What is the nature of sleep?
 Most people think of sleep as a state of
unconsciousness, punctuated by brief periods of
dreaming.
Sleep is actually a state of
altered consciousness,
characterized by certain
patterns of brain activity
and inactivity.
Facts about Sleep
 Most adults need seven or eight hours' sleep a night
 A giraffe sleeps for an average of 1.9 hours a day
 A cat sleeps for an average of 12 hours a day
 Famous figures like, Margaret Thatcher, Napoleon and
Florence Nightingale only needed four hours
 An adult sleeping for eight hours will burn
approximately 50 calories
 Almost two thirds of the population claim they do not
get enough sleep
Why do we sleep?
 While the exact function of
sleep is unknown, but
according to the evolutionary
theory, sleep evolved to
conserve energy and protect
us from predators.
 According to the
repair/restoration theory,
sleep is thought to be
necessary for
restorative/healing value,
both physically and
psychologically.
Loss of Sleep…
 suppressed immune system
 impaired creativity and
concentration
 slowed performance and
misperceptions on
monotonous tasks
Benefits of Sleep
 restoration of energy
 repairing of brain and body
tissue
 release of growth hormones
Stages of Sleep
 Each night, we go through
four to five cycles of
distinct sleep stages.
 Each stage has its own
rhythm and corresponding
changes in brain activity
and behavior.
 The average person
progresses through the
stages of sleep 3 to 6 times
per night.
http://educationportal.com/academy/lesson/sleepcycle.html#lesson
Stage 0
 This period of falling asleep is also called the hypnagogic
state. (hip-na-gog-ic)
 relaxed with eyes closed
 brain briefly emits alpha waves = associated with
absence of concentrated thought and relaxation
Stage I
 sensory images and slow rolling eye
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movements
theta waves on an EEG-- lower in
amplitude and frequency than alpha
waves
pulse slows more, muscles relax,
breathing uneven
If awakened during this stage, you would
report that you were “just drifting.”
Lasts from 30 seconds to about 10 mins.
Stage II
 Brain waves shift from low-frequency
waves to high frequency waves
 Eyes roll slowly from side to side
 About 50% of our sleep time is in stage II
Stage III
 About 30 minutes into sleep= drift down
into a deeper level of sleep
 larger-amplitude delta waves begin to
sweep your brain every second or so
Stage IV
 Deepest sleep of all
 Often difficult to wake
 Large, regular Delta Waves occurring
more than 50% of the time
 If awakened by a loud noise = may feel
disorientated
 Talking out loud, sleepwalking, and bedwetting—all of which may occur at this
stage—leave no trace on the memory
Rapid Eye Movement =REM sleep
 muscles are more relaxed, eyes begin to move rapidly
 pulse rate becomes irregular
 levels of adrenal and sexual hormones in blood rise
 face or fingers twitch
 large muscles in your arms and legs are paralyzed
 brain shows waves that closely resemble those of a person
fully awake = REM sleep is called active sleep
Stages of Sleep--REM
 Stages I-IV are called NREM (non-
REM) or quiet sleep.
 It is during REM sleep that almost all
dreaming normally takes place.
 REM sleep lasts about 15-45 minutes
after which you retrace the steps to
Stage IV.
Sleep Disorders: When Sleep
Becomes a Problem
Are you one of those lucky people who takes sleep
for granted? If so you may be surprised to discover
the following facts:
•An estimated 2/3 of adults suffer from sleep problems
and about 25 percent of children under age 5 have a sleep
disturbance
•One in five adults is so sleepy during the day that
sleepiness interferes with their daily activities.
•Each year [Americans] spend more than $98 million on
over-the-counter sleep aids and another $50 million on
coffee to keep them awake during the day.
Sleep Disorders: Dyssomnia &
Parasomnia
 Psychologists divide sleep disorders into two major
diagnostic categories:
 1) Dyssomnias: problems in the amount, timing, and
quality of sleep
 2) Parasomnia: abnormal disturbances occurring
during sleep
Sleep Disorders:
Dyssomnia
 Insomnia:
 “lack of sleep”
 persistent difficulty falling asleep or staying asleep, or wake
up too early
 10% of the population
 serious insomnia = other medical or psychological
disorders also (alcohol and other drug abuse, anxiety
disorders, and depression)
 most popular treatment = drugs—either over the counter
pills or prescription tranquillizers and barbiturates (which
decrease Stage 4 and REM sleep therefore affect the quality
of sleep)
Sleep
Disorders:
Dyssomnia
 Sleep Apnea:
 “no breathing”
 repeated interruption of breathing during sleep
 air passages to the lungs are physically blocked or the
brain stops activating the diaphragm
 may kill neurons in the brain critical for learning and
memory
 can also lead to high blood pressure, stroke, heart
attack
Sleep Disorders:
Dyssomnia
 Narcolepsy:
 sudden and irresistible onset of sleep during normal
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waking hours
afflicts one person in 2000
runs in families
REM-like sleep suddenly intrudes into the waking
state of consciousness
sudden attacks of muscle weakness or paralysis
Long daily naps and stimulant or antidepressants may
help reduce the frequency
Sleep Disorders:
Parasomnias
 Nightmares: Anxiety-arousing dreams generally occurring
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near the end of the sleep cycle, during REM sleep
Night Terrors: Abrupt awakenings from NREM (nonrapid-eye-movement) sleep accompanied by intense
psychological arousal and feeling panic
Sleep walking: Tends to accompany night terrors also
occurs during NREM sleep.
Sleep talking occurs in REM and NREM sleep
These events are more common in children, but they
can also occur in adults, usually during times of stress
or major life events.
Help with Sleep Disorders
During the Day:
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Exercise—it works away tension
Avoid Stimulants—coffee, tea, soft drinks, chocolate
Avoid Late Meals & Heavy Drinking
Stop Worrying—focus on problems at a set time earlier in the
day
 Use Pre-sleep Rituals—follow the same routine every night
In Bed:
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Use progressive muscle relaxation-tense and relax muscle groups
Yoga-type gentle exercises to help relaxation
Imagine yourself in a tranquil setting
Use deep breathing
Warm bath or shower can induce drowsiness
Psychoactive Drugs Overview:
 http://education-
portal.com/academy/lesson/psychoactivedrugs.html#lesson