26 Consciousness and Sleep

In the 1968 Stanley Kubrick movie 2001: A Space Odyssey, we are treated to a view of the possible evolution of computer thought. One of the real stars of the movie is HAL-9000, a computer that has more personality than the astronauts on the spaceship HAL controls. HAL has emotions and is intelligent and seemingly aware of itself and of other people. In short, HAL-9000 is conscious, or at least seems to be. But HAL is a character in a story taking place in 2001. It is now 2020, and real computers, able to perform 400 quadrillion operations per second (that is 400,000,000,000,000,000), probably far outstrip the fictional HAL in terms of sheer computing power. These computers can also outperform humans in a great many areas. Supercomputers are used to accurately simulate climate and weather, combine data from around the world to help simulate possible outcomes and develop vaccines and treatments for COVID-19 and other diseases, and play chess (and Jeopardy) at above world-championship level. Still, however, no one is even close to programming a computer to make it conscious.

Of course you know that you are conscious. But what does that mean? The ultimate challenge for a science of the mind may be to figure out what consciousness is. Throughout history, the concept of consciousness has been explained in terms of mystery, wonder, religion, and even weirdness. Inside and especially outside of psychology, you will discover that people have different, sometimes very different, definitions for it. For a scientist, consciousness may be an even harder concept to define than emotion is (see Module 20).

Nevertheless, section 26.1 proposes a working definition. Once we agree on a definition, we can begin to understand some of the psychological principles that underlie consciousness. The later sections, then, turn to some of the changes in consciousness that we can experience. Section 26.2 is about the sometimes mysterious state of consciousness called hypnosis. Sleep and dreaming, as complex, interesting, and important phenomena related to consciousness, deserve a bit more coverage. Section 26.3 describes a lot of our scientific knowledge about sleep and dreams, and section 26.4 covers the most important practical fact about sleep (that most adults do not get enough).

26.1 Consciousness

26.2 Hypnosis

26.3 Sleep and dreaming

26.4 Sleep deprivation

READING WITH A PURPOSE

Remember and Understand

By reading and studying Module 26, you should be able to remember and describe:

• Consciousness and attention, working memory, and explicit memory (26.1)
• Hypnosis (26.2)
• Functions of sleep (26.3)
• Circadian rhythms: suprachiasmatic nucleus (26.3)
• Sleep stages (26.3)
• Sigmund Freud’s views on dreams (26.3)
• Modern dream interpretation (26.3)
• Dream contents (26.3)
• Activation-synthesis theory of dreaming (26.3)
• Neurocognitive model of dreaming (26.3)
• Effects of sleep deprivation (26.4)
• Sleep Hygiene (26.4)

Apply

By reading and thinking about how the concepts in Module 26 apply to real life, you should be able to:

• Recognize parallels between dream content and waking cognition (26.3)

Analyze, Evaluate, and Create

By reading and thinking about Module 26, participating in classroom activities, and completing out-of-class assignments, you should be able to:

• Identify problems in your life that might be a consequence of sleep deprivation (26.4)
• If you are sleep deprived, explain what might prevent you from increasing the amount of sleep that you get (26.4)

 26.1. Consciousness

Philosophers have been interested in consciousness for hundreds of years. The most famous and important philosophical debate about it has been whether the mind (the source of consciousness) is separate from the body, a viewpoint called dualism, or whether it is part of the body, a viewpoint called monism. René Descartes (1637/1931; 1641) was the most famous philosopher to argue the dualist viewpoint. The body, being essentially mechanical, must obey the laws of physics. The mind, or consciousness, according to dualists, is not a part of the body, and it is not a physical entity. Therefore, it does not obey the laws of physics, and any attempt to understand it using the same principles through which we understand physical systems will fail. Dualists often, although not necessarily, equate the mind with the soul, the essence of an individual that continues to exist after the body has died. In contrast, Thomas Hobbes, a contemporary of Descartes, championed the monist viewpoint. Monists contend that mind is simply part of the body, that there is no separation. As Hobbes (1650) put it, thinking is motion within the brain.

Today, after more than 350 years of debate, most neuroscientists agree with Hobbes (Crick, 1994). Neuroscientists largely agree that consciousness must be a result of brain activity, but who knows what activity? The problem is that no one has made great progress in figuring out exactly what consciousness is.The last great intellectual quest of Francis Crick, the Nobel prize winning biologist who co-discovered the structure of DNA with James Watson, was to try to understand consciousness. He ended up scaling back his goals considerably, settling for outlining a blueprint for how to examine consciousness and proposing a model of how one portion of consciousness, awareness of a visual scene, might be realized in the brain (Crick, 1994; Koch & Crick, 2000).

A Definition of Consciousness

In everyday conversation, we tend to use the word consciousness to describe a state that a person is in. In other words, an individual is either conscious or unconscious, corresponding roughly to whether he or she is awake or asleep (or knocked out, in a coma, or something similar). This seems like a reasonable approach, but it does not take us very far. Consider wakefulness versus sleep. What is it about being awake that means you are conscious and about being asleep that means you are unconscious? Our brains are extremely active during both. You might propose that when you are awake you are aware of the external environment and that when you are asleep you are not. Even that will not work, however. At any given moment, awake or asleep, you are aware of some aspects of the environment and not aware of others. People can be unaware of things going on right in front of their eyes while awake. And even while asleep, you maintain enough awareness of the outside world that you do not fall out of bed.

As confusing as these examples seem, they may help us to solve the problem of defining consciousness. Instead of thinking about consciousness as a state that describes a whole person, we can think of consciousness as a rough synonym for awareness. Whether we are awake or asleep, we are aware of something at all times. In other words, we are always conscious of something. We may be conscious, or aware, of stimuli from the outside world, of our own thoughts and feelings, and of our selves (Schacter, 2000).

We are making a little bit of progress. Using the term “awareness” in place of the more unwieldy “consciousness” helps, and we are in agreement that this awareness resides solely in the physical brain, but it doesn’t really tell us where this state of mind or how it arises. Attention, working memory, and explicit memory are involved, but it is not clear how central to consciousness they are (Koch & Crick, 2000). Many processes and brain areas are involved in creating consciousness. One key idea is that the sharing or exchange of information across different brain areas is important. Dehaene & Changeux,(2011) proposed that awareness arises through the sharing of information among the prefrontal cortex, parietal, and occipital lobes, for example. You may recall that the hippocampus is a brain area that is involved in explicit memory (memory with a conscious “I recall” feeling), but not implicit memory. It may be that this consciousness is a byproduct of the connections that the hippocampus has with multiple brain areas, again allowing that exchange of information.

You might also recall that in Module 4, we defined working memory is the current contents of consciousness—in other words, what you are thinking about, or aware of, at the current moment. It is a simple-seeming idea, but a great many brain areas are involved. Networks connecting areas of the frontal lobes to parietal lobes, the prefrontal cortex, and areas in the temporal lobes all seem to be important for working memory. (Chai et al., 2018). Our descriptions here might also remind you of Attention from Module 13, particularly the process of selective attention, choosing which element you are experiencing to focus on and which to filter out. It turns out that attention, too, involves multiple cortical areas throughout the separate lobes (as well as some sub-cortical areas; Lindsay, 2020).

To summarize, the first key idea is sharing information across multiple areas. A second key idea that appears throughout these different descriptions is control. We select in attention, we move information into working memory, we search memory to retrieve from explicit memory. Many researchers refer to executive control as an essential process to allow consciousness to exist. The key area that is most important for executive control is the prefrontal cortex. So although as we have been emphasizing, multiple brain areas contribute, the prefrontal cortex is a possible candidate for “consciousness center” because of its role in executive control (Chai et al., 2018; Koch & Crick, 2000; Lindsay, 2020).

26.2. Hypnosis

Many people inside and outside of psychology refer to hypnosis as an “altered state of consciousness” (Yapko, 1995). This characterization makes hypnosis sound quite mysterious. We once got our hands on a book that promised to teach us, “How to secretly hypnotize anyone.” (As a special bonus, it came with “How to secretly read anyone’s mind,” at no additional cost.) The ad for the books, in the back of a comic book if we remember correctly, promised that it would teach how to secretly control friend and foe alike. Hey, for only ten dollars, what do you have to lose? Ten dollars, as it turns out. Apparently, the secret to both secret mind-reading and secret hypnosis was to secretly “join minds” with your unaware subject. Secretly. Unfortunately, the books secretly forgot to explain how one was supposed to accomplish the “mind-joining.”

Perhaps hypnosis is the only legitimate topic in psychology that could be touted in the same advertisement as a mind-reading book. It has an interesting fictional and real history that makes it seem almost magical. The concept of hypnosis has been associated with evil and with the supernatural, as in the creepy stare that Bela Lugosi’s Dracula used to subdue his victims and in the 1960 B-rated horror movie The Hypnotic Eye, in which a stage hypnotist places attractive women in hypnotic trances so that his psychopathic assistant can attack and disfigure them (at long last, we have recently discovered that this movie is available to stream legally if you are interested). Movies have also depicted hypnosis as a tool to allow people to relive past lives, something that has been claimed in the real world, too. When not evil or supernatural, hypnosis is still often presented as bizarre, a fact you can verify by attending a stage hypnotist’s performance. You may not see someone cluck like a chicken, but you will walk out shaking your head and thinking, “How did the hypnotist get those people to do that?”

Given these popular images of hypnosis, it is easy to overlook the fact that hypnosis is a tool used by some legitimate and competent psychotherapists. The common view in psychology is that it is very likely real but is widely misunderstood. We have a pretty good idea what you can accomplish with hypnosis. It can be used to control pain, manage stress and anxiety, and help clients in psychotherapies change behavior (Yapko, 1995). And yes, for entertainment purposes, a stage hypnotist can probably lead many people to cluck like a chicken. We also have a pretty good idea what hypnosis is not: It is not a mysterious window to past lives or the hidden unconscious of Freudian psychoanalysis. It is not a tool to help uncover hidden or repressed memories, as it is more likely to trigger false memories than uncover genuine ones (Spanos, 1996). It is probably not even an altered state of consciousness, at least not any more than watching television is.

We are not so clear about what hypnosis is, however. Consider this observation: In PsycInfo, the American Psychological Association database of research in psychology, there were 13,862 listings under the subject heading “Hypnosis” in summer 2020. Only 736 of those also used the subject heading “Theories,” and many of these articles are theories of other phenomena that use hypnosis as part of the explanation. In other words, we do not have much less to say when it comes to a theoretical explanation of what hypnosis is.

We like to think of hypnosis as a somewhat extreme version of two common phenomena. First, at all times, we focus our attention on some stimuli and block out others, a phenomenon we referred to as selective attention earlier. Second, individuals very commonly comply with requests, orders, or suggestions from other people; in other words, they are obedient or readily persuaded (Module 21). Hypnosis is simply a method that enables one person (the hypnotized subject) to focus his or her attention on another individual (the hypnotist) or on stimuli that the hypnotist emphasizes. The hypnotist then gives suggestions with which the hypnotized subject is likely to comply. Both of these phenomena, our ability to selectively attend and our suggestibility, are quite ordinary. For example, have you ever been so involved in a conversation that you walked right past your destination? This is essentially the same phenomenon as a common experience under hypnosis, a subject’s failure to see an object that should be in plain view. And in 2019, the advertising industry spent 247 billion dollars in the United States alone, counting on people’s tendency to comply with suggestions (Guttmann, 2019).

One last way to show that there is nothing magical about hypnosis is to point out that everything we know can be accomplished with hypnosis—including controlling pain, managing stress and anxiety, helping psychotherapy clients change their behavior, and even clucking like a chicken—can be accomplished without it. For example, if you ask people to pretend that they are hypnotized, you can get them to do just about any behavior that a genuinely hypnotized subject will do (Barber, 1979; Orne & Evans, 1965; Spanos, 1996). In addition, more than 40 years of research has demonstrated that many of the therapeutic benefits achieved with hypnosis can be achieved equally well without it (Barber & Hahn, 1962; Hyman et al. 1986; Lang, 1969; Spanos, 1991; Spanos et al. 1994).

When you are sleeping, you have a fairly dramatic shift in your awareness or consciousness. In essence, you cannot pay attention while sleeping, so there is something very different about being asleep and being awake. Still, I would not want to refer to sleeping as being unconscious, because you are certainly aware of something. For example, you are aware enough of your surroundings that you can be easily awakened at various points throughout the night (although it is quite difficult at other times), and most adults rarely if ever fall out of bed. More notably, perhaps, we become aware of an entire new world several times every night, the world of our dreams. Thus it is reasonable to think about sleep as a large change in your consciousness but not as a shift into unconsciousness.

Although researchers have been making great progress over the past few decades in figuring out what sleep is and why we sleep, there is much that we still do not know. Sleep is a puzzle. However, it does seem to be extraordinarily important biologically. Think about it. All animals spend a portion of the day or night relatively motionless and completely defenseless. Any predator that can figure out where an animal typically sleeps would have an easy meal just ready for the taking. There must be an enormous biological benefit to sleep to offset that kind of risk.

Most people probably think that we sleep in order to rest, but there is much more to it than that. After all, simply slowing our activity down to a level that is less than usual provides our bodies with rest. The unique benefit of sleep seems to be that it helps us to rebuild and restore the body. For example, we store energy in our brains while we sleep. Glycogen, a substance that we derive from food, is the main source of energy throughout the body. The longer we stay awake, the lower the levels of glycogen in the brain. When we sleep, the supply of glycogen in the brain is replenished (Kong et al., 2002). Sleeping also helps us to boost our immune system (Everson, 1993; Rechtschaffen et al., 1983; Bryant, Trinder, & Curtis, 2004). And while we sleep our pituitary gland releases growth hormone, important for both growth and repair and maintenance throughout the body (see 11.3).

Circadian Rhythms and the Biological Clock

As you know from your own experience, we have biological patterns of activity throughout the 24-hour day, which are known as circadian rhythms. At night, while we are sleeping (typically), all physiological activity is slowed: Heart rate and breathing are slow, brain activity is slow, body temperature is reduced. As morning approaches, these systems begin to speed up, peaking often in the early afternoon. Many people experience a slight dip in energy before things pick up again heading into the evening. In the late evening, the body systems start slowing down again until reaching their lowest point again, about 24 hours after the start of the cycle.

Circadian rhythms and the sleep-wake pattern are guided by a tiny section of the hypothalamus called the suprachiasmatic nucleus, which could be considered our “biological clock.” Although the basic circadian rhythm is produced inside of the body, the biological clock uses light from the outside world to fine-tune it to correspond to the 24-hour day. Basically, light hitting the retina leads the biological clock to send signals that cause the pineal gland—another gland located in the brain—to release the hormone melatonin. After a while, accumulations of this hormone make us sleepy.Sec9.3The fine-tuning occurs as a result of naturally occurring light, making our circadian rhythms last a few minutes longer than 24 hours. The electric lights to which we are exposed every day have an additional effect, making our actual circadian rhythms last around 25 hours (Czeisler et al., 1999).

If you use the right amounts of light at the right times, you can reset the biological clock to make an individual sleepy or awake at just about any time you want (Shanahan, Zeitzer, & Czeisler, 1997). If you expose people to light early in the evening, it delays the biological clock, making them stay awake later. Light in the early hours of the morning, say 3:00 am, sets the biological clock earlier, making it easier to wake up in the morning. An alarm clock that turned on the lights in the middle of the night might be quite effective at helping people wake up more easily in the morning. If you decide to invent such an alarm clock and grow rich doing so, remember where you got the idea.

One last interesting point about the biological clock and light: Researchers have discovered that light hitting other areas of the body can also reset the biological clock. In one study, the researchers shined bright lights on the back of participants’ knees for three hours a day and shifted their circadian rhythms as much as earlier researchers had done using light exposure to the eyes (Campbell & Murphy, 1998). Of course, this finding suggests that a “knee-wrap” version of our alarm clock would be just as effective as one that turned on the room lights, without disturbing our sleep at 3:00 am. Again, remember where you got the idea.

Sleep is not a constant “unconscious” state; rather, there are five recognizable and somewhat distinct periods of sleep that we repeat throughout the night, and the differences between the stages give us some clues about the functions of sleep and what we lose by not getting enough of it. Although researchers have made great strides in identifying functions of different periods of sleep, a lot of work remains.

The four separate periods are called sleep stages. Altogether, the stages constitute a complete ninety-minute (or so) sleep cycle, which repeats itself—with some changes, as you will see—throughout the night. You can often recognize which stage someone is in by examining brain activity levels and the person’s responsiveness to the external environment. If you have an EEG (electroencephalograph) machine (Modules 1, 11, and 14), go hook yourself up to it and look for the patterns of brain activity associated with the separate stages of sleep. An EEG records the general level and speed of neural activity in different parts of the brain through electrodes that are placed on the scalp. The EEG can pick up on the synchronized pattern of activity that takes place as electrochemical signals flow across neurons. Researchers typically refer to these patterns of brain activity as  brain waves. They differ from each other in strength, speed, and regularity (that is, how synchronized the different areas of the brain are). Generally speaking, the less active your brain is, the slower and more regular the brain waves are. Each of the sleep stages has a characteristic type of brain wave associated with it.

Right before you fall asleep, the brain waves that the EEG picks up are called alpha waves. They are reasonably fast, fairly strong waves. As you drift off to sleep, you enter Stage 1, and your brain produces slower and less regular waves called theta waves. You can think of entering Stage 1 sleep as being like taking one step into a room and keeping the door open behind you. Although you are in the room, you can get out easily. When you are in Stage 1 sleep, you are unaware of most aspects of the environment. You can become briefly aware of some stimuli, though. Frequently, these stimuli, such as the jerk of a muscle, will wake you up momentarily. This, of course, is the famous “head bob” that we often see during a lecture: people whose heads keep slowly falling forward until they jerk suddenly and startle themselves awake. During Stage 1 sleep you might also experience brief dreamlike images and sensations, such as a bright light, or a loud noise, the feeling of floating or being touched; these are called hypnagogic sensations (Dement, 1999). Because people often slip in and out of Stage 1 sleep, it is difficult to say that they are really asleep during this stage.

NREM 2 or Stage 2

After, you slip into Stage 2 sleep. This is when you are clearly asleep, but we would call this light sleep. Stimuli from the outside environment are very unlikely to reach conscious awareness while asleep, but you can wake up easily. Theta brain waves continue (a bit slower than in Stage 1), but now two new kinds of waves are present. Sleep spindles are short bursts (about 2 seconds long) of more rapid brain waves, about twice as fast as theta waves. K-complexes are bursts of a single higher-voltage wave. We spend about half of our time sleeping in Stage 2

NREM 3 or Stage 3

Stage 3 is characterized by slow brain waves, called delta waves. Stage 3 is deep sleep. Not only does next to nothing make it in from the outside environment, it is quite difficult to wake up from Stage 3 sleep. Much of the restoring functions of sleep probably occur during Stage 3; it is the stage in which most of the growth hormone is released by the pituitary gland, for example (Obal & Krueger, 2004). Also, most of the enhancement of the immune system that occurs during sleep probably happens in Stage 3 (Bryant, Trinder, & Curtis, 2004). Stage 3 is also the stage in which sleepwalking occurs for some children (some adults, too, but it becomes quite rare the older you get).

REM Sleep

In a way, it is good that the fourth stage is not called Stage 4, because it is very different from the other three sleep stages. Besides, it does not generally happen after Stage 3. Instead, in the first few hours of sleep tend to cycle between Stages 1 and 3 a few times. Then later, deep sleep (Stage 3) tends to stop and is replace by REM. The name REM stands for rapid eye movements, which is one of the more noticeable facts about this stage. While you are in REM sleep, your eyes move back and forth rapidly under your eyelids, as if you were watching some scene. A second very noticeable fact about REM sleep, at least to the person experiencing it, is that this is the stage during which most dreaming occurs. In addition, brain waves become faster, more like the awake waves (alpha). Breathing and heart rate increase, almost as if you were awake, and genital arousal occurs. But the body is otherwise motionless, as if paralyzed. It is this mismatch between high internal activity and motionless body that has led some observers to label REM sleep paradoxical sleep. REM sleep is clearly important—if we are deprived of this stage of sleep, we spend more time in it the next time we sleep—and researchers are beginning to unravel the mysteries of its functions. Because infants and children have a great deal more REM sleep than adults do, it is likely that this stage is important for brain development and for helping us to keep our neural synapses tuned up.

For many years, researchers have suspected that REM sleep helps us to store events into long-term memory (Feldman & Dement, 1968; Chernik, 1972). The results over the years were inconsistent, however. One possibility is that REM sleep is important for procedural memories (for example learning a new physical skill, but not for declarative memories (facts and episodes) in most cases (Rasch & Born, 2013). There is some evidence that REM sleep improves creative problem-solving (Can et al. 2009).

Many researchers have been examining the idea that non-REM sleep is also important for memory, and they have made some important discoveries. For example declarative memory seems to improve with Stages 3, slow wave sleep (Rasch & Born 2013; Wagner et al. 2004). Even the sleep spindles of Stage 2 may help us to store memories (Gais et al. 2001). Thus there is a good possibility that all of the sleep stages are important for memory. Here is a summary of the sleep stages. Note that it does not include information about the role of different stages in different kinds of memory.

Perhaps the most interesting observation about sleep is that we become conscious of a whole new world, the dream world, while we are in that state of awareness. As you may have already known, dreaming occurs principally during REM sleep. Although we do experience dreamlike images during other sleep stages, only during REM sleep do the dreams seem to follow some kind of story line. Because they are so interesting, observers have long suspected that dreams serve some important psychological purpose.

Sigmund Freud proposed perhaps the first comprehensive explanation of the meaning of dreams. He believed that dream images reflect the hidden desires and impulses contained in the unconscious, chiefly related to sex and aggression. By dreaming about these impulses instead of acting on them in real life, we could release them safely. Now, you probably realize that our dreams are not entirely filled with images of sex and aggression. Freud, too, realized this. His answer was that these impulses are too threatening for us to even dream about them openly. Instead, dream images reflect these hidden impulses symbolically. For example, according to psychoanalytic interpretation of dreams, long, thin objects, such as sticks or guns, symbolically represent penises, and dreaming about dancing represents sexual intercourse.

Most current researchers reject this kind of dream analysis. Modern content analyses, detailed descriptions of the topics and images of people’s dreams, are a key source of evidence against Freud’s view. For example, a great many of our dreams are reminiscent of worries and concerns that we are conscious of during our waking lives (Domhoff, 1996; 2003; 2010; Hall & Nordby, 1972). Freud also noted that emotions in dreams commonly did not match the content (Freud, 1900). For example, you might be frightened by an everyday event in a dream. Modern content analyses have suggested that Freud was a victim of the confirmation bias, however, noticing only those cases that confirmed what he already believed. In reality, content analyses reveal that the large majority of dream content is accompanied by the appropriate emotions (Foulkes, et al 1988; Merritt et al. 1994).

Many therapists, and more than a few book authors, still enthusiastically embrace a version of symbolic dream interpretation. However, the research that we used to show how Freud’s version of dream interpretation is wrong applies equally well to the more recent versions of symbolic interpretation. The problem does not lie in the possibility that dreams have symbolic meaning. It seems very likely that many dream images do have such meanings for people. The problem is that the meaning probably differs for different people. For example, you may dream about garbage because, as one “Dream Dictionary” puts it, you have something or someone in your life you need to get rid of or “throw out.” But another individual might dream about garbage because it is Wednesday night, and they have to remember to get the garbage cans out to the front of the yard in time for trash collection on Thursday morning.

It may even be that your dreams are not as weird as you think. If you have three REM stages per night, you probably have a minimum of three dreams per night (remember, we also dream during non-REM stages—Domhoff, 2003). You do not remember them all, so think about which ones are more likely to be remembered. Suppose, for example, that you had four dreams last night. One was about sitting at the breakfast table, eating your typical breakfast of Cocoa Puffs and orange juice. The second was about sitting in psychology class, listening to a lecture about classical conditioning, and the third found you driving to McDonald’s for a quick cheeseburger. In the fourth, you rode a flying yellow penguin and were dressed in a flowered tuxedo while you battled a three-headed dragon that shot beams of vanilla, strawberry, and hydrochloric acid ink. Which one do you think that you would remember? This is, of course, the availability heuristic at work. Aspects of an event that make it available to memory will cause us to mistakenly conclude that the event is common. Indeed, research has found that factors such as intensity, vividness, bizarreness, and length are related to the likelihood that a dream would be recalled (Cohen & MacNeilage, 1974; Schredl, 2000). In reality, the most consistent finding from content analyses of dreams is that our dreams tend to be clearly and obviously related to the events that are going on in our waking lives; in other words, they are mundane (Domhoff, 2003; 2010).

We apparently need a theory of dreams that explains not their bizarreness and symbolic meaning but their “ordinariness.” Two good candidate theories are the activation-synthesis theory and the more recent neurocognitive theory. According to activation-synthesis theory (Hobson, 1988; Hobson & McCarley, 1977; Hobson, Pace-Schott & Stickgold, 2000), dreams begin when random bursts of neural activity occur in the brainstem while in REM sleep. These neural signals reach the forebrain, especially the limbic system, where the brain tries to weave them into a coherent story. The theory does a pretty good job of explaining why dream images do not really fit together very well; it proposes that our dreams reflect the best job that the brain can do at making sense of a series of random thoughts. The theory has difficulty explaining a few notable observations, however. First, signals from the brainstem may not be essential for starting a dream. Second, not all dreaming occurs during REM sleep. Third, and perhaps most importantly, dreams are not quite random. As we pointed out earlier, there is a strong similarity between the contents of dreams and the events of waking consciousness, and they may not be as bizarre as people think. Even the well-known abrupt changes of scene that occur during dreaming are probably more similar to the way we think when we are awake than it seems at first (Chapman & Underwood, 2000). Have you ever traced your “stream of consciousness”? You might look out of the window and notice that snow is covering the ground. That makes you think about weather, warm weather in fact, so you think about going to Florida. Then, that reminds you that you will be traveling to Florida in a few months to attend a friend’s wedding. In the span of 3 seconds, your thinking jumped from snow outside to attending a wedding in Florida months from now, a change that would very likely qualify as an “abrupt change of scene” if it occurred during a dream.

These shortcomings of the activation-synthesis theory led William Domhoff (2003; 2010) to offer a neurocognitive model of dreaming. His theory proposes that a specific neural network is responsible for dreaming; the network is spread through the limbic system, areas surrounding the limbic system, and specific parts of the cortex. Dreams occur when this network becomes active without any external stimulation—in other words, when we are asleep. The idea is that dreaming is a process that is very similar to the way our minds wander when one thought reminds us of another, and another, and another. Many of the brain areas involved in the neural network for dreaming are the same ones that are active during waking cognition. Hence there should be substantial overlap between dreams and waking thought (just as content analyses have indicated that there are). In essence, Domhoff believes that there is nothing particularly special about dreaming. His neurocognitive model essentially considers dreaming an extension of normal waking cognition and consciousness. Although researchers are still very much trying to sort out how dreaming occurs and what it means, the data are beginning to converge and reveal that Domhoff may be right: There are many more similarities between dreaming and waking cognition than first appear.

26.4 Sleep Deprivation

How much would you pay for an elixir that:

• Increases your energy, eliminates fatigue, and gives you more energy than you ever thought possible.
• Makes you more productive at work or school—you will accomplish more in less time. Friends, colleagues, and associates will marvel at how much you can do.
• Improves your memory, concentration, attention span, reasoning ability, critical thinking skills, vocabulary and communication skills, and decision-making skills. Your increased mental ability will astound your friends and frighten your foes.

But wait there’s more. If you act now, we will include a free sample of elixir that also:

• Improves your mood. You will be less angry and irritable and will have a better sense of humor. You will be more sociable and more interested in socializing.
• Enhances your immune system. You will succumb to viral and other illnesses far less often.
• As an added bonus, improves your physical coordination and makes you a safer driver.

These elixirs leave no bitter aftertaste, have no unpleasant side effects, and are 100% safe and legal. Now, how much would you pay?

As overblown as these claims may seem, the truth is, there is an “elixir” that does all of this and more, and it does not cost you a penny. It is called getting enough sleep.

From a practical standpoint, the most important fact about sleep is probably not that it marks a change in your consciousness or that you spend 55% of the night in Stage 2 or even that it affects memory. Rather, it is that you probably do not experience it enough. In other words, you are probably suffering from sleep deprivation. 

The US Centers for Disease Control and Prevention reported that 35% of US adults sleep less than 7 hours per night, the minimum amount they estimated necessary for healthy functioning. Indeed, the National Sleep Foundation (2020) found that 28% of US adults feel sleepy 5 – 7 days per week (yes, essentially every day). And college students are certainly not spared. One multi-university study found that 36% of students sleep less than 7 hours per night. Sleep expert James Maas (1998) once reported that college students frequently score as badly as sufferers of serious sleep disorders on measures of alertness and daytime sleepiness.

Importantly, you do not have to know that you are sleep deprived to be sleep deprived. In one study, a group of college students who averaged 7 hours of sleep per night and who reported that they were not particularly sleepy were encouraged by researchers to get as much sleep as they could for a period of time. The students initially increased the amount of sleep to about 9.5 hours per night before leveling off at a bit over 8. By the end of the research study, the students showed large improvements in alertness, mood, and reaction time (Kamdar et al., 2004).

Some people have been sleep deprived for so long that they think that the way they feel is normal. Students complain that they were put to sleep by a boring professor. Professionals complain that they were put to sleep by a boring after-lunch meeting in a warm room. Half of the adults in the US believe that it is normal to feel so sleepy in mid-afternoon that it is hard to stay awake (National Sleep Foundation [NSF], 2002). In reality, there is only one reason why healthy people fall asleep when they are not supposed to. They are not getting enough sleep when they are supposed to. Well-rested people do not fall asleep when they should be awake. James Maas notes that the “sleep-inducing” situations simply serve to reveal the underlying sleepiness that is already there. So, unintended sleep is the first clue that you are sleep deprived. Researchers and clinicians often use a simple scale called the Epworth Sleepiness Scale to measure sleepiness. The scale (which requires a license to use) asks 8 questions about a person’s likeliness to doze off while doing several everyday activities.

James Maas offers a simple 5 question test you can take to estimate if you are sleep deprived. You can access it here.

There are some very serious consequences of sleep deprivation, in addition to the obvious effects on your schoolwork, job, and social relationships. Sleep-deprived people are prone to accidents. For example, medical interns who worked a 24-hour shift every three days made 36% more serious medical errors than they did when working without the long shift and with fewer overall hours (Landrigan et al. 2004). More generally, a recent survey of US parents with children under 10 found that 48% of the parents admitted to driving while drowsy, and 10% admitted that they have actually fallen asleep at the wheel (National Sleep Foundation [NSF], 2004). The National Highway Traffic Safety Administration has estimated that at least 100,000 drivers per year are involved in police-reported automobile accidents (National Safety Council, 2020).

Sleep deprivation also reduces levels of leptin, a protein produced by the body that controls appetite, which may lead to overeating (Flier & Elmquist, 2004). Thus, there is a link between sleep deprivation and obesity, which was demonstrated in a survey of 18,000 adults. Those who got 6 hours of sleep per night had a 23% increased risk of obesity; 5-hour sleepers had a 50% increased risk, and people who averaged 2 to 4 hours of sleep had a 73% increased risk (National Health and Nutrition Examination Survey [NHANES], 2004).

How Much Sleep Should You Get?

Although individuals have different sleep needs, we can make some broad generalizations. Many people think that they can function just fine on 6 or 7 hours of sleep per night. Although that may be true for a small number of people, most sleep experts contend that the majority of us have just gotten used to the lower levels of functioning and quality of life that come along with getting too little sleep. There are occasional cases of people who remain healthy and alert with as few as 3 hours of sleep (Jones & Oswald, 1968). These people are probably extremely rare, however. Some can function reasonably well on 7 hours per night. Many people probably need at least 8, and others need even more.

You can use 8 hours as an approximate starting point to determine your own sleep needs. If you are currently nowhere near 8 hours, take a serious look at the sleep-deprivation effects throughout this section. You are likely to recognize yourself in there. In order to figure out how much sleep you really need, you obviously have to increase the amount that you get and find out how it affects you. It is a very simple concept; you just increase until the sleep-deprivation effects go away. You need to make the changes gradually, however, giving your body time to adjust to even small changes in your sleep pattern. Sleep experts recommend going to bed 15 to 30 minutes earlier than usual for a week. Keep adding 15 to 30 minutes of sleep every week until you can get up in the morning without an alarm clock. That is how much sleep you should be getting, and if you are like most people it is at least an hour more than you currently get.

How Can You Get Enough Sleep?

Over the years, we have not been able to persuade many of our students to increase the amount of sleep that they get. Their main objection is that there are too few hours in the day for them to do everything they need to do. Meeting school, job, and family responsibilities while trying to maintain a semblance of a social life seemingly leave little time to lie in bed unproductively for nine hours per night. In essence, these people cannot accept the idea that when well-rested you are so much more efficient that you can accomplish far more in far less time. Take another look at some of the performance and thinking-related problems associated with sleep deprivation. It really is not outrageous to suggest that if all of these abilities improved—as they very likely would if you got enough sleep—you could accomplish all that you do now, do it in less time, and do it better.

In addition to figuring out your personal sleep needs and doing your best to sleep that much every night, it is important to practice sleep hygiene, essentially habits that promote sufficient restful sleep. Some important habits to cultivate are:

• Make your sleep environment ideal for sleep. The temperature should be on the cool side, perhaps 65 degrees for most people. The room should be completely dark, so blackout curtains or a sleep mask might be necessary. You can also minimize noise distractions by wearing earplugs. Try to use your bed for sleep only.
• Train your circadian rhythms to make you alert when you are awake and not when you are trying to sleep by having a consistent sleep schedule. Try to go to sleep and wake up at the same time every single day, including weekends. Unfortunately, we fear that we have already lost many of you. It is, of course, impossible to do this. You know that there are some nights when you will have to stay up later than usual and some mornings when you will have to get up earlier than usual. But every time you have a significant departure from your normal routine, try to go back to it the next night. It will probably take you a few days to recover from the sleep deprivation fully, but having that routine is the key idea. If you go to sleep and wake up at the same time every day, your body gradually synchronizes itself with this consistent pattern of activity. In other words, your circadian rhythms will exactly match your sleep-wake schedule.
• Make up for lost sleep. This rule is contrary to what many people believe. It is a myth that you cannot make up for lost sleep. Go to bed earlier than usual instead of sleeping in (sleeping in makes it harder to get to sleep the next night). And do not try to regain all of your lost sleep in one night if you have a large sleep debt.