Dreams are among the most personal and mysterious human experiences. They’re also one of the most ephemeral. Memories of our dreams are often incomplete and fleeting. You may wake from sleep with sharp and vivid recollections of a dream and strong residual emotions, only to lose those memories quickly, often within just a few minutes. Much of the experience of dreaming goes unremembered and unrecorded, seemingly beyond our grasp.
It’s fascinating to learn about dreaming, to discover patterns and themes that appear in dreams across cultures and ages, and to speculate about the purpose of dreams in our lives. Have you ever wondered how scientists actually go about studying dreams? It’s a challenging endeavor, one that has evolved over many generations of scientific inquiry. Today, our ability to collect and interpret scientific information about dreams is growing in exciting directions, as technology opens up new opportunities to observe the dreaming brain.
We can think about the scientific study of dreams in different ways. One approach to dream investigation involves the study of dream content — the themes, emotions, images, and events that occur and unfold within dreams themselves. Another aspect of dream research looks at the activity of the brain and body while dreaming occurs. These two broad avenues often intersect overlap, with scientific inquiries that examine both dream content and dream mechanics. Some of the latest and most illuminating advances in dream research do just that. Both ways of investigating dreams can shed light on the nature and purpose behind our very complicated and compelling ability to dream.
Throughout human history, people have sought to analyze, interpret, and decode dreams. Ancient cultures often regarded dreams as mystical and divine communications, and dream interpreters were relied upon as sage practitioners and translators of the meanings and messages of dreams. Classical scholars including Plato and Aristotle developed a framework for interpreting dreams as expressions of unconscious desires. The 19than 20thcentury studies of psychoanalysis delved deeply into dream interpretation, building in different ways on the idea that dreams were a terrain in which to grapple with unfulfilled and unconscious drives. Scientists in the 20thcentury implemented new and rigorous scientific standards to the study of dreams, analyzing dream content in carefully designed and controlled experiments using statistical and empirical methods. Across this vast span of historical inquiry, there’s something that all of these approaches have in common: the dream report. A great majority of scientific inquiry into dreaming has relied upon gathering details about dreams from dreamers themselves. Dream reports and dream journals have been collected in countless numbers, and have formed the basis for groundbreaking and important discoveries about dreams.
This method of using dream reports and dream journals as a basis for scientific investigation is still actively in use today. Dream reports are collected in sleep laboratories under controlled conditions, often waking sleepers at specific intervals in order to retrieve dream information. Among other things, this method of studying dreams has allowed scientists to make associations between characteristics of dreams and certain phases of sleep — both REM sleep and non-REM sleep — and to link dreaming experiences with specific neurological activity. Scientists also use dream reports that have been created by people sleeping at home, in their natural sleep settings.
Through research that relies on dream reports, scientists have accumulated a rich body of information about the themes and emotions contained in dreams, and about dream narratives. Dreams of falling, being chased, of flying, and of being unprepared for a test or exam are some of the most common dream events that occur among people of diverse cultures, backgrounds, and experiences. Dream reports have allowed scientists to track the human capacity to dream as it develops throughout childhood. Dream reports have enabled scientists to compare dream content across cultures, to highlight differences in the ways that men and women tend to dream, and to explore associations and connections between dreaming and waking life. Research using dream reports has provided detailed information about characteristics of nightmares, and how these dreams may relate to waking-life experiences of stress, trauma, and fear.
Scientists have for several decades been able to rely on methods beyond dream reports to investigate questions about dreams. Studies of sleep using electroencephalography (EEG) in the 1950s revealed for the first time detailed data about the activity of the sleeping brain. Scientists began to be able to “see” the brain active and working during sleep — and while dreaming. EEG studies led to the identification of the different stages of sleep, including REM sleep, with its highly active and variable brain activity. Research of REM sleep using EEG enabled scientists to make the first associations between REM sleep and dreaming. EEG remains the most common tool that scientists in laboratory use to observe the brain during sleep. Cells within the brain communicate with electrical impulses, and EEG measures this electrical activity. In studying dreaming, this allows scientists to observe what areas and networks of the brain are active and communicating during dreaming.
Brain imaging tools, including fMRI, are also now used regularly to capture data about the neural activity associated with sleep and dreaming. Functional magnetic resonance imaging (fMRI), works by recording blood oxygen levels and blood flow throughout the brain. Higher levels of activity in the brain require more oxygen and greater blood flow, and fMRI allows scientists to identify areas of the brain that are soaking up oxygen while dreaming is taking place.
Research using brain-imaging techniques has allowed scientists to explore a wide range of theories about the purpose and function of dreaming. Among others, scientists are actively investigating ideas that dreams are an extension of waking consciousness, that dreams are a kind of rehearsal space for the mind to play out potentially threatening or difficult waking-life situations, and that dreams are the brain’s way of stitching together a narrative from the electrical impulses it generates during sleep. Brain imaging is enabling scientists to explore the possible role of dreams in memory making, as well as dreams’ possible function in processing emotions. Recent studies using brain-imaging techniques have provided scientists with new details about the characteristics of lucid dreaming, a form of dreaming in which the dreamer possesses awareness of being in a dream, and can manipulate and control their dreams.
Some of the latest dream research combines brain imaging with dream reporting to examine both neural activity and dream content. Some dream researchers are using a technique called neural decoding to both decipher and even predict visual imagery in dreams, based on observations of brain activity.
Dreams are a compelling area of research for scientists, in part because there’s still so much to learn about how, and why, we dream. For all the scientific attention paid to dreaming, many of the most fundamental and important questions about dreaming remain unanswered. For scientists, dreams are — at least for now — an endlessly tantalizing mystery.
Michael J. Breus, PhD
The Sleep Doctor™
Originally published at www.thesleepdoctor.com on May 15, 2015.