Although I’ve long been fascinated by patterns of dream content (e.g., settings, characters, emotions, themes etc) that can be observed over a series of dreams, my interest in the field began with my own experiences with lucid dreaming. Other types of dreams that hold a particular fascination for me include nightmares, flying dreams, and recurrent dreams.
Although the overwhelming majority of dream reports contain visual and, to a lesser extent, kinesthetic elements, the presence of other sensory modalities has also been noted in both lab and home dream reports.Over 50% of dream reports contain auditory experiences while explicit references to olfactory, gustatory and pain sensations occur in less than 1% of all dream reports. One study found that women’s dream reports were more likely to contain olfactory or gustatory sensations whereas references to auditory and pain experiences occurred in a higher percentage of men’s dreams. That the more infrequent modalities of smell, taste and pain occur at all in dreams is an important demonstration of the representational capacities of dreaming.
Another excellent question. So what exactly is a lucid dream?
Various definitions of the experience have emerged in the literature. The simplest of these states that lucid dreams are those in which the subject is aware that he or she is dreaming. Other researchers have added a qualifier: that one has to become perfectly or fully aware that one is dreaming. Exactly what is meant by the terms "perfectly" or "fully" is usually not explicitly stated, but usually involves the ability to consciously exert control over events in the dream scenery. It should be noted, however, that even though lucidity in dreams is often accompanied by varying degrees of dream control, this ability is not in itself a sufficient indicator of lucidity. A broader and more precise definition of what constitutes a lucid dream is given by Stephen LaBerge who suggests that the consciousness experienced by a lucid dreamer is not unlike that which is experienced during the waking state. Thus LaBerge writes that
"the lucid dreamer can reason clearly, remember freely, and act volitionally upon reflection, all while continuing to dream vividly.”
Similarly, Tart (1979) states that a lucid dream consists of more than just having the dreamer realize "This is a dream." Like LaBerge, he suggests that in a lucid dream
"the 'higher' mental processes that we think of as characterizing waking consciousness, such as memorial continuity, reasoning ability, volitional control of cognitive processes, and volitional control of body actions (at least for the dream body), all seem to be functioning at a lucid, waking level.”
Others have also adhered to this conceptualization of the lucid dream state.
It would appear then that the lucid dream experience may be best understood if placed on a continuum. At one end we would have what may be called low-level lucidity, in which an individual may realize that he or she is dreaming, but then wake up, or simply relapse into non-lucid dreaming. In the middle of the continuum would fall those lucid dreams in which the dreamer, in addition to knowing that he or she is dreaming, can also exert some degree of control over the dream environment and retain some but not all of his or her waking mental faculties. Thus a person in this situation may be able to move about in the dream scenery as he or she pleases, but may be unable to alter some aspects of the dream, remember what day it is, or remember what their agenda for the following day consists of. At the high end of the continuum are those dreams in which an individual can exert a considerable amount of control over the dream content and, most importantly, is in possession of his or her mental faculties to the same extent as if the person were fully awake.
To this continuum should also be added what Celia Green has termed "pre-lucid dreams" as well as the phenomenon of "false-awakenings." The former refers to those dreams "in which the subject adopts a critical attitude towards what he is experiencing, even to the point of asking himself 'Am I dreaming?' but without realizing that he is in fact doing so.” The latter refers to those dream experiences in which one dreams that one has woken up, usually in their normal sleep environment. Both of these phenomena are known to occur in lucid dreamers, especially novices.
In these past few years, there has seen a veritable explosion in the number of companies offering all kinds of substances (drugs, supplements) and devices (headgear, home EEG devices, gadgets delivering low doses of transcranial stimulation) to help people have lucid dreams. Although these products are widely marketed and often accompanied by strong claims about their success rates, little independent research has been conducted on their effectiveness. Moreover, there exist many self-training techniques that may give you better results. A clear-eyes look at these technologies for lucid dream induction can be found here in this excellent piece in NY Mag: http://nymag.com/scienceofus/2016/10/these-strange-gadgets-claim-to-teach-you-how-to-lucid-dream.html
If you’d like to learn more about self-training in lucid dreaming, you can read about some of these methods in this research article from our lab.
There is a growing appreciation among health specialists and the general public that nightmares are a frequent sleep problem with important consequences for sleep quality and mental health. Large student and community-based epidemiological studies across different countries indicate that 8% to 29% of adults report monthly nightmares while 2% to 6% report weekly nightmares. Community surveys assessing incidence of nightmare “problems” rather than frequency found that between 5% and 8% of the adult general population report a current problem with nightmares, while about 6% report a past problem.
Finally, one of our own studies based on almost 10 000 dream reports collected in home dream logs from over 550 participants showed almost 3% of all prospectively collected dream narratives were nightmares (very disturbing dreams that wake up the dreamer) while bad dreams (disturbing dreams which do not cause the dreamer to awaken; they are remembered only after being awakened by external factors such as an alarm clock or later during the day) accounted for almost 11% of the dream reports. Thus almost 15% of all remembered dreams are considered to be highly disturbing dreams.
The most frequent themes in nightmares are:
(1) physical aggression (threat or direct attack to one's physical integrity by another character, including sexual aggression, murder, being kidnapped or sequestered;
(2) interpersonal conflict (conflict-based interaction between two characters involving hostility, opposition, insults, humiliation, rejection, infidelity, lying, etc.);
(3) failure or helplessness (difficulty or incapacity of the dreamer to attain a goal, including being late, lost, unable to talk, losing or forgetting something, and making mistakes);
(4) Health-related concerns and death (presence of physical illness, disease, health-related concerns, or death of a character or of the dreamer);
(5) being chased (dreamer being chased by another character but not physically attacked);
(6) apprehension/worry (dreamer is afraid or worried about someone or something, without an objective threat being present);
(7) evil presence (seeing or feeling the presence of or being possessed by an evil force, including monsters, aliens, vampires, spirits, creatures, ghosts, etc);
(8) accidents (the dreamer or another character is involved in an accident, including vehicle accidents, drowning, slipping, falling, etc.);
(9) Disaster/calamity (plausible events ranging from relatively small scale anomalies such as a fire or flood in one's house or neighborhood to larger scale disasters such as earthquakes, war, the end of the world, etc);
(10) Insects/vermin (presence of or infestation, bites or stings from insects, rats, snakes, etc.)
The list above is based on a careful analysis of thousands of dream reports collected prospectively (for example, on daily dream logs) as opposed to asking people about the last nightmare they remember on a questionnaire. Themes of falling or being paralyzed appear infrequently in dream logs, but their high saliency makes them particularly memorable and thus more likely to be recalled in interviews or questionnaires long after their occurrence and many people can remember having one of these nightmares at least once in their lifetime, often many years ago. So nightmares of falling or being paralysed are certainly common in the sense that many people remembering having had such a nightmare at least once in their lifetime, but the themes above occur much more frequently over any given week, month, or year.
Also, it is important to bear in mind that themes of falling, being paralyzed, or suffocation may well represent other commonly experienced parasomnias such as hypnic jerks, isolated sleep paralysis, or sleep terrors. When faced with broadly defined questionnaire items, people may be more likely to report these types of sleep experiences as if they were nightmares. Providing subjects with clear definitions for nightmares as well as sleep terrors and requiring actual dream narratives to be reported in daily logs greatly reduces the inclusion of other sleep phenomena in these results.
Men’s nightmares were are more likely than women's to contain themes of disaster/calamity as well as of war and terror. In addition, themes of interpersonal conflicts are twice as frequent in women's nightmares than in men’s.
Although fear is the most frequently reported emotion in nightmares and bad dreams, almost half of all disturbing dreams contained primary emotions other than fear. These can include anger, sadness, and frustration. Also, we’ve published several studies showing that nightmares with these kinds of emotions are rated as being just as intense and disturbing as fear-driven nightmares. This is why the American Academy of Sleep Medicine defines nightmares as disturbing mental experiences rather than frightening dreams.
Another great question. I think one reason people think most dreams are bizarre is because those are the kinds of dreams we tend to share with others. If you wake up one morning and remember a dream where you were studying for an exam, or were stuck in traffic, or talking to some friends, you’ll likely not go out of your way to tell others. But, if while stuck in traffic a giant eagle grabbed your car in its talons and lifted you high above the city and flew you and your automobile across the sky, and then set you down by building where you work, then you may want to tell someone! Some people have also argued that by virtue of their unusual and salient nature, bizarre dreams are more likely to be remembered than their mundane counterparts.
There’s also the question of what we mean by bizarre. For instance, bizarreness can refer to likelihood of occurrence of the dream content in waking life, its degree of his adherence to natural laws, or to the presence of discontinuities and incongruities in the dream. Thus, dreaming of seeing someone hit by lightning is certainly unusual, but not bizarre in the sense of soaring through the air like a bird, or experiencing a sudden change in the dream setting (e.g., from being in a park to finding yourself back in a school from your childhood). And things can certainly be “off” in dreams, like seeing your best friend but realizing his voice is that of someone else, or that he inexplicably has no hair, or oddly long and crooked teeth.
That being said, studies of dream reports collected from laboratory and non-laboratory settings converge in showing that for the most part, dreams are a reasonable simulation of waking life in terms of characters, social interactions, activities and settings. Specifically, dreams typically contain the self from a first person perspective, take place in real and spatially coherent commonplace environments, tend to contain realistic recreations of familiar characters (e.g., family members, friends, colleagues) and similar to waking life, are nearly always organized around social interactions with others, including emotional and intellectual exchanges. Thus, contrary to older theories emphasizing bizarreness and disguise in dreams, modern dream research shows that a majority of dreams are best understood as simulations of life experiences that emphasize interpersonal and social interactions.
Of course, that is not denying that dreams can sometimes be very bizarre and that the dreams of some people are definitely stranger than the dreams of others.