What Are Dreams Made Of?

Daniel is shown the interpretation of the king's dream

Source: The story of the Bible from Genesis to Revelation, Public domain, via Wikimedia Commons

What are dreams made of and are they important? Questions like this are still the subject of scientific research long after the ancient Sumerians began interpreting dreams as portents of the future some 5000 years BCE (Black and Green, 1992).

One answer to the question about what dreams are made of is relatively straightforward. I like the definition offered by Meaidi, Jennum, Ptito and Kupers (2014) who said “Dreams are a state of consciousness caused by self-generated sensory, cognitive, and affective processes” (pg. 592). “Self-generated” means that these experiences are produced from within the brain itself, rather than being the end result of a message sent to the brain for interpretation from the world outside of us. I would add that dreams represent an altered state of consciousness. When we’re asleep, we’re not connected to and responding to signals from the outside world, or at least not in the usual way.

All of our senses are represented in dreams. Dreams almost always contain visual information, and about 40 to 60% of dreams feature sound. Touch is less frequently experienced in dreams (about 15-30% of dreams), and rarer still (less than 1% of the time) are dreams featuring olfactory or taste sensations (Zadra, Nielsen and Donderi, 1998).

Given the prominent role sensory experiences play in dreams, scientists wondered if the amount of experience with a particular sensory system the dreamer had might influence the role that senses have in dreams. For example, do the dreams of musicians feature music more often than do the dreams of non-musicians? Uga, Lemut, Zampi, Zilli and Salzarulo (2005) wanted to find out so they asked both professional musicians and non-musicians to complete a questionnaire about their musical experiences. Musicians were asked about things like their age at the beginning of musical training, and time devoted to daily practice. Non-musicians were asked about the time they spent listening to music. Both groups of volunteers were also asked to keep “structured” dream logs for a total of 30 days. These logs asked specific questions about whether they heard music in their dreams and whether the music was something they had heard before or original in the dream.

Both groups recalled the same number of dreams across the study, and both groups were able to recall about the same amount of content in the dreams. The dreams of musicians contained significantly more music than did the dreams of non-musicians, and the younger the musicians were when they started learning music, the more music they remembered in their dreams. About 55% of the musician’s dreams featured known musical pieces, 28% featured original music and 17% featured an unusual version of a known piece of music.

The Nightmare (c. 1781), by Henry Fuseli. Oil on canvas, 101.6 × 126.7 cm. Detroit Institute of Arts

Source: Tulip Hysteria / Go to albums, CC BY 2.5, via Wikimedia Commons

What about the dreams of individuals who have experienced loss of a sensory system. Do their dreams change along with their experiences of the world? Meaidi, et al., (2014) compared the dream content of three groups of volunteers. Congenitally blind (CB) individuals who had never experienced visual stimulation, a group of late blind (LB) people (carefully defined in the study) and sighted control (SC) participants. The researchers measured overall health, and psychological health (anxiety and depression) for all three groups. They also asked participants to rate their sleep over the past month using the Pittsburgh Sleep Quality Index (PSQI) that assesses both sleep quality and sleep disturbances. To measure dream content, participants were asked to track the content of every dream they could remember across a 4-week period. Dreamers were asked about all sensory experiences in the dreams, regardless of the sensory system, as well as specific visual imagery and clarity in the dreams, the social interactions and bizarreness of the dream, and whether the dreamer would categorize the dream as a nightmare.

None of the CB group reported any visual elements in their dreams, and the LB group reported significantly fewer visual dreams than the SC group. Both blind groups reported significantly more dreams featuring sound and tactile sensations than did the SC group. In addition, the CB group experienced significantly more dreams with olfactory sensations, and a significantly higher number of aggressive encounters in their dreams, as well as more nightmares, than did LB and SC groups. There were no differences in the number of dreams featuring success, positive or negative emotions across these three groups. The authors concluded that blindness altered the sensory components of dreams, not just visually, but across all sensory systems. They speculated that the increased number of nightmares experienced by the CB group might be related to a higher number of potentially threatening daily experiences this group had.

And, in a fascinating look at the effect of what we eat on our dreams, Nielsen, Radke, Picard-Deland and Powell (2025) examined the effect of diet on dream content. They asked a very large group of volunteers to take an online survey asking about the effect of their diet on their dreams. They found that about 40% of the people surveyed reported that what they ate either worsened their overall sleep (24%) or made their sleep better (20%). Desserts and sweets as well as dairy were associated with more frequent nightmares and higher nightmare recall. Food allergies and intolerances were also associated with more nightmares. Unhealthy eating habits predicted negative dreams and nightmares, while healthy eating habits predicted better dream recall overall and more positive dreams.

What we experience with our senses, all of our senses, is incorporated into our dream life. We dream what we taste, smell, hear, feel and see.