D.W.L (chief investigator and principal investigator). All data are anonymized and NVIVO source data with meaningful coded units are provided with this paper (see Supplemental Tables 1, 2