The document discusses sleep and wakefulness from a neurological perspective. It describes how sleep is a brain process characterized by different stages, including non-REM sleep (NREM) and REM sleep. NREM and REM sleep can be measured using electroencephalography (EEG) brain wave patterns. Factors such as age, circadian rhythms, homeostasis, and the autonomic nervous system regulate sleep-wake cycles.

1. SLEEP
Dr. Reem Al-Sabah
Psychology 220
Faculty of medicine

2. Sleep and Wakefulness
What are the similarities between sleep and
wakefulness?
 We think while awake and during sleep
(dreaming indicates that we think when we
sleep).
 We form memories while awake and while we
sleep (the fact that we can remember our
dreams).

3.  People who are asleep may be sensitive to their
environment (e.g., parents awakened by their
baby’s cry; some people walk in their sleep).
 Abe to plan ahead (deciding to and actually
waking up at a particular time).

4. The Basics of Sleep
 Sleep is universal and essential for survival.
 Three basic characteristics of sleep:
1. Sleep is a brain process
2. It is a active process
3. It is not a single process

5. Measuring Brain activity
 Because sleep is a brain process it is commonly
studied by recording brain electrical activity.
 Electroencephalogram (EEG) is the graphic
recording of the electrical changes (or brain
waves) produced by the electrodes placed on the
scalp.

7.  Electroencephalography (EEG) activity is
characterized by both frequency and amplitude of
the brain waves.
 Frequency: how many times the waves appear
per second [cycles per second (cps); or hertz
(Hz)]
 Amplitude: how high the waveform is on the
paper tracing [measures in microvolts (μV)]

8. EEG Activity
 Generally divided into four categories according to
ranges of frequency from slowest to fastest:
1. Delta waves: 0.5-3 Hz (cycles per second)
2. Theta waves: 4-7 Hz
3. Alpha waves: 8-13 Hz
4. Beta waves: 14-25 Hz
 Analysis of the pattern of brain waves suggests there
are 5 stages of sleep.

9. Stages of Sleep
 Stage 1
 Stage 2
 Stage 3 [NRM sleep]
 Stage 4
 REM (Rapid Eye Movement)

10. Description of the Stages of Sleep
When awake, most people exhibit brain wave, EEG
patterns that can be classified into:
 Beta waves (14-25 hertz)
 Awake stage (day to day wakefulness)
 highest in frequency and lowest in amplitude, and
also more desynchronous than other waves (not very
consistent in their pattern)
 Alpha waves (8-13 hertz)
 During periods of relaxation, while still awake, our
brain waves become slower, increase in amplitude
and become more synchronous.

11. Stage 1 sleep
 Light sleep, lasts about 5 minutes.
 Body temperature begins to drop, muscles become
relaxed, eyes move slowly from side to side, but easily
jarred into wakefulness.
 Brain waves less regular, reduced amplitude
 theta waves (4-7 Hz): which are even slower in
frequency and greater in amplitude than alpha
waves.
 The difference between relaxation and stage 1 sleep
is gradual and subtle.
 Low amplitude = increased cerebral activation

12. Stage 2 sleep
 First stage of established sleep.
 Lasts 10-20 minutes (first time it occurs).
 Eyes still, heart rate and breathing slower than
when awake, irregular brain activity.
 Overall, about ½ the night is spent in stage 2 sleep.

13.  theta wave activity continues interspersed with
two unusual wave phenomena which occur
approximately every minute.
 Sleep spindles: a sudden increase in wave
frequency
 K-complexes: a sudden increase in wave
amplitude.
 Stages 1 and 2 are relatively "light" stages of
sleep. Person will often report not being asleep
at all.

14. Stage 3 and 4 sleep
 Slow waves, 1-2 Hz- Delta waves.
 Delta waves are the slowest and highest
amplitude brain waves.
 There is no real division between stages 3 and 4.
 Stage 3 is considered delta sleep in which less
than 50% of the waves are delta waves.
 stage 4 more than 50% the waves are delta
waves.

15.  Delta sleep is our deepest sleep, the point when
our brain waves are least like waking.
 It is most difficult stage in which to wake sleepers,
and when they are awakened they are usually
sleepy and disoriented.
 Delta sleep is when sleep walking and sleep
talking is most likely to occur.
 Deeper stages of sleep (3 and 4) occur at the
beginning of the night.

16. REM Sleep (Rapid Eye Movement)
 Characterized by a sudden and dramatic loss of
muscle tone (the skeletal muscles of a person during
REM sleep are effectively paralyzed).
 A sleepers brain waves demonstrate characteristics
that are similar to waking sleep, a combination of
alpha, beta, and desynchronous waves.
 This is the stage of sleep most associated with
dreaming.
 REM becomes more prominent in the second half of
the night.
 Usually four or five REM periods in an 8-hour night.

17. REM Sleep (Cont.)
 In REM sleep, sensory stimuli do not reach the
brain and there are no motor outputs.
 Areas of the brain involved in the processing of
emotional memories show increased activation.
 80% of people who wake up during REM sleep
will report having a dream (visually vivid with
emotional and illogical features, like what we
typically associate with “dreams”).

18.  If you wake up during NREM sleep you will
remember your dream(s) about 50% of the time
(dreams not as vivid as in REM sleep, they are
more directly related to events in your life).
 The longer the period of REM sleep, the more
elaborate the reported dream.

19. EEG Recordings

20. Stage Description Frequency
1. day to day 1. Beta waves 14-25 Hz
Awake wakefulness. 2. Alpha waves 8-13 Hz
2. Wakeful relaxation
with eyes closed
Stage 1 “light sleep” Theta waves 4-7 Hz
Stage 2 “light sleep” Theta waves 4-7 Hz
sleep spindles and
K-complexes
Stage 3 “deep sleep” Delta waves 0.5-3 Hz
(slow wave sleep)
Stage 4 “deep sleep” Delta waves 0.5-3 Hz
(slow wave sleep)
REM sleep Associated with combination of alpha, beta,
dreaming and desynchronous waves.

21. Sleep Architecture

22. Sleep and Age
Childhood
 Newborns typically spend 70% of each day asleep.
 Newborns spend more time in REM sleep than
children and adults.
 The percentage of REM sleep declines until
adolescence and then stabilizes at adult levels.
 A circadian pattern of wake and sleep at 1-2
months (rhythmic melatonin secretion identifies at
12 weeks).
 Sleep continues to be polyphasic with decreasing
amounts of daytime napping until age 4 or 5 years.

23.  From ages 5-10 years, children are usually
good sleepers with few arousals.
 Total sleep time usually decreases throughout
childhood.
 However, amount and quality of sleep drops
sharply with puberty (due to hormonal and
psychosocial reasons)

24. Old Age
 Sleep becomes lighter with more and longer
nighttime awakenings.
 Near disappearance of deep or slow wave
sleep.
 REM sleep drops to 18% or less in old age.

25. NREM Sleep REM Sleep
Quiet sleep Dreaming sleep
Almost no eye Very rapid eye movements
movements
Decrease heart and Increased heart rate
breathing rates
Muscles relaxed Almost paralyzed (except for
heart, diaphragm, eye
muscles, smooth muscles)
Decrease in brain’s Increase in brain’s metabolic
metabolic rate(approx. rate
30%)
Inactive brain in a very Awake brain in a paralyzed
relaxed body body

26. How is Sleep Regulated?
1. Autonomic Nervous System Balance
 Sleep is associated with an overall change in ANS
balance toward parasympathetic dominance.
 Increases in sympathetic activity may disturb
sleep
 Endogenous causes
(fear, anxiety, worry, muscle tension , pain)
 Exogenous causes
 (stimulant drugs, excessive heat,
sudden/intrusive noise)

27.  Two important characteristics of ANS activity
relative to sleep disruption:
1. Classical conditioning of autonomically
mediated responses.
(e.g., if the bed is repeatedly associated with
frustrating and unsuccessful attempts to sleep,
insomnia may become conditioned).
2. The long refractory period following
sympathetic nervous system activation.
(e.g., once sympathetic arousal has occurred, it
may take a while before the sleep-promoting
autonomic balance returns).

28. 2. Homeostatic Drive for Sleep
 Prolonged sleepiness produces sleep debt.
 The longer individuals remain awake, the
sleepier they become.
 Homeostatic mechanisms help regulate both
sleep in general and the specific stages of sleep.
 When one is deprived of REM sleep, an “REM
debt” accrues. When a person then sleeps REM
sleep rebounds above normal levels. (similar
findings found in SWS deprivation).
 Thus, there are specialized functional brain
requirements for different types of sleep.

29. 3. Circadian Rhythm
The clock-dependent alerting process: the
process in the brain that arouses us at a particular
time each day.
 Controlled by the ‘biological clock’ in the center
of the brain.
 This clock controls the circadian rhythms, which
are rhythms of the body (psychological and
physiological changes, as well as rhythms of
alertness) that occur approximately every 24
hours.
 The biological clock is affected by exposure to
light: Daylight signals it to stop production of
melatonin (a hormone that induces sleep)

30. Sleep Theory
Why are we awake and asleep at different
times?
 Opponent-process model of sleep and
wakefulness (Edgar & Dement, 1992): The brain
possesses two opponent processes that govern
the tendency to fall asleep or remain awake.

31.  These two opponent processes interact to
produce our daily cycle of sleep and
wakefulness.
 The relative strength of these two processes
determines whether we are awake or asleep.
 During the day, process #3 usually stronger than
process #2.
 Late at night, the biological clock becomes
inactive and we fall asleep.

32. Common Types of Sleep
Disorders

33. Sleep Disorders
 About 90% of adults sleep between 6-9 hours per
night.
 Most adults require 71/2 - 8 hours of sleep to not
feel sleepy during the day.
 Sleep disorders are often associated with medical
conditions, substance use, environmental factors,
emotional disorders, or stressful life events.
Sleep Disorder: occurs when the inability to sleep
well produces impaired daytime functioning or
excessive sleepiness.

34. Deprivation
 Most people occasionally deprive themselves
of adequate sleep.
 Fatigue and sleep deprivation can be the
cause of many types of accidents.
 Loss of as little as an hour of sleep increases
likelihood of inattentiveness, mistakes, illness,
and accidents.

35.  Common sign of sleep deprivation:
the inability to get through the day without a
temporary loss in energy and alertness,
usually occurring in mid-afternoon .
(this is not due to eating a heavy meal, sitting
in a warm room, or listening to a boring
lecture)

36. Insomnia
 A complaint of poor quality, insufficient, or
nonrestorative sleep.
 Difficulty falling asleep,
 Difficulty getting back to sleep during the night
 Inability to return to sleep
 Although a real condition, it can be a subjective
matter.
 People seem to overestimate the amount of sleep
lost.

37. Narcolepsy
 Relatively rare sleep disorders.
 Narcolepsy
 chronic neurological disorder caused by the brain's
inability to regulate sleep-wake cycles normally.
 Recurring irresistible attacks of drowsiness with the
likelihood of falling asleep anytime.
 Episodes may occur anytime several times a day
lasting from a few seconds to 30 minutes.
 It is the intrusion of REM episodes into the waking
hours.
 Runs in families.

38.  Sleepiness is associated with 3 other symptoms
(the narcolepsy tetrad)
1. Cataplexy: a sudden decrease in muscle tone
when awake, often triggered by strong emotion or
surprise.
2. Hypnagogic or Hypnopompic hallucinations:
vivid visual images or sounds that occur as the
person is either falling asleep or waking up from
sleep
3. Sleep paralysis: as a sleeper is awakening and
normal inhibition of muscle tone during REM sleep
fails to end when the sleeper becomes awake.
 All three represent a failure of the neural
mechanisms that keep the REM sleep state
separate from the waking state.

39. Apnea
 the individual stops breathing while asleep
 May be due to:
 Failure of the brain to send “breathe” signals to
the diaphragm and other breathing muscles,
thus stopping breathing.
 Muscles at top of throat become too relaxed,
allowing the windpipe to partially close, forcing
breathing muscles to pull harder on incoming
air, causing the airway to completely collapse.

40. Sleep-Wake Schedule Disorders
 Jet Lag: results from rapid changes in time zone
due to transmeridian travel.
 Symptoms: insomnia, fatigue, gastrointestinal
complaints.
 Which is easier to adjust to: west-bound or east-
bound travel?
 Shift Work: an acute change in work schedule.
 Symptoms: insomnia, mood changes, GI
complaints.

41.  Delayed Sleep Phase Syndrome: is the inability to
both fall asleep and wake up at desired times
consistent with societal norms.
 Suffer from sleep-onset insomnia.
 Symptoms: grogginess in the morning, irritability.
 Best functioning is in the early evening.
 Advanced Sleep Phase Syndrome: is the inability
to stay awake in the evening and stay asleep in the
early morning.
 Suffer from sleep-maintenance insomnia.
 May become sleep deprived from postponing their
bedtime while still being unable to sleep later in the
morning.

42. Sleep Hygiene
www.sleepasssociation.org
 Maintain a regular sleep routine
 Avoid naps if possible
 Don’t stay in bed awake for more than 5-10 minutes.
 Don’t watch TV or read in bed.
 Do not drink caffeine inappropriately
 Avoid inappropriate substances that interfere with sleep
 Exercise regularly
 Have a quiet, comfortable bedroom
 Have a comfortable pre-bedtime routine (a warm bath,
shower, Meditation, or quiet time).