One of the most interesting fields in neuroscience and the study of consciousness is the relatively new study of dreaming. Researchers like Stephen La Berge and Keith Hearne began to study dreams when the practice was new and obscure, and through their efforts brought the field increasingly into the mainstream. The study of dreams is called oneirology, and researchers who study dreams are called oneirologists. Unlike the practice of dream interpretation, oneirology does not attempt to find subjective meaning in specific dreams. Rather, oneirologists study dreams to determine correlations between them and important functions in the brain. Oneirology is the scientific and quantitative study of the act of dreaming.

The work of the Marquis d’Hervey de Saint Denys and Alfred Maury in 1653 became the first formal exploration of the role of dreaming in human psychology. They also coined the term oneirology, but the field did not really expand until the first half of the 20th century, with the advent of techniques that could measure activity in the brain such as the electroencephalogram (EEG), which measures the brain’s electrical activity. In 1952, while measuring the brain activity of sleeping patients, researchers Nathaniel Kleitman and Eugene Aserinsky discovered that their subjects exhibited EEG activity that closely resembled the activity of their brains when awake. This apparent state of awareness while the subjects were asleep was accompanied by rapid movement of the eyes under their lids. Though they didn’t know it yet, Kleitman and Aserinsky had documented the dreaming state of the brain.

The independent discovery of lucid dreaming by Stephen LaBerge and Keith Hearne in the 1980’s spurred further research into dreaming and the mechanisms by which our brains generate dreams. The opportunity to use lucid subjects who could be instructed to perform various activities in their dreams has opened up possibilities for experiments that measure things like the subjective versus objective time duration of dreams.

The early studies of dreams resulted in discoveries that have built the foundation of modern dream studies. For instance, based on self-reports of dreamers and EEG measurements of sleepers’ brains, researchers like Aserinsky discovered that human beings dream every night, multiple times a night, regardless of whether or not they remembered those dreams. Before this research, dreams were commonly held to be an occasional phenomenon. Most dreams last between 5-20 minutes (not the 30 seconds to 1 minute that people often thought), and humans dream for an average of two hours per night. That means people spend an average of 6 years of their lives dreaming!

The clinical study of dreams also revealed that humans undergo two distinct states of sleep with regard to dreaming: REM (rapid eye movement) sleep, characterized by dreams and a state of consciousness that is closer to the waking state, and NREM (non-rapid eye movement) sleep, in which people usually don’t dream, or at least don’t remember those dreams. When people do remember dreams they had in NREM sleep, the content is usually mundane and may be just a static image rather than a narrative sequence.

There are a number of areas for more research that concern scientists who study dreams. Current areas of inquiry focus on how dreams might aid memory formation and consolidation, speculate about the evolutionary functions of dreaming, and examine possible links between abnormal dreams or sleep states and mental disorders. For instance, researchers are beginning to think that REM and NREM sleep may correspond to the consolidation of different kinds of memories: NREM sleep may correspond to the encoding of episodes and factual memory, and REM may serve to encode the emotional content of memories, which would explain why dreams are often emotionally moving in humans.

One concept emerged from the possible link between dreaming and memory formation is the hypothesis that there might be two categories of dreams. “Authentic dreaming” refers to dreams with content that closely reflect actual experiences or memories from the dreamer’s waking life, or that he or she can relate to easily. A dream where you get up, have breakfast and go to class or work would be an “authentic dream” under this definition. Dreams that parallel real life are thought to be the result of a process called synaptic refreshment that may occur during sleep, in which neurons fire along pathways that encode specific memories in order to strengthen them.

Then there’s “illusory dreaming”, in which the brain generates content that is bizarre, incongruent with your actual life, or flat out impossible. Scientists think that illusory dreaming might result when the process of synaptic refreshment goes awry, causing your memory circuits to accumulate errors. The idea is that older memories have been refreshed multiple times and had a chance to accumulate more errors, which can surface as bizarre “illusory dreams”. Ironically, dreams with impossible content, like being able to fly or teleport to different locations, are often the most enjoyable!

In studying dreams, researchers have also discovered several influences on dreaming. One of the most basic is smell: experiments requiring dreamers to self-report their dreams demonstrated that sleepers exposed to pleasant smells like roses generally had positive dreams, whereas those exposed to negative smells like rotting eggs usually had unpleasant dreams. Also, the frequency of your dreams may be influenced by your interpersonal attachments: surveys of people who have gone in for therapeutic treatment suggests that people who subconsciously felt less secure in their relationships tended to dream more frequently and vividly than people who felt secure in these attachments. (Of course, this applies to normal, unconscious dreaming in the absence of deliberate practices to enhance dream recall.)

There are many questions still to be answered through studying dreams, not least of which is how some “dream herbs” work to potentiate dream recall and make people lucid during their dreams. It’s still a wide-open field for anyone who wants to study dreams, sleep and consciousness!