From the 1950s to the 1980s, many sleep researchers believed that virtually all of our dreaming occurs during REM sleep. Because of this mistaken belief and because brain activity during REM sleep looks very similar to that seen during the waking state, sleep researchers were particularly interested in understanding its causes, as well as what happens in the brain and mind during REM sleep.
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 makes up about 20% of the sleep period, it seems likely that it has some very important functions. In order to discover these functions, some early researchers deprived people of REM sleep over several nights in order to see what would happen (Dement, 1960; Dement & Kleitman, 1957).
In selective sleep-deprivation studies, sleep researchers deprive participants of either REM sleep or SW sleep, but allow them get a full night’s sleep otherwise. The rationale for this is that, by depriving people of a particular stage of sleep, the functions of that stage will be revealed by looking for impairments in biological and/or psychological processes. Participants in REM-deprivation studies were deprived of REM sleep for 4-5 nights in a row. In general, researchers observed the following three changes (although not all participants experienced them):
- Participants entered REM more and more frequently the longer they were deprived of it.
- Participants felt unrested and often had difficulty concentrating during the day.
- 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.
Theories of REM Sleep & Dreaming
Activation-synthesis theory. Over the years, several theories have been developed to try to explain why we spend so much time in REM. However, there is little evidence for any of them. Perhaps the most influential has been the activation-synthesis theory proposed by J. Allan Hobson and Robert McCarley (Hobson, 1988; Hobson & McCarley, 1077), which states that the activation of the brain during REM sleep has two functions:
- the development of new connections between parts of the brain;
- the maintenance of existing connections between parts of the brain.
The brain stem becomes very active during REM sleep and this activity “wakes up” many other areas of the brain, especially the cerebral cortex, which is associated with perception, language, and higher-level thought processes. Hobson and McCarley (1977) speculated that this activation is important for the preservation of both new and old connections in the brain (e.g., 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 (1977) concluded that dreams occur because of widespread brain activation that affects areas important for perception (seeing, hearing, feeling, etc.) and movement. This activity causes us to “hallucinate”: we are convinced that we actually are experiencing the external world. One possible problem with this idea is that dreaming also occurs during NREM sleep, although some evidence suggests that dreams in REM sleep differ from those in NREM sleep. A more important problem is that there still is not adequate evidence in support of the theory. Current research on REM sleep and the brain has been influenced strongly by the activation-synthesis theory: most researchers now assume that REM sleep is important for the development and maintenance of the brain and its connections (Hobson, 2009).
Psychoanalytic theory. 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 (Ellenberger, 1970; Freud, 1917; Macmillan, 1997).
Freud wanted to understand the development of personality, especially the development of abnormal personality. He believed that everything we did was the outcome of various desires and wishes (motives) that conflict with one another. For example, I would bet that, right now, you’re 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 doesn’t require as much mental effort. 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 go 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 decided not to read this section at all, and never plan to. So, out of this identical conflict, different behaviors, emotions, and thoughts arise in each person. These differences among individuals in how conflicts are resolved indicate personality differences.
For Freud, the most important conflicts occur at the unconscious level. Freud claimed that some conflicts upset us so much that we move them into the unconscious — a process known as repression. By doing this, we no longer are aware of them. For example, Freud stated that beginning at about the age of three years, we 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 (Freud, 1900). These feelings, he said, come into conflict with other motives, such as our desire to be loved by our parents, which conflicts with the agressive feelings we have for the same-sexed parent. Furthermore, he said, we eventually become aware of societal standards of behavior that prohibit such feelings towards parents. The result is that we become very distressed about our desires. Because of this distress, Freud argued, we repress this conflict by about six years of age: we push the secret and forbidden desires into our unconscious.
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 (Freud, 1900). When you are awake, you sometimes fantasize because it can be fun; and these waking fantasies may satisfy, to varying extents, a conscious wish or desire. You may daydream, for example, about being a rich and famous person. For Freud, dreams are fantasies of this kind —fantasies that partially satisfy our unconscious wishes and desires. The problem, however, is that, even during sleep, we don’t want to become aware of these illicit desires because they still would upset us.
We don’t dream about our repressed desires directly, therefore, we dream about something that represents these desires. In other words, according to Freud, the unconscious desires are transformed into dream images that symbolize what they mean to us. For example, if a man’s dream involves his sexual desires for 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 (who symbolizes his mother) and then getting into a fight with the principal (who symbolizes his father). In this way, Freud argued, the man can satisfy to some extent his repressed desires while remaining unaware that he is doing so. If we start to become aware of the actual meaning of the dream, Freud claimed that the dream then turns into a nightmare, which causes us to wake up before we become fully aware of what the dream really means.
You now should be able to see that, for Freud, dreams have two levels:
- The latent content. A dream’s latent content is the set of unconscious motives (desires) that underlie the dream — the ones that we don’t want to become aware of (the word latent means hidden). In other words, the latent content is the set of repressed desires that represents the true meaning of the dream. In our example, the man is dreaming about his Oedipal desires and wishes, although he doesn’t know it.
- The manifest content. A dream’s manifest content is the narrative (the storyline or plot) of the dream. It is what you tell another person when you describe a dream (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 his therapeutic sessions, Freud listened to the manifest content of his patients’ dreams and then interpreted them in terms of their latent content. By interpreting the dream’s narrative in terms of the unconscious desires underlying the dream, Freud tried to make his patients aware of the repressed conflicts that he believed were motivating the patient’s abnormal behaviors.
Is Freud’s theory of dreaming a good one? Over the years, this theory has been criticized by many psychologists, psychiatrists, and others (for criticisms of this and other psychoanalytic theories, see: Dufresne, 2003; Dufresne, 2007; Esterson, 1993; Macmillan, 1997). 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 is that, if Freud’s theory is true, people might spend more time dreaming when their unconscious conflicts are activated. For example, when a parent dies, we might expect that this would activate Oedipal desires, and that this activation might cause them to spend more time dreaming. It seems, however, that this doesn’t occur: people dream about the same amount each and every night regardless of what is happening in their lives.
Furthermore, as described in the previous section, there is some evidence that other animals dream. For example, you may have noticed that dogs sometimes 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 finds so upsetting that it would need to repress them. Of course, dreaming in dogs and other animals may have other causes, just as some dreaming in humans might have 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.
The biggest problem with Freud’s theory, however, is that it is just too difficult to test (Cioffi, 1998): researchers cannot observe unconscious desires directly and, therefore, there is no way to check whether a therapist’s interpretation of a dream is 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.
If you ever wondered what Sigmund Freud sounded like, you can listen here to a brief recording he made in 1938, less than a year before he died.
REM Sleep Behavior Disorder
In a previous section, you learned about sleep paralysis, which usually occurs when someone … REM Sleep Behavior Disorder (RBD) …. [STUDENTS, WHEN STUDYING, PLEASE USE THE DISCUSSION OF REM SLEEP BEHAVIOR DISORDER PROVIDED IN CLASS.] apparently is caused by abnormal activity in the area of the brain that paralyzes the muscles during REM sleep (Ferini-Strambi, et al., 2005; Schenck & Mahowald, 2002). Although these behaviors look very similar to sleepwalking, they are not the same: sleepwalking occurs during SW sleep and, therefore, is not associated with dreaming (there is little or no dreaming during Stages 3 and 4). Anch, Browman, Mitler, and Walsh (1988) described one case of RBD:
A 54-year-old businessman and church leader has been complaining of mild dizziness and headaches for 7 days. At 3:30 a.m., his wife is awakened from a sound sleep by his mumbling long tirades of horrid profanities. The man then sits up in bed with his eyes open, but not seeming to be focused on anything in the room. He clumsily hits at his wife three times, striking her only once in the face. He then lies down and returns to peaceful sleep. Similar events occur again at 5:00 a.m. During the following day, he is surprised to hear of his nocturnal behavior and shows no impairment in his waking activity. However, he begins to exhibit profane vocalizations and violent actions 3-4 times each night. (p. 87)
Another man tried to hit his wife while he was sleeping, and when he woke up, said that he had been dreaming about an argument with a coworker…..FINISH SECTION [PSY 101 STUDENTS: The “FINISH SECTION’ comment is just a note to myself to finish the RBD. Everything else I want you to learn already is in the reading. In future sections, whenever you see a capitalized comment, it is just a note to myself–a note you usually don’t need to worry about.]
Narcolepsy is another sleep disorder that involves REM sleep. It occurs when an individual is in both a waking state and a REM state….. FINISH
Here is a short video that shows narcolepsy in Doberman Pinschers:
Study Questions for Section 2-12
- What is a selective sleep-deprivation study?
- What is a REM-deprivation study?
- What happens to people who are selectively deprived of REM sleep for several nights in a row?
- What happens to REM-deprived subjects when they finally are allowed to sleep undisturbed?
- What is the main claim of the activation-synthesis theory of REM sleep?
- What are some important difficulties for the activation-synthesis theory of REM sleep?
- What is the main claim of the psychoanalytic theory of dreaming?
- What role did the concept of “wish fulfillment” have in Freud’s theory of dreaming?
- 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.
- What are some important difficulties for the psychoanalytic theory of dreaming?
- What is REM Sleep Behavior Disorder (RBD)?
- How are RBD and sleepwalking similar to and different from each other?
Practice Quiz for Section 2-12
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