Author: jlienhart

Dreams are made up of what we sense and feel, and of the way in which all of our perceptions, knowledge and experiences inform our mental representations of the world. The sense of sight is therefore not necessary to dream. And the dreams of blind people are indeed filled with sensations – olfactory, gustatory, tactile… – since sleep carries echoes of the way in which these people experience the world while awake.

According to neurologist Isabelle Arnulf, such non-visual sensations only appear in about 1% of dream reports among sighted people. This is not too surprising when we know that sight is a dominant sense in human beings: almost half of our brain is devoted to processing visual information and the exercise of vision even slightly inhibits the brain activity linked to other senses! We also tend, for cultural reasons, to give more salience to visual sensations. Sighted people thus associate most of their experiences with images rather than sounds, tastes or smells.

Conversely, some studies have shown that people lacking this dominant sense dream much more widely of scents, sounds, music, touch sensations, etc. The brain activity of blind and sighted people for inst ance has been observed during sleep in dream phases: in those born blind, the areas linked to odors, sounds and touch are particularly irrigated, significantly more than in the sighted people.

Thus, while a person with normal vision will dream of a loved one by mobilizing visual memories (shape of the face, color of the skin, hair and eyes, height, build, clothes, etc.), a blind person will rather associate a loved one with a combination of non-visual experiences such as voice timbre, enunciation, body odor, perfume, etc. It is these sensations that will manifest in the dream to represent and identify the person present.

In one of her autobiographies, The World I Live in (1908), famous American author Helen Keller, who lost her sight and her hearing before she turned two, explains : “In my dreams I have sensations, odors, tastes, and ideas which I do not remember to have had in reality. […] I smell and taste as much as in my waking hours”. And she goes on to recall a particularly lifelike olfactory dream: “Once I smelt bananas, and the odor in my nostrils was so vivid that in the morning, before I was dressed, I went to the sideboard to look for the bananas. There were no bananas, and no odor of bananas anywhere !”

Of course, the dream experience of people who lost their sight after the age of 5 or 6 is very different from that of someone who never possessed the visual sense. Often, images, shapes and colors persist in their dreams, to which are added, certainly more frequently than for the sighted, impressions coming from the sense of touch and the chemical senses. The entire sensorium is thus mentally engaged in their dream state, providing them with rich and much varied sleeping adventures!

Although he was not a great advocate for the sense of smell, psychiatrist Sigmund Freud was among the first to mention olfactory dreams. He discussed this mysterious phenomenon in his 1899 book, The Interpretation of Dreams, in which he gave the example of a thirteen-year-old boy who regularly had vivid nightmares in which “there was a smell of pitch and brimstone”. Before him, those who were interested in the subject of dreams often dismissed the existence and possibility of olfactory or gustatory dreaming. Psychologist Paul W. Radestock, for instance, considered that “in the case of dreams, the senses of smell and taste provide the fewest elements” and didn’t give it much more thought.

Although it is now well-admitted that olfactory dreams do exist – whether the olfactory content is central to the dream’s meaning or not -, scientists are still investigating what prompts them and why most people never or rarely experience them. Interviewed by the BBC in 2014, Francesca Faruolo, who was director of the Bologna Festival dell’Olfatto, suggest that olfactory dreams are more prevalent in people who, in their everyday lives, are “either very sensitive to smells or have a highly trained sense of smell.” A 2021 study published in Brain Sciences actually corroborated this theory by showing that reports of chemosensory dream content were “more frequent in individuals with greater odor awareness”. Such individuals are logically more likely to experience mental odors created by the regions of their brains usually involved in olfaction, while no odorants are actually present!

This would also explain why most people don’t dream in scents. Our sense of smell is indeed largely disregarded in Western cultures. It was long deemed dispensable, unrefined, unworthy of being cultivated. The parts of our brain devoted to the treatment of olfactory information thus lack a conscious, consistent training, and our odor naming capabilities are generally relatively poor. With a strong socio-cultural bias in favor of visual perceptions, most of our olfactory experience goes unnoticed. How then could it resurge in the dream state?

A Canadian study about “Prevalence of Auditory, Olfactory, and Gustatory Experiences in Home Dreams”, published in 1998 in the journal Perceptual and Motor Skills, showed that olfactory and gustatory sensations only occurred in approximately 1% of the 3372 dream reports collected by the team, although approximately 35% of men and 41% of women reported having had a dream with olfactory content at some point in time. “A significantly greater percentage of women than men reported one or more dreams containing references to olfactory sensations” underline the authors. One possible explanation advanced by researchers is that women are maybe more interested in odor than men which would explain that olfactory experiences are more frequently reported in women’s dreams… 

Another study published in Imagination Cognition and Personality in 2005, aimed to determine whether people who claim to dream about smells are being truthful in their report, and to differentiate olfactory dreams from olfactory hallucinations which are sometimes experienced by individuals suffering from mental health issues, epilepsy and other conditions. The resulting data did provide more compelling accounts of olfactory dreams suggesting that not only are these dreams genuine, they are also not limited to those with diagnosed unusual conditions.

This study also revealed that olfactory dreams have “features similar to actual olfaction (emotive and brief)” and are “representative of odors encountered in everyday life” such as bacon, curry, pastries, oranges, pizza, tomatoes, wine, cigars, cigarettes, smoke, blood, soap, sunscreen, grass, etc.  In other words, olfactory dreams tend to be shorter and more emotionally-charged than vision dreams and olfactory dreamers most often perceive smells familiar to them. One of the most recent studies on the subject, published in 2022 in Physiology & Behavior, confirms this and explains that “odors perceived in dreams are mainly related to food, burning and smoke, body odor, nature, and certain environments and objects.” Olfactory dreams thus might not get as strange and unhinged and circonvoluted as some vision dreams can, but they are, when they occur, a powerful experience and a testimony to the remarkable and yet still perplexing potency of our olfactory brain! 

And although they might constitute an agreeable experience when they pertain to food, natural landscapes or cosmetics, it is notable that such dreams aren’t always pleasant! A 39-year-old woman quoted in the 1998 study described her dream in this way: “These two guys that I had hired to clean my house are in my home. […] I go upstairs to check what they have done and see their big dog, a pitbull, that they have tied with a long rope. The dog is walking everywhere in the house. There’s a disgusting smell and everything is a mess”. In this case, better to dream it than actually live it!