Dr. Reem Al-Sabah

Psychology 220

Faculty of medicine

SLEEP

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).

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).

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

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.

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)]

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.

Stages of Sleep

Stage 1

Stage 2

Stage 3 [NRM sleep]

Stage 4

REM (Rapid Eye Movement)

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.

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

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.

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.

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.

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.

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.

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”).

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.

EEG Recordings

Stage Description Frequency

Awake

1. day to day

wakefulness.

2. Wakeful relaxation

with eyes closed

1. Beta waves 14-25 Hz

2. Alpha waves 8-13 Hz

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

dreaming

combination of alpha, beta,

and desynchronous waves.

Sleep Architecture

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.

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)

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.

NREM Sleep REM Sleep

Quiet sleep Dreaming sleep

Almost no eye

movements

Very rapid eye movements

Decrease heart and

breathing rates

Increased heart rate

Muscles relaxed Almost paralyzed (except for

heart, diaphragm, eye

muscles, smooth muscles)

Decrease in brain’s

metabolic rate(approx.

30%)

Increase in brain’s metabolic

rate

Inactive brain in a very

relaxed body

Awake brain in a paralyzed

body

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)

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).

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.

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)

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.

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.

Common Types of Sleep

Disorders

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.

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.

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)

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.

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.

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.

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.

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.

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.

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).