James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Chapter Nine
Wakefulness and Sleep
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
2 of 35
Endogenous Cycles
•
Endogenous: generated by the body regardless of
environment
– circannual rhythm: prepares animals for seasonal
changes even when caged without clues to the season
– circadian rhythm: rhythms that last a day and are
synchronized
• wakefulness and sleep
• hormone secretion
• frequency of eating
• body temperature
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Biological Clock
•
•
Duration for humans is between 24-25 hours (24.2 in one
study)
– we cannot adjust to 22 or 28 hour day
– can be lengthened somewhat by bright lights
Insensitive to most interference, e.g., not affected by:
– food or water deprivation
– x-rays
– tranquilizers
– alcohol, anesthesia
– lack of oxygen
– most kinds of brain damage
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Suprachiasmatic Nucleus (SCN)
•
•
SCN: area of the hypothalamus that sets circadian rhythm
– if damaged, rhythms are less consistent, not
synchronized to light and dark patterns
– neurons produce circadian rhythm in tissue cultures
– genes interact with proteins per and tim to generate
rhythm
• mutant per gene accelerates biological clock
Pineal gland releases melatonin 2 hrs before bedtime
– pill may help adjust to new time zone but effect of long
term use unknown
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Figure 9.3
Figure 9.3 The suprachiasmatic nucleus (SCN) of rates and humans. The SCN is located at the base
of the brain, just above the op[tic chiasm. The optic chiasm was torn off when the brain was sliced to make
the slides shown in (a) and (b), which show 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 that the
level of activity in SCN neurons is much higher in section (a), in which the rat was injected during the day,
than in section (b), in which the rat received the injection at night. (Source: W.J. Schwartz & Gainer, 1977 ©
A sagittal section through a human brain shows the SCN and the pineal gland.)
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Setting and Resetting Biological Clock
•
Biological clock is primarily reset by light, the zeitgeber, or
time giver
– blind people produce circadian rhythms longer than 24
hours
– under constant bright light, hamsters developed two
periods of wakefulness and sleep
– also affected by noise, meals, exercise and temperature
– marine animals affected by tide
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Setting and Resetting Biological Clock cont.
•
•
Jet lag
– going west we stay up later and phase-delay our
circadian rhythm
– going east we sleep earlier and it is phase-advanced
– flight attendants experience some memory impairments
Shift work
– many people may not adjust completely to night work, still
feel groggy and do not sleep well during day
– less light in night environment
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Figure 9.5
Figure 9.5 Jet lag. Eastern time is later than western time. People who travel six time zones east must
wake up when their biological clocks say it is the middle of the night, and will try to go to sleep when their
biological clocks say it is just late afternoon.
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Setting and Resetting Biological Clock cont.
•
SCN reset by axons in retinohypothalamic pathway from
retina to hypothalamus
– retinal ganglion cells do not contribute to vision and
respond to overall average amount of light
– light still resets biological clock in mice with few rods and
cones
– light resets circadian rhythm in blind mole rats
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Stages of Sleep
•
•
•
Electroencephalograph (EEG) measures electrical potentials
– potentials are net average of all neuron activity, an
objective measure of sleep or wakefulness
Stage 1
– irregular, jagged, low-voltage waves
– activity high but declining
Stage 2
– sleep Spindles, burst of 12-14 Hz waves lasting at least
half a second
– K-complex: sharp high-amplitude negative wave followed
by a smaller, slower positive wave
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Stages of Sleep cont.
•
•
Stage 3 & 4, slow-wave sleep
– start of large amplitude waves at least half second
– half of activity is slow-wave by stage 4
– deepest sleep, least responsive to stimuli, hard to awake
After about 60-90 minutes, we cycle back from 4 to 3 to 2
and then to rapid eye movement sleep (REM)
– repeats all night
– early evening: more stages 3 - 4 and less REM
– late evening: more REM and less stages 3 - 4
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Rapid Eye Movement (REM) Sleep
•
•
•
•
•
Irregular, low-voltage, fast EEG waves
Rapid eye movements and postural muscle paralysis
Penile erection and vaginal moistening
Irregular heart rate, blood pressure and breathing rates
Dreams reported by 80-90% of persons awakened during
REM
– likely to have more complicated plots and striking visual
imagery than non-REM stage dreams
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Rapid Eye Movement (REM) Sleep cont.
•
Research
– REM associated with loose associations (e.g., thiefwrong)
• possible explanation for why dreams seem to jump
around in haphazard, complicated way
– non-REM associated with strong associations (e.g., longshort) and simpler dreams
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Figure 9.9
Figure 9.9 Polysomnograph records from a male college student. A polysomnograph includes records
of EEG, eye movements, and sometimes other data, such as muscle tension or head movements. 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; and the bottom line is time marker, indicating 1-second units. Note the abundance of slow
waves in stages 3 and 4. (Source: Records provided by T.E. LeVere.)
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Brain Mechanisms of Wakefulness and Arousal
•
•
Cut through midbrain separating forebrain and part of
midbrain from all lower structures
– animal enters prolonged state of sleep because reticular
formation is damaged
– but, cut each of the individual tracts that enter medulla
and spinal cord and animal continues to have normal
wakefulness and sleep
Reticular Formation:structure in midbrain that extends from
the medulla into the forebrain
– sends axons into brain and into spinal cord
– pontomesencephalon area maintains arousal in wide
regions of cerebral cortex
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Brain Mechanisms of Wakefulness and Arousal cont.
•
•
•
Locus coeruleus: small structure in the pons
– emits bursts of impulses in response to meaningful events
– important for information storage, almost completely
inactive during sleep, maybe why we forget dreams
Basal forebrain axons go to thalamus and cerebral cortex
– increases arousal, learning and attention
– damage leads to decreased arousal, impaired learning
and memory, extensive in Alzheimer’s Disease
Hypothalamus
– couple of paths stimulate arousal by releasing histamine
– antihistamines cross blood-brain barrier and cause
drowsiness
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Getting to Sleep
•
•
•
Reduce temperature in the brain and body
– body cools when lying down and blood flows to periphery
and warms hands and feet
Decrease stimulation
– quiet room
– low or no light
Adenosine produces sleepiness
– accumulates during the day and declines during sleep
– caffeine inhibits adenosine, increasing arousal
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Getting to Sleep cont.
•
•
Prostaglandins: chemicals present in much of body that
promote sleep
– accumulate during the day and decline during sleep;
during day
– inhibits hypothalamic cells that increase arousal
Basal forebrain and hypothalamus promote sleep by
releasing GABA, an inhibitory transmitter
– if damaged, prolonged wakefulness results
– anesthesia works by increasing GABA release
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Figure 9.11
Figure 9.11 Brain mechanisms of sleeping and waking. Green arrows indicate excitatory connections;
red arrows indicate inhibitory connections. Neurotransmitters are indicated where they are known. Although
adenosine is shown as a small arrow, it is a metabolic product that builds up in the area, not something
released y axons. (Source: Based on Lin, Hou, Sakai, & Jouvet, 1996; Robbins & Everitt; and Szymusiak,
1995.)
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Brain Function in REM Sleep
•
•
•
Pons and limbic systems - activity increases (note limbic
system is active during emotional arousal when awake)
Parietal and temporal cortex - activity increases
Primary visual cortex, motor cortex, dorsolateral prefrontal
cortex - activity decreases
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Brain Function in REM Sleep cont.
•
•
PGO (pons-geniculate-occipital) waves, high amplitude
electrical potentials, occur during REM sleep
– neural activity first in pons, second in lateral geniculate
nucleus of thalamus and third in the occipital cortex
– high density of PGO waves after deprivation of REM
sleep
– each PGO wave is synchronized with an eye movement
Cells in pons contribute to REM by inhibiting motor neurons
that control body’s large muscles
– prevents acting out during sleep
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Figure 9.13
Figure 9.13 PGO waves. PGO waves start in the pons (P) and then show up in the lateral geniculate (G)
and the occipital cortex (O). Each PGO wave is synchronized with an eye movement in REM sleep.
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Abnormalities of Sleep
•
•
•
Insomnia: you have insomnia if you feel consistently tired
– we often do not get the 6-8 hours of sleep we need
– noise, worries, drugs, out of circadian rhythm, diseases,
depression, anxiety, etc.
– tranquilizers may relieve sleep but create other problems
Onset insomnia: trouble falling asleep
– body temperature still falling at normal sleep time so can’t
fall asleep right away
Maintenance insomnia: wake frequently during the night
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Abnormalities of Sleep cont.
•
•
Termination insomnia: body temperature rises at normal
sleep time so wake up sooner and can’t go back to sleep
– rapid entry into REM sleep, ahead of regular onset
Sleep Apnea: inability to breathe while sleeping
– narrow airway closes in sleep posture, common among
obese men (surgery can remove excess tissue)
– brain mechanisms for respiration fail to work in elderly
(mask delivering air under pressure can help)
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
25 of 35
Figure 9.15
Figure 9.15 Insomnia and circadian rhythms. A delay in the circadian rhythm of body temperature is
associated with onset insomnia; an advance is associated with termination insomnia.
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
26 of 35
Abnormalities of Sleep cont.
•
Narcolepsy: gradual or sudden attacks of sleepiness during
the day
– occasional cataplexy, muscle weakness while the person
remains awake
– sleep paralysis, inability to move when falling asleep
– hypnagogic hallucinations, dreamlike experiences
– much like intrusion of REM-like state into wakefulness
– treatments
• stimulant drugs such as pemoline (Cylert) or
methylphenidate (Ritalin)
• may relieve sleep but create other problems
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Abnormalities of Sleep cont.
•
•
Periodic limb movement disorder
– repeated involuntary movement of the legs and arms
every 20-30 seconds, may awaken person
– common among middle-aged and older
– sometimes treated with tranquilizers but may leave
person sleepy during the day
REM behavior disorder
– move around vigorously during REM, acting out dream
– multiple areas of damage in pons and midbrain
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Abnormalities of Sleep cont.
•
•
•
Night terrors
– occur during NREM sleep, common in children
– nightmares occur during REM (usually can describe)
Sleep talking occurs in most people during REM and NREM
Sleepwalking runs in families
– common in children 2-5, mostly early at night during stage
3-4 sleep
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
29 of 35
Why Do We Sleep?
•
Repair and restoration theory
– the main function of sleep is to enable the body to repair
itself, especially the brain, after the exertions of the day
– support
• after several days a rat’s immune system eventually
fails, loses resistance to infection and brain activity
ceases
• sleep increases during illness
– not supported by fact that how long we sleep is not
dependent on activity during the day
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Why Do We Sleep? cont.
•
Evolutionary theory
– we sleep to conserve energy, body temperature drops
and we save energy
• Ex: hibernation (even sleep a lot on days awake)
– sleep varies with time needed to search for food and
safety from predators
• Ex: horses and grazing animals sleep less compared
to wolves and other predatory animals
– theories are complementary and compatible
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Functions of REM Sleep
•
Effects of REM deprivation
– irritability, anxiety, impaired concentration, weight gain,
increased appetite
– animal experiment with rats led to death
– REM rebound: REM sleep increased from 19% to 29% of
night’s sleep when allowed to sleep undisturbed
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Functions of REM Sleep cont.
•
Hypotheses
– REM helps discard useless connections formed during
the day
– assists in memory formation, especially motor skills
• rats deprived of paradoxical sleep forgot location of
platform under water
• human males had trouble remembering a motor skill
– moving eyes increases supply of oxygen delivery to
cornea of eye (don’t get oxygen from blood)
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
33 of 35
Biological Perspectives on Dreaming
•
Activation-synthesis hypothesis
– during dreams, various parts of the cortex are activated
by the input arising from the pons and environmental
stimuli
• the cortex synthesizes a story to make sense of all of
the activity
– OR: because there is few stimuli from environment,
dreamer may process information stored in memory
– vestibular stimuli also may give feeling of flying, falling
– feeling of not being able to move true since muscles
turned off
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Biological Perspectives on Dreaming cont.
•
Clinico-anatomical hypothesis
– dreams begin with arousing stimuli from the brain’s own
motivations, memories, and arousal
– but brain does not react in normal way
• input from V1 primary visual cortex is suppressed
• primary motor cortex is suppressed to prevent action
• no censorship by prefrontal cortex to say “this is not
possible”
James W. Kalat
Biological Psychology, 8th Edition
Chapter 9: Wakefulness and Sleep
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Biological Perspectives on Dreaming cont.
•
Clinico-anatomical hypothesis cont.
– inferior parietal cortex and V2 plus visual areas of
temporal cortex are active
• damage in these areas result in no dreams (parietal
cortex) or no visual content (visual areas)