Sleep & Body
Rhythms
What is Consciousness?
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Consciousness – Your immediate awareness of thoughts,
sensations, memories, and the world around you.
Experience of this tends to blend together.
William James – described consciousness as a "stream" or
"river" that is always changing but unified and unbroken.
Consciousness first studied through introspection (verbal
self-reports) and later rejected in favor of studying only
observable overt behavior.
1950's brought a new desire to study consciousness for two
reasons.
1. Complete understanding of behavior had to consider the role of
conscious mental processes.
2. Psychologists had created more objective ways to study
consciousness.
Body Rhythms
•Natural variations we experience daily in our
consciousness as a part of our sleep-wake cycle.
•Most people experience at least two peaks in mental
alertness:
1.morning around 9:00 or 10:00 and
2.8:00 or 9:00 PM.
–Slumps in your mental alertness occur at about 3:00 PM
and 3:00 AM.
Biological Rhythms
• Periodic physiological fluctuations
• Can affect physiological functioning
• Fall into three main categories
– Circadian Rhythms
– Ultradian Rhythms
– Infradian Rhythms
Circadian Rhythms
• Any rhythmic change that occurs approximately
once in a 24-hour cycle
• body temperature
• cortisol secretion
• sleep and wakefulness
• In the absence of time cues, the cycle period will
become somewhat longer than 24 hours
• Many of your processes like blood pressure,
hormones, pain sensitivity along with sleep and
wake cycles vary over the day
Sleep and Circadian Rhythms
• Play “Sleep and Circadian Rhythms”
(6:09) Module #13 from The Brain:
Teaching Modules (2nd edition).
• Intro to Circadian Rhythms & Cave
Experiment
The Body’s Clock
• Suprachiasma
tic nucleus
(SCN)—
cluster of
neurons in the
hypothalamus
that governs
the timing of
circadian
rhythms
• Melatonin—
hormone of
the pineal
gland that
produces
sleepiness
The Body’s Clock: How it works
• Special photoreceptors in the retina regulate the
effects of light on the body’s circadian rhythms
• In response to morning light, signals from these
special photoreceptors are relayed via the optic
nerve to the suprachiasmatic nucleus.
• In turn, the suprachiasmatic nucleus causes the
pineal gland to reduce the production of melatonin, a
hormone that causes sleepiness.
• As blood levels of melatonin decrease, mental
alertness increases.
• Daily exposure to bright light, especially sunlight,
helps keep the body’s circadian rhythms
synchronized and operating on a 24-hour schedule.
How Melatonin works:
• More melatonin = sleepy and reduce activity levels
(between 1-3 AM)
• Less Melatonin = more alert and active. Body stops
produced melatonin shortly before sunrise and sunlight
suppresses melatonin levels throughout the day
• Jet Lag – Since your body is still operating on the time
you left from, your melatonin levels will be off causing
a disruption in your circadian rhythms and making you
mentally fatigued, depressed, irritable and have
problems sleeping.
• Night workers will always have some problems due to
sunlight resetting their biological clock.
Biological Rhythms
• Play “Can You Beat Jet Lag?” (6:44)
Segment #15 from Scientific American
Frontiers: Video Collection for
Introductory Psychology (2nd edition).
• How light is used by the body to “reset”
your biological clock.
Circadian Rhythms
• Play “Circadian Rhythms” (3:58)
Segment #9 from Psychology: The
Human Experience.
• Lack of Sleep (on-call workers) & Job
Performance
• What are the “down times” during the
day?
Ultradian Rhythms
• Biological rhythms that occur more than
once each day
• Example: Cycling through the stages of
sleep throughout the night
Infradian Rhythms
• Biological rhythms that occur once a
month or once a season
• Example: Women’s menstrual cycle or a
bear’s winter hibernation
Biorhythms vs. Circadian Rhythms
• Biorhythms – pseudoscience that says people have
three natural rhythms that follow cycles. 23-day
physical cycle, 28-day emotional, and 33-day
intellectual functioning. These are determined by
the date of your birth.
• Chronobiology – study of biological rhythms over
time. Studies have not scientifically proven that
biorhythms play a role in certain events (pg. 141).
A Sleep Survey
Most people will spend about 22 years of
their life sleeping.
How much are you spending?
1. To the nearest quarter hour, what is your
bedtime on a school night?
2. On the average, how many minutes does
it take you to fall asleep after going to
bed?
3. To the nearest quarter hour, how many
hours of sleep do you get on an average
school night?
A Sleep Survey
4. In an average night, how many times do
you wake up?
5. On a scale of 1 to 10, with one being poor
and 10 being wonderful, rate the quality of
your sleep on a typical night.
6. On a scale of 1 to 10, with one being easy
and 10 being difficult, how hard is it for
you to wake up in the morning?
A Sleep Survey
7. In a typical 7-day week, how many naps
do you take?
8. When are you generally most awake and
alert?
-Morning
-Afternoon
-Evening
-Night
A Sleep Survey
9. After a typical night’s sleep, how many
dreams do you recall?
10. Which term most accurately describes
your typical dream?
-Pleasant
-Unpleasant
-Neutral
Sleep and Sleep
Deficit
Sleep Deprivation Effects
• Hurts performance on simple, boring tasks more than
challenging ones
• Decreases efficiency of immune system functioning
• Raises the levels of stress hormone cortisol which is linked
to damage of the brain cells responsible for learning &
memory
• Safety and accident issues
• Contributes to hypertension, impaired concentration,
irritability, premature aging, etc.
• After one night of sleep deprivation, people have episodes
of sleep lasting a few seconds called microsleeps
• See NBC Report on Sleeplessness in America (2 min)
• See NBC Report on Sleep Study (3 min)
Sleep Deprivation
(National Transportation Safety Board, 1995)
Why We Sleep
•Most people need 8-8.5 hours of sleep to function but most Americans
sleep 7-7.5 hours. Almost 1/3 of Americans get less than 6 hours. 74%
women sleep less than 8 hours a night.
•Most teens need 9 hours and 15 minutes of sleep a night. Average
teenager's biological clock doesn't prepare them to awaken until 8 or 9
AM. This can interfere with memory and learning. Students with most
sleep did better on grades and exams.
•Getting less sleep than you need can cause harmful changes in
metabolic and endocrine functioning. Study found after only one week
of sleep restriction of 4 hours of sleep a night, subjects had glucose
levels that were no longer normal.
•REM deprivation will cause subjects to have REM rebound in which
they spend more time in REM sleep in an effort "catch up."
•Stage 3 & 4 NREM deprivation – people will have NREM rebound and
"catch-up" by spending more time in these stages.
Functions of Sleep
• Restoration theory—body wears out during the day
and sleep is necessary to put it back in shape
– NREM sleep sees increases in the release of growth
hormone, testosterone, prolactin.
– REM sleep plays a role in rate of brain development that
occurs in the early stages of the lifespan.
• Adaptive theory—sleep emerged in evolution to
preserve energy and protect during the time of day
when there is little value and considerable danger
– Animals with few natural predators sleep the most while
animals with many sleep less.
– Hibernation occurs during the time of year most hazardous
to the animal.
Hypothalamus
• Sleep control center in the brain
• Monitors changes in light or dark in the
environment
• Changes levels of hormones in the body
Melatonin
• A hormone that helps regulate daily
biological rhythms
• Linked to the sleep-wake cycle
• Melatonin level increases during the
night and decreases with exposure to
morning light
IMPROVING SLEEP & MENTAL
ALERTNESS
• Dealing with Morning Brain Fog or Sleep Inertia
• Staying in bed until the last possible moment will
only intensify disorientation as you hustle to work.
• Best way to treat it is to allow for more passage of
time.
• Set your alarm 15 minutes earlier and make it so you
have to get up to turn it off.
• Drink something with caffeine and sit near sunlight.
• Read something to get your brain engaged.
Coping with the Night Shift
• Avoid frequent shift changes
• Easier to lengthen your days than shorten
them. Progress morning to evening to
night shifts.
• If working at night use bright lights
especially early on in the shift to adjust
your circadian rhythm.
• Take melatonin in the daytime to help you
sleep.
Sleep Deprivation Studies
• Play “Catching Catnaps” (11:45) Segment
#13 from Scientific American Frontiers:
Video Collection for Introductory Psychology
(2nd edition).
• Which stages of sleep are most important?
• Can a person survive on naps alone?
• How does lack of sleep or “bonus” sleep
affect mood?
Improving the Quality of Your Sleep
• Avoid going to sleep in the "forbidden zone" of wakefulness that
usually occurs between 8-10PM.
• Don't drink or eat caffeine-containing drinks or foods. See table
4.7 on pg. 175 for common sources of caffeine.
• Don't go to bed very hungry or full
• Moderate exercise during the day helps but not just before sleep.
• Raise your core body temperature with a warm bath or shower.
• Develop a consistent bedtime routine.
• Avoid depressant drugs which promote sleep but reduce REM
sleep.
• Write down concerns and why you plan to do about them the
next day or redirect your thoughts to something relaxing to deal
with stress.
Sleep Stages, REM,
and Dreaming:
The Stages of Sleep
Electroencephalograph (EEG)
• A machine that amplifies and records
waves of electrical activity that sweep
across the brain’s surface
• Electrodes are placed on the person’s
scalp to measure the waves
• Used as a means to measure the stages
of sleep
Electroencephalogram (EEG)
• Electrodes placed on the scalp provide a gross record of the
electrical activity of the brain
• EEG recordings are a rough index of psychological states
EEG Waves of Wakefulness
• Awake and
attentive: low
amplitude,
fast, irregular
beta waves
• Awake, but
non-attentive:
large, regular
alpha waves
Awake, attentive
1 second
Beta waves
Awake, nonattentive
Alpha waves
1 second
Onset of Sleep
• Awake & alert, your brain produces small, fast brain
waves called beta waves.
• As you lay down and close your eyes, your brain's
electrical activity gradually gears down generating
slightly larger and slower alpha brain waves.
• During drowsy, presleep stage you may experience
vivid sensory phenomena called hypnagogic
hallucinations.
• Most common hallucination is that of falling which
can produce a myoclonic jerk or sleep starts –
involuntary muscle spasm of the whole body that jolts
the person completely awake.
Stage 1 Sleep
• Breathing is slowed.
• Brain waves become irregular.
• It is easy to wake the person, who will
insist they are not asleep.
• Lasts only a few minutes.
• Familiar sounds fade away but your can
regain alertness if something interrupts
you.
• Some imagery is common although no
very strange or vivid.
Stages of Sleep
Stage 1
Stage 1
Stage 2 Sleep
• Brain wave cycle slows.
• Appearance of sleep spindles or brief bursts of
brain activity and K complexes or large highvoltage spikes of brain activity that
periodically occur.
• Brain activity slows considerably and
breathing becomes rhythmic.
• Slight muscle twitches occur.
• Brain waves begin to slowly switch from
Theta waves to slower and larger delta waves.
Stage 2
K Complex
Stages 3 and 4 Sleep
“Slow Wave Sleep”
• Increase in delta waves (large and slow
waves per second) 20% = Stage 3. More
than 50% = Stage 4.
• First time through stage 4 is about 30 minutes
and is where one gets rejuvenated
• During the first stage 4 of sleep, heart rate,
blood pressure and breathing drop to their
lowest levels and it is very hard to wake up.
• Sleepwalking occurs here.
• People can "wake up" during stage 4 and do a
simple task and not remember it.
Stage 3
Stage 4
Stages of Sleep1-4
Quick Review
• Sleep stage 1: brief
transition stage when
first falling asleep
• Stages 2 through 4
(slow-wave sleep):
successively deeper
stages of sleep
• Characterized by an
increasing percentage
of slow, irregular,
high-amplitude delta
waves
Sleep stage 1
1 second
Sleep stage 2
Spindlers (bursts of activity)
Sleep stage 4
Delta waves
REM Sleep
• Stages 1 - 4 considered N-REM (non-REM
sleep)
• Rapid eye movement (REM Sleep) as eyes
move quickly back and forth
• Most dreaming occurs in REM sleep but
muscle activity is suppressed to keep you
acting them out.
• If denied REM sleep and then allowed a
person will experience REM Rebound and
will increase their time in REM by 50%.
“Catching Up” on REM sleep.
REM Sleep
REM: Paradoxical Sleep
• During REM sleep brain wave patterns are
similar to when a person is awake
• Visual and motor neurons in the brain fire
like they do when you are awake.
• Eyes dart back and forth and heart rate, blood
pressure and respirations fluctuate up and
down.
• REM sleep is sometimes called paradoxical
sleep as one’s physiology is close to that of
being awake but the brainstem blocks all
muscle movement
• The first REM cycle lasts for 5 to 15 minutes.
Stages of Sleep
• Upon reaching stage 4 and after about 80 to 100
minutes of total sleep time, sleep lightens, returns
through stages 3 and 2
• REM sleep emerges, characterized by EEG
patterns that resemble beta waves of alert
wakefulness
– muscles most relaxed
– rapid eye movements occur
– dreams occur
• Four or five sleep cycles occur in a typical night’s
sleep; less time is spent in slow-wave, more is
spent
in REM
Typical Night’s Sleep
Stage 4/REM Changes
Sleep Changes through Life
Sleep
• Play “Sleep: Brain Functions” (11:12)
Module #14 from The Brain: Teaching
Modules (2nd edition).
• Review of the stages of sleep.
• What happens to animals that are not
allowed to sleep?
• What defines normal & abnormal sleep?
• Categories of Sleep Disorders
Dream Facts:
• 25% of your night’s sleep or 2 hours is spent dreaming.
• Sleep Thinking – Vague, uncreative, bland thoughts about
real-life events that take place in NREM. Occur more than
dreams.
• Dreams have 5 basic characteristics:
• Emotions can be intense
• Content & Organization are usually illogical
• Sensations are sometimes bizarre
• Bizarre details are uncritically accepted
• Dream images are difficult to remember
• Dreams occur in both NREM and REM sleep however they
are more frequent and last longer in REM.
• People usually have 4-5 episodes of dreaming a night.
Dreams happen in real time.
Brain During REM Sleep
•PET scans reveal that brain activity is much different in REM
sleep than when you’re awake.
•Frontal Lobe and Primary Visual Cortex (registers visual info
from retinas) are essentially shut down during REM meaning
you are shut out from the external world and rational thought
so you accept your dreams no matter how bizarre they are.
•Amygdala & hippocampus of the limbic system which deal
with emotion and memory are highly active as are the brain’s
visual areas.
What do we Dream About?
• Most dreams are about everyday life.
• Some themes are found across cultures. (See
Common Dream Themes Table 4.3 pf. 155)
• Aggression is more common than friendliness in
dreams.
• Environmental cues during dreaming may be
incorporated into the dream.
• What you really want to know about dreams? (Read
more - In Focus 4.4, pg. 157)
Why don’t remember our dreams?
• Areas of the brain used in forming memories (frontal
lobe) are shut down during REM sleep and
neurotransmitters that are used to make memories are
greatly reduced.
• More likely to remember a dream if you wake up
during it. Visual encoders tend to be better at
remembering dreams. Vivid dreams are more likely
to be recalled.
• Distractions when you awaken can cause problems
with remembering dreams.
• Brain seems programmed to forget most of what
occurs during sleep.
Types of Dreams
•True dream—vivid, detailed dreams
consisting of sensory and motor sensations
experienced during REM
• Sleep thought—lacks vivid sensory and
motor sensations, is more similar to daytime
thinking, and occurs during slow-wave
sleep
• Lucid dreaming
Physiological Function Theory
• Neural activity during REM sleep
provides periodic stimulation of the
brain.
Psychoanalytic Interpretation
• Sigmund Freud – Dreams are the fulfillment of
wishes. Unacceptable thoughts of sex & aggression
are repressed when you are conscious but come forth
when you are asleep in the form of dreams.
• Dreams were “the royal road to the unconsciousness”
and a “safety valve” that allowed for the release of
unconscious and unacceptable urges.
• Two components of Dreams
• Manifest Content – dream images themselves
• Latent Content – Disguised psychological meaning of
the dream.
• Research does not support his theories.
Activation Synthesis Model
• Brain activity during sleep produces dream
images (activation) which are combined by the
brain into a dream story (synthesis).
• Meaning is to be found by analyzing the way the
dreamer makes sense of the progression of
chaotic dream images.
OR, to put it another way:
• Activation of brain stem area (Pons) arouse
other brain areas including visual and auditory
and limbic systems.
• Brain responds to these internally created
signals and assigns them meaning using
memories, emotions and sensations.
Activation-Synthesis Theory
• Dreams are
the mind’s
attempt to
make sense
of random
neural firings
in the brain as
one sleeps.
Information-Processing Theory
• Dreams serve an important memoryrelated function by sorting and sifting
through the day’s experiences
• Research suggests REM sleep helps
memory storage.
REM & Memory Consolidation
• Memory Consolidation – converting new
memories into a long-term, relatively permanent
form.
• REM seems to help with procedural memories
(skills like riding a bike).
• REM seems to improve performance on learned
tasks.
• Brain areas activated during training on a task
actually are reactivated during REM sleep
perhaps stabilizing the neural connections
formed in the recent training experience.
Dream Research
• Play “What’s in a Dream?” (13:00) Segment #14
from Scientific American Frontiers: Video
Collection for Introductory Psychology (2nd edition).
• Dream research with Alan Alda.
• What happens biologically when we dream during
REM sleep?
• Where do stories of our dreams come from?
• How brains try to make sense of nonsense.
• What kind of tasks are more difficult if you have
random sleep loss?
• Can dreaming help us learn?
Sleep Disorders and
Sleep Problems:
Individual Differences
in Sleep Drive
• Some individuals need more and some less than the
typical 8 hours per night
• Nonsomniacs—sleep far less than most, but do not
feel tired during the day
• Insomniacs—has a normal desire for sleep, but is
unable to and feels tired during the day
Sleep Disorders Quick List
• Insomnia—inability to fall asleep or stay asleep
• REM sleep disorder—sleeper acts out his or her
dreams
• Night terrors—sudden arousal from sleep and intense
fear accompanied by physiological reactions (e.g.,
rapid heart rate, perspiration) that occur during slowwave sleep
• Narcolepsy—overpowering urge to fall asleep that
may occur while talking or standing up
• Sleep apnea—failure to breathe when asleep – See
clip of it here.
Insomnia
• Recurring problems falling asleep or
staying asleep
• Sleeping pills tend to inhibit or suppress
REM sleep; worsen the problem
• Alcohol suppresses REM sleep; also
worsens the problem
• Studies show most people overestimate
how long it took them to get to sleep
Sleep Apnea
• A sleep disorder characterized by
temporary cessations of breathing
during sleep and consequent momentary
reawakenings.
• Tend to be loud snorers
• Continuous Positive Airway Pressure
machine
Narcolepsy
• A sleep disorder characterized by uncontrollable sleep
attacks
• Person goes directly into REM sleep
• Nervous system getting aroused tends to trigger the
sleep attack
• Narcolepsy has a genetic link and runs in some breeds
of dogs.
• Rusty the Narcoleptic Dog (Click to View)
• Other Dogs with Narcolepsy (Click to View)
• Teenagers Living with Narcolepsy (Click to View)
Somnambulism
• Formal name for sleepwalking
• Starts in the deep stages of N-REM
sleep
• Person can walk or talk but remembers
nothing of the experience
• Sleep Walking has been linked to Sleep
Deprivation. (NBC Report – 2 min.)
Night Terrors
• Sleep disorder characterized by high arousal and
appearance of being terrified
• Happens during stage 4 sleep; mostly children
• The children seldom remember the event.
Other Sleep Disorders
• Bruxism – teeth grinding
• Enuresis – bed wetting
• Myoclonus – sudden jerk of a body part
occurring during stage 1 sleep
– Everyone has occasional episodes of
myoclonus