Why Do Psychedelic Experiences Feel “Realer Than Real”? A Scientific Explanation

This article delves into the science behind the profound sense of reality and insight—often described as feeling “realer than real”—that characterizes mystical experiences induced by psilocybin, and offers a rational explanation for this extraordinary phenomenon.

Synopsis

Drawing on a 2025 paper from Phenomenology and the Cognitive Sciences, we will explore the “Relaxed Beliefs Under Psychedelics” (REBUS) hypothesis. This theory suggests that psilocybin temporarily quiets the brain’s predictive filters, allowing for a more direct and intense experience of sensory reality. This process not only explains the “noetic” or insightful quality of mystical experiences but also demystifies their spiritual significance without diminishing their therapeutic value.

The Mystery of the Mystical Experience

For centuries, people have reported profound, life-altering experiences that they describe as mystical, spiritual, or transcendent. These moments, characterized by a sense of oneness, a dissolution of the self, and a feeling of encountering a fundamental truth, have often been shrouded in mystery. One of the most consistently reported features of such experiences, especially those induced by psilocybin, is their powerful sense of being “realer than real.” This is what the pioneering psychologist William James called the “noetic quality”—the feeling of gaining deep, undeniable insight into the nature of reality.

For those who have not had such an experience, this can sound baffling. How can a subjective, internal event feel more real than our everyday, consensus reality? For many, this has been a barrier to taking psychedelic therapy seriously, dismissing it as mere hallucination. But what if there was a scientific explanation for this phenomenon? A growing understanding of the brain is beginning to provide a rational framework for understanding why these experiences feel so profoundly true.

Introducing the “Bayesian Brain” and the REBUS Hypothesis

To understand how this works, we first need to understand a key concept in neuroscience: the “Bayesian brain.” This theory posits that our brain doesn’t just passively receive information from our senses. Instead, it actively predicts what it expects to see, hear, and feel based on a lifetime of experience. These predictions, or “priors,” act as filters, shaping our perception of reality to be more efficient. Most of the time, this system works wonderfully, allowing us to navigate the world without being overwhelmed by sensory information.

A 2025 paper in Phenomenology and the Cognitive Sciences applies this model to psychedelic experiences through the “Relaxed Beliefs Under Psychedelics” (REBUS) hypothesis (1). The theory suggests that psilocybin works by temporarily “relaxing” the brain’s high-level priors. In other words, it quiets down the predictive filters that constantly shape and constrain our perception. When these filters are turned down, what happens?

Turning Down the Filter, Turning Up Reality

According to the REBUS model, when the brain’s predictive filters are relaxed, the influence of raw sensory input is dramatically increased. Your brain is taking in more information from your senses, without the usual concepts and categories being imposed upon it. This raw, unfiltered stream of consciousness is what gives the mystical experience its noetic, “realer than real” quality. You are, in a sense, experiencing reality more directly.

This is why the experience often feels ineffable, or impossible to put into words. Our language is built upon the very concepts and categories that have been temporarily dissolved. It also explains the sense of unity and the dissolution of the self. The brain’s high-level prediction of a separate “me” is one of the strongest priors we have. When that belief is relaxed, the boundary between self and other can melt away, leading to a profound sense of connection with the world.

A Modern Replication of Ancient Wisdom

The link between psychedelics and mystical experiences is not new. The famous “Good Friday Experiment” in 1963 showed that divinity students given psilocybin were far more likely to report having a complete mystical experience during a Good Friday service than those who received a placebo. More rigorous modern studies by researchers at Johns Hopkins have replicated these findings, with a majority of participants rating their psilocybin experience as one of the most personally meaningful and spiritually significant events of their lives, on par with the birth of a child or the death of a parent (2).

What the REBUS hypothesis provides is a scientific framework for these consistent findings. It demystifies the mystical, not by explaining it away, but by explaining its mechanism. The profound sense of truth and insight is not a delusion; it is a predictable consequence of altering the brain’s predictive processing system. The experience feels real because, in a very real sense, the brain is processing more reality.

Why This Is So Important for Therapy

Understanding the science behind the mystical experience is crucial for psychedelic-assisted therapy. The therapeutic breakthroughs often seen in these sessions are highly correlated with the occurrence of a mystical-type experience. When a person gains a new, profound perspective on their life, their problems, and their connection to the world, it can be a powerful catalyst for change.

By understanding that this experience is a result of a temporary shift in brain function, we can help patients integrate these insights in a grounded, meaningful way. It allows therapists to validate the profound reality of the experience without requiring a belief in the supernatural. It bridges the gap between science and spirituality, creating a therapeutic model that is both evidence-based and deeply human. 

If you are curious about the potential of psychedelic-assisted therapy to provide new perspectives on your own life challenges, we are here to help guide you. Our practice is committed to providing safe, evidence-based care that honors the full spectrum of human experience. Contact us to schedule a consultation and learn more.

References

(1) Villiger, D. (2025). Mystical experience in the Bayesian brain. Phenomenology and the Cognitive Sciences. https://doi.org/10.1007/s11097-025-10107-1

(2) Griffiths, R. R., et al. (2006). Psilocybin can occasion mystical-type experiences having substantial and sustained personal meaning and spiritual significance. Psychopharmacology, 187(3), 268–283. https://doi.org/10.1007/s00213-006-0457-5

Disclaimer: Psychedelic Assisted Psychotherapy has not been approved by any regulatory agencies in the United States, and the safety and efficacy are still not formally established at the time of this writing.