“We wake from one dream into another dream.” – Ralph Waldo Emerson
From ancient times (when dreams were considered to hold prophetic powers) to the neurological phenomena studied today, dreams remain one of psychology’s and biology’s most enduring mysteries. Dreams have probably been of interest as long as people have been conscious, which is to say, as long as they have distinguished between dreams and ordinary waking life. Dreaming may be defined as a mental state - an altered state of consciousness, which occurs during sleep.
Dreams usually involve fictive events that are organized in a story-like manner, characterized by a range of internally generated sensory, perceptual, and emotional experiences.1 Throughout the past few decades, several biological and psychological theories have been proposed about the purpose of dreaming and its regulatory effect on the psyche and physiology.2, 3
Earlier theories by psychoanalytic scholars such as Sigmund Freud and Carl Jung suggested that dreams constitute a meaningful reflection of unconscious processes, while others have argued that dreams are not inherently meaningful. This article examines some of the bioregulatory mechanisms – physical and non-physical – associated with dreaming.
Many ancient cultures have attributed symbolic meaning and even prophetic significance to dreams.4, 5, 6, 7, 8, 9 Attitudes to dream evaluation vary depending on the culture from which they arise. Dreams are considered important, real, and public in some cultures, but nonsignificant and personal in others.
While there has always been a great interest in the psychology of human dreams, it was not until the end of the 19th century that Sigmund Freud and Carl Jung put forth some of the most widely-known modern theories of dreaming. Dreams, Freud famously stated, are "the royal road to the unconscious."10 Freud held that one purpose of dreams was to allow the psyche to take un-acted upon impulses and desires and fulfill them away from the conscious mind. Essentially, Freud considered dreaming an expression of repressed conflicts or desires. He believed that the basic function of dreaming was to allow the discharge of repressed instinctual impulses in such a way as to preserve sleep, and that the instigating force causing dreams to occur was always an instinctual, unconscious wish. Freud considered these unconscious wishes to be predominantly sexual in nature. For Freud, because dreams contained unacceptable and unpleasant wishes, this explained why dreams are so regularly and so easily forgotten.11
Carl Jung (1875 -1961), a Swiss psychoanalyst, was a friend and follower of Freud, but soon developed his own ideas about how dreams are formed. The main difference between the two great thinkers was that Jung, unlike Freud, believed the unconscious mind is not animalistic in nature, and that our individual primordial behaviors are not driven by instinct, sex or violence. Jung also believed that dreams had psychological importance, but proposed different theories about their meaning. Unlike Freud, who often suggested that specific symbols represented specific unconscious thoughts, Jung believed that dreams can be highly personal and that interpreting these dreams involved knowing a great deal about the individual dreamer.
Jung believed that dreams had their own language. Jung saw dreams as the psyche’s attempt to communicate important things to the individual, and he valued them highly, as a way of knowing what was really going on. The things we see in our dreams are not signs that represent one specific idea, but rather fluid images to which we ascribe meaning based on our individual experiences. For Jung, dreams may reveal truths, philosophical revelations, illusions, fantasies, memories, plans, irrational experiences or even prophetic visions. They are a natural expression of our imagination and use the most straightforward language at our disposal: mythic narratives. Because Jung rejected Freud’s theory of dream interpretation (that dreams are designed to be secretive), he also did not believe dream formation is a product of discharging our tabooed sexual impulses. Jung took a more rigorous approach, explaining dreams as a sort of “shaped energy," inchoate emotions or thoughts released by the deep subconscious and entrained into narratives by higher regions of the brain. Jung did not believe that dreams need to be interpreted for them to perform their function. Instead, he suggested that dreams are doing the work of integrating our conscious and unconscious lives, and he called this the process of individuation.12, 13, 14
Biology of Sleep and Dreaming
In 1913, French Scientist Henri Pieron authored a book entitled “Le problème physiologique du sommeil," which was the first text to examine sleep from a physiological perspective. This work is usually regarded as the beginning of the modern approach to sleep research. Dr. Nathaniel Kleitman, known as the “Father of American sleep research," began work in Chicago in the 1920s questioning the regulation of sleep and wakefulness, and of circadian rhythms. Dr. Kleitman’s early work included studies of sleep characteristics in different populations and the effect of sleep deprivation. In 1953, Dr. Kleitman, together with Eugene Aserinsky, discovered that dreaming was associated with REM sleep. REM refers to "rapid eye movement," the darting of the eyes under closed lids. They found that sleepers could recall dreams most frequently if they were awakened when their eyes appeared to be moving rapidly beneath their eyelids. This discovery in turn gave researchers a tool with which to monitor dreams.15
As a process, sleep is cyclical. It is divided into REM sleep and 3 stages of non-REM; each has a distinct brainwave frequency and associated physiology. The discovery of REM sleep and its close association with dreaming, and the subsequent elaboration of the non-REM (NREM) / REM sleep cycle has ushered in a new era in the study of dreams. Although dreams have been reported from all sleep stages in laboratory experiments, most dreaming occurs during REM sleep. Generally dreams that occur during NREM sleep are less formed and structured and recall of the content of those dreams is much more limited.16
In evolutionary terms, REM sleep seems to be relatively recent, and has been identified in humans, other warm-blooded animals, and birds. Earlier studies have suggested it appears early in life, in the third trimester in humans, and research has produced evidence the brain of the fetus may in a sense be “seeing” images long before its eyes are opened. Thus, the REM state appears to help the brain build neural connections, especially in the visual areas.
REM sleep is characterized as global high-frequency and low amplitude electroencephalogram (EEG) activity (similar to the waking state), as well as increased heart rate, respiratory activity, and muscle atonia (i.e. temporary muscular paralysis). In this state we dream the most and our brain activity resembles that of waking life. Yet, at the same time, our muscles go slack and we lie paralyzed as if our brain is protecting our bodies from acting out the stories we dream.
It is important to note, however, that REM sleep and dreaming can be dissociated: lesions in the forebrain can leave REM sleep intact while dreaming ceases, whereas brain stem lesions can prevent REM sleep from occurring while individuals continue to report dreams after awakening.17
Tactile percepts, odors, tastes, as well as pleasure and pain are not as commonly reported following REM sleep awakenings.18, 19 Oftentimes the sensational and perceptual experiences of the dream world are unlike those which occur in the world of wakefulness. Alterations from waking life experiences include sensory distortions, misidentifications of characters and places, changes in spatio-temporal integration (e.g. the integration of time and location of an event), misbinding of objects’ features, dissociation, and transpositions (e.g. frequent and abrupt changes in the dream narrative).20
Reports following REM sleep awakenings consistently contain more emotional content than those following NREM sleep.21 Dreamers tend to report elevated levels of joy, surprise, anger, fear, and anxiety, whereas sadness, guilt, and depressed affect tend to be less common.22, 23, 24 A proposed explanation for this emotional finding could be related to a less critical self-reflection during dreams.25
Because REM dream reports frequently contain fear and anxiety-related elements, it has been suggested that the realistic representation of fear in dreams and nightmares serves as a threat simulation in a harmless environment in order to prepare individuals for dangerous situations in real life.26, 27, 28 It has also been shown that several periods of dreaming during one night may be related to the same emotional conflict.29 This can also take the form of a recurring dream.
Non-REM Sleep (NREM)
NREM sleep is now commonly divided into three different stages designated as N1, N2, and N3. The third stage (N3 sleep), also known as deep sleep or slow-wave sleep, was referred to as NREM sleep stages III and IV in earlier terminology30 and is in several ways physiologically distinct from REM sleep. NREM sleep is characterized by a global low frequency and high amplitude EEG signal, slow and regular breathing and heart rate, as well as low blood pressure.
During the sleep-onset phase (N1), individuals frequently experience hypnagogic hallucinations while being unaware that they have already fallen asleep.31 These experiences share some similarities with dreams during REM sleep in terms of dream bizarreness, but are typically characterized by emotional flatness.32, 33 Sleep stage N1 reports frequently contain accounts of dreaming (80–90% of the time), but these reports tend to be shorter than those following periods of REM sleep. Reports after awakenings from NREM sleep N3 contained accounts of dreaming 50–70% of the time.34 Only a few reports contained elements of dreaming after awakenings from N3 sleep early during the night, when large slow waves are most prevalent in the EEG signal.35
Duration and Sequence of Sleep Stages
Sleep progresses in a series of four or five more or less regular sleep cycles of non-REM and REM sleep throughout the night, sometimes referred to as ultradian rhythms (“ultradian” meaning within a day). The first sleep cycle is typically around 90 minutes in length, with the succeeding cycles averaging around 100-120 minutes, (although some individuals may have longer or shorter average cycles), and they are usually shorter in children. Each cycle follows the stages of non-REM sleep (stage N1 – stage N2 – stage N3) and then, after a period in deep stage 3 slow-wave sleep, back through the stages (stage N3 – stage N2 – stage N1). Thus, as the night progresses, the time spent in deep stage 3 sleep decreases and the time spent in REM sleep increases, so that there is a greater proportion of stage 3 sleep earlier in the night, and a greater proportion of REM sleep later in the night, particularly during the final two sleep cycles.
A typical hypnogram showing sleep stages and cycles in adult sleep
(Images by Luke Mastin)
Each sleep cycle is made up of several different stages of non-REM and REM sleep, the overall proportions of which are shown in this pie chart.
For most of the 20th century, scientific dreaming theories were mainly psychological. Over the last few decades, numerous other theories have been put forth to illuminate the mystery behind human dreams. Modern psychologists and neurologists, armed with imaging equipment including PET scans, MRIs and EEGs, have taken things to a deeper and more technical level, speculating that dreaming is the brain’s way of dumping excess data, consolidating important information, and keeping us alert to danger and more.
Since the discovery of rapid eye movement sleep, the neural underpinnings of dreaming have become increasingly better understood. In 1977, Drs. Allan Hobson and Robert McCarley of Harvard University presented a more mechanistic, neurophysiological model of the dream process they called “the activation-synthesis model of dream production.” They proposed the primary motivating force for dreaming is not psychological, but rather physiological, since the time of occurrence and duration of dreaming sleep are quite constant, suggesting a preprogrammed, neurally-determined genesis. (Many counter-argue by saying that this predicted dream occurrence does not account for the content of the dream that likely is psychologically important.)
Hobson and McCarley suggested that the occurrence of dreaming sleep is physiologically determined by a “dream state generator” located in the brain stem. This brain stem system periodically triggers the dream-state with such predictable regularity that Hobson and McCarley were able to mathematically model the process to a high degree of accuracy. During the REM periods produced when the dream-state generator is switched “on,” sensory input and motor output are blocked, and the forebrain (i.e., the cerebral cortex, the most advanced structure in the human brain) is activated and bombarded with partially random impulses generating sensory information within the system. The activated forebrain then synthesizes the dream out of the internally generated information, trying its best to make sense out of the nonsense it is being presented with.36
More recent theories suggest that dreams fulfill an adaptive function related to emotion regulation, hormone regulation, learning, and memory consolidation.37, 38 Other theories propose that dreaming may play an important role in reactivating and further consolidating novel and individually relevant experiences that occurred during waking hours.39, 40 Dreams might also constitute a biological defense mechanism, which has evolved as a capacity to repeatedly simulate threatening situations.41
Brain Imaging Sleep Research
The development and application of brain imaging techniques is revealing another very significant new body of findings concerning the functioning of the brain during REM sleep. Although several research groups have utilized different imaging techniques and subject procedures, striking consistencies have emerged. The groups of Maquet, Braun, and Nofzinger all report a very specific, selective pattern of activation of forebrain structures, suggesting that the brain is organized to carry out particular functions in a concerted fashion.42, 43, 44 Structures in the brain stem, thalamus, and basal forebrain that mediate arousal are also activated. A major role for emotion and drive is suggested by high levels of activation of parts of the hypothalamus and the limbic and paralimbic systems. It is also demonstrated that the amygdala may be particularly connected to the role of anxiety in dreaming.
Maquet and Braun also found a widespread deactivation of the dorsolateral prefrontal cortex, which correlates well with the diminished executive functioning in dreams. Maquet et al, emphasizing the role of the amygdala, suggest that REM sleep is involved in processing ‘‘emotionally significant memories.’’45
Nofzinger and colleagues interpret the pattern of activation as supporting the view that one function of REM sleep is the integration of neocortical activity with hypothalamic-basal forebrain regulatory and motivational reward mechanisms. They see their findings as consistent with a role for REM sleep in memory consolidation, and specifically dream content, associated with internally generated, or instinctual behaviors that subserve adaptive mechanisms.46
A special form of dreaming is the lucid dream, in which the dreamer is aware that he or she is dreaming. Lucid dreamers can remember the events of waking life while dreaming, although they have no awareness of the real external world in which they are sleeping. Also, they appear to be able to control the plot of the dream while remaining asleep. Lucid dreaming is relatively rare, but most people have had at least one lucid dream, and it has been estimated that about 20% of the population dream lucidly at least once per month.47
According to the most frequently used sleep scoring criteria, lucid dreaming is considered a part of REM sleep and usually transpires during late night REM sleep periods.48, 49 However, some research suggests that lucid dreaming may also occur during periods of NREM sleep.50, 51
Lucid dreaming has a special status compared with non-lucid REM and NREM dreaming because it is a skill that may be trained and occurs only rarely in untrained individuals. Dream lucidity can be achieved through metacognitive training, developing autosuggestions, external sensory stimulation, and through frequently contemplating about one’s own state of consciousness.52, 53, 54, 55
Subjects often succeed in becoming lucid when they tell themselves, before going to sleep, to recognize that they are dreaming by noticing the bizarre events of the dream. An experimental advantage is that subjects can signal that they have become lucid by making a sequence of voluntary eye movements. In combination with retrospective reports confirming that lucidity was attained and that the eye movement signals were executed, these voluntary eye movements can be used as behavioral indication of lucidity in the sleeping, dreaming subject, as evidenced by EEG and EMG tracings of sleep. Such signal-verified lucid dreams, in which dreamers not only realize that they are currently dreaming but are also able to deliberately control their own behavior, enabling them to signal lucidity by making prearranged patterns of eye movements, constitute lucid control dreams. Since dream lucidity can be trained and signalized in experimental settings by means of the eye-signaling technique56, 57, it constitutes a promising endeavor for dream and consciousness research.
The average person spends nearly 25 years of their life sleeping. By learning the art of lucid dreaming, or becoming fully conscious in the dream state, you can find creative inspirations, promote emotional healing, gain rich insights into your waking reality, and much more. The following two books are excellent guides to lucid dreaming:
Robert Waggoner's Lucid Dreaming: Gateway to the Inner Self is a practical guide for more information on lucid dreaming. Told in an autobiographical form, this book breaks down the five phases of lucid dreaming and walks readers through successfully mastering them all. Intriguing and inspiring, this is a handy guide for beginners or experienced lucid dreamers.
Dr. Stephen LaBerge’s Lucid Dreaming: A Concise Guide to Awakening in Your Dreams and in Your Life is distilled from his more than 20 years of pioneering research at Stanford University and the Lucidity Institute, including many new and updated techniques and discoveries.
One of the greatest puzzles of sleep concerns memory for dreams. We probably have, on average, at least 4-5 dreams every night, but we typically remember, at best, only one of these. The contrast between the large number of dreams that occur in the night, and the small number of dreams remembered in the morning, raises the question of what accounts for the remembering and forgetting of dreams.
Whether or not a dream is recalled at all depends a great deal on the timing of awakening. Awakening while a REM period is ongoing most often results in dream recall; recall rate drops off rapidly if the awakening is delayed until after the REM period has ended. Findings have been interpreted to suggest that most dreams are lost to recall by 8 minutes after the end of the REM period. It appears that most dreams are forgotten only in the sense that they have never been committed to memory. Hence, a dream journal will help facilitate dream memory.
2011 research published in the Journal of Neuroscience provides compelling insights into the mechanisms that underlie dreaming and the strong relationship our dreams have with our memories.58 Cristina Marzano and her colleagues at the University of Rome explain how humans remember their dreams. The scientists predicted the likelihood of successful dream recall based on a signature pattern of brainwaves. In order to do this, the Italian research team invited 65 students to spend two consecutive nights in their research laboratory. During the first night, the students were left to sleep, allowing them to get used to the sound-proofed and temperature-controlled rooms. During the second night, the researchers measured the students’ brainwaves while they slept.
Our brain experiences five types of electrical brainwaves: theta, delta, alpha, beta and gamma. Each represents a different speed of oscillating electrical voltages and together they form the electroencephalography (EEG). The Italian research team used this technology to measure the participants’ brainwaves during various sleep-stages. The students were woken at various times and asked to fill out a diary detailing whether they dreamt, how often they dreamt, and whether they could remember the content of their dreams. They found that those participants who exhibited more low-frequency theta waves in the frontal lobes were more likely to remember their dreams.
This finding is significant, because the increased frontal theta activity the researchers observed looks just like the successful encoding and retrieval of autobiographical memories seen while we are awake. That is, it is the same electrical oscillations in the frontal cortex that make the recollection of episodic memories possible. Thus, these findings reveal that the neurophysiological mechanisms that we use while dreaming (and recalling dreams) are the same as when we construct and retrieve memories while we are awake.
Lastly, it has been reported that people who have little or no dream recall may have a deficiency of vitamin B6. This certainly makes sense in that vitamin B6 is a required coenzyme for the synthesis of dopamine, epinephrine, GABA, melatonin, norepinephrine, and serotonin - all of which influence sleep and regulate the body clock.
Another study, conducted by the same research team in 2011, used MRI techniques to investigate the relation between dreaming and the role of deep-brain structures. In this study, the researchers found that vivid, bizarre and emotionally intense dreams (the dreams that people usually remember) are linked to parts of the amygdala and hippocampus. While the amygdala plays a primary role in the processing and memory of emotional reactions, the hippocampus has been implicated in important memory functions, such as the consolidation of information from short-term to long-term memory.59
Thermoregulation and Sleep
Sleep and thermoregulation are strongly tied together. One of the results of inhibiting sleep in lab animals is that they lose the ability to regulate their body temperature. In addition, brain and body temperature vary across stages of sleep. The temperature of both the brain and the body fall during NREM sleep. The longer the NREM-sleep episode, the more the temperature falls. By contrast, brain temperature increases during REM sleep.
It has been shown that slightly increasing body temperature dramatically improves the quality of sleep. The percentage of the sleep spent in deep sleep increases with less waking at night. These effects are usually most pronounced in the elderly and in people who suffer from insomnia. Hence, wearing sleep clothing and even a sleep stocking-cap are useful aids to maintain warmth at night that will promote restful sleep. Sleep clothes, however, need to be light and breathable. They should not be too heavy (since that would induce sweating). Additionally, a hot bath before bed may promote sleep.
The ideal temperature for falling asleep is between 60 and 67 degrees Fahrenheit (not too warm - to avoid sweating; but not so cool that one would awake a few hours later shivering).
Sleep and Dream Chemistry
Dreams are also associated with different chemicals released during sleep. In many respects the electrical activity of the dreaming brain is like that of the waking brain, but the chemistry is entirely different. Our bodies release chemicals in a 24-hour cycle, nudging us to do certain activities at certain times. Each of these cycles is called a circadian rhythm.
One of the most important chemicals involved in the sleep process is melatonin. To maintain our 24-hour sleep schedule, the body translates information about time of day into melatonin production. This process starts in the eye’s retina. When the retina is exposed to light, a signal is relayed from the retina to an area of the brain, called the suprachiasmatic nucleus, which plays a role in making us feel sleepy or wide awake.
The suprachiasmatic nucleus sends signals to other parts of the brain that control hormones and body temperature. Signals then travel from the brain down the spinal cord and back up to the pineal gland, a small pinecone-shaped organ in the brain where melatonin production takes place. The pineal is like the adrenal medulla in the sense that it transduces signals from the sympathetic nervous system into a hormonal signal. During the day, such signals prevent the pineal gland from producing melatonin. But when it is dark outside, these signals are not activated, and the pineal gland is able to produce melatonin. In other words, exposure to light prevents melatonin release, which keeps us awake, and lack of exposure to light causes melatonin release, which tells us to “go to sleep”.
Thus, the amount of melatonin in our bodies starts increasing in the evening (related to a decrease in light). Melatonin levels in the blood stay elevated for about 12 hours - all through the night - before the light of a new day (when they fall back to low daytime levels by about 9 am). Daytime levels of melatonin are barely detectable. When taken in low doses at the appropriate time, supplemental melatonin can help advance or delay the sleep-wake cycle.
Polish Physiological Society © Konturek, S. J., Konturek, P. C., Brzozowski, T. & Bubenik, G. A. J. Physiol. Pharmacol. 58 (Suppl. 6), 23–52 (2007)
Melatonin is derived from the essential amino acid tryptophan. The synthesis of melatonin from tryptophan occurs through a multistep process. First, tryptophan is converted to another amino acid, 5-hydroxytryptophan, through the action of the enzyme tryptophan hydroxylase, and then to the neurotransmitter serotonin by an enzyme called aromatic amino acid decarboxylase. Serotonin’s conversion to melatonin involves two enzymes: serotonin-N-acetyltransferase (SNAT), which converts the serotonin to N-acetylserotonin with the addition of an acetyl group (COCH3), and hydroxyindole-O-methyltransferase (HIOMT), which transfers a methyl group (CH3) to the N-acetylserotonin. The activities of both enzymes rise soon after the onset of darkness.
The amount of melatonin produced depends on the activity of SNAT, which peaks when it is dark outside. Exposure to light induces signals that, as explained earlier, travel from the retina to the suprachiasmatic nucleus and then to the pineal gland, resulting in the degradation of SNAT. However, at night, SNAT is phosphorylated. Phosphorylation, which is simply the addition of a phosphate group (PO43−) to a protein or other organic molecule, prevents SNAT from being degraded and thus increases melatonin production. When it is morning, SNAT is degraded again, and the amount of melatonin decreases.
Melatonin supplementation has been shown to facilitate restful sleep. Some researchers have suggested that at certain doses, melatonin increases the number of dreams a person remembers by artificially prolonging the amount of time spent in REM sleep. Taking melatonin may also increase a person’s chances of experiencing a lucid dream for a similar reason, by elevating them to a more self-aware state while they are still in REM sleep. Most importantly, sleeping in total darkness is necessary to keep melatonin production at its peak levels.
Melatonin is not the only chemical that determines our sleep schedule - adenosine also plays an important role. Adenosine is created naturally within the body from the combination adenine, a nitrogen-based substance, and ribose, a sugar. Adenosine is classified as a xanthine. Every cell in the body contains some adenosine (contained within DNA and RNA).
Adenosine operates as a neuromodulator in the brain, and has the effect of inhibiting many of the bodily processes associated with wakefulness, particularly those involving the neurotransmitters norepinephrine, acetylcholine and serotonin. Adenosine as an inhibitory neurotransmitter slows down the activity of neurons. However, adenosine is neither stored nor released as a classical neurotransmitter and is thought to be formed inside cells or on their surface, mostly by the breakdown of adenine nucleotides.
The extracellular concentration of adenosine increases in the cortex and basal forebrain during prolonged wakefulness and decreases during the sleep recovery period. Therefore, adenosine is proposed to act as a homeostatic regulator of sleep and to be a link between the humoral and neural mechanisms of sleep-wake regulation. Adenosine appears to accumulate in the bloodstream when awake and, like melatonin, eventually produces drowsiness. Inside the brain, adenosine levels exert a major influence on the regulation of non-REM sleep. This regulating effect occurs when an enzyme called adenosine deaminase breaks down, or metabolizes, adenosine molecules. The rate of this metabolism influences the intensity and duration of sleep when slow brainwaves are present. Metabolism also reduces the brain’s adenosine supplies, and your adenosine levels drop as sleep continues.
Caffeine as a xanthine has a chemical structure like that of adenosine. Both molecules have a double-ring structure, which allows caffeine to bind to adenosine receptors. Unlike adenosine, however, caffeine does not activate these receptors or suppress neuron activity. By reducing the concentration of available adenosine receptors, caffeine slows the rate of reaction: less bound adenosine means we feel less sleepy.
GABA (gamma-aminobutyric acid)
GABA is a naturally occurring neurotransmitter involved in the central nervous system inhibitory activity. It is the brain’s “brake fluid.” GABA decreases or stops the transmission of nerve impulses. GABA is also responsible for “sleep paralysis.” Sleep paralysis is when you are conscious, but unable to move (as if paralyzed). This happens when a person passes between sleep stages. The person will pass from wakefulness to falling into deep sleep. During the transition, there is a problem where the person will wake up, but is unable to move or talk, even though they are awake. Sleep paralysis occurs at 2 different times: the first is while falling asleep (called hypnagogic or predormital sleep); the second is when waking (called hypnopompic or postdormital sleep). During sleep, the body alternates between REM and NREM cycles. During REM the muscles are basically shut off. Sleep paralysis occurs when the person wakes up and is aware of their surroundings, but the REM cycle is not complete (so that person will not be able to move or speak until the REM cycle has finished).
The nerve receptors in the voluntary muscles play a role in this phenomenon. One is called the ionotropic GABAA (which responds to both glycine and gamma aminobutyric acid); the other is metabotropic GABAB. The combination of the two at the same time is what causes the muscles to be unable to move.
Supplemental GABA has been shown to help produce restful sleep. (Individuals with insomnia have reduced GABA production.) Many of the most effective sleeping pills increase activity at the GABA neurons. Pure GABA is over-the-counter and an excellent natural alternative to GABA-like pharmaceuticals.
The activity of acetylcholine neurons, in general, is associated with cortical arousal (increase in wave frequency) and desynchrony, as measured by an EEG. Hence, there is a great deal of evidence that acetylcholine is associated with REM sleep. For example, release of acetylcholine in the cortex is highest during waking and REM sleep, and lowest during delta sleep or deep sleep. In REM sleep, the nerve cells that use acetylcholine are active, while those that depend on other neurotransmitters, like norepinephrine and serotonin, are quiet.
The acetylcholine neurons that are most important in the sleep process have cell bodies in the pons and the basal forebrain. The pons is located at the base of the brain just above the medulla. Structures at the base of the brain, particularly those located in the pons, play a very big role in sleep and biological rhythms. The basal forebrain is located just in front of and above the hypothalamus (in a standing human). The acetylcholine neurons in these two different areas play slightly different roles in sleep.
Norepinephrine and Serotonin
The other two neurotransmitters that have been implicated as playing an important role in sleep are norepinephrine and serotonin. The cell bodies that are most important in sleep with these two neurotransmitters are in the locus coeruleus and the raphe nuclei (for norepinephrine and serotonin, respectively).
Norepinephrine and serotonin levels do not increase with the cortical arousal and desynchronization that accompanies REM sleep. In fact, the exact opposite is the case. Both neurotransmitters are at their lowest levels during REM. Further, norepinephrine and serotonin agonists repress REM activity, and antagonists increase it. Thus, it appears that these two neurotransmitters play a complementary role with acetylcholine, in that they act to control and suppress REM activity, while acetylcholine acts to initiate and maintain REM. In fact, norepinephrine neurons in the locus coeruleus and serotonin neurons in the raphe nuclei both send projections, which synapse on acetylcholine neurons in the peribrachial area.
Most people forget almost all dreams soon after waking. Research indicates that the chances of dream recall are greatly reduced if one delays in awakening a dreamer even just five minutes after the end of REM. After another five or ten minutes, there is very little chance of any recall at all. One of the unexplained theories says that lack of the neurotransmitter norepinephrine in the cerebral cortex is responsible for forgetting dreams after awakening.
Keeping a Dream Journal
For anyone interested in learning more about their psyche and unconscious motivations from dreaming, it is useful to keep a dream journal. Recording dreams on a regular basis and tracking their themes and patterns over time will become an invaluable source of insight into important concerns, activities, and relationships in the waking world. The first way to begin a dream journal is by making some retroactive entries. For example, write out the earliest dream remembered, no matter how small or seemingly insignificant. Recording especially memorable dreams from the past can be a good way of initiating a dream journaling practice going forward into the future.
Regular journal-keepers typically place a pad of paper and a pen next to their bedside, and when they wake with a dream in mind, they immediately write it down. Because these bedside notes are often scrawled in semi-legible form, people will usually transcribe their dreams later in the day, either into better handwriting or a word-processing system. It is also possible to use voice-to-text programs. Whichever method is used, the main goal is to set up a smooth, friction-free process to record as much of the dream as can be remembered, as soon upon awakening as possible. With a dream journal it is easier to identify recurrent dreams, symbolic patterns and the emotional content of dreams. Lastly, giving the dream a title can help symbolically structure the dream so that it may be easier interpreted.
There are no simple or universal answers to the meanings behind particular dreams. Dreams and their meanings are unique to the individual. Thus, the best person to analyze the true meaning of a dream is the dreamer. It can, however, be helpful to have a few reference books on hand for dream interpretation. Because dream symbols and their meanings are often not literal, but metaphorical, a dream dictionary can also be helpful for decoding and interpreting dream symbols, and how they may relate to your waking life events and emotions. There are numerous excellent books that can help facilitate dream interpretation.
Two of my personal favorites include What your Dreams are Telling You by Cindy McGill and Inner Work: using Dreams and Active Imagination for Personal Growth by Robert Johnson.
Another excellent classic is Dreams by Carl G. Jung - R.F.C. Hull (Translator) Extracted from Volumes 4, 8, 12, and 16; this includes: "The Analysis of Dreams," "On the Significance of Number Dreams," "General Aspects of Dream Psychology," "On the Nature of Dreams," "Individual Dream Symbolism in Relation to Alchemy," and "The Practical Use of Dream-Analysis." Jung’s insights and illuminations of archetypal images and energies has provided many keys to doorways of understanding story (of being), and images of Psyche. He has spurred further interests in myth, and creation stories.
Another useful source is the online Dreams Dictionary.
Out-of-Body Experiences During Sleep (“Astral Projection”)
Probably the most controversial and misunderstood occurrence during sleep is what has come to be known as an “out-of-body experience,” (OBE) also called “astral projection.” This is usually understood to be the act of separating the “astral body” from the physical body, so that the astral body can travel away from the physical body, carrying with it the consciousness of the traveler. Normally, this phenomenon occurs as part of the sleep process, usually at the deepest dream level. However, this phenomenon can also can be induced by: (a) specific OBE techniques, (b) surgical operations, (c) brain traumas, (d) sensory deprivation, (e) near-death experiences, (f) psychotropic substances (mushrooms, LSD, peyote), (g) electrical stimulation of the brain, and (h) forms of meditation, among others.
When the person is conscious of this separation it is called “conscious astral projection” and has long been part of Tibetan Buddhism. In Tibetan Buddhist tradition, separating consciousness from body is known as "po-wa." meditation. The term out-of-body experience was introduced in 1943 by George N. M. Tyrrell in his book Apparitions and popularized by Charles T. Tart, Ph.D,. a leader in the area of consciousness studies. This term was adopted by researchers such as Celia Green and Robert Monroe as an alternative to spiritualistic terms such as "astral projection." In 1968, Green published an analysis of 400 first-hand accounts of out-of-body experiences. Robert Monroe has achieved worldwide recognition as an explorer of human consciousness and out-of-body experiences. His research, beginning in the 1950s, produced evidence that specific sound patterns have identifiable, beneficial effects on our capabilities. For example, certain combinations of frequencies appeared to enhance alertness; others to induce sleep; and still others to evoke expanded states of consciousness. He founded the Monroe Institute - and in 1971 wrote Journeys Out of the Body.
Researcher Waldo Vieira described the OBE phenomenon as a projection of consciousness. A closely related experience is autoscopy (AS), which is characterized by the experience in which an individual perceives the surrounding environment from a different perspective, from a position outside of his or her own body.
This separation phenomenon has fascinated mankind from time immemorial and has been cross-culturally recorded throughout history. Astral projection (OBE/AS) is abundant in folklore, mythology and spiritual literature. Only recently has research of this phenomenon begun to be published. Yet, despite many case studies, systematic neurological studies of OBE and AS remain few, and, to date, no testable neuroscientific theory exists.
Some of the earliest 20th-century accounts of astral projection come from Sylvan J. Muldoon (1903-1969) in his classic books Projection of the Astral Body (1929), The Case for Astral Projection (1936) and The Phenomena of Astral Projection (1951). These books contain records of many years of experimenting with astral projection, which bear the stamp of authenticity. In the world of astral projection, Muldoon was one of the early pioneers in the field. Numerous other researchers and texts have followed.
Research by Dr. Olaf Blanke60 in Switzerland has attempted to account for OBE experiences in neuro-physiological terms. Dr. Blanke found that it is possible to reliably elicit “OBE-like experiences” by stimulating regions of the brain called the right temporal-parietal junction (TPJ). The TPJ incorporates information from the thalamus and the limbic system, as well as from the visual, auditory, and somatosensory systems. The TPJ also integrates information from both the external environment as well as from within the body. The TPJ is responsible for collecting all this information and then processing it.61, 62 Dr. Blanke has explored the neural basis of OBE-like experiences by showing how they are reliably associated with lesions in the right TPJ region. But no such experiences were found by stimulating any other area of the brain - suggesting the mental imagery of TPJ stimulation is of one's own body.63 Dr. Blanke's Laboratory of Cognitive Neuroscience has become a well-known laboratory for OBE research.
Dr. Michael Persinger (who recently passed on August 14, 2018, at the age of 73) performed research like Olaf Blanke using magnetic stimulation (the "God Helmet") applied to the right temporal lobe of the brain, and discovered a telepathic link to OBEs. Dr. Persinger found evidence for objective neural differences between periods of remote viewing in two individuals believed to have psychic abilities. Dr. Persinger undertook his research on Sean Harribance and Ingo Swann, a renowned remote viewer who has taken part in numerous studies.64 Examination of Harribance revealed enhanced EEG activity within his right parieto-occipital region, which is consistent with evidence of early brain trauma in these regions. In a second study, Ingo Swann was asked to draw images of pictures hidden in envelopes in another room. Individuals with no knowledge of the nature of the study rated Swann's comments and drawings as identical to the remotely viewed stimulus at better-than-chance levels. Additionally, on trials in which Swann was correct, the duration of electrical activity over the right occipital lobe was present longer. An MRI examination found anomalous white brain matter signals focused in the perieto-occipital interface of the right hemisphere that were not expected for his age or history.
Without drifting too far into OBE sleep experiences, it is interesting to note that Carl Jung worked with physicist Wolfgang Pauli in an attempt to correlate quantum mechanics with the astral world. Modern biologists, such as Rupert Sheldrake, influenced by Jungian ideas, has theorized the existence of organizing fields of life called "morphic fields" consisting of memories and drives. Also, Dr. Raymond Moody, M.D., although not an astral projectionist, is thought of as "the father of the near-death experience" and has written a very popular book, Life after Life, on the subject of out-of-body travels associated with the dying.
Dreaming is a unique and universal bioregulatory feature of human experience. Theories on the function of REM sleep and dreaming, with which it has a contingent relationship, remain diverse. They include facilitation of memory storage, reverse learning, anatomical and functional brain maturation, hormonal restoration, and psychoemotional restructuring. Another proposed purpose is to simulate threatening events, and to rehearse threat perception and threat avoidance. It is possible that one function is grafted onto another as the personality develops. Other more mechanistic theories claim that dreaming is a random byproduct of REM sleep physiology and that it does not serve any natural function. However, dream content and experience are not as disorganized as such views imply. The form and content of dreams is not random, but instead, very organized, personal and selective, and serves a purpose both physiologically and psychoemotional. Dreaming offers a door to knowledge, and into the dreamscape of inner self.
Let’s sleep on it.