REVIEW Sleep and Dreams

Learning Objectives

Page 103

Test Yourself by taking a moment to answer each of these Learning Objective Questions (repeated here from within the module). Research suggests that trying to answer these questions on your own will improve your long-term memory of the concepts (McDaniel et al., 2009).

Question

8-1 What is sleep?
ANSWER: Sleep is the periodic, natural loss of consciousness—as distinct from unconsciousness resulting from a coma, general anesthesia, or hibernation. (Adapted from Dement, 1999.)

Question

8-2 How do our biological rhythms influence our daily functioning?
ANSWER: Our bodies have an internal biological clock, roughly synchronized with the 24-hour cycle of night and day. This circadian rhythm appears in our daily patterns of body temperature, arousal, sleeping, and waking. Age and experiences can alter these patterns, resetting our biological clock.

Question

8-3 What is the biological rhythm of our sleeping and dreaming stages?
ANSWER: Younger adults cycle through four distinct sleep stages about every 90 minutes. (The sleep cycle repeats more frequently for older adults.) Leaving the alpha waves of the awake, relaxed stage, we descend into the irregular brain waves of non-REM stage 1 (NREM-1) sleep, often with hallucinations, such as the sensation of falling or floating. NREM-2 sleep (in which we spend the most time) follows, lasting about 20 minutes, with its characteristic sleep spindles. We then enter NREM-3 sleep, lasting about 30 minutes, with large, slow delta waves. About an hour after falling asleep, we begin periods of REM (rapid eye movement) sleep. Most dreaming occurs in this stage (also known as paradoxical sleep) of internal arousal but outward paralysis. During a normal night's sleep, NREM-3 sleep shortens and REM and NREM-2 sleep lengthens.

Question

8-4 How do biology and environment interact in our sleep patterns?
ANSWER: Our biology—our circadian rhythm as well as our age and our body's production of melatonin (influenced by the brain's suprachiasmatic nucleus)—interacts with cultural expectations and individual behaviors to determine our sleeping and waking patterns.

Question

8-5 What are sleep's functions?
ANSWER: Sleep may have played a protective role in human evolution by keeping people safe during potentially dangerous periods. Sleep also helps restore and repair damaged neurons. REM and NREM-2 sleep help strengthen neural connections that build enduring memories. Sleep promotes creative problem solving the next day. Finally, during deep sleep, the pituitary gland secretes a growth hormone necessary for muscle development.

Question

8-6 How does sleep loss affect us, and what are the major sleep disorders?
ANSWER: Sleep deprivation causes fatigue and irritability, and it impairs concentration, productivity, and memory consolidation. It can also lead to depression, obesity, joint pain, a suppressed immune system, and slowed performance (with greater vulnerability to accidents). Sleep disorders include insomnia (recurring wakefulness); narcolepsy (sudden uncontrollable sleepiness or lapsing into REM sleep); sleep apnea (the stopping of breathing while asleep; associated with obesity, especially in men); night terrors (high arousal and the appearance of being terrified; NREM-3 disorder found mainly in children); sleepwalking (NREM-3 disorder also found mainly in children); and sleeptalking.

Question

8-7 What do we dream?
ANSWER: We usually dream of ordinary events and everyday experiences, most involving some anxiety or misfortune. Fewer than 10 percent of dreams among men (and fewer still among women) have any sexual content. Most dreams occur during REM sleep.

Question

8-8 What functions have theorists proposed for dreams?
ANSWER: There are five major views of the function of dreams. (1) Freud's wish-fulfillment: Dreams provide a psychic "safety valve," with manifest content (story line) acting as a censored version of latent content (underlying meaning that gratifies our unconscious wishes). (2) Information-processing: Dreams help us sort out the day's events and consolidate them in memory. (3) Physiological function: Regular brain stimulation may help develop and preserve neural pathways in the brain. (4) Neural activation: The brain attempts to make sense of neural static by weaving it into a story line. (5) Cognitive development: Dreams reflect the dreamer's level of development. Most sleep theorists agree that REM sleep and its associated dreams serve an important function, as shown by the REM rebound that occurs following REM deprivation in humans and other species.

Terms and Concepts to Remember

Test yourself on these terms.

Question

sleep (p. 87)
circadian [ser-KAY-dee-an] rhythm (p. 87)
REM sleep (p. 88)
alpha waves (p. 89)
hallucinations (p. 89)
delta waves (p. 89)
suprachiasmatic nucleus (SCN) (p. 92)
insomnia (p. 96)
narcolepsy (p. 97)
sleep apnea (p. 97)
night terrors (p. 98)
dream (p. 99)
manifest content (p. 100)
latent content (p. 100)
REM rebound (p. 102)
the biological clock; regular bodily rhythms (for example, of temperature and wakefulness) that occur on a 24-hour cycle.
a sleep disorder characterized by uncontrollable sleep attacks. The sufferer may lapse directly into REM sleep, often at inopportune times.
the large, slow brain waves associated with deep sleep.
the tendency for REM sleep to increase following REM sleep deprivation.
a sleep disorder characterized by high arousal and an appearance of being terrified; unlike nightmares, night terrors occur during NREM-3 sleep, within two or three hours of falling asleep, and are seldom remembered.
periodic, natural loss of consciousness—as distinct from unconsciousness resulting from a coma, general anesthesia, or hibernation. (Adapted from Dement, 1999.)
recurring problems in falling or staying asleep.
a pair of cell clusters in the hypothalamus that controls circadian rhythm. In response to light, the SCN causes the pineal gland to adjust melatonin production, thus modifying our feelings of sleepiness.
false sensory experiences, such as seeing something in the absence of an external visual stimulus.
a sequence of images, emotions, and thoughts passing through a sleeping person's mind.
a sleep disorder characterized by temporary cessations of breathing during sleep and repeated momentary awakenings.
according to Freud, the underlying meaning of a dream (as distinct from its manifest content).
the relatively slow brain waves of a relaxed, awake state.
according to Freud, the remembered story line of a dream (as distinct from its latent, or hidden, content).
rapid eye movement sleep; a recurring sleep stage during which vivid dreams commonly occur. Also known as paradoxical sleep, because the muscles are relaxed (except for minor twitches) but other body systems are active.

Experience the Testing Effect

Test yourself repeatedly throughout your studies. This will not only help you figure out what you know and don’t know; the testing itself will help you learn and remember the information more effectively thanks to the testing effect.

Question 3.4

1. Our body temperature tends to rise and fall in sync with a biological clock, which is referred to as .

Question 3.5

2. During the NREM-1 sleep stage, a person is most likely to experience

A.
B.
C.
D.

Question 3.6

3. The brain emits large, slow delta waves during sleep.

Question 3.7

4. As the night progresses, what happens to the REM stage of sleep?
ANSWER: It increases in duration.

Question 3.8

5. Which of the following is NOT one of the reasons that have been proposed to explain why we need sleep?

A.
B.
C.
D.

Question 3.9

6. What is the difference between narcolepsy and sleep apnea?
ANSWER: With narcolepsy, the person periodically falls directly into REM sleep, with no warning; with sleep apnea, the person repeatedly awakens during the night.

Question 3.10

7. In interpreting dreams, Freud was most interested in their

A.
B.
C.
D.

Question 3.11

8. How has neural activation been used to explain why we dream?
ANSWER: The activation-synthesis theory suggests that dreams are the brain's attempt to synthesize random neural activity.

Question 3.12

9. “For what one has dwelt on by day, these things are seen in visions of the night” (Menander of Athens, Fragments). How might the information-processing perspective on dreaming interpret this ancient Greek quote?
ANSWER: The information-processing explanation of dreaming proposes that brain activity during REM sleep enables us to sift through what one has dwelt on by day.

Question 3.13

10. The tendency for REM sleep to increase following REM sleep deprivation is referred to as .

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