Normal
Sleeping
Jameel Adnan, MD.
Community & Primary Health Care
KAAU-RABEG BRANCH
Round Map
Introduction
Sleep Stages
Sleep Architecture
REM Latency vs Sleep latency
Changes with age
Function of Sleep
Introduction
 Thousands of articles about sleep and sleep
disorders appear each year in medical and
psychological journals
 >80 different sleep disorders have been described.
 Despite the intensive efforts that these publications
reflect, there is still no definitive explanation for
why we sleep.
Introduction
 Sleep is not a passive process, but rather an active
state that is as complex as wakefulness.
 The brain is not "at rest" during sleep; it is involved
in a wide variety of activities.
 Sleep Stages
Sleep Stages
 Two general states:
o Rapid Eye Movement sleep (REM)
o Non-Rapid Eye Movement sleep (NREM).
 NREM sleep is further subdivided into four NREM
stages.
1. REM Sleep
1. REM Sleep
 The brain is active, and the body is inactive.
 three main features:
1. A low voltage, fast frequency EEG pattern
2. The presence of rapid eye movements
3. An atonic electromyogram (EMG)
1. REM Sleep
1. A low voltage, fast frequency EEG pattern,
resembles an active, awake EEG pattern. So, REM
sleep is sometime called paradoxical sleep.
2. The presence of rapid eye movements.
The chances are high that the patient will report
dreaming if awakened during this period.
1. REM Sleep
3. An atonic ElectroMyoGram (EMG)
o Consistent with inactivity of all voluntary muscles
except the extraocular muscles
o The individual is paralyzed during REM sleep.
o Result from direct inhibition of alpha motor
neurons.
 All three primary characteristics of REM sleep are
not always present simultaneously.
1. REM Sleep
 Phasic and tonic REM sleep
REM sleep consists of two different states, based
on the occurrence of rapid eye movements
o Phasic REM sleep.
o Tonic REM sleep.
1. REM Sleep
o REM sleep is a predominantly parasympathetic (vagal)
state, but during phasic REM sleep, there are sudden
bursts of sympathetic nervous system (SNS) activity
associated with rapid eye movements.
o These bursts of SNS activity have been reported to be
associated with sudden increases in arterial blood
pressure, cardiac or cerebral ischemia (frequently in the early
morning hours) cardiac arrhythmias, and sudden changes
in heart and respiratory rates .
1. REM Sleep
 Short central apneas and hypopneas are also
common during phasic bursts of rapid eye
movements.
 Long cardiac asystoles have been noted to occur in
otherwise healthy young individuals during phasic
bursts of REMs.
2. NREM Sleep
2. NREM Sleep
 consists of 4 sleep stages
 defined primarily by the frequency and amplitude of the EEG
• The brain is inactive, the body is active.
 Stage 1 sleep
• It is the transition from wakefulness to deeper sleep
• characterized by fast EEG frequencies in the theta range (4 to
7 Hz).
• It is the lightest stage of sleep, patients awakened from
stage 1 sleep typically do not perceive that they were
actually asleep.
• 2-5 % of total sleep time in young adults
NREM Sleep
Stage 2 sleep
 Called intermediate sleep
 A true physiologic stage of sleep.
 40-50 % of total sleep time.
 is characterized by a slowing of EEG frequency and
an increase in EEG amplitude.
NREM Sleep
 Two distinct features of NREM sleep appear on the EEG
for the first time in this sleep stage:
o Sleep spindles. transient "spindle" shaped features of
the EEG frequency of 12-14 Hz lasting at least 0.5
seconds. They are most prominent at the vertex of the
scalp.
o k-complexes. These consist of a well delineated
negative sharp wave immediately followed by a positive
component standing out from the background EEG with
a total duration ≥0.5 seconds, usually maximal in
amplitude over the frontal regions.
NREM Sleep
Stages 3 and 4 sleep (combined)
 deep sleep or slow wave sleep,
 20 % of total sleep time in young adults.
 characterized by a transition to an EEG with high
amplitude delta EEG waves (1.5 to 3 Hz).
Sleep Architecture
Sleep Architeture
 Sleep stages occur in cycles lasting 90-120 min
each.
 4-5 cycles occur during a typical night of sleep.
 During the first half of the night, the individual
typically passes from wakefulness briefly into stage
1 sleep and then to stages 2, 3, and 4. Stages 3 and
2 reappear, after which REM sleep is observed for
the first time.
 During the second half of the night, stage 2 and
REM sleep alternate.

o
o
o
Abnormalities of sleep architecture
Narcolepsy REM sleep occurring earlier than 90 to 120 minutes
Irregular sleep/wake organization,
Withdrawal from certain medications (e.g., tricyclic
antidepressants, MAOI)
o Depression.
 Sleep disorders will increase the number of sleep stage
changes and may completely disrupt the normal cycling
of sleep.
REM Latency vs Sleep latency
 REM Latency:
o The period lasting from the moment of fall asleep
to the first REM period. Last app. 90 min
o Depression and narcolepsy are examples of shorten
REM latency
 Sleep Latency:
o The time needed before actually fall asleep .last
app. 15 min
o Insomnia is an example of increase sleep latency
Changes with age
 Quantity and Quality of sleep change significantly
with aging.
 Deep or slow wave sleep (stages 3 and 4) declines
 Light sleep (stage 1) increases.
 The number of arousals and the amount of
wakefulness also increase in later years.
Multiple sleep latency test
 an objective measure of daytime sleepiness
 used for >15 years
 the sleepier an individual is, the faster he will fall asleep.
 The following protocol is typically used:
o The patient is given 4-5 opportunities to nap, usually at two
hour intervals during the day.
o On each occasion, the individual is asked to lie down on a
bed in a quiet, darkened sleep room and fall asleep as
quickly as possible.
o The EEG, eye movements, and muscle tone are measured
during the test.
 The latency from wakefulness to sleep onset is
measured to determine the "sleep latency."
 Each session is terminated after 15 minutes of
sleep.
 The process is repeated during each of the four to
five naps, and a mean sleep latency across all the
naps is computed.
Minutes
sleepiness
0-5
Severe
5-10
Troublesome
10-15
Manageable
15-20
Excellent
Polysomnogram
Function of Sleep
Function of Sleep
o The Restorative Theory of Sleep, states that some
process during sleep restores tissue and prepares
the body for the next day.
o The Adaptive Theory of Sleep proposes that sleep
increases survival.
o The Energy Conservation Theory states that a low
metabolism for energy conservation is the function
of sleep.