As indicated by the derivation of the term hypnosis, an intimate connection between the sleep state and the hypnotic state has been a popular theory. Although it is not definite what hypnosis is, it is now known that hypnosis is not sleep or normal waking consciousness (5). Multiple studies done on the physical characteristics of waking, hypnosis and sleep states indicate that distinct differences do exist between the three and lend support to the notion that hypnosis is an alternate state of consciousness. Hypnosis is differentiated from sleep due to lack of alteration in blood flow to cerebral vessels; no change in basal metabolism, blood glucose, respiratory rate, or blood pressure; and lack of undulatory eyeball movements upon entering hypnosis (2). Patients under hypnosis can hear as well as respond to the voice of the hypnotist and are generally aware of their surroundings. Interestingly, these characteristics show no deviation from the characteristics of the waking, conscious state. As a result of these similarities, it has been thought that the hypnotic state is more closely related to normal consciousness than to the sleep state (10). A couple characteristics found in the hypnotic state that do differentiate it from the waking state are an increase in oral temperature, an enlargement of vessels in the white of the eye, and in instances of high stress, an increase of venous blood flow through appendages (2). The main and perhaps most interesting difference between the three is shown in the electroencephalographic (EEG) patterns; there is an increase in delta activity and a higher frequency activity observed during phases of hypnosis that are not observed in either the waking or sleeping state (3).
Now that we know that hypnosis is a unique state from both sleep and wake, the question that arises is: if each of these states differs from each other, is there truly any relation between the three of them? The early misconceptions about the relationship between the hypnotic state and the sleeping state, along with similarities between the waking state and the hypnotic state, seem to suggest that there is. More evidence to support a relationship between these three states is easily found. A popular method of hypnotism called induction involves immobilization and relaxation of the patient. During this procedure the hypnotist generally tells the patient that they are getting sleepy. The reference to sleep is thought to help act as a destructive force toward the normal waking state of consciousness, which needs to be "destroyed" to facilitate any alternate state of consciousness (9). It should not be much of a surprise then that hypnosis has been found capable of leading to sleep and sleep capable of leading to hypnosis (10). There are even sleep inducing drugs that can lead to hypnosis. One last piece of evidence is the EEG patterns. If EEG patterns were placed on a timeline, the differences between deep sleep, meditation and hypnosis would progress in a gradual manner (5).
All of this leads me to believe that there is definitely a connection between the sleep state and the hypnotic state. When integrating the relationship between the waking state, the hypnotic state and the sleep state, it seems that the they fall nicely into a progressive pattern of consciousness; the waking state being defined as the highest level of consciousness while the sleep state is defined by the least level of consciousness. Though there has been disagreement over this continuum pattern of consciousness, it is supported by the fact that there is a transitional period between the waking state and the sleep state that mimics the hypnotic state (11).
Assuming we are correct that the hypnotic state is a unique state related to other forms of consciousness, the question that follows is what exactly is this state? It has been suggested that in order to have a comprehensive understanding of hypnosis, it is necessary to study its relationships with multiple models and theories including neuroscience, cognitive science, psycho-social development, language, creative language and philosophical issues relevant to mankind (7). Numerous theories have attempted to come up with a plausible explanation, yet none have achieved a "comprehensive understanding of hypnosis." Two main categories include: psychological theories, like the suggestibility theory and the role-playing theory that emphasize the motivation and expectation of the patient, while physiological theories like the sleep hypothesis, emphasize the neural and organic processes involved in hypnosis. The role-playing theory proposed that the patient is acting the role of a hypnotized subject while really in a conscious state. The suggestibility theory proposes that hypnosis is goal-directed state that is at a more unconscious level than role-playing (2).
While both of these theories are capable of encompassing some hypnotic phenomenon, currently, the theory that best accounts for the various aspects of the hypnotic state is Ernest Hilgard's Neodissociation Theory. This theory proposes that there are multiple levels of awareness that can become dissociated from one another. Evidence for this theory comes from a phenomenon called the "hidden observer." These patients were able to report different experiences at different levels of awareness. For example, a patient that is under hypnotic suggestion for anesthesia reported feeling no pain at one level, estimated an appropriate level of pain at another level and had no awareness of the hidden observer or pain at the conscious level (4). This hidden observer phenomenon was not observed in all patients. It would be interesting to see if patients capable of this phenomenon had a higher than normal hypnotizibility than most patients; this could lend support to the fact that dissociation is the underlying mechanism for hypnosis. The idea of dissociation poses many other new questions as well- like what functions are being split, what prompts these splits to occur and is it possible that these splits can relate to other phenomenon like multiple personality disorder (6)?
In some of the literature, this split has been described as a splitting of consciousness into different streams or the splitting of the subconscious from the conscious mind (1,8). Splitting between the subconscious and the conscious mind allows for the subconscious to respond more easily to suggestion and imagery. In this state, the subconscious is also more free to focus on what one's self wants to change. The relaxed environment associated with hypnosis facilitates this by separating the mind from everyday concerns (8). The idea that consciousness itself is split also incorporates this notion of increased suggestibility due to dissociation; in this case, it is thought that hypnosis weakens areas in charge of controlling behavior and therefore allows behavior to be induced from external suggestion (1). Either scheme coincides with what is already known about hypnosis because both state that the patient is conscious, yet acknowledges that this consciousness is distinctly different than normal consciousness. Both schemes are also able to account for the fact that patients experience hypersuggestibility during hypnosis. In the case of the splitting from the subconscious from the conscious, the scheme also explains why self-hypnosis is feasible; the self-conscious is capable of directing itself without the help of the hypnotist.
The main result of this increased ability to respond to suggestion is the utilization of hypnosis in a wide range of therapeutic activities. Hypnosis is supposedly capable of altering memory, perception and physiological aspects; case studies have shown that hypnosis can act as anesthesia during surgery, can reduce blood clotting, and can alleviate nausea and breathing problems (4). Its use is also suggested for overcoming addictions, phobias and obsessions (5). Interestingly, experiments show that hypersuggestivity is not linked solely to hypnosis. One hypothesis is that hypersuggestivity is also influenced by the immune system (6). This could provide for a reason for the supposed healing powers of hypnosis.
Perhaps even more important than the medical benefits offered by the hypersuggestive state of hypnosis, is the scientific benefits offered by understanding such a complex and variable phenomenon. The early research into hypnosis focused on and illustrated the existence of a hypnotic state and that it could have physical effects (6). Although these assertions have become fairly well accepted, there is a lot about hypnosis that is still being debated and researched. I have become convinced that hypnosis is indeed a form of consciousness that is distinct from the sleeping and waking state. Even in exploring this one assertion, there seems to be ample amount of detail that is not known. Hypnotism's relationship to consciousness and hypersuggestivity make it relevant to many other interesting phenomena like multiple personality disorder and sleep. Personally, I think it is this complex web of connections with other phenomena that is the most fascinating, unexpected and promising characteristic of hypnosis.
2) An Attempt to Define Hypnosis, Hynotherapy, and Curative Hypnotherapy According to Current Evidence. , An overview of theories associated with hypnosis.
3) The Neurophysiology of Hypnosis- Tables. , Differences between waking state, sleep state and hypnotic state.
4) Go Inside: The Reality of Hypnosis. , An overview of hypnosis and its possible uses.
5) Hypnosis. , A paper with a very general look at hypnosis.
6) Hypnosis.com: Frequently Asked Questions. , A discussion about dissociation and suggestibility.
7) Hypnosis.com: Frequently Asked Questions 1. , A discussion about history and existence of hypnosis.
8) Hypnosis In the UK. , A brief description of hypnosis and its history.
9) Induction of Altered States: Going to Sleep, Hypnosis and Meditation. , A discussion about how altered states of consciousness arise.
10) What is Hypnosis? , Another overview of hypnotic phenomenon.
11) How Hypnotism Should be Used for Medical Purposes. The implications of hypnosis