Characteristics of Altered States of
Consciousness
Characteristics of Altered States of
Consciousness


Most people spend about two thirds of the
day in normal waking consciousness.
When a person notices their level of mental
functioning changing they are usually
entering an altered state of consciousness.
Altered States of Consciousness

The term altered state of consciousness
refers to any state of consciousness which is
distinctively different in level of awareness
and experience from NWC, in terms of level
of awareness and experience, the quality and
intensity of sensations, perceptions, thoughts,
feelings, and memories that are experienced.

In an ASC mental processing shows distinct
changes specific to that particular state.
Altered States of Consciousness

Some ASC’s are natural – sleep & dreaming

Others are purposely induced – meditation, hypnosis,
drug taking

Humans induce ASC for relaxation, therapy, or escapism
from pressures in their lives
Common characteristics of ASC’s:
-Distortions of perception & cognition,
-Disturbed sense of time,
-Changes in emotional feeling, changes in self control

1. Distortions in perception and
cognition
An ASC seems to have two effects on the senses- it either
makes them more receptive or dulls them so that some
sensations are not experienced at all.
Some drugs heighten sensory experience ie, colours seem
brighter, tastes and smells stronger, sounds louder or more
variable, and touch more sensitive, whereas meditation can
dull our experience of pain.
Distortions in perception

Perceptions are often so distorted in an ASC
that people may lose their sense of identity
(who they are) or experience the feeling of
being outside their body or someone else
entirely. This can occur with the use of the
drug Ketamine.
Ketamine & Out of body Experiences

What Is Ketamine?
Ketamine is an anesthetic used on both
animals and humans; it also has been used
in human medicine for pediatric burn cases
and dentistry, and in experimental
psychotherapy. It is being abused by an
increasing number of young people as a "club
drug," and is often distributed at "raves" and
parties.
Distortions in Cognition
Thought processes are often more disorganised
during a waking ASC, as well as during dreaming.
 In an ASC:
-thinking is often illogical and lacking in sequence
-difficulties may be experienced in problem-solving
-people may have trouble remembering events that
have occurred in an ASC.
 When consuming alcohol people are often unable to
recall the events that occurred while intoxicated.
 Marijuana use can also impair short term memory
and thinking.

Meditation & Cancer

Meditation
specialists
believe
visualisation
and guided
meditation
can help
cancer
sufferers
gradually
remove
cancer.
2. Disturbed sense of time



Estimation of time is frequently distorted in an
ASC
Time passes at a different speed than normal
Either faster – Eg sleeping for 8 hours and it
feels like 30 mins or vice versa
Think…

Have you ever seen a person under the
influence of alcohol or drugs, who has shown
completely different emotional responses that
they normally would?
3. Changes in emotional awareness


ASC’s can put peoples emotions into a state
of turmoil resulting in uncharacteristic
responses
Eg. Under the influence of alcohol some
people display their feelings/emotions more
freely while others can become quite
aggressive

In other ASC’s people have reported feeling
emotionless; that is having no feelings at all.

In some ASC’s people may have
inappropriate emotional reactions. Eg.
laughing at hearing the news of a friends
death or crying at a joke.
Think!

Have you ever witnessed someone under the
influence of alcohol or drugs who has shown
a complete lack of self control?
4. Changes in self-control

Changes in our ability to maintain self-control
are often evident during ASC’s

Eg. In an alcohol induced state people may
have difficulty coordinating and controlling
movements (stumbling).

In a hypnotic state, some people are more
open to suggestion.
STATES WITHIN ALTERED
STATES OF CONSCIOUSNESS
Daydreaming




Daydreaming is an ASC in which we shift our attention
from external stimuli to internal, thoughts, feelings and
imagined scenarios.
The shift occurs naturally and usually without being
aware.
More likely to occur when you are stationary than when
you are moving around.
Different from a night dream physiologically- minimal eye
movement and alpha waves present.
Daydreaming

-
-
-
There are many proposed purposes for daydreaming
such as:
Freud believed it was to allow us to do in our fantasies
what we are unable to do in reality.
Singer (1975) proposed that daydreaming enables us to
mentally try out a range of courses of action that could
be applied to certain situations.
He also suggested it can help us to solve problems.
Some suggest we daydream to stay mentally alert in
situations in which there is insufficient external
stimulation.
Alcohol-induced state
What is alcohol?
Usually refers to drinks such as beer, wine or
spirits containing ethyl alcohol- a substance
that can cause drunkenness and changes in
consciousness, mood and emotions.
Ethyl alcohol requires no digestion and seeps
into the bloodstream via the gastrointestinal
tract.




Alcohol is considered a psychoactive drug.
These are chemicals that change conscious
awareness, perception or moods.
Alcohol is also classified as a depressant
meaning that although it initially produces a
mild euphoria, it lessons our inhibitions and
depresses the activity of the brain centers.
Effects depend on the concentration of
alcohol consumed, the amount, and variables
related to the individual.
The effects of alcohol on consciousness:
a shortened attention span
 impaired perceptions
 impaired thinking
 impaired memory
 slower reaction times
 reduced self-awareness
 impaired emotional awareness
 impaired perception of time
 less self-control
 difficulty with voluntary muscle control and fine movements
 deterioration in performance of complex tasks
Table 2.4 pg 120

Practising meditation


The experience of pain is less intense and
meditation can provide relief from pain in
some cases.
Brainwaves experienced in meditation are
similar to those people experience when
falling asleep or when they are actually
asleep.
Meditative state



Many forms such as yoga, Zen and transcendental
meditation each of which has its basis in Eastern
religion like Buddhism and Hinduism.
Meditation involves the use of a technique to
deliberately alter NWC in order to induce an ASC
characterised by a deep state of relaxation.
It typically involves altering the normal flow of
conscious thoughts by focusing on a simple
stimulus like breathing or a body part.
Measuring states of consciousness
Can you think of how we
measure states of
consciousness?
Measuring physiological responses of
consciousness

A state of consciousness cannot be measured
directly like physical characteristics.

It is because of this that it is called a psychological
construct.

A psychological construct is a concept used to
describe something that is believed to exist, but that
cannot be directly observed or measured.
Measuring states of consciousness

1. Self-report: limited because subjective:
individuals may



be dishonest,
struggle to articulate,
forget details
2. Behavioural observations: limited because
can’t observe inside the body
Measuring states of consciousness
SO! Psychologists usually rely on measuring…

3. Physiological responses: Useful as objective. Limited:
may indicate illness or multiple ASCs




Heart rate: ASC usually ↓, e.g. sleep; can ↑, e.g. stimulant drugs
GSR: positive correlation with arousal
Body temperature: drops ~1°C during sleep, high temps (e.g.
fever) can induce ASC
EEG: electrical activity within the brain is graphed
1. EEG
Electrical Activity of the Brain
Brain wave patterns
form EEG readings.
Vary in:
Frequency – brainwaves
per second
Amplitude – size of the
peaks and troughs

High Frequency
Low Amplitude
Electrical Activity of the Brain
The size and number of brain waves change with different states of
consciousness:

Normal waking consciousness – Beta waves: High frequency,
Low amplitude (Ie. Lots of waves but not very high)

Extremely relaxed – Alpha waves: High Frequency, Larger
amplitude

Early stages of sleep – Theta waves: Medium frequency, Some
high amplitude

Deep Sleep – Delta waves: Low Frequency, High amplitude
Remember!
B
(wide awake)
A
T
D
(fast asleep)
Remember!
Beta: Busy Brain – awake & alert
Alpha: Almost Asleep – resting
Theta: They’re asleep
Delta: Deep Sleep – also know as
slow wave sleep
Brain Waves Patterns
2. Heart Rate

May increase or decrease in an ASC.

While a person is asleep, unconscious or
meditating, heart rate is likely to decrease.

When a person is experiencing ASC’s
associated with the use of substances that
are stimulants, heart rate is likely to increase.
3. Body Temperature

Body temperature is less variable than heart
rate; however there is a general pattern
indicating changes in body temperature in
altered states.

The most obvious change is during sleep;
body temperature drops by more than 1°C
while asleep.
4. Galvanic Skin Response

The theory is that; the
more relaxed you are
the dryer your skin is
and so the higher the
skins electrical
resistance. When you
are under stress your
hand sweats and then
the resistance goes
down.
3. Galvanic Skin Response

The galvanic skin response is a physiological
response that indicates the change in the resistance
of the skin to an electrical current.

Electrical conductivity increases as physiological
arousal increases.

To measure the GSR electrodes are attached to the
finger or the palm of the hand as these areas have
less hair.

The electrodes enable detection and measurement
of how easily the electrical current passes through
the skin.

Changes in the GSR are closely associated with
emotional experiences.

An individual may show high arousal (and thus less
resistance) when stressed in an exam (NWC) or
when on drugs (ASC). Thus, GSC can not be used
solely as an indication of what state of
consciousness a person is in.

Using one form of measure can be
misleading as anxiety or illness can change
the measure and may not reflect the actual
state of consciousness. Experts therefore use
a number of measures at one time including
self reports.
ASC: Sleep
Sleep is studied in a sleep lab
Sleep

During the altered states of consciousness associated
with sleep, our awareness and our perception of
ourselves and the events occurring around us differ
from when we are awake and in a state of normal
waking consciousness.

Just as there are different levels of awareness within
NWC, when we sleep we also experience different
states of consciousness.

Eg. When we dream while asleep we experience a
distinctly different state of consciousness than that of
when we are asleep but not dreaming.
Sleep

Sleep can be described as a regularly
occurring altered state of consciousness that
typically occurs spontaneously and is
primarily characterised by a loss of conscious
awareness.

Although sleep usually occurs naturally it can
sometimes be induced.
Sleep

Over a lifetime we spend about one third of
our time asleep.

If we live to around 75 years of age we will
spend about 25 years of that sleeping.
Methods used to study sleep

Most sleep research takes place in sleep
laboratories.

These are often attached to hospitals.

The ‘bedroom’ is attached to a control room
where the researchers will observe and
monitor sleep patterns throughout the night.
Methods used to study sleep



Research participants go to sleep at their normal
time and follow their normal routine before going to
bed.
The laboratory is fitted with devices to monitor and
record various physiological responses of the
sleeper during the course of the night.
This is often called polysomnography.
Polysomnography is an intensive study of a
sleeping person involving simultaneous monitoring
and recording of various physiological responses of
the sleeper during the course of the night.
Methods used to study sleep

-
The main sources of data that provide
information about a persons sleep patterns are:
Electrical activity of the brain
Information about eye movements
The body’s muscle tone or tension
Heart rate
Body temperature
Respiration
Video monitoring
Self-reports
Ways to study the physiology of sleep:

EEG: electroencephalogram:
Record of changes in electrical potential in
the brain.

EMG: electromyogram: record of muscle
tension beneath the chin.

Electro-oculogram: record of spontaneous
eye movement.
Ways to study sleep
Electro=electrical impulse
Gram=graph
Each detects, measures, amplifies and records
electrical activity in graph from.
 EEG: electroencephalogram
halo=head=brain activity
 EOG: electro-oculargram
Each term has
same start
Ocular=optic=eye movement
and end.
 EMG: electromyogram
Use middle
Myo=muscle activity
as cue.
EEG patterns during sleep
An electroencephalograph (EEG) is a device that detects, amplifies
and records the electrical activity that is spontaneously generated by
the brain.
EEG recordings show that as a person falls asleep, and throughout a
typical sleep period, the brain produces distinguishable patterns of
electrical activity called brain waves.
EEGs discussed in terms of:

Amplitude – height or size of wave

Frequency –number of waves per second
EMG patterns during sleep

The electromyograph (EMG), is a device used to
detect, amplify and record the electrical activity of
muscles.

EMG recordings generally show the strength and
electrical activity occurring in the muscles, which
indicates changes in muscle activity (movement) and
muscle tone (tension).

This information is obtained by attaching electrodes to
the skin above the particular muscles whose activity is
being monitored.
EMG patterns during sleep

These records are displayed as line graphs.

Similar to the EEG recordings, EMG records
show that there are identifiable changes in
muscular activity during the course of a
typical night’s sleep.

Eg. There are periods of time when our
muscles are very relaxed whereas at other
times our muscles go into spasm.
EOG patterns during sleep



The electro-oculargram (EOG) is a device for
measuring eye movements or eye positions by
detecting, amplifying and recording electrical
activity in eye muscles that control eye
movements.
The records of the EOG are also recorded on a
line graph.
They have lead psychologists to clarify the
difference between two main types of sleep
pattern- rapid-eye movement sleep and nonrapid-eye movement sleep.
Heart rate and core body temperature


Both heart rate and core body temperature
gradually drop as we progressively drift from
lighter sleep to deeper sleep and then gradually
increase as we come out of deeper sleep into
lighter sleep.
Unlike body temperature, there can be sudden
and quite dramatic changes in heart rate. These
are commonly associated with dreaming, or
sleep phenomena like nightmares and night
terrors or sleep disorders like sleep apnea.
Video monitoring



Most sleep labs are also fitted with video
monitoring to observe any external
physiological changes.
These use modern technology to film in low
light and allow researchers to replay and
analyse sleep behaviour.
This is particularly useful with participants
who have a serious sleep disorder.
Self-reports
Most commonly sleep diaries and questionnaires.
 A sleep diary is a self-reported record of an individuals
sleep and waking time activities, usually over a period of
several weeks.
 Things that are usually recorded include:
- The time when trying to fall asleep
- The time when sleep onset occurred
- The number, time and length of awakenings
- The time of waking up
- The time of getting up
Other inclusions may be naps, alcohol consumption,
caffeine, and use of medication, meal times and exercise.

Characteristics of sleep:

The use of EEG, EMG and EOG measures in
human sleep research has lead to a universally
agreed classification of sleep into distinct stages.

Stages 1-4 are characterised by different depths of
sleep and are known as non- rapid eye movement
sleep (NREM).

A 5th stage is characterised by short bursts of rapid
eye movements and is know as rapid eye movement
sleep (REM sleep)
Characteristics of patterns of sleep

Over the course of a typical night’s sleep we
experience two distinctly different states, or types of
sleep known as NREM sleep and REM sleep.

These occur in continuous cycles, with one following
the other.

In adults one cycle of NREM sleep lasts for about
70-90 minutes, and consists of four distinct stages,
each of which can be identified by a different brain
wave pattern.
Characteristics of patterns of sleep

A period of REM sleep follows each period of NREM
sleep.

Therefore NREM is sometimes referred to as the
fifth stage of sleep.

A complete sleep cycle consists of a period of
NREM sleep (but not necessarily all four stages)
and a period of REM sleep (which tends to increase
in duration as the night progresses).

Generally a complete sleep cycle lasts about 80-120
minutes, and we go through this cycle about four or
five times during eight hours of sleep.
NREM sleep

Approximately 80% of our sleep time is spent in
NREM sleep, and typically the first half of the night
has more NREM than the second half.

During NREM sleep the brain is active (but not as
active as during REM sleep or NWC).

NREM sleep consists of 4 different stages.

When we first close our eyes and begin to relax our
brain emits a burst of alpha waves.
Falling asleep

Alpha wave patterns are associated with relaxation and
drowsiness.

They produce a pattern of relatively high frequency and
medium amplitude waves.

The transition of being awake to being asleep is known as a
hypnogogic state and is characterised by slow rolling eye
movements.

During this stage people may experience:
Flashes of light
Feelings of floating or weightlessness
Dreamlike images
Jerky movements
-
NREM stage 1

Stage 1 occurs when we drift in and out of a true
sleep state.

Physiological changes include:
Decrease in heart rate
Decrease in respiration
Decrease in body temperature
Decrease in muscle tension
-

A hypnic jerk may be experienced in which the body
seems to go into spasm or jerk.
NREM stage 1

The EEG patterns will show a decrease in alpha
waves and these will be replaced by the more
irregular theta waves. (Theta waves- mixture of high
and low amplitude).

Stage 1 lasts for around 5-10 minutes

If we are woken during this stage, we may feel as if
we have not slept at all.
NREM stage 2

Stage 2 is a light stage of sleep.

It lasts for around 10-20 minutes.

Physiological changes:
Body movements lessen
Breathing becomes more regular
Blood pressure and temperature continue to fall
Heart rate is slower
-
-
NREM stage 2

Brain waves are mainly theta waves, but slightly lower in
frequency and higher in amplitude than the theta waves
produced in stage 1.

During stage 2, brief bursts of higher frequency brain wave
activity called sleep spindles periodically appear on the EEG
reading.

Sleep spindles last for about 1 second and indicate that the
person is truly asleep.

EEG patterns also show bursts of low frequency and high
amplitude waves, called k complexes in response to
arousing stimuli.
NREM stage 3

Stage 3 is the start of the deepest period of sleep.

Lasts for about 10 minutes

-
Physiological changes:
Body movements lessen
Breathing continues to be slow and steady
Blood pressure and temperature continue to fall
Heart rate is slower
-
The individual is extremely relaxed.
-
NREM stage 3

In this stage people are difficult to arouse

During stage 3 there is a reduction in the brain’s
electrical activity, and delta waves begin to appear in the
EEG reading.

The presence of delta waves marks the beginning of
slow wave sleep (SWS) so called because of the slower
frequency delta waves.

Generally we begin SWS within an hour of falling asleep,
and remain in it for around 30 minutes.
NREM stage 4

Stage 4 is the deepest stage of sleep.

Physiological signs:
Muscles are completely relaxed and we barely
move.
-

Delta waves dominate the EEG patterns and are
even slower and larger than in stage 3.

A person in this stage is very difficult to wake.
NREM stage 4

People who wake up in this stage may take up to 10
minutes to orient themselves and may be mentally
confused.

Psychologists use the term sleep inertia when
referring to this mental lag.

In the first cycle of sleep a person may spend up to
20 minutes in stage 4, however as the night
progresses less time is spent in stage 3 and 4. In
those cycles close to the morning there may be no
time spent in these stages.
NREM stage 4

It is during this stage of sleep that sleep phenomena
such as sleep walking, sleep talking and night
terrors may occur.

The progression through NREM sleep from stage 14 takes about 45-60 minutes before we
progressively move back up through stages 3, 2,
and then 1.
REM sleep

REM sleep is a period of rapid eye movement sleep
during which the eyeballs rapidly move beneath the
closed eyelids.

EEG patterns show irregular waves consisting of low
amplitude, relatively high-frequency beta waves like
those produced in alert wakefulness.

The body’s internal functioning is more active during
REM sleep than during NREM sleep.
REM sleep

-
-

Physiological changes:
Heart rate is faster and more irregular
Blood pressure rises
Breathing is quicker and more irregular
Most muscles are limp except for the occasional
twitch or jerk
REM sleep is sometimes called paradoxical sleep
because internally the brain and body are active but
the body appears calm and inactive.
REM sleep

One explanation for this paralysis is so that we are
unable to act out our dreams.

It is in REM sleep that most dreaming occurs.

We all dream several times a night even if we do not
remember dreaming.

Dreaming also occurs during NREM sleep but the
dreams are less frequent, less memorable, less vivid
and less fragmented that those of REM sleep.
REM sleep

-
-

Some suggestions about the reasons for REM
sleep:
REM sleep may assist in consolidating new
memories in the brain
Probably serves an important biological need
Throughout the night we pass continuously through
NREM and REM sleep cycles, with REM periods
lengthening and occurring closer together as the
night progresses.
Sleep patterns summary

Awake
EEG: beta waves: high F, low A

NREM Stage 1 (drowsy)
EEG: alpha waves: mid-high F, mid-low A
EMG: Reduction in muscle tension (but muscles still
active)
Other sign: hypnic jerk
EOG: May be slow, rolling movements
Sleep patterns

NREM Stage 2 (light sleep)
EEG: theta waves = low F, mixed A.
Sleep spindles (burst of high F)
K complexes (burst of high A).
EMG: Medium Activity
EOG: No movement

NREM Stage 3 (sleep)
EEG: theta & delta waves = higher A, lower F
EMG: Medium or Low Activity
EOG: No movement
Sleep patterns

NREM Stage 4 (deep sleep)
EEG: delta waves = high A, low F
EMG: Medium or Low Activity
EOG: No movement

REM (Rapid Eye Movement)
EEG: Beta waves: irregular bursts of high F, low A
EMG: Low Activity (temporary paralysis)
EOG: Sharp, intermittent eye movements
REM
NREM
Cataplexy: muscles relax
to near paralysis
Individual can still move
Eyes move rapidly
Eyes don’t move
Most dreaming occurs
Some dreams
Purpose:
Consolidation of LTM
Purpose:
Physical growth and body
repair
~20% of adult’s sleep
~80% of adult’s sleep
Typical Sleep Pattern

Sleep cycles of 90mins through night.

NREM stage 1 to 4, then back, then REM.

More time in NREM at start of night

More time in REM later in night
CHANGES IN SLEEP PATTERNS
OVER THE LIFESPAN

The amount of time spent in each stage is
highly variable.

Eg. Poor sleepers are likely to spend less
time in stage 4 and REM sleep.

The amount spent in each stage also
changes across the lifespan.




Eg. A newborn infant sleeps for around 16 hours
a day and around 50% of that is REM sleep.
By the end of infancy, total sleep time drops to
around 12-13 hours and about 25-30% is REM
sleep.
By the end of childhood and onset of
adolescence, total sleep time drops to around 9
hours and about two hours or 20% is REM
sleep.
By late adulthood, the total sleep time averages
six to seven hours, with about one third in REM
sleep.

People in their sixties and older tend to report
that their sleep is much lighter with increased
awakenings than when they were younger.

By age 90, stage 3 and stage 4 is rarely
experienced, if at all.
Negative correlation between age and hours of sleep.
Negative correlation between age and REM sleep.
Sleep-wake cycle shift during
adolescence



-
In general adolescents tend to lesson the hours they
sleep each night from 10 to less than 8 between the
ages of 13-19.
Studies have found however, that adolescents require
more than 9 hours sleep a night to function well when
asleep.
They also seem to have a higher percentage of sleep
problems like:
Taking a long time to fall asleep
Insufficient night time sleep
Difficulty waking in the morning

-
This can lead to difficulties in daytime
functioning like:
Difficulty concentrating in class
Mentally ‘drifting off’ or falling asleep in class
Lethargy
Problems staying motivated.

Each day our body goes through a cycle called
a circadian rhythm during which hormones
are produced to control bodily functions.

Melatonin is one of these hormones and this
causes us to feel sleepy at night.

The cycle is also linked to external cues like
sunlight, alarm clocks, meal times and even
television.

During adolescence there is a hormonally
induced shift of the body clock about two
hours, making the adolescent sleepier one
or two hours later.

This is known as the sleep-wake cycle shift
and this affects their ability to fall asleep at
the earlier time that they would of as a child.
This also means that they have the biological
need to sleep a couple of hours longer in the
morning.





For teenagers, this is virtually impossible
given their school and work schedules.
As a results this nightly sleep loss can
accumulate as a sleep debt; that is, sleep
that is owed and needs to be made up.
Eg. A nightly sleep debt of 90 minutes
between Monday and Friday would add up to
a total sleep debt of seven and a half hours.
Often on the weekends teenagers would
sleep for longer to make up for this debt
which can also be problematic.
THE PURPOSE OF SLEEP
Research investigated on the effects of
sleep deprivation and the amount of
sleep has lead to a number of theories
that provide answers about WHY we
need to sleep.
 Most theories however, can provide
some explanation for the reasons why
sleep is such a necessity.

Restoration

-
-

Restorative theories propose that sleep provides
‘time out’ to help us recover from depleting activities
during waking time that use up the body’s physical and
mental resources.
Allows us to replenish the energy used up during the
day
Allows damaged cells to be repaired
Allows muscles to be detoxified and rid themselves of
waste products
This is supported by our view that we feel tired before
we go to sleep and replenished when we wake up in
the morning.
Evidence



Study 1: When we are asleep our physiological
functions slow down and growth hormone which
promotes body repair is secreted at a much higher
level than when awake.
Study 2: Athletes who competed in a 92km
marathon found that when allowed to sleep as long
as they wanted to they slept significantly longer and
deeper in the following two nights after the race.
Study 3: Experiments with rats have found that
prolonged sleep deprivation results in the
breakdown of various bodily tissues and death
within three weeks.
Restoration

NREM sleep is believed to be important for
repairing and restoring the body whereas
REM sleep is believed to restore the brain
and may have a role in higher mental
functions like memory and learning.
NREM
REM
-Physical growth, tissue
repair and recovery
from the effects of
fatigue occur during
stages 3 and 4 of
NREM sleep.
-Brain growth and
restoration occur during
REM sleep.
-REM is a lot more
predominant in infants
than in later years
indicating that REM
sleep plays an
important role in brain
development in the
early years.
Restoration



Psychologists generally believe that REM sleep
has some biological quality that we need.
When lab patients are woken each time they
enter REM sleep they do not seem to show any
adverse signs, however, when left to rest
normally they will spend more time in REM sleep
than usual. This indicates that there is a need for
them to ‘catch up’ on lost REM sleep.
This is called REM rebound which involves
catching up on REM sleep immediately following
a period of lost REM sleep when next asleep.
SURVIVAL


The survival theory of sleep proposes that
sleep evolved to enhance survival by
protecting an organism through making it
inactive during the part of the day when it is
most risky or dangerous to move about.
Sleep serves the function of protecting the
sleeper from harm or death, and therefore
enhances survival of the species.
Evidence



Animals with few natural predators, such as lions,
tigers and gorillas, sleep as much as 15 hours a
day.
Grazing animals like horses, zebras and cows have
many predators and would struggle to escape from
them. They cannot hide easily, climb trees or burrow
quickly to escape danger and therefore tend to only
sleep around 4 hours total in the day.
Smaller animals like bats and possums eat less food
and take less time to digest it as well as usually
sleeping in safe places. This means they do not
need to spend much time awake.
Evidence


Humans sleep at night because we are highly
visual creatures who need light to find food
and do other things necessary for survival.
At night it may have been best for us during
our evolution to be asleep at night to avoid
any dangers.
Criticisms


One criticism is that it does not explain why
sleep involves a loss of awareness since the
loss of consciousness during sleep may
place the organism at greater risk.
There is only limited evidence to support
each of these theories.
SLEEP DEPRIVATION
Sleep deprivation

The term sleep deprivation means going without
sleep.

The extent of discomfort depends on the individual,
the amount of sleep lost, and the period of time over
which the deprivation occurs.
Sleep deprivation

Research into sleep deprivation has identified
different effects for different kinds of sleep loss.

3 categories:
Total deprivation
Partial deprivation
Selective deprivation
1.
2.
3.

We will focus on total deprivation and partial
deprivation.
Sleep deprivation

Unethical to conduct research on humans so most
total deprivation research has been conducted on
animals.

Rats have been the main participants.

The sleep deprived rats typically were unable to
maintain a constant body temperature, resulting in
excessive heat loss.

They eventually died after 2-3 weeks.
Sleep deprivation

Autopsies show that the rats immune systems had
collapsed, resulting in blood poisoning and untimely
death.

It was then proposed that sleep is vital to the
regulation and stability of an animals internal
environment and this may also apply to humans.

Research conducted on people that have voluntarily
become sleep deprived has found that although
there are some serious psychological and
physiological effects none of these are permanent.
Sleep Deprivation: partial
Tiredness
Lack of energy
Lapses in attention
Inability to concentrate for long periods
Low level of motivation
Impaired motor skills
Irritability
Occasional headaches
Decline in ability to perform cognitive tasks
Slower reaction times on motor tasks
Thinking in irrational and illogical ways
Difficulty making decisions
Partial sleep deprivation




Generally over a short period of time, partial sleep
deprivation has temporary and relatively minor effects.
A person can also quickly recover when the sleep debt
is repaid.
People, however, underestimate the effects of partial
sleep deprivation over a prolonged period.
William Dement (1999) believes that millions of people
throughout the world are ‘living less than an optimal
life and functioning at less than optimal level, impaired
by an amount of sleep debt that they are not even
aware they are carrying’.




He believes that the high level of sleep
deprivation in adolescents could even be fatal
as they are in a high risk of accident
category.
30% of road accidents occur when drivers fall
asleep on long boring stretches of road.
After only 4 hours of sleep deprivation,
reaction time is as much as 45% lower than
usual.
Memory processes may also be impaired.
Total sleep deprivation



Studies on the effects of total sleep
deprivation in humans have tended to rely on
convenience samples.
In one case of total sleep deprivation,
teenager Randy Gardener stayed awake for
264 consecutive hours (11 days) as part of a
high school science project.
Although he experienced a range of
physiological and psychological effects
throughout the experience, he did not
experience any long lasting effects.


Some people however, experience more
debilitating effects like depression,
hallucinations, delusions and paranoia.
In 1959, American DJ Peter Tripp remained
awake for 100 hours for charity and began to
experience severe psychological disturbances.
He claimed to see a rabbit run along the radio
booth (hallucination) and cobwebs in his shoes.
He had difficulty thinking clearly and
remembering things. Eventually he became
paranoid believing people were trying to drug
him to force him asleep.

He was escorted home after 201 hours
without sleep and slept continuously for 13
hours. When he woke he had returned to
normal.
Sleep Deprivation
Psychological Effects:
 Impaired cognition due to reduced concentration,
motivation and attention.
 Increased irritability
 Ability to perform simple tasks more affected than
performance on complex tasks
 Moodiness
 Increased anxiety
 Impairment of memory processes (STM)
 Depression
 Hallucinations, delusions & paranoia
Sleep Deprivation
Physical Effects
 Sleepiness and fatigue
 Droopy eye lids
 Difficulty focusing
 Slurred speech
 Increased sensitivity to pain
 Hand tremors
 Headaches
After 5 consecutive days:
 The heart and respiratory system become slower
 Body temperature drops
 The immune system is lowered making us more vulnerable
to illness
Sleep deprivation

After 3-4 sleep-free days we involuntarily drift into
microsleeps

A microsleep is a very short period of drowsiness
or sleeping that occurs while the person is
apparently awake.

During a microsleep the EEG pattern resembles the
early stages of NREM sleep.

During this time the person will have no recollection
of the events unfolding.

We do not seem to have to fully compensate
for all sleep lost, but we will make up for lost
sleep by gaining a few extra hours over the
next few nights.
Sleep deprivation vs alcohol




Does fatigue really kill?
Yes!
20 hours sleep-free = perform at same level
as with BAC 0.05%
24 hours sleep-free = perform at same level
as with BAC 0.10%