Things that Yorams know: Why do we stay awake in a dream?

Judit reports with amazement about a dream in which she smelled fresh bread and asks if there really are fragrant dreams?

The answer is: maybe.

Of the five senses with which we are blessed, dreams are mainly composed of visual and auditory images: the sense of touch and the senses of taste and smell are deprived. In experiments where people are asked to keep a dream diary or when people are woken up from their sleep immediately after The phase of rapid eye movements (REM) that usually accompanies dreams   Dramatic and rich in events and images, it was found that almost 100% of the dreams contain images, most of them are accompanied by a sound track, but less than a tenth of the dream stories include a sense of touch. In men, a smell appears in only one thousand of the dreams and in women in about 1.5% of them. A sense of taste is reported in slightly less than XNUMX percent of dreams regardless of gender. In an interesting experiment in which 11,180 dream stories of one person were analyzed who bothered to record his dreams every night from September 1984 to July 2014 it turned out that tastes and smells were reported in only 33 of them (0.3%) most of these reports were actually of unpleasant smells. About a quarter of people remember at least one dream during their life in which they smelled or tasted and most of them report the smell of food.

Why are dreams so sterile in terms of smell?

It is possible that the dreams are completely odorless and what is nevertheless reported are real smells that penetrated the nostrils during sleep. There are those who claim that evolution censored some of the sensations from the plot of the dream so that "real" sensations from the outside world that might imply danger would wake us up. For example, most voices in a dream are speech, and thus the sound of the alarm clock will not often become part of the plot of the dream, but will perform its role and wake us up. The sense of touch, according to this line of thought, plays such a marginal role in the plot of the dream that a real touch, such as that of a predator, will jump us out of bed, the lack of sensation in the dream is the basis for the saying "I pinched myself to prove that I am not dreaming". Other senses that do not participate in the dream are proprioception - the sense of the position of body parts in relation to each other and kinesthesia - the sense of relative movement of body parts. These senses simply do not go to sleep and allow us when we woke up from sleep to know with our eyes closed what the position of our body is and to wake up when we are shaken. If a new smell may herald an approaching danger, then it makes sense to leave it out of the plot of the dream. The problem with this explanation is that a person can be woken up from his sleep by sound, touch or moving a body part, but it is difficult to impossible to base an alarm clock on any scent: pleasant or repulsive. The brain activity test during sleep shows a response to the smell but no effect on the depth of sleep. Indeed, undisturbed sleep from swelling underlies the human ability to establish a stable relationship and enables the existence of the family institution.

Another possibility is that the smell is simply dropped from the memory and the story of the dream we are reporting. Smell is different from any other sense in the way information is processed and stored. When we learn something through the sense of sight or hearing we give it a name: a word that will bring the object to mind. When we learned that the barking hairy creature is a "dog", then the word "dog" written or spoken will bring up in our mind an image of the animal and the word "barks" the familiar sound. On the other hand, it is difficult to imagine the smell of a rose even when explicitly asked to do so. Occasional smells bring up a wealth of memories and associations, but the opposite direction is blocked: the smell fades when it is not physically present. The disconnection between the experiences of taste and smell and language is demonstrated, for example, by the difficulty of the "Master Chef" participants to name the ingredients of a dish from which they ate and without the sense of texture contributed by the sense of touch, this task would have been much more challenging. Unlike other senses, it is impossible to mentally construct combinations of images of smells and tastes. Whoever chooses a table in the store can imagine how it will look with the chairs at home, but only virtuous individuals can imagine biting into a strawberry with mustard.

We all know illusions of the sense of sight, but it turns out that the weakness of memory and imagination of fragrances means that it is even easier to deceive the sense of smell. Since it is difficult to restore a smell in memory, it depends on the context and it is easy to influence the judgment through external information. An amusing example was already presented in the 19th century: open a bottle of perfume in the corner of the room and ask those present to raise their hands when the smell reaches them, within a few minutes most hands will raise even if the bottle contains clean water. A televised hoax that told viewers about a technology for transmitting scent to the home receivers not only brought many viewers to feel the scent on television but even to complaints from upset viewers about an allergic reaction to the "smell" that flooded the living room.

Plenty of research has shown that many smells will be judged as pleasant or repulsive depending on the name attached to them. Even butyric acid, a volatile substance characteristic of spoiled butter, was rated by subjects as a pleasant smell when they were told they were smelling parmesan cheese. The smell is associated with emotional memories that it evokes in us, menthol is identified in the US mainly with association drugs which makes it unpleasant for Americans, the exact same substance is perceived as pleasant in Europe where it is associated with sweets.

The olfactory gland in the brain is directly connected to the amygdala which processes emotions and memories which is part of the primitive "limbic" system of the brain. This is how the smells bypass the information processing system based on encoding the input into words in the language. In an experiment in which subjects sleeping in the REM stage were exposed to a pleasant smell (roses) and hydrogen sulfide that smelled like fried eggs, it turned out that the dreams remained odorless, but those who smelled roses in their sleep reported more pleasant dreams and those who received a dose of hydrogen sulfide experienced negative emotions in the dream.

It is possible that the smells of the dream, similar to the smells of the real world, simply do not translate into words but into the memories they bring up and the feelings they evoke, therefore the story we tell ourselves and others about the dream through language is also absent.

Thanks to Dr. Rachel S. Herz for her help.

Did an interesting, intriguing, strange, delusional or funny question occur to you? sent to ysorek@gmail.com

More of the topic in Hayadan:

• And in a dream I saw
• The loneliness of a scientific researcher: about the book "Einstein's Dreams"
• Prophetic dreams - was it, or did I dream a dream?