What Are Hypnopompic Hallucinations and Why Do They Occur?
Imagine waking up and seeing a person standing in the corner of your room. Alternatively, what if you were waking up and all of sudden seeing the world as if through a kaleidoscope, hearing someone calling your name who isn’t there, or feel a hand on your shoulder? Then the moment disappears and you fully wake up, unsure whether what you just experienced was a dream, a hallucination, or if you’re just going nuts. These experiences are known as hypnopompic hallucinations and occur alongside sleep paralysis.
Some describe hypnopompic hallucinations as “accounts of supernatural assaults” or paranormal experiences because it is clear that it is not a dream if one has experienced it, yet they can be so confusing or feel so real and terrifying that it unsettles the individual for some time after. These hallucinations are vivid sight, sound, or physical sensory experiences that occur in the short period between sleep and full wakefulness. For the majority of people, this is a normal occurrence of the transition; but, for some, it could be a sign of narcolepsy, insomnia, or certain mental health disorders.
It has not yet been confidently determined why hypnopompic hallucinations occur, but current research suggests that it is either because they are neurologically similar to daytime hallucinations and dreams or because REM sleep states intrude on wakeful consciousness. Simply, it could be due to the brain not switching from asleep to awake all at once as it should, so perception, movement, awareness, and reality monitoring systems become active while dream-like states are experienced as though they are happening in reality.
How Are These Experiences So Vivid?
Hypnopompic hallucinations are brief, but come in a wide variety of possible experiences. Visual experiences can include seeing shapes, people, animals, or other images, auditory experiences can be voices, conversations, or random sounds, and physical sensations can include feeling as though one’s body is distorted, or they are floating, falling, or unable to move.
Research on sleep paralysis has linked the intensity and realism of these experiences to sensations like chest pressure, difficulty breathing, and unusual bodily experiences that are common during REM sleep; however, other researchers argue that this phenomenon must occur during non-REM sleep. All in all, the evidence as a whole points toward a complex transition between sleep states as the culprit of these hallucinations rather than a problem with one state.
In-Between States
Though we don’t know why this phenomenon occurs, the science of hypnopompic hallucinations is in reality more complicated than simply “you’re dreaming”, because you’re not. Going from sleep to awake requires changing brain states, and that transition can cause various unusual combinations of sensory processing and awareness to occur. The brain is normally able to distinguish between a perception that is from the outside world or within oneself through a process called reality monitoring. However, within a hypnopompic hallucination, one is unable to ask themself “Am I awake or dreaming?”, and, whereas memories or imaginary experiences cannot become strong enough to fool one into thinking they are reality, dreams can. The brain can dream a sound, image, or physical sensation internally, but the perceptual system can take that information and turn it from a thought to a stimulus. For example, if one is having a hallucination of seeing a figure standing beside their bed, that is perceived as real to the brain and the nervous system even if there is no one there.
One study described hypnopompic experiences as a part of a continuum between dreaming and waking that ranges from flashes of imagery to highly realistic situations, sleep paralysis, false awakenings, and out-of-body sensations. This explains why an individual can feel as though they are awake while still experiencing something fake that was generated by their sleeping brain; because the transition they are going through made them aware of themselves and the bedroom while dream activity was still happening. In certain cases, false awakenings can occur where one actually believes they have woken up, and, in that state, the hypnopompic experience can reenact one’s actual environment so well that it is difficult or impossible at the moment to tell what is reality and what is a hallucination. That is why these hallucinations can be far more alarming, during and after the experience, than a nightmare.
Why Sleep Paralysis Makes This More Terrifying
Sleep paralysis is a temporary paralysis of the skeletal muscles that can occur alongside waking mental activity during the sleep-wake transition. Meaning someone can have hypnopompic hallucinations while they are also in a state of sleep paralysis. During sleep paralysis, a person becomes aware of their environment and that they are awake, but cannot move or speak. This is because the brain puts the muscles into a temporary paralysis while in REM sleep to stop the individual from acting out their dreams, but then the brain wakes from REM sleep before the paralysis ends due to a timing mismatch. So, if someone is having a hypnopompic hallucination that something terrifying is happening, that feeling of fear can be amplified by the complete inability to move or speak, rendering one feeling completely trapped and helpless in their experience.
So Is There Something Wrong With Your Brain If You Experience This?
Chances are, no. Hypnopompic hallucinations are quite common, up to 70% of people experience them at least once, and alone are not an indicator of any type of mental disorder. They differ from the kind of hallucinations that would occur with conditions like schizophrenia since they come on specifically during the sleep-wake transition rather than during full wakefulness. However, they can happen more frequently if someone has a sleeping disorder like narcolepsy. With narcolepsy there is a disruption in the sleep-awake cycle that makes the transitions less stable, hence the increase in potential hypnopompic hallucination experiences.
Overall, hypnopompic hallucinations are not a brain malfunction, but rather a mix up in the brain transitioning. For a few seconds or minutes, dreaming, perception, and reality can overlap, causing the illusion of voices or figures that vanish when you awake. It just all feels so real because the brain areas that create our real-life experiences are active before the systems for understanding that the experience is a dream have caught up.
ABOUT THE WRITER
Guest Writer
Olivia Mickles is a current undergraduate student at Lehigh University studying Psychology with minors in Cognitive Science and Sociology. Her main research interests include clinical and health psychology. She has been a guest writer for Remember Magazine since July 2026.
References
Cheyne, J. A., Rueffer, S. D., & Newby-Clark, I. R. (1999). Hypnagogic and hypnopompic hallucinations during sleep paralysis: Neurological and cultural construction of the night-mare. Consciousness and Cognition, 8(3), 319–337. https://doi.org/10.1006/ccog.1999.0404
D’Agostino, A., & Limosani, I. (2010). Hypnagogic hallucinations and sleep paralysis. Narcolepsy, 87–97. https://doi.org/10.1007/978-1-4419-0854-4_8
Foffani, G. (2023). To be or not to be hallucinating: Implications of hypnagogic/hypnopompic experiences and lucid dreaming for brain disorders. PNAS Nexus, 3(1), pgad442. PubMed Central. https://doi.org/10.1093/pnasnexus/pgad442
Waters, F., Blom, J. D., Dang-Vu, T. T., Cheyne, A. J., Alderson-Day, B., Woodruff, P., & Collerton, D. (2016). What is the link between hallucinations, dreams, and hypnagogic–hypnopompic experiences? Schizophrenia Bulletin, 42(5), 1098–1109. https://doi.org/10.1093/schbul/sbw076
What are hypnopompic hallucinations? (2021, June 23). Sleep Foundation. https://www.sleepfoundation.org/how-sleep-works/hypnopompic-hallucinations
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