The Oneirogen Hypothesis, Psychedelics & Ancient Dream Practices

What is a dream? Is it random flickers of memory and past lives, or a deep symbolic dialog with the hidden architecture of the mind? Are we always dreaming? Does that imply we live two worlds? One or maybe two different consciousnesses? Are dreams a manifestation of our consciousness; the B-side of waking life?

If you’ve ever laid in that liminal space between sleep and wakefulness, where images are vivid, emotions intense, and time elusive, you’ve brushed the very terrain explored by a new scientific proposal that’s been rippling through psychedelic theory: the oneirogen hypothesis.

This hypothesis bridges the hallucinatory effects of classical psychedelics and the brain’s own replay-dependent plasticity—the process whereby patterns of neural activity “replay” earlier experiences during states like sleep and dreaming, strengthening memories and sculpting emotional learning. Instead of viewing psychedelic visions as chaotic noise, this model frames them as turbocharged dream-like replays, deeply tied to how we encode and transform experience. (Bredenberg, Normandin, Richards, & Lajoie, 2025)
This recently published study especially got my attention as it’s coming out of Montreal, notably, The Mila - Quebec AI Institute, The University of Montreal, my alma mater, and McGill University. The authors used computational modeling based on the Wake-Sleep algorithm, which simulates how the brain alternates between encoding external sensory information (wake phase) and internally generating activity patterns (sleep/dream phase).

The oneirogen hypothesis proposes that classical psychedelics induce visual hallucinations by shifting the brain into a more dream-like processing state, by 5-HT2A receptor activation, where top-down generative signals from higher brain regions increasingly dominate over bottom-up sensory inputs from the eyes.
In simpler terms: normally, when you're awake, your visual experience is primarily driven by what your eyes actually see (bottom-up processing). During dreams, your brain generates visual imagery internally without external input (top-down processing). The oneirogen hypothesis suggests psychedelics create a hybrid state where you're awake but your brain processes vision more like it does during dreams—internal imagery becomes amplified and can override or distort actual visual input.

Now hold that thought for a moment and picture ancient Egypt.

Recent multimodal analyses of a Ptolemaic Egyptian Bes-vase unearthed in Saqqara have revealed something astonishing: residues of Peganum harmala (Syrian Rue), rich in β-carbolines, Nymphaea caerulea (blue water lily), and Cleome alongside fermented fruit compounds, an intoxicating botanical blend capable of shifting neurochemistry and perception. β-carbolines, like those found in the Ayahuasca vine, are potent reversible MAO-A inhibitors, allowing other psychoactive compounds to flourish in the nervous system. (Tanasi, D., van Oppen de Ruiter, B.F., Florian, F. et al, 2024)These findings constitute the first direct evidence of psychoactive substances in an Egyptian ritual context and suggest intentional inclusion of these plants in ceremonial practice. (Tanasi, D., van Oppen de Ruiter, B.F., Florian, F. et al, 2024) The vessel itself is shaped with the head of Bes, a deity strongly associated with protection, fertility, childbirth, and domestic well-being in ancient Egyptian religion — themes supported by textual and material evidence linking Bes iconography with maternal and protective contexts. (Penn Museum)

The study’s authors note that the mixture may have been used in rituals aimed at inducing altered states, possibly within the so-called “Bes Chambers” at Saqqara, locations historically associated by Egyptologists with dream-oracular practices for confirming pregnancy and seeking divine guidance.

Across ancient Egypt and the wider Mediterranean, dream incubation — intentionally sleeping in sacred spaces to receive healing or prophetic dreams — was a recognized practice. Temples often provided designated areas where supplicants slept with the expectation of divine communication through dreams, particularly for healing and guidance. (Nielsen, T., 1988) In this light, psychoactive preparations may have been used to facilitate vivid dream states that structured participants’ experience of the sacred, supported by culturally embedded rituals for meaning-making and healing.

Dream incubation (enkoimesis) in ancient Greek Asclepian sanctuaries was a ritualized therapeutic practice where participants slept in sacred healing temples to receive revelatory dreams from Asclepius, functioning as an early form of "dream-psychotherapy" that integrated spiritual, psychological, and somatic healing. (Papageorgiou MG., 1974) before sleeping in designated sacred spaces (abaton) within the temple complex. (Kapotsis, G., 2025)
During this therapeutic incubation, participants sought apocalyptic dreams that would provide divine guidance for healing, for curing ailments, for truths and knowledge—either through symbolic messages requiring interpretation or, in some accounts, direct miraculous cures. (Papageorgiou MG., 1974) (Kapotsis, G., 2025) The practice treated dreams as a form of communication between gods and mortals, reflecting the predominant ancient Greek view that dreams were divine in origin. (Barbera J., 2008) (Palagini L., et al., 2011)

What happens when we bring the oneirogen hypothesis into dialogue with these ancient practices?

Modern neuroscience tells us that psychedelics reorganize the brain’s predictive models, increases entropy in neural networks, and invigorates the hippocampal replay mechanisms that are active during sleep. Classical psychedelics and compounds like β-carbolines may push the mind into dream-like processing while awake, blending memory reactivation with vivid symbolic imagery. In other words: psychedelics don’t just disrupt; they amplify the brain’s dreaming architecture.

Seen in this light, ancient dream rituals may have been early neuro-cultural technologies—purposeful, ritualized methods for tuning consciousness, strengthening certain neural reconstructions of self, memory, and meaning.

From Saqqara to Eleusis, from oneirogenic chambers to today’s psychedelic practices, one trajectory persists: humans have always sought to enter the place where the mind reshapes itself. Whether through plant medicines, ritual sleep, or modern compounds, the goal remains the same: understanding subjective experience, and in doing so, transforming it.

What if the ancients were early cartographers of consciousness? What if their dream rituals were not proto-psychology but functional neuroscience wrapped in ritual, myth, and community?

The oneirogen hypothesis gives us a language to talk about ancient dreams and modern psychedelia as reflections of the same fundamental human capacity: the ability to make meaning from the mind’s own hidden machinery.

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Bredenberg Colin, Normandin Fabrice, Richards Blake, Lajoie Guillaume (2025) The oneirogen hypothesis: modeling the hallucinatory effects of classical psychedelics in terms of replay-dependent plasticity mechanisms eLife 14:RP105968. https://doi.org/10.7554/eLife.105968.2

Tanasi, D., van Oppen de Ruiter, B.F., Florian, F. et al. Multianalytical investigation reveals psychotropic substances in a ptolemaic Egyptian vase. Sci Rep 14, 27891 (2024). https://doi.org/10.1038/s41598-024-78721-8

Childbirth Magic: Deciphering Bed Figurines from Ancient Egypt, Charlotte Rose, 2017, Penn Museum, https://www.penn.museum/sites/expedition/childbirth-magic/

USF study confirms Egyptians drank hallucinogenic cocktails in ancient rituals. New paper’s findings reveal a mix of psychedelic drugs, body fluids and alcohol likely used for fertility rituals.

Ancient methods of dream incubation: Bodily methods of inducing spiritual presence. Bulletin of the Montreal Center for the Study of Dreams, 3(3- 4):6-10; please cite as T. Nielsen (2012), Dream incubation: ancient techniques of dream influence, www.dreamscience.ca)

Incubation as a Form of Psychotherapy in the Care of Patients in Ancient and Modern Greece. Psychotherapy and Psychosomatics. 1974. Papageorgiou, M.G.

Sleep and Dreaming in Greek and Roman Philosophy. Sleep Medicine. 2008. Barbera, J.
Sleep, Dreaming, and Mental Health: A Review of Historical and Neurobiological Perspectives. Sleep Medicine Reviews. 2011. Palagini L, Rosenlicht N.

Sleep Incubation [Enkoimesis] in Medical Practice at Asclepieia of Ancient Greece - The Ancient Greek Sleep Medicine. Sleep Medicine. 2025. Kapotsis G, Steiropoulos P, Rovina N, Vagiakis E, Trakada G.