ABSTRACT: Based on the correlation of the author's own dreams to the state of his body immediately after awakening from a dream scenario, this paper proposes that the function of dreams and nightmares during sleep is: a) to wake up the sleeping brain, at least for the purpose of changing frequently the position of the body tired under the influence of gravity for better relaxation, and b) under adverse conditions, to fully alert the brain to take control of the body to defend itself. The author believes that dreams and nightmares constitute an essential part of a self-alarm system needed by a sleeping brain.

1. INTRODUCTION

Everyone dreams. It is reported that even the unborn baby dreams as do other mammals (1, 2). Varying roles have been attributed to dreaming and I have tried to summarize some of them below in this text. However, scientists so far have not been able to understand the real purpose of sleep or the dreaming during sleep in human biology.

Throughout human history, interpretations of dreams have played a very important role in the lives of human beings. People have made important decisions based on what they saw in their dreams and have accordingly influenced not only their own lives but also the lives of many other people. Some people have declared themselves as prophets or representatives of God or even God itself and hence have founded religions based on their dreams.

Some dream scenarios are pleasant while others may be terrifying to the dreamer. Some dream scenarios are so bizarre that they almost appear to be supernatural in character and yet have never been experienced or learned indirectly by the dreamer. Close examination of what can be remembered about the dream immediately after awakening from a dream scenario indicates that the following aspects are common to all dreams:

• At some point during dreaming, the person wakes up.
• After awakening, there is an urgent feeling to change body position.
• At the moment of awakening, some parts of the body feel discomfort as compared to the rest of the body. If nothing else, the side on which one has been sleeping feels as if it is tired of being slept on - due to the continous effect of gravity.
• The dream scenario seen just before waking up seems to be related to the condition of the body at that time.

People have always asked questions regarding dreams. What are dreams? Why do we dream? What meaning should be attributed to a dream scenario? Do dreams carry any messages about the past, present and future of the dreamer? What is the mechanism that generates dreams and many more? Many researchers have put forward theories aimed at answering such questions and also about the function of dreaming. Some of the theories expressed by prominent authorities are summarized below.

Sigmund Freud was one of the dream researchers who is most celebrated in the western world. In his "The Interpretation of Dreams", (1), Freud puts forward a dream theory in which he proposes that the function of dreaming is to act as guardian of sleep and also as a means of "wish fulfillment" for the oppressed wishes. He says that the driving forces for dreams are the repressed wishes that are formed from experiences that the dreamer has had during the day or at other times. Freud attributes meanings to scenes and characters seen in dreams and tries to decode the inner world of the dreamer by using these assumed meanings. Modern research about dreaming does not support Freud's dream theory.

Freud, before proposing his own theory of dreams, discusses theories put forward by other researchers before or contemporary to him. Accordingly, Freud classifies the sources of dreams into four categories, (1, page 27). They are:

1) External sensory (objective) excitations,

2) Internal sensory (subjective) excitations,

3) Internal (organic) somatic stimuli, and

4) Purely physical sources of stimulation.

Ernest Hartmann summarizes his views on function and dreaming as follows, (2,3):

"Dreams consist of images that include memories of experiences connected with important feelings of the dreamer. These images are both a way of representing the feelings and experiences with which they are connected, and a way of organizing them so that they can be meaningfully integrated by the dreamer. This integrative process is usually more or less successful but when it is not, the dream may be only a representation of the problem without any integration or solution. The classical psycoanalytic view of dreams is not really contradicted by this approach except for the idea of drive discharge. As in the traditional view, dreams are meaningful, contain material related to past unsolved problems or conflicts, and are thus the source of understanding of the patient. They are important to psychologic function, however, not as a vehicle for satisfying unfulfilled or forbidden wishes, but because they provide a mechanism for maintaining a continuity and meaningfulness in our life experiences, allowing us to draw on past experiences to modify old modes of behaviour."

Berger (4) refers to the following theories regarding the function of dreaming, which is also known as Rapid Eye Movement (REM) sleep:

The Ontogenetic Theory

Proposed by Roffwarg, Muzio and Dement (5), the theory suggests that REM sleep provides endogeneous afferent stimulation necessary for structural differentiation and maturation of the central nervous system during fetal and neonatal life, when brain growth is maximal. The high percentage of time spent in REM sleep in both the premature and full-term newborn mammal and its subsequent decline with increase in age has been presented as the principal evidence for this theory.

The Phylogenetic Theory

This theory proposed by Snyder (6) suggests that REM sleep first evolved in the mammal to serve a "sentinel" or vigilance function necessary for survival from attack by other species. Snyder suggested that REM sleep prvides periodic cortical arousal throughout sleep preparatory to the brief awakenings which usually terminate REM periods, so that the animal has sufficient 'critical reactivity' to adequately 'test' the environment for dangerous elements.

The Homeostatic Theory

This theory proposed by Ephron and Carrington (7) suggests the existence of a homeostatic interplay between REM sleep and non REM (NREM) sleep to account for the sequential relationship seen between these two sleep states. They proposed that the loss of cortical 'tonus' or 'vigilance' during deep NREM sleep provides the organism with needed rest, and must be maintained within adaptively appropriate limits. In order to preserve the continuity of sleep, but maintain the level of cerebral excitation within these limits, Ephron and Carrington suggested that REM sleep serves the function of periodically increasing cortical 'tonus'.

The Oculomotor Innervation Theory

This theory proposed by Berger (8) himself suggests that REM sleep provides a mechanism for the establishment of the neuromuscular pathways involved in voluntary conjugate eye movements in both phylogenesis and ontogenesis; and that throughout mammalian life REM sleep furnishes periodic innervation of the oculomotor system during extended periods of sleep, in order to maintain facilitation of binocularly coordinated eye movement into subsequent wakefulness.

Francis Crick and Graeme Mitchison have recently proposed a radically new role fpr dreaming, (9). Quoting from New Scientist (10), the theory, in summary, says that "during dreams the brain is eliminating or 'unlearning' spurious patterns of activity in the cerebral cortex (the part of the brain concerned with thinking), in order to maintain its efficiency as a mechanism for the storage and retrieval of information. Cortical cells are interconnected in complex, overlapping networks, so that if one cell fires, others will also be excited in consistent patterns. Crick and Mitchison suggest that these patterns are the basis of memory. Computer scientists have developed models of such networks that are capable, like the brain, of 'learning' new information. Having learned, they can always produce an appropriate reaction to that information when they encounter it in future. Unlike conventional digital computers, these models store information in terms of the strengths of the various connections between cels in the network, or of the firing thresholds of the cells. These are not fixed at the outset but can be adjusted through 'training'. With adequate training, a model network will produce an appropriate response even when given only part of the original input. A single network can store many associations in this way. However, if it becomes overloaded it ceases to perform efficiently. It may produce 'fantasies' or 'hallucinations' - undesireable patterns of activity that Crick and Mitchison call "parasitic modes of behaviour". They suggest that if the real brain is anything like the theoretical model, such parasitic modes are bound to arise frequently during an individual's lifetime and that the brain must have evolved some way of eliminating them.

The purpose of this paper is not to dwell on the interpretation of dreams but, rather discuss the role of dreaming during sleep. Particularly from the point of view that a sleeping body needs a security system for the survivability of the species during sleep.

In this paper, I present my view regarding the brain's need for sleep. I also propose a new role for dreaming which, I believe, has not been considered before and is the most likely explanation of the purpose of dreaming and nightmares in the biology of human and other mammals. The proposed role for the dreaming is based on observations of many of my own dreams.

I present my view regarding the function of dreaming during sleep for humans and other mammals who have adopted sleeping as one form of living through evolution.

The method of analysis which I used to capture some of the dream scenarios and their relation to the position of my person at the moment of waking up is also outlined in the text.

Various questions related to dreaming and sleep are discussed in the text in view of the presented dream theory.

A summary of the presented view and a list of references used in this study are given at the end of the paper.

2. BRAIN'S NEED FOR SLEEP

It appears that one of the design principles being used by Nature is that the organism be self sufficient to the capacity of its basic structure after it has gone through its growth period. Although limited help for a limited time may be provided by the parent organism, the new member of the species must be on its own in all aspects of its life in the struggle for survival. Nature probably never intended to have doctors, psychologists, social workers, etc. to help the struggling member of each creation to sustain its life.

A living organism is a 'machine' based on living organic components, the building blocks of which are the living cells.

All machine systems, whether based on organic or inorganic components, need maintenance after some duration of operations. There is no machine system that works indefinitely. Any machine operated continuously long enough will eventually break down and become inoperative. In order to prolong the useful life of a machine system, it must be maintained. Carrying out regular maintenance on a machine system helps it to operate in the way it was designed to operate and give the service that is expected of it. The maintenance of the machine may be in terms of preventive and corrective maintenance.

Corrective maintenance on a system implies that the system has already reached a state in which normal functions of the system cannot be carried out. Once the system breaks down due to partial or complete failure of one or more of its components as a result of continuous operation of the system, then, corrective maintenance, involving repairs and/or replacement of components and/or subsystems, may have to be carried out in order to restore the broken down system to its normal operational state. Corrective maintenance may be carried out at the molecular and cell level of organisms.

Partial or complete breakdown of a 'machine' system (such as a living organism) must be avoided so that only the minimal amount of corrective maintenance is performed. This is an essential requirement, since during such activity, the organism is most vulnerable to aggressive elements that may attack the body from both the external and internal environments. The organism is incapacitated to the degree that it is unable to carry out some of the normal defence functions needed for its survival. Hence, it is at the mercy of its environment where other living organisms are ready to take advantage of the situation and devour the incapacitated organism for their own survival.

Regular preventive maintenance prolongs the useful life of a machine system between system breakdowns. Particularly in living organisms, the "breakdown state" must be avoided for as long as possible, since it is quite likely that such a state would lead the organism to its death. It would be in the best interest of the living organism if its bio-system allowed for regular and self-applied preventive maintenance of itself in order to avoid situations requiring corrective maintenance, particularly at levels higher than the cell level.

Among the two types of maintenance, corrective maintenance is much more costly in terms of energy, time and skills as compared to preventive maintenance. Hence, preventive maintenance should be the preferred mode of maintaining bio-systems. For example, consider the self-healing and replacement of components (i.e., the regeneration of parts of the brain and the body). Such corrective maintenance would require not only comparatively more energy and skills (specialization) but also a longer time to complete the process of self replacement and repair.

It may be that one of the objectives of Nature as applied to living organisms is that the structure of the living organism must not allow system breakdowns due to its own functions (operations). In other words, the preventive maintenance must be the preferred rule rather than the exception for self survival. All functions of the body must evolve around this underlying priciple.

If this principle is in fact being used in real life for sustaining the normal functionality of a living organism, then, built into the system, there must be time allowance for doing preventive maintenance on the system. In human beings, mammals and other organisms which sleep, this function is probably carried out mostly during sleeping.

As human beings, we are able to observe a feeling of relaxed body and mind, freshness and rejuvination after sleep. These feelings seem to be the indication that some maintenance is taking place during the sleep mode.

It is most likely that the presence and absence of light on a cyclical basis, (i.e., day and night on Earth) caused the "sleep mode" to evolve for the higher order organisms (such as birds and mammals) as part of a self performed preventive maintenance system. Turning off the brain's and body's daytime functions during sleep (for at least one third of the day) is itself a form of preventive maintenance. By not operating continuously, the brain prolongs its own and the rest of the body's life.

Negative feelings and mental and physical stresses build up during the waking life of a higher order organism (such as a human being) due to interaction with the environment for survival. The effects of stress and negative feelings on the body and brain are upsetting and disruptive. They help to speed up the breakdown of the organism's normal functioning, probably by disturbing the body's immune system. It would, therefore, be a natural requirement that such feelings and stresses be inhibited from influencing the immune system of the body so that it can effectively perform its function of defending the organism. This is an important preventive maintenance measure that seems to be performed best during sleep.

Being "self sufficient" is probably one of the most important objectives for most of the living organisms. In a normal and healthy body, time must be reserved in order to get rid of the built up tensions and depressions without being coached by others. This is important for the survivability of the species. In fulfilling this requirement, the brain (being the central information processing, evaluating and controlling center of the body) must be responsible for carrying out the preventive maintenance (self healing) functions on the organism.

In view of these considerations, it may be assumed that "sleeping is required for the self maintenance of the brain and the body".

Brain cells are not regenerated nor is any abnormality in the brain (and in its communications system with the rest of the body) readily self corrected by the use of corrective maintenance. In view of this situation, the brain cells must be made to serve longer by preventive rather than by corrective maintenance. It seems that this is probably what is taking place in the brain. The brain goes to sleep regularly, probably as a preventive maintenance measure, to prolong the life of the brain. During sleep, preventive maintenance in many forms may be taking place at the cell and/or molecular level. In time, the nature of the self-performed preventive maintenance during sleep will eventually be understood and defined by scientists.

In living organisms that sleep, the self-performed preventive maintenance on the brain and the rest of the body may be in the form of:

• Self clean-up.
• Manufacturing chemicals that are required for the functioning of the brain and the rest of the body.
• Suppressing the manufacture of chemicals that are not required at that time for the functioning of the brain and/or the rest of the body.
• Replenishing (i.e., renewing and strengthening) the basic functional
• instructions provided naturally (i.e., genetically) and stored in the memory system of the brain.
• Mental and physical relaxation.
• Relieving the body's immune system from the negative influences of mental and physical stresses so that the immune system can carry out its function of fighting potential illnesses of the brain and the body.
• Self diagnostic activities at the molecular, cellular and/or higher levels.
• Rearrangement and/or readjustment of neuron connections.

3. BRAIN'S NEED FOR A SELF-ALARM SYSTEM

The human body has been provided with a very extensive sensing and communication system that is used primarily as the "alarm and control communications network" needed for the survivability of the body. Various sensory systems located throughout the body provide the means to detect signals coming from the external world and from within the body, while the body is awake. The detected signals are transmitted to the brain where they are processed and evaluated whereupon relevant commands are transmitted by the brain to the particular organs of the body so that the desired actions may be carried out. In a healthy and undrugged body, this is an ongoing process while the body is awake.

One third of our lives is spent in sleep. In this state, the brain seems to acquire a state of unconsciousness during which it does not respond to stimuli at levels it would normally respond to while the body is awake. Hence, the sleeping body is exposed not only to many dangerous conditions that may exist in its immediate external environment, but also to possible harmfull situations created by the body's own physical, physiological and psychlogical states, i.e., stresses existing at that time. Even though most parts of the body are relaxed during sleep, some parts may become highly stressed - that is, driven to the level of discomfort by the body's own weight (i.e., under the continuous effect of gravity or by other prevailing conditions that are external or internal to the body such as the need to go to bathroom). If the brain does not wake itself up from the sleeping mode, the body could do itself irreversible harm. It is clear that a human body or any other mammal or organism which has adopted to sleeping as one form of living must have a self-alarm system capable of waking up the brain during such hazardous conditions.

It seems that Nature, through evolution, has indeed provided a self-alarm system for the human brain and for other mammals that sleep. I believe that part of this self-alarm system of the brain is manifested in the form od "dreaming" and "nightmares" during sleep. I reached this conclusion after observing, almost on every occasion that I could analyze, the presence of a very close correlation between my own dreams and the condition I found myself in at the moment of waking up.

During the dreaming mode, all kinds of dream patterns are generated. These patterns may address combinations of all the sensory systems of the body. Most of these dream patterns seem to be lost immediately upon waking up. Visual scenarios of dreams are particularly susceptible to light. They fade away quickly on opening the eyes in a lit environment.

Some of the dream and nightmare patterns generated during dreaming seem to be related to the effects of the external and/or internal conditions causing discomfort at that time, especially to the last few seconds that cause the awakening of the brain. For example, a part of the body may become numb due to a blocking of blood circulation caused by the body's position during sleep. Body sensors, associated with the area having discomfort, signal the situation to a part of the brain, probably the cerebellum, which may be acting as the "watchguard" of the brain while the brain is asleep. I propose that such a part of the brain acts as the "Sleep-Time Operations Center" (STOC) for the total body. The STOC probably uses the incoming signals to induce dream patterns or scenarios which in turn stimulate the brain to change from "sleep" mode to "awake" mode. In this transition, the brain becomes awake for a short time, but long enough for the brain to send the necessary commands to the body to change its sleeping position and/or to eliminate or reduce the discomfort. The brain may then resume its sleep mode once again or stay awake for a while. This can occur frequently during sleep.

It seems that the severity of discomfort experienced by the body or the seriousness of the threat to the body leads the dream scenario into a nightmare scenario from which the subject wakes up in an agitated state. Particularly, the presence of situations, where any part of the neck and/or head are physically threatened during sleep, are observed, almost with certainty, immediately after awakening from a dream in which one sees himself being threatened. In these situations, the dream scenario is invariably far less than pleasant.

For instance, the blockage of circulation in the neck area in one sleeping situation and in the hand area in another do not have the same degree of severity for the body. In the first case, prolonged sleeping in that condition can be detrimental to life. One could end up with self strangulation. In the second case, the worst that could happen may be to cause permanent injury to the hand. Although both situations lead into nightmares, the dream scenarios induced by physical threats to life support systems (such as breathing and blood circulation to the brain through the heart and neck) seem to be highly violent in nature and terrifying to the brain. Such situations can readily arise by having, for example, a bedding material wrapped around the neck tightly. Conditions like this seem to invariably cause frightening dreams from which the brain wakes up suddenly and in an agitated state. Because of the frightening aspect of the dream scenario, the brain becomes fully alert after waking up from the nightmare and does not go back to sleep for some time. Attaining this extra alertness from the brain seems to be a requirement that Nature demands for the survivability of the sleeping brain and hence of the species. It is a way of ensuring that the brain becomes fully awake and alert in commanding the necessary bodily actions to take place in order to alleviate the impending physical danger to the body.

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