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Module 15
Waking and Sleeping Rhythms (cont’d)
Sleep
• Given an average life-expectancy of seventy-five
years, an average person spends 25 years in
sleep and 5 years of that dreaming.
• Biological rhythms that control sleep
 Circadian rhythm: 24 hour cycle
 Sleep stages: biological rhythm of sleep
Why do we sleep?
• Sleep provides a time-out period so that the
body can eliminate waste products from the
muscles, repair cells, strengthen the immune
system, conserve energy and recover physical
abilities lost during the day.
• Sleep is crucial for memory formation
• Growth hormone is relased during sleep
Evolutionary Theory
Cross-species Comparisons of Daily Hours of Sleep
Biological rhythm of sleep: Sleep
stages
Stages of sleep
 Stage 1. Transition from wakefulness to sleep
 Transition into sleep is abrupt
 Resembles hallucinations  experiences with no
stimulus
 Sensations of falling, floating, vivid images
 Stage 2. Brief bursts of rapid brain activity
 Deep relaxation
 Lasts about 20 mins
Stages of sleep
Stage 3. Transitional stage into deep sleep
 Lasts a few minutes
 Low-frequency slow delta waves emerge
 Stage 4. Deep sleep
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All delta waves
Lasts about 30 mins
Difficult to awaken
Brain continues to process stimuli outside of
consciousness
 Certain sounds, monitoring of movement
 REM sleep
REM sleep
Recurring sleep stage with rapid brain waves
Clearly observable signs
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Heart rate increases
Breathing becomes rapid and irregular
Eyes dart around
Sexual arousal even without sexual dreams
REM sleep  Dreams
 Paradoxical sleep”: muscles are relaxed, but
other body systems are aroused
 Brainstem blocks brain’s messages
 If awakened after REM stage, you will
remember dreams
 Vivid, emotional and storylike dreams
 If you are deprived of REM sleep, REM stages
will increase following the period of deprivation
 REM rebound
Stages in a Typical Night’s
Sleep
Awake
Sleep
stages
1
2
3
REM
4
0
1
2
3
4
Hours of sleep
5
6
7
Stages in a Typical Night’s Sleep
Minutes
of
Stage 4
and
REM
Decreasing
Stage 4
25
20
15
Increasing
REM
10
5
0
1
2
3
4
5
Hours of sleep
6
7
8
How much do we sleep?
Newborn babies sleep about 16 hours a day
 Spend more time in REM sleep
Adults (should) sleep about 8 hours a day
Need for sleep varies from person to person
 Genetic effects
 Cultural effects
 If unhindered, most adults sleep for about 9 hours a
night
The brain will keep account of sleep debt for
about 2 weeks
Sleep Deprivation
Lack of sleep may result in...
slowed reaction time, slurred speech, aching
muscles, blurred vision, clinical depression, color
blindness, decreased mental activity, decreased
concentration, decreased ability for the immune
system to fight off sickness, dizziness, fainting,
general confusion, hallucinations,hand tremors,
headache, hypertension/hyperactivity, impatience,
irritability, memory lapses/memory loss,
psychosis, pale skin tone, weight gain...
if takes longer- mental activities may get distorted
permanently
Sleep Deprivation
Less sleep,
more accidents
Accident
frequency
More sleep,
fewer accidents
2,800
2,700
4,200
2,600
4000
2,500
3,800
2,400
3,600
Spring time change
(hour sleep loss)
Monday before time change
Fall time change
(hour sleep gained)
Monday after time change
Golden Rules of Sleep
1. Get An Adequate Amount of Sleep Every Night
At minimum most people need to obtain at least sixty to
ninety minutes more sleep than they presently get.
2. Establish A Regular Sleep Schedule
Your brain does not have a different biological clock for
weekdays and weekends.
3. Get Continuous Sleep
Six hours of good, solid sleep is often more restorative
than eight hours of poor, fragmented sleep. Don't allow
yourself to doze on and off for many hours.
4. Pay back your sleep debt in a timely fashion.
Make up for any lost sleep as soon as possible. Sleep loss is
cumulative. If you lose several hours on a given night, you
will become more and more sleepy in the ensuing days,
even though you get your "normal" sleep. Remember:
 You cannot replace lost sleep at once.
 When you sleep longer to catch up, try to do so by going
to bed earlier than usual.
 You cannot make up for large sleep losses during the
week by sleeping in on the weekends.
 A nap during the day can help you pay back your sleep
debt. The important rule is to return to your regular sleep
schedule as soon as possible.
Reference: http://www.powersleep.org/goldenrules.htm by Dr.
B. James Maas, Department of Psychology at Cornel Univ.
Sleep Disorders
 Insomnia
 Persistent problems in falling or staying asleep, poor
quality sleep
 Seen more in women and elderly
 Narcolepsy
 Uncontrollable sleep attacks (REM sleep) during the day
 Caused by an abnormality in the part of the brain that
regulates sleep & has a genetic component
 Sleep Apnea
 Temporary cessation of breathing during sleep
 Momentary reawakenings
 May be related to weight or upper respiration system
problems. Alcohol and sedatives aggravate the condition
Sleep Disorders
 Night/Sleep Terrors
 mostly affects children
 occur within 2 or 3 hours of falling asleep, usually
during Stage 4
 high arousal-- appearance of being terrified, panic
 seldom remembered
 may indicate extreme anxiety or other psychological
problems
 Nightmares are not sleep disorders, just dreams with
frightening content.
Dreams
Dreams - 6 years of our lives!
 Dreams are sequence of images, emotions, and
thoughts passing through a sleeping person’s mind
 REM dreams are vivid and emotional
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80% are characterized by negative emotions
Most dreams are non-sexual
Most dreams are associated with daily experiences
Dreams can be associated with actual stimuli
 Noise, odor in the sleeping environment
 Non-REM dreams are less frequent and less
memorable.
Why do we dream? DREAM THEORIES
To satisfy our wishes: Freudian Theory of
Dreams
To file memories: Information Processing Theory
of Dreams
To develop neural pathways: Physiological
Function of Dreams
Random neural activity in the brain: Activation
Synthesis Theory of Dreams
Dreams reflect brain maturation: Cognitive
Theory of Dreams
Why do we dream?
Freudian: To satisfy our wishes
 Dreams are where unacceptable emotions are
expressed
 The manifest content may be the acceptable
“censored” version of the latent unacceptable content
 This view is discredited
Information processing: To file memories
 REM sleep promotes memory
 The experiences of the day are replayed during REM
sleep
Why do we dream?
Physiological: To develop neural pathways
 REM sleep stimulates the brain  new neural
pathways
Activation synthesis: to make sense of random
activation of the brain
 During sleep random areas on the cortex and the
limbic system  visual content and emotional content
 Frontal lobe is largely inactive  no inhibition and
logical reasoning
Cognitive: A reflection of brain maturation
 Dreams repeat waking concepts and knowledge
Sleep and Dreams
 Psychologists used to believe that dreaming occurred
infrequently.
 Now they believe that REM sleep and dreaming are biologically
adaptive.
 All mammals experience REM sleep.
 REM rebound
 There is evidence that REM is important for brain maturation.
 In newborns, 50% of sleep is REM sleep
 Later in childhood and adulthood, about 20% of sleep is
REM sleep.
 Sleep facilitates memory.