1. Chapter 8 Wakefulness and Sleep

2. Endogenous Circannual Rhythms, Part 1
Some animals generate endogenous circannual rhythms, internal mechanisms that operate on an annual or yearly cycle
Example: birds migratory patterns; animals storing food for the winter

3. Endogenous Circadian Rhythms, Part 2
All animals produce endogenous circadian rhythms, internal mechanisms that operate on an approximately 24 hour cycle
Sleep cycle
Frequency of eating and drinking
Body temperature
Secretion of hormones
Urination
Sensitivity to drugs

4. The Daily Activity of a Squirrel Kept in Total Darkness
Figure 8.1 Activity record of a flying squirrel kept in constant darkness
The thickened segments indicate periods of activity as measured by a running wheel. Note that this free-running activity cycle lasts slightly less than 24 hours.
Adapted from “Phase Control of Activity in a Rodent,” by P. J. DeCoursey, Cold Spring Harbor Symposia on Quantitative Biology, 1960, 25, pp. 49–55

5. Daily Pattern of Body Temperature
Figure 8.2 Mean rectal temperatures for nine adults
Body temperature reaches its low for the day about 2 hours after sleep onset; it reaches its peak about 6 hours before sleep onset.
Adapted from “Sleep-Onset Insomniacs Have Delayed Temperature Rhythms,” by M. Morris, L. Lack, and D. Dawson, Sleep, 1990, 13, pp. 1–14

6. Daily Pattern of Positive Moods
Figure 8.3 Reported positive mood over time
During 30 hours in an unchanging laboratory environment, the average young adult reported most pleasant mood in the late afternoon or early evening, and the least pleasant mood around 5 a.m. to 7 a.m. The pattern was similar for those who started the procedure in the morning (above) or in the evening (below).
From “Nature’s clocks and human mood: The circadian system modulates reward motivation,” by G. Murray, C. L. Nicholas, J. Kleiman, R. Dwyer, M. J. Carrington, N. B. Allen, et al., 2009, Emotion, 9, pp. 705–716

7. Setting and Resetting the Biological Clock, Part 1
The purpose of the circadian rhythm is to keep our internal workings in phase with the outside world
The human circadian clock generates a rhythm slightly longer than 24 hours when it has no external cue to set it
Resetting our circadian rhythms is sometimes necessary

8. Setting and Resetting the Biological Clock, Part 2
Zeitgeber: German meaning “time giver”; refers to the stimulus that resets the circadian rhythm
Examples: sunlight, tides, exercise, meals, arousal of any kind, meals, temperature of environment, etc.
Depression, irritability, and impaired job performance are effects of using something other than sunlight as a zeitgeber

9. Jet Lag
Refers to the disruption of the circadian rhythms due to crossing time zones
Stems from a mismatch of the internal circadian clock and external time
Sleepiness during the day, sleeplessness at night, and impaired concentration
Traveling west “phase-delays” our circadian rhythms
Traveling east “phase-advances” our circadian rhythms

10. Jet Lag – More Difficult Flying East
Figure 8.5 Jet lag
Eastern time is later than western time. People who travel six time zones east fall asleep on the plane and then must awaken when it is morning at their destination but night back home. © Cengage Learning 2013

11. Shift Work Sleep duration depends on when one goes to sleep
Working at night does not reliably change the circadian rhythm
People adjust best to night work if they sleep in a very dark room during the day and work under very bright lights at night

12. Morning People and Evening People
Cycles can differ between people and lead to different patterns of wakefulness and alertness
Change as a function of age
Young children are morning people
Adolescents are often night people
As an adult, it partially depends upon genetics

13. Mechanisms of the Biological Clock
Mechanisms of the circadian rhythms
The suprachiasmatic nucleus
Genes that produce certain proteins
Melatonin levels

14. The Suprachiasmatic Nucleus (SCN)
The main control center of the circadian rhythms of sleep and temperature
Located above the optic chiasm and part of the hypothalamus
Damage to the SCN results in less consistent body rhythms that are no longer synchronized to environmental patterns of light and dark

15. The Suprachiasmatic Nucleus (SCN) of Rats and Humans
Figure 8.7 The suprachiasmatic nucleus (SCN) of rats and humans
The SCN is at the base of the brain, as seen in these coronal sections through the plane of the anterior hypothalamus. Each rat was injected with radioactive
2-deoxyglucose, which is absorbed by the most active neurons. A high level of absorption of this chemical produces a dark appearance on the slide. Note the greater
activity in SCN neurons of a rat injected during the day (a), than in one injected at night (b). (c) A sagittal section through a human brain showing the location of the SCN and the pineal gland.
Adapted from “Suprachiasmatic nucleus: Use of 14C-labeled deoxyglucose uptake as a functional marker,” by W. J. Schwartz & H. Gainer, Science 1977, 197: pp. 1089–1091, AAAS/American Association for the Advancement of Science

16. The Suprachiasmatic Nucleus (SCN) and the Circadian Rhythm
Generates circadian rhythms in a genetically controlled, unlearned manner
Single cell extracted from the SCN and raised in tissue culture continues to produce action potential in a rhythmic pattern
Various cells communicate with each other to sharpen the circadian rhythm

17. The Suprachiasmatic Nucleus (SCN) and the Retinohypothalamic Path
Light resets the SCN via a small branch of the optic nerve known as the retinohypothalamic path
Travels directly from the retina to the SCN
The retinohypothalamic path comes from a special population of ganglion cells that have their own photopigment called melanopsin
The cells respond directly to light and do not require any input from the rods or cones

18. Resetting the SCN Without Sight
Figure 8.8 A blind mole rat
Although blind mole rats are blind in other regards, they reset their circadian rhythms in response to light. Courtesy of Eviatar Nevo

19. The Biochemistry of the Circadian Rhythm
Two types of genes are responsible for generating the circadian rhythm
Period: produce proteins called PER
Timeless: produce proteins called TIM
PER and TIM proteins increase the activity of certain kinds of neurons in the SCN that regulate sleep and waking
Mutations in the PER gene result in odd circadian rhythms or decreased alertness if deprived of a good night’s sleep

20. Melatonin, Part 1
The SCN regulates waking and sleeping by controlling activity levels in other areas of the brain
The pineal gland secretes melatonin, a hormone that increases sleepiness

21. Melatonin, Part 2
Melatonin secretion usually begins two to three hours before bedtime
Melatonin feeds back to reset the biological clock through its effects on receptors in the SCN
Melatonin taken in the afternoon can phase-advance the internal clock and can be used as a sleep aid

22. 8.2 Stages of Sleep and Brain Mechanisms
Sleep is a specialized state evolved to serve particular functions
What are the mechanisms for producing sleep?

23. Sleep Sleep is a state that the brain actively produces
Characterized by a moderate decrease in brain activity and decreased response to stimuli
Sleep differs from the following states:
Coma, vegetative state, minimally conscious state, and brain death

24. Other Interruptions of Consciousness, Part 1
Coma: extended period of unconsciousness characterized by low brain activity that remains fairly steady
Person shows little response to stimuli
Vegetative state: person alternates between periods of sleep and moderate arousal but no awareness of surrounding
Some autonomic arousal to painful stimulus
No purposeful activity/ response to speech

25. Other Interruptions of Consciousness, Part 2
Minimally conscious state: one stage higher than a vegetative state marked by occasional brief periods of purposeful action and limited speech comprehension
Brain death: no sign of brain activity and no response to any stimulus

26. Stages of Sleep – EEG
The electroencephalograph (EEG) allowed researchers to discover that there are various stages of sleep
Allows researchers to compare brain activity at different times during sleep
A polysomnograph is a combination of EEG and eye-movement records

27. Brain Activity Recorded on an EEG During Sleep
Figure 8.10 Sleeping person with electrodes in place on the scalp for recording brain activity Hank Morgan/Rainbow/RGB Ventures LLC dba SuperStock/Alamy

28. Stage 1 Sleep
Alpha waves are present when one begins a state of relaxation
Stage 1 sleep is when sleep has just begun
The EEG is dominated by irregular, jagged, and low voltage waves
Brain activity begins to decline

29. Stage 2 Sleep Stage 2 sleep is characterized by the presence of:
Sleep spindles: 12- to 14-Hz waves during a burst that lasts at least half a second
K-complex: a sharp wave associated with temporary inhibition of neuronal firing

30. Slow Wave Sleep – Stage 3 and Stage 4
Stage 3 and stage 4 together constitute slow wave sleep (SWS) and is characterized by:
EEG recording of slow, large amplitude wave
Slowing of heart rate, breathing rate, and brain activity
Highly synchronized neuronal activity

31. Paradoxical or REM Sleep
Rapid eye movement sleep (REM) describes periods characterized by rapid eye movements during sleep
Also know as paradoxical sleep: deep sleep in some ways, but light sleep in other ways
EEG waves are irregular, low-voltage, and fast
Postural muscles of the body are more relaxed than other stages

32. Polysomnograph Records
Figure 8.11 Polysomnograph records from a college student
For each of these records, the top line is the EEG from one electrode on the scalp. The middle line is a record of eye movements. The bottom line is a time marker, indicating 1-second units. Note the abundance of slow waves in stages 3 and 4.
Source: Records provided by T. E. LeVere

33. NREM and REM Cycles, Part 1
Stages other than REM are referred to as non-REM sleep (NREM)
When people fall asleep, they progress through stages 1, 2, 3, and 4 in sequential order
After about an hour, the person begins to cycle back through the stages from stage 4 to stages 3 and 2 and then REM
The sequence repeats with each cycle lasting approximately 90 minutes

34. NREM and REM Cycles, Part 2
Stage 3 and 4 sleep predominate early in the night
Length of stage decreases as the night progresses
REM sleep is predominant later at night
Length increases as the night progresses
REM is strongly associated with dreaming, but people also report dreaming in other stages of sleep

35. Typical Sequences of Sleep Stages
Figure 8.12 Sleep stages on three nights
Columns indicate awake (A) and sleep stages 2, 3, 4, and REM. Deflections in the line at the bottom of each chart indicate shifts in body position. Note that
slow-wave sleep occurs mostly in the early part of the night’s sleep, whereas REM sleep becomes more prevalent toward the end. Source: Based on Dement & Kleitman, 1957a

36. Brain Mechanisms of Wakefulness and Arousal – Reticular Formation
Various brain mechanisms are associated with wakefulness and arousal
The reticular formation is a part of the midbrain that extends from the medulla to the forebrain and is responsible for arousal

37. Brain Mechanisms of Wakefulness and Arousal – Locus Coeruleus
The locus coeruleus is a small structure in the pons whose axons release norepinephrine to arouse various areas of the cortex and increase wakefulness
Usually dormant while asleep

38. Brain Mechanisms of Wakefulness and Arousal – Hypothalamus
The hypothalamus contains neurons that release “histamine” to produce widespread excitatory effects throughout the brain
Antihistamines produce sleepiness

39. Brain Mechanisms of Wakefulness and Arousal – Orexin
Orexin releases acetylcholine-releasing cells in the basal forebrain to stimulate neurons responsible for wakefulness and arousal
The basal forebrain is an area just anterior and dorsal to the hypothalamus

40. Brain Mechanisms of Wakefulness and Arousal – GABA and Acetylcholine
Cells of the basal forebrain release the inhibitory neurotransmitter GABA
Inhibition provided by GABA is essential for sleep
Other axons from the basal forebrain release acetylcholine, which is excitatory and increases arousal

41. Brain Mechanisms of Sleeping and Waking
Figure 8.13 Brain mechanisms of sleeping and waking
Green arrows indicate excitatory connections. Red arrows indicate inhibitory connections. Neurotransmitters are indicated where they are known. Source: Based on J.-S. Lin, Hou, Sakai, & Jouvet, 1996; Robbins & Everitt, 1995; Szymusiak, 1995

42. Sleep and the Inhibition of Brain Activity
Functions of the inhibitory neurotransmitter GABA are also important for:
Decreasing the temperature and metabolic rate
Decreasing the stimulation of neurons

43. Sleep as a Local Phenomenon
Sleep can be localized within the brain
Sleepwalkers: awake in one part of the brain and asleep in others
Lucid dreaming: dreaming but aware of being asleep and dreaming
The pons remaining in REM while other brain areas wake up: causes the inability to move

44. Brain Structures for Arousal and Sleep
Neurotransmitter(s) It Releases
Effects on Behavior
Pontomesencephalon
Acetylcholine, glutamate
Increases cortical arousal
Locus Coeruleus
Norepinephrine
Increases information storage during wakefulness; suppresses REM sleep
Basal Forebrain (Excitatory Cells)
Acetylcholine
Excites thalamus and cortex; increases learning, attention; shifts sleep from NREM to REM
Basal Forebrain (Inhibitory Cells)
GABA
Inhibits thalamus and cortex
Hypothalamus (parts)
Histamine
Increases arousal
Orexin
Maintains wakefulness
Dorsal Raphe and Pons
Serotonin
Interrupts REM sleep
© Cengage Learning

45. Brain Function in REM Sleep, Part 1
During REM sleep:
Activity increases in the pons and the limbic system
Activity decreases in the primary visual cortex, the motor cortex, and the dorsolateral prefrontal cortex

46. Sleep Disorders A sleep disorder associated with inadequate sleep
Caused by a number of factors, including noise, stress, pain, diet, and medication
Can also be the result of disorders such as epilepsy, Parkinson’s disease, depression, anxiety or other conditions
Dependence on sleeping pills or alcohol and shifts in the circadian rhythms can also result in insomnia

47. Sleep Disorders as a Result of Phase Delay
Figure 8.16 Insomnia and circadian rhythms
People with a phase delay have trouble getting to sleep. People with a phase advance have trouble staying asleep. © Cengage Learning

48. Sleep Apnea
A sleep disorder characterized by the inability to breathe while sleeping for a prolonged period of time
Consequences: sleepiness during the day, impaired attention, depression, and sometimes heart problems
Causes: genetics, hormones, old age, obesity and deterioration of the brain mechanisms that control breathing
Effects: cognitive impairment may result

49. Medical Options to Improve Sleep Apnea
Figure 8.17 A continuous positive airway pressure (CPAP) mask
The mask fits snugly over the nose and delivers air at a fixed pressure, strong enough to keep the breathing passages open. Russell Curtis/Science Source

50. Narcolepsy, Part 1
A sleep disorder characterized by frequent periods of sleepiness
Gradual or sudden attack of sleepiness
Occasional cataplexy: muscle weakness triggered by strong emotions
Sleep paralysis: inability to move while falling asleep or waking up
Hypnagogic hallucinations: dreamlike experiences

51. Narcolepsy, Part 2
Seems to run in families, although no gene has been identified
Caused by lack of hypothalamic cells that produce and release orexin
Primary treatment is with stimulant drugs (i.e., Ritalin), which increase wakefulness by enhancing dopamine and norepinephrine activity

52. Periodic Limb Movement Disorder
The repeated involuntary movement of the legs and sometimes the arms while sleeping
Legs kick once every 20 to 30 seconds for periods of minutes to hours
Usually occurs during NREM sleep

53. REM Behavior Disorder
Associated with vigorous movement during REM sleep
Usually associated with acting out dreams
Research suggest that inadequate GABA and other inhibitory neurotransmitters may be responsible

54. Night Terrors and Sleepwalking, Part 1
Night terrors are experiences of intense anxiety from which a person awakens screaming in terror
Usually occurs in NREM sleep
“Sleepwalking” runs in families, mostly occurs in young children, and occurs mostly in stage 3 or 4 sleep
Not associated with dreaming

55. Night Terrors and Sleepwalking, Part 2
It is not dangerous to wake a sleepwalker
A condition similar to sleepwalking is sexsomnia: engaging in sexual behavior while asleep
Can pose a threat to romances and marriages

56. 8.3 Why Sleep? Why REM? Why Dreams?
We’ve evolved mechanisms to force us to sleep
Inhibitory processes in our brains force us to become less aroused and less alert, and thus to sleep

57. Functions of Sleep Some of the many functions of sleep include:
Resting muscles
Decreasing metabolism
Performing cellular maintenance in neurons
Reorganizing synapses
Strengthening memories

58. Sleep and Energy Conservation
The original function of sleep was probably to conserve energy
Conservation of energy is accomplished via:
Decrease in body temperature of about 1-2 Celsius degrees in mammals
Decrease in muscle activity

59. Hibernation is Analogous to Sleep
Decrease in body temperature to only slightly above that of the environment
Heart rate and brain activity drop to almost nothing
Neuron cell bodies shrink, and dendrites lose almost a fourth of their branches
Replaced later when body temperature increases

60. Sleep and Memory, Part 1
Sleep also plays an important role in enhancing learning and strengthening memory
Performance on a newly learned task is often better the next day if adequate sleep is achieved during the night
Increased brain activity occurs in the area of the brain activated by a newly learned task while one is asleep

61. Sleep and Memory, Part 2
Patterns of activity in the hippocampus during learning were similar to those shown during sleep
Suggests that the brain replays its daily experiences during sleep
The brain strengthens some synapses and weakens others during sleep
Sleep spindles increase in number after new learning: correlated with nonverbal IQ

62. Amounts of REM Sleep
Humans spend one-third of their life asleep; about one-fifth is spent in REM

63. Functions of REM Sleep
Research is inconclusive regarding the exact functions of REM
During REM:
The brain may discard useless connections
Learned motor skills may be consolidated
Maurice (1998) suggests the function of REM is simply to shake the eyeballs back and forth to provide sufficient oxygen to the corneas

64. The Relationship Between Age and REM Sleep for Humans
Figure 8.19 Sleep patterns for people of various ages
REM sleep occupies about 8 hours a day in newborns but less than 2 hours in most adults. The sleep of infants is not quite like that of adults, however, and the criteria for identifying REM sleep are not the same. Source: From “Ontogenetic Development of Human Sleep- Dream Cycle,” by H. P. Roffwarg, J. N. Muzio, and W. C. Dement, 1966, Science, 152, pp. 604–609. Copyright 1966 AAAS. Reprinted by permission.

65. Sleep and Dreams (cont.)
Meaning of dreams:
- day residue and stimulus incorporation
- dream interpretation:
- manifest content
- latent content
I deleted the original slide ten.
2008 McGraw-Hill Co., Inc. All rights reserved

66. 30 Common Dream Symbols
Animals often represent the part of your psyche that feels connected to nature and survival. Being chased by a predator suggests you're holding back repressed emotions like fear or aggression.
Babies can symbolize a literal desire to produce offspring, or your own vulnerability or need to feel loved. They can also signify a new start.
Being chased is one of the most common dream symbols in all cultures. It means you are feeling threatened, so reflect on who is chasing you (they may also be symbolic) and why they are a possible threat in real life.
Clothes make a statement about how we want other people to perceive us. If you dream symbol is shabby clothing, you may feel unattractive or worn out. Changing what you wear may reflect a lifestyle change.
Crosses are interpreted subjectively depending on your religious beliefs. Some see it as symbolizing balance, death, or an end to a particular phase of life. The specific circumstances will help define these dream symbols.
Exams can signify self-evaluation, with the content of the exam reflecting the part of your personality or life under inspection.
Death of a friend or loved one represents change (endings and new beginnings) and is not a paranormal prediction of any kind. If you are recently bereaved, it may be an attempt to come to terms with the event.
Falling is a common dream symbol that relates to our anxieties about letting go, losing control over a situation, or somehow failing after a success.
Faulty machinery in dreams is often caused by your language centers being shut down while asleep, making it difficult to dial a phone, read the time, or search the internet. It can also represent performance anxiety in life.
Food is said to symbolize knowledge, because it nourishes the body just as information nourishes the brain. Food for thought?
Demons are sneaky evil entities which signify repressed emotions. You may secretly feel the need to change your own behaviors for the better.
Hair has significant ties with sexuality, according to Freud. Abundant hair may symbolize virility, while cutting hair off in a dream shows a loss of libido. Hair loss may also express a literal fear of going bald or becoming unattractive.
Hands are always present in dreams but when they are tied up it may represent feelings of futility. Washing your hands may express guilt. Looking closely at your hands in a dream is a good way to become lucid.
Houses can host many common dream symbols, but the building as a whole represents your inner psyche. Each room or floor can symbolize different emotions, memories and interpretations of meaningful events.
Killing in your dreams does not make you a closet murderer; it represents your desire to "kill" part of your own personality. It can also symbolize hostility towards a particular person and the desire to see them suffer.

67. Marriage may be a literal desire to wed or a merging of the feminine and masculine parts of your psyche.
Missing a flight or any other kind of transport is another popular dream, showing your frustration over possibly missing out on important opportunities in life. It's most common when you're struggling to make a big decision.
Money can symbolize self worth. If you dream of exchanging money, it may show that you're anticipating some changes in your life.
Mountains are obstacles, so to dream of successfully climbing a mountain can reveal a true feeling of achievement. Viewing a landscape from atop a mountain can symbolize a life under review without conscious prejudice.
Nudity is one of the most common dream symbols, revealing your true self to others. You may feel vulnerable and exposed to others. Showing off your nudity may suggest sexual urges or a desire for recognition.
People (other dream characters) are reflections of your own psyche, and may demonstrate specific aspects of your own personality.
Radios and TVs can symbolize communication channels between the conscious and subconscious minds. When lucid, ask them a question...
Roads, aside from being literal manifestations, convey your direction in life. This may be time to question your current "life path".
Schools are common dream symbols in children and teenagers but what about dreaming of school in adulthood? It may display a need to know and understand yourself, fueled by life's own lessons.
Sex dreams can symbolize intimacy and a literal desire for sex. Or they may demonstrate the unification of unconscious emotions with conscious recognition, showing a new awareness and personal growth.
Teachers, aside from being literal manifestations of people, can represent authority figures with the power to enlighten you.
Teeth are common dream symbols. Dreaming of losing your teeth may show a hidden fear of getting old and being unattractive to the opposite sex.
Being trapped (physically) is a common nightmare theme, reflecting your real life inability to escape or make the right choice.
Vehicles may reflect how much control you feel you have over your life - for instance is the car out of control, or is someone else driving you?
Water comes in many forms and can symbolize the subconscious mind. Calm pools of water reflect inner peace while a choppy ocean can suggest unease.