From the 1950s to the 1980s, many sleep researchers believed that virtually all of our dreaming occurs during REM sleep. Because of this belief (which isn't true: dreaming also occurs frequently during light sleep) and because brain activity during REM sleep looks very similar to the waking state, sleep researchers since the 1950s have been particularly interested in understanding what is happening during REM and what causes it. Adults spend about one to two hours per night in REM sleep (which, if we live 75 years, equals over 40,000 hours of our lives — almost five years). Given that REM sleep takes up about 20% of the sleep period, it seems reasonable to infer that it has some some very important functions. In order to discover possible functions of REM sleep, some early work involved depriving people of REM sleep over several nights in order to see what would happen.

In selective sleep-deprivation studies, early sleep researchers deprived participants of either REM sleep or SW sleep, while otherwise letting them get a full night’s sleep. They predicted that, by depriving participants of a particular stage of sleep, the purposes of that stage would be revealed through particular impairments in biological and/or psychological functioning. In this section, we are concerned with REM-deprivation studies, in which participants were awakened each time they entered REM sleep but otherwise were allowed to get a full night's sleep. Participants usually were deprived of REM sleep for 4-5 nights in a row. In general, researchers observed the following changes (although not all participants experienced them):

(a) Participants entered REM more and more frequently the longer they were deprived of it.
(b) Participants felt unrested and often had difficulty concentrating during the day.
(c) When finally allowed to sleep undisturbed through the night, participants often exhibited a REM-rebound effect, in which the amount of REM showed a significant increase for 1-2 nights.

The REM-rebound effect, in particular, suggested to researchers that REM sleep must have important functions: the body seems to work hard to make up for REM deficits. Nevertheless, as with total sleep-deprivation studies, no drastic changes were reported for any specific mental or biological process. For example, people deprived of REM for several nights in a row did not become psychotic.

Over the years, several theories were developed to try to explain why we spend so much time in REM. Nevertheless, there is little evidence for any of them. Perhaps the most influential has been the activation-synthesis theory of J. Allan Hobson and Robert McCarley (Hobson, 1988). The activation-synthesis theory is based on the finding that, during REM sleep, the brain stem becomes very active — activity that “wakes up” large areas of the rest of the brain. Hobson and McCarley speculated that the brain needs to be activated several times during the night to help in the development and maintenance of connections in the brain (for example, those connections that develop when we learn something new). They also believed (incorrectly, as already stated) that dreaming occurs only during REM. Thus, Hobson and McCarley explained dreams as being the result of the widespread brain activation that occurs during REM sleep: areas of the brain involved in seeing, hearing, and feeling the world become active due to activity in the brain stem. This activity, according to Hobson and McCarley, then causes us to, in a sense, “hallucinate” so that we think we are seeing, hearing, and feeling the outside world even though we are not. The problem with this idea, as we saw earlier, is that dreaming also occurs during NREM sleep. Thus, even if this theory is correct about the causes of REM dreaming (and there is little evidence at this point that it is), the theory still cannot explain the occurrence of dreams during NREM sleep when many areas in the brain are less active.

Another theory of dreaming that was very influential in psychiatry, psychology, and the wider American culture during much of the twentieth century was developed by Sigmund Freud. From about 1895 until his death in 1939, Freud developed a set of ideas and therapeutic practices known as psychoanalysis — an approach that assumes that human behaviors, thoughts, and emotions are caused by unconscious conflicts among competing motives.

Freud wanted to understand the development of personality, especially the development of abnormalities of personality. He believed that everything we did was the outcome of various desires and wishes (motives) in conflict with one another. For example, I would bet that, right now, you are experiencing conflicting desires: a part of you wants to read this section carefully so that you can understand it better, and another part of you would like to be doing something else that is more fun. You are experiencing conflict. The outcome of this conflict will be different for each of you, however. Some of you will race through this section so that you can then go on and do other things. Some of you will force yourselves to concentrate on the material anyway and continue to read it carefully. Others of you have already looked away and are no longer reading this. And still others of you never opened this file in the first place, and don’t ever plan to. So, out of this identical conflict, different behaviors, emotions, and thoughts arise in each person. These individual differences in how conflicts are resolved indicate personality differences.

For Freud, the most important conflicts between motives occur at the unconscious level. These are conflicts of which we do not want to be aware because we are trying to forget them: they upset us too much. Therefore, according to Freud, we push them into the unconscious level where they can remain hidden from our awareness (a process known as repression). For example, Freud claimed that all of us, beginning at about the age of three years, develop strong sexual feelings for our opposite-sexed parent (boys for their mothers and girls for their fathers) and aggressive feelings for our same-sexed parent (boys for their fathers and girls for their mothers). He called this the Oedipus Complex. These feelings, he said, come into conflict with other motives, such as our desire to be loved by the parent towards whom we are feeling aggression. Furthermore, we eventually become aware of societal standards of behavior that prohibit such feelings towards our parents. The result is that we become very distressed about experiencing these desires. Because of our distress, Freud claimed, by about six years of age we repress this conflict: we push the illicit (secret and forbidden) desires into our unconscious. In this way, we become unaware of them and, hence, they no longer can upset us consciously.

What do such unconscious conflicts have to do with dreaming? Freud argued that a major function of dreams is wish fulfillment: he believed that dreams allow us to partially satisfy our desires through fantasy. When you are awake, you sometimes fantasize because it can be fun, and these waking fantasies can satisfy to some extent a conscious wish or desire. You may daydream, for example, about being a rich and famous person, and this daydream will satisfy your desire to some extent. For Freud, dreams were fantasies of this kind: dreams partially satisfy unconscious wishes and desires. The problem, however, is that, even during sleep, we don’t want to be completely aware of our unconscious desires because they still upset us.

Freud said that, because of this, we don’t dream directly about our repressed desires. Instead, we dream about something that symbolizes these desires for us — we transform the repressed desires into something else that represents them in a way that, at the conscious level, we won't recognize. For example, if a man’s dream involves his Oedipal desires to have sex with his mother (assuming, for now, that men actually have such desires), he may dream about going out on a date with his third-grade teacher from forty years before (symbolizing his mother) and getting into a fight with the principal (symbolizing his father) who was dining at the same restaurant. In this manner, Freud claimed, the man can satisfy to some extent his repressed motives while remaining unaware that he is doing so. Freud stated that nightmares are dreams in which we are in danger of becoming aware of our repressed desires. When the actual desire threatens to break into conscious awareness, we become terrified and wake up.

In his theory of dreaming, Freud distinguished two levels of the dream:

(a) The latent content of the dream is the actual set of unconscious motives (desires) — the ones which we don't want to become aware of (the word latent means hidden). In other words, the latent content is the set of unconscious desires that represents the true meaning of the dream. In our example, the man is dreaming about his Oedipal desires and wishes towards his parents even though he doesn’t know it.
(b) The manifest content of a dream is the actual narrative (story line) of a dream — it is what you tell another person when you describe the dream you had (the word manifest means expressed directly or observed). In our example, the man dreamed about taking his third-grade teacher on a date and getting into a fight with his principal.

In therapy, Freud would listen to the manifest content of his patients' dreams and then interpret them in terms of their latent content. By interpreting “what was expressed ” (the manifest content) in terms of “what was hidden” (the latent content), Freud tried to make his patients aware of the unconscious desires that he believed were motivating the patient’s mental problems.

Is Freud’s theory of dreaming a good one? Over the years, it has been criticized severely by many psychologists, psychiatrists, and others. Its biggest problem is that much of the research designed to test the theory does not support it. What sorts of predictions might be dreived from Freud’s theory? One possibility is that, if Freud's theory is true, people should dream more when their unconscious conflicts are activated. For example, with regard to the Oedipal Complex, perhaps people will dream about it more when a parent dies, or when their parents divorce, and so on. But we find that these predicted observations don’t occur. It seems that people dream about the same amount each and every night: about 85% of the time in REM, about 50% of the time in Stage 1, and about 10% of the time in Stage 2.

Furthermore, as described in the previous section, there is some evidence that other animals dream. For example, you may have noticed that dogs can bark and look quite agitated while sleeping. If Freud's theory is true — if dreaming is caused by the need to express repressed desires in a hidden form — one might wonder what kinds of desires a dog may find so upsetting that it would need to repress them. Of course, dreaming in dogs and other animals may be due to other causes, just as some dreaming in humans might be due to other causes; but the existence of dreaming in animals suggests that Freud's theory is, at least, not complete, and that one might even be deceived by interpretations of dreams that focus primarily on repressed desires.

Probably the biggest problem with Freud’s theory is that it is just too difficult to test: we have no direct access to the unconscious desires that are thought to be the wellsprings of the dream. Because we have no direct access to these desires, there is no way to check whether a therapist's interpretation of a dream is actually correct. This fact coupled with the fact that therapists with different backgrounds will give very different interpretations of the same dream suggests that we need to be cautious of any theory that attributes dreaming to the expression of something in the unconscious. Thus, although variants of Freud’s theory of dreaming are still very popular among many therapists, most scientific researchers studying dreaming find his theory to be of historical interest only.

Study Questions for Section 2-12

1. What is a selective sleep-deprivation study?
2. What is a REM-deprivation study?
3. What happens to people who are selectively deprived of REM sleep for several nights in a row?
4. What happens to REM-deprived subjects when they finally are allowed to sleep undisturbed?
5. What is the main claim of the activation-synthesis theory of REM sleep?
6. What are some important difficulties for the activation-synthesis theory of REM sleep?
7. What is the main claim of the psychoanalytic theory of dreaming?
8. What role did the concept of "wish fulfillment" have in Freud's theory of dreaming?
9. How would you define the terms "latent content" and "manifest content" in your own words? Try to apply these terms to one of your dreams or to one of the dreams of someone you know.
10. What are some important difficulties for the psychoanalytic theory of dreaming?

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