Hypnagogia – why do we hallucinate before falling asleep? by Fatima Sheriff

“Phantasmata”, “praedormitium”, “oneitogogic images”, and my personal favourite: “dreamlets”… all proposed terms for the phenomenon of hallucinating as you fall asleep. Coming from the Greek for “sleep” and “guide”, ‘hypnagogia’ categorises a mixture of sensory experiences occurring around 10 minutes into “pre-sleep’. In the UK, 37% of people surveyed reported these hallucinations with a further 12.5% reporting “hypnapompic” hallucinations upon waking up, myself among the latter.

A study performed by Noreika involved those in hypnagogia pressing a button when a vision appeared while monitored with an EEG. A correlation was found, not with any abnormality in brain waves, but with “sudden changes towards the orderly brain state during sleep”. The theory is that when the cluster of cells in the reticular activating system (regulating tiredness) slows the activity of the brain, there can be “glitches”. Though there are 5 standard stages of sleep with the frequency of brainwaves decreasing, this process is more complex within time and space.

It depends on the subtle dynamics of brain regions: the occipital lobe contains the visual cortex so one may observe shapes and images, but during hallucinations the frontal lobe is ‘off’. Therefore, one would lack understanding of these visions nor be able to interact with them. Shapes may vary between individuals but “phosphenes”, which are speckles of light, are commonly reported (what you can see if you place enough pressure on your eye when shut).


Hypnagogic images can be less abstract and random: research into the “the Tetris effect” found that the repeated images after playing the game Tetris for two hours could remain somewhat imprinted and re-emerge before sleep. This occurred in all novices within the experiment, implying the brain was processing the learning, compared to only half of the experts. Experts also reported seeing the older Nintendo version, highlighting the integration of experience and new memories. Fascinatingly, this could be unrelated to declarative memory as even amnesiacs unable to remember whether they had played the game reported the characteristic blocks of shape. In a more multimodal form, skiers also reported feeling the sensation of snow around their feet.

Combinations of sensory experiences create more immersive hallucinations. Auditory variations include hearing conversations but not understanding the words, random music, white noise and in more extreme cases, “Exploding Head Syndrome” (EHS). This is an alarming combination of loud imagined sounds and a “hypnic jerk”, a common experience where you are jolted awake. Up to 18% of students surveyed reported this, however “this is unrepresentative of true prevalence as students are prone to lack of sleep.” (wow, way to call me out). Though scary, once understood, sufferers can just be irritated by the interruption and go back to sleep.  

Kinaesthetic experiences are more likely during the transition from faster alpha waves to slower delta waves within the prefrontal cortex, where you can imagine motor actions. Other more terrifying reports include feeling frozen and dazzled, something pushing on your chest and even a jolt of electricity. In this minority of cases, rather than a pseudo-hallucination with a passive viewer, some experience a full hallucination that they wrongly believe to be real. This potentially explains some alien abduction experiences and supernatural encounters.

Becoming self-aware and lucid during these hallucinations may unlock previously untapped creative potential, certainly according to Salvador Dali, who recommended “the slumber with a key.” This process was both named metaphorically and literally; he suggested that artists should nap while lightly holding a metal key and observe the images within the hypnagogic stupor. Then as sleep paralysis sets in, the artist would drop the key and wake themselves, and presumably hurriedly scribble what their unrestrained mind had shown them.

Pioneers of Gothic literature have written of similar sources of inspiration like Edgar Allan Poe and Mary Shelley who said: “I saw with eyes shut but acute vision”. Even Charles Dickens wrote a passage in Oliver Twist that beautifully encompasses the “passing visionary scenes”. Observing the mind when it is more fluid and hyperassociative is thought to help introduce unusual intuitive associations that may be lost when one is awake and logical. For instance, in 1865 August Kekule spoke of seeing a snake biting its tail, the mythical symbol of the ouroboros in a dream, thus inspiring him to consider benzene are a ring shape. If true, this story would prove a prime example of hypnagogic inspiration (though Wotiz’ insight into his paperwork may prove otherwise)

It is important to note that in most cases, hypnagogic experiences are benign though more common in people with a tendency to sleep less deeply. Oliver Sacks wrote a lot about destigmatising hallucinations; not necessarily looking to them for deeper meaning but acknowledging that they don’t necessarily indicate an unhealthy mind. So next time you see strange lights on the way to the land of nod, just enjoy the show.  

Extra information:

For those who wish to attempt this inspiration napping, the article can be found here with instructions for the ‘Upright Napping Procedure’ by Nielsen, using the physical action of nodding off to reawaken.


Turn to page 398 to read the passage in Oliver Twist that sounds remarkably hypnagogic


Comprehensive critique to Kekule’s dream claim:



  1. https://www.youtube.com/watch?v=1RvBvYrklXM

  1. https://www.scribd.com/document/323896592/Hypnagogia-The-Nature-and-Function-of-the-Hypnagogic-State-Vol-I-Andreas-Mavromatis

  2. https://www.ncbi.nlm.nih.gov/pubmed/8894197

  1. https://www.theatlantic.com/science/archive/2016/04/deciphering-hypnagogia/478941/

  2. https://www.academia.edu/33150155/Replaying_the_Game_Hypnagogic_Images_in_Normals_and_Amnesics

  3. http://www.bbc.com/future/story/20150409-i-have-exploding-head-syndrome

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