The most important findings of scientific dream research can be summarized in nine key points. Many important questions about dreaming remain unanswered, but these nine findings have solid empirical evidence to support them.
- Rapid eye movement (REM) sleep is a trigger for dreaming, but is not identical with dreaming. All mammals have sleep cycles in which their brains pass through various stages of REM and non-REM sleep. Dreaming seems to occur most often, and most intensely, in REM sleep, a time when many of the brain’s neuro-electrical systems have risen to peak levels of activation, as high as levels found in waking consciousness. However, dreaming occurs outside of REM sleep, too, so the two are not identical; REM sleep is neither necessary nor sufficient for dreaming.
- REM helps the brain grow. The fact that REM sleep ratios are at their highest early in childhood (newborns spend up to 80% of their sleep in REM, whereas adults usually have 20-25% of their sleep in REM) suggests that REM, and perhaps dreaming, have a role in neural maturation and psychological development.
- Dreaming also occurs during hypnogogic, hypnopompic, and non-REM stage 2 phases of sleep. In the transitional times when a person is falling asleep (hypnogogic) or waking up (hypnopompic), various kinds of dream experiences can occur. The same is true during the end of a normal night’s sleep cycle, when a person’s brain is alternating exclusively between REM and non-REM stage 2 phases of sleep, with a relatively high degree of brain activation throughout. Dreams from REM and non-REM stage 2 are difficult to distinguish at these times.
- The neuro-anatomical profile of REM sleep supports the experience of intense visionary imagery in dreaming. During REM sleep, when most but not all dreaming occurs, the human brain shifts into a different mode of regional activation. Areas of the prefrontal cortex involved in focused attention and rational thought become less active, while areas in the limbic system (involved in emotional processing, memory, and instinctive responses) and the occipital lobe (involved in visual imagination) become much more active. This suggests that the human brain is not only capable of generating intense visionary experiences in dreaming, it has been primed to do so on a regular basis.
- The recurrent patterns of dream content are often continuous with people’s concerns, activities, and beliefs in waking life. This is known as the “continuity” hypothesis, and it highlights the deep consistency of waking and dreaming modes of thought. People’s dreams tend to reflect the people and things they most care about in the waking world. A great deal of dream content involves familiar people, places, and activities in the individual’s waking life. The dreaming imagination is fully capable of portraying normal, realistic scenarios. This means dreaming is clearly not a process characterized by total incoherence, irrationality, or bizarreness.
- The discontinuities of dreaming, when things happen that do not correspond to a normal waking life concern, can signal the emergence of metaphorical insights. Research on the improbable, unreal, and extraordinary elements of dream content has shown that, on closer analysis, this material often has a figurative or metaphorical relationship to the dreamer’s waking life. Metaphorical themes and images in dreams have a long history in the realm of art and creativity, and current scientific research highlights the dynamic, unpredictable nature of dreaming as an endless generator of conceptual novelty and innovation.
- Dream recall is variable. Most people remember one to two dreams per week, although the memories often fade quickly if the dreams are not recorded in a journal. On average, younger people tend to remember more dreams than older people, and women more than men. Even people who rarely remember their dreams can often recall one or two unusual dreams from their lives, dreams with so much intensity and vividness they cannot be forgotten. Dream recall tends to respond to waking interest. The more people pay attention to their dreams, the more dreams they are likely to remember.
- Dreaming helps the mind to process information from waking life, especially experiences with a strong emotional charge. From a cognitive psychological perspective, dreaming functions to help the mind adapt to the external environment by evaluating perceptions, regulating emotional arousal, and rehearsing behavioral responses. Dreaming is like a psychological thermostat, pre-set to keep us healthy, balanced, and ready to react to both threats and opportunities in the waking world. Post-traumatic nightmares show what happens when an experience is too intense and painful to process in a normal way, knocking the whole system out of balance.
- The mind is capable of metacognition in dreaming, including lucid self-awareness. During sleep and dreaming the mind engages in many of the activities most associated with waking consciousness: reasoning, comparing, remembering, deciding, and monitoring one’s own thoughts and feelings. Lucid dreaming is one clear example of this, and so are dreams of watching oneself from an outside perspective. These kinds of metacognitive (thinking about thinking) functions were once thought to be impossible in dreaming, but current research has proven otherwise. Dreaming has available the full range of the mind’s metacognitive powers, although in different combinations from those typically active in ordinary waking consciousness.
For further reading:
Barrett, Deirdre and Patrick McNamara, ed.s. The New Science of Dreaming. Westport: ABC-Clio, 2007.
Bulkeley, Kelly. Big Dreams: The Science of Dreaming and the Origins of Religion. New York: Oxford University Press, 2016.
Domhoff, G. William. Finding Meaning in Dreams: A Quantitative Approach. New York: Plenum, 1996.
Hurd, Ryan and Kelly Bulkeley, ed.s. Lucid Dreaming: New Perspectives on Consciousness in Sleep. Westport: ABC-Clio, 2014.
Kryger, Meir H., Thomas Roth, and William C. Dement, ed.s. Principles and Practice of Sleep Medicine. Fourth Edition. Philadelphia: Elsevier Saunders, 2005.
Maquet, Pierre, Carlyle Smith, and Robert Stickgold, ed.s. Sleep and Brain Plasticity. New York: Oxford University Press, 2003.
Pace-Schott, Edward, Mark Solms, Mark Blagrove, and Stevan Harnad, ed.s. Sleep and Dreaming: Scientific Advances and Reconsiderations. Cambridge University Press, 2003.
Pagel, James. The Limits of Dream: A Scientific Exploration of the Mind/Brain Interface. New York: Academic Press, 2010.
Solms, Mark. The Neuropsychology of Dreams: A Clinico-Anatomical Study. Mahway: Lawrence Erlbaum, 1997.