The AASM Manual for the

Scoring of Sleep and

Associated Events

Two to three pass method:

PASS #1:
Staging at 30 second epochs (epoch by epoch
approach)
Score Spontaneous arousals at 30 second epochs
Observe and note for any cardiac arrhythmias
PASS #2:
Score respiratory events (either 90, 120, or 300 sec)

PASS #3:
Score PLMS

Read between the lines

Pattern Recognition
Understanding Sleep Architecture
Dont spend more than 1-2 seconds per epoch

EEG Derivations
F4-M1
C4-M1
O2-M1
Backup electrodes : F3-C3, O1, and M2 to allow display - F3-M2, C3-M2
and O1-M2

Alternative Derivations: FZ-CZ, CZ-OZ, C4-M1

Backup electrodes: Fpz, C3, O1 and M1 to allow for display - Fpz for
FZ, C3 for CZ or C4, O1 for OZ, and M2 for M1

Recommended
F4-M1
C4-M1
O2-M1

Backup
F3-M2
C3-M2
O1-M2

Alternative
Fz-Cz
Cz-Oz
C4-M1
Backup
FpZ M2 C3 O1

Fz Cz/C4 Oz M1

Frontal-central region

Beta waves, interspersed

throughout low-amplitude
mixed-frequency activity;
bursts with *benzodiazepine
and barbiturate ingestion

Frontal Lobe
K-complexes and
Delta waves

Central region

Spindles; Vertex Sharp

Waves; Saw-tooth Waves;
other theta-range activity

Occipital Lobe
www.disabled-world.com/artman/uploads/brain-diagram.jpg

Alpha/PDR activity now

referred to as
Posterior Dominant Rhythm
PDR

*Can also result in excessive spindle activity

Rationale for EEG Derivations

Maximal amplitude displayed from the site
of origin using recommended referential
derivations, but mastoid placement can
contain EMG and EKG artifact.
Alternative bipolar derivations purportedly
record LESS artifact from EMG and EKG,
but will not display maximal amplitude from
site of origin.

Recommended:
E1-M2 and E2M2

E1 is placed 1 cm
below the left outer
canthus not
lateral

E2 is placed 1 cm
above the right
outer canthus not
lateral

Alternative: E1-Fpz
and E2-Fpz

E1 placed 1 cm
below and 1 cm
lateral to the left
outer canthus

E2 placed 1 cm
below and 1 cm
lateral to the right
outer canthus

Differences in EOG Placement

Recommended derivation - eye movement
direction, oblique movements, and low
amplitude signals are not displayed; artifact
more readily seen.
Alternative derivation - vertical movements
seen as in-phase deflections; horizontal
movements as out-of-phase deflections;
oblique movements are recorded.

3 recording electrodes recommended

One midline electrode - 1 cm above the inferior

edge of the mandible

Two electrodes placed 2 cm below the inferior

edge of the mandible; one 2 cm right and the
other 2 cm left of the midline.

G1

G2

G2

Epoch Scoring
30-second epoch scoring with a stage assigned
to each epoch
If two or more sleep stages occur on one epoch,
assign the score to the stage comprising the
majority of the epoch

Sleep Stage Terminology

The stages of sleep are defined as:
Stage W (Wakefulness)
Stage N1 (NREM 1)
Stage N2 (NREM 2)
Stage N3 (NREM 3)
Stage R (REM)

Stage W
Represents alert wakefulness to drowsiness
Comprised of more than 50% Alpha/PDR
rhythm (8-13 Hztypically 9-11 Hz in adults)
Alpha/PDR rhythm is maximal over occipital
region during eye closure
Alpha/PDR rhythm is attenuated when eyes
are opened and replaced by a low-amplitude,
mixed-frequency EEG pattern

Additional parameters to assist in scoring:

Eye Blinks conjugate vertical movements in the 0.52 Hz range; seen when eyes are opened or closed

Reading eye movements trains of conjugate eye

movements; slow phase followed by a rapid phase in
opposite direction

Rapid eye movements seen in stage W when a

subject scans the environment; EMG tone is normal
or high; eye movements are conjugate, irregular, and
sharply peaked

W eyes closed

W eyes open with blinks

LAMF EEG
Excessive HFF on EOG

W eyes open with blinks

Blink artifact in EEG
Excessive HFF on EOG

W eye closure with alpha/pdr

W slowing EEG with sleep

onset in latter half of epoch

EEG:

Theta waves 4-7 cps

Also known as Low Voltage Mixed Frequency (LVMF) waves

Vertex Sharp Waves: Monophasic surface-negative sharp waves;
followed by a positive component lasting < 0.5 sec duration
Seen maximally over the central regions

EOG:
Slow Eye Movements may occur
(primarily from wake to N1)
EMG:
Generally elevated but a little lower
than Wake

Stage N1
In most subjects, Stage N1 indicates sleep onset
(the start of the first epoch that is scored as any
stage other than Stage W)
In Alpha/PDR producers, Stage N1 is scored when Alpha/PDR is
replaced and > 50% of the epoch contains LAMF activity
Continue to score an epoch with a LAMF background as N1, even if there is a
K complex if it is associated with an arousal, and there are no spindles or K
complexes not associated with an arousal

N1 previous epoch N1; LAMF EEG

without sleep spindles or K complexes

N1 previous epoch N1; LAMF

EEG without sleep spindles or K
complexes in first half of epoch

Stage N1
In non-Alpha/PDR producers, score Stage
N1 when any of the following appear:
4-7 Hz activity with slowing of background by > 1
Hz from those of Stage W
Vertex sharp waves
Slow eye movements
*Chin EMG is variable but usually lower than in Stage W; no impact on
scoring
*Vertex sharp waves and slow eye movements not required to score N1
*Slow eye movements may appear prior to Alpha/PDR attenuation in
Alpha/PDR producers; earlier scoring of sleep onset in non-Alpha/PDR

producing subjects may be a result

EEG:

Theta waves (4-7 cps) interspersed

with K-complexes and/or sleep
spindles (13-16 cps).

K-Complex: a well-defined negative sharp wave,

followed immediately by a positive component
standing out from the background EEG; total
duration > 0.5 seconds; usually maximal in
amplitude using frontal derivations. For an
arousal to be associated it must commence <
1s after termination of the K complex

Sleep spindles: train of distinct waves with

frequency 11-16 Hz (most commonly 12-14 Hz)
with a duration > 0.5 seconds, usually maximal
in amplitude using central derivations.
EOG:

Same activity as EEG

EMG:
Relatively elevated but a little lower
than that of Wake.

Begin scoring stage N2 if one or both of the

following occur during the first half of that
epoch or the last half of the previous epoch:
a. One or more K-complexes unassociated
arousals
b. One or more trains of sleep spindles

Continue to score epochs with low amplitude,

mixed frequency EEG activity without Kcomplexes or sleep spindles as Stage N2 if
they are preceded by:
a) K-complexes unassociated with arousals or
b) Sleep spindles

Ending Stage N2
End stage N2 when there is a/an:
Stage Transition to W, N3, or REM
EEG Arousal - results in a transition to N1 or W
unless N2 criteria are met
If a major body movement occurs followed by
SEMs and low-amplitude, mixed-frequency EEG
without non-arousal associated K complexes or
sleep spindles

score the epoch following the MBM as N1 if SEMs

if no eye movements, score as N2

Major Body Movement

A Major Body Movement is scored when muscle
artifact or movement artifact obscure more than
half of the epoch
If Alpha/PDR is present on the MBM epoch (even <15
seconds), score it as Stage W
If Stage W precedes or follows the MBM epoch, score it as
Stage W
If no Alpha/PDR is present, score the MBM epoch the same
stage as the epoch that follows it

EEG: 3 criteria needed:

1.
2.
3.

0.5 3 cps
Amplitude must be at least 75 V from peak-to-peak
Occupying 20% of the epoch (cumulative)
Sleep spindles may be present No change in Definitions or Rules.
One note added explaining that K complexes are considered to be
slow waves if they meet the definition of slow wave activity.

EOG: Same activity as EEG

EMG: Variable amplitude; often lower than in Stage N2

and sometimes as low as in Stage R.

The 75 V criteria applies to all ages:

Slow wave sleep amplitude decreases with age but the

decrease is in parallel to frequencies of other EEG
waveforms

Slow wave activity measuring >75 V can be detected at

any age and should be scored from F4-M1 or FZ-CZ
(frontal derivations)

Slow-wave amplitude progressively increases as subject

age decreases

Rapid eye movements are conjugate, irregular, and

sharply peaked with an initial deflection < 500 ms in
duration

Chin EMG tone is no higher than in any other sleep

stage and usually at the lowest level of the entire
recording

Sawtooth waves are sharply contoured or

triangular, often serrated, 2-6 Hz waves which often
precede bursts of REMs. Maximal over the central
regions

EEG:

Theta waves (4-7 cps)

Alpha waves present but 1-2 cps slower than that of Wake
Sawtooth waves (sharply contoured, triangular; often serrated (2-6
Hz) preceding bursts of rapid eye movements.

EOG:

Rapid Eye Movements may be present

EMG:
Significantly reduced compared to
Non-REM sleep.

Transient muscle activity replaces the terminology

phasic twitches. These bursts are usually < 0.25 s
and are superimposed on low EMG tone

Can be observed in the chin EMG, anterior tibialis

EMG, or EEG/EOG derivations

Neither TMA or sawtooth waves are required to score

stage REM, but each support the scoring of stage
REM

Score REM sleep on epochs with all of the following:

Low-amplitude, mixed-frequency EEG activity

Chin EMG tone is low (at its minimal level)

Rapid eye movements are present

Continue to score REM, even in absence of REMs if:

The EEG remains LAMF
The chin EMG tone remains relatively low
There are no K complexes or sleep spindles

Stage REM
Discontinue REM sleep when:
There is transition to stage W or N3 (stage )
Chin EMG muscle tone increases (Stage N1)
A K complex without arousal or a spindle occurs in
first half of the epoch with no REMs (Stage N2)
An arousal occurs followed by SEMs (or stage )
A major body movement is followed by SEMs (or
stage )

In between epochs of definite stage N2 and

definite R, score an epoch with a distinct drop in
chin EMG in the first half of the epoch to the level
seen in stage R as stage R if all of following
criteria are met, even in the absence of REMs:

Absence of non-arousal associated K complexes

Absence of sleep spindles

In between epochs of definite stage N2 and

definite R, score an epoch with a distinct drop in
chin EMG in the first half of the epoch to the level
seen in stage R as stage N2 if all of following
criteria are met:

Presence of non-arousal associated K complexes or

sleep spindles
Absence of REMs

In between epochs of definite stage N2 with

minimal chin EMG tone and definite R without
further drop in chin EMG tone, score an epochs
as stage R if all of following criteria are met, even
in the absence of REMs

Absence of non-arousal associated K complexes

Absence of sleep spindles

HOW TO MEASURE EVENTS

1. Apnea or Hypopnea: The beginning of the event is from the
nadir
(lowest point) of the preceding breath (that is clearly reduced) to
the
Beginning of the first breath that approximate the baseline
amplitude.
2. Measure an Apnea using the Oronasal Thermal sensor and a
Hypopnea using the Pressure Transducer if you are performing
a diagnostic study. If you are performing a PAP titration, use the
PAP device flow signal for determining the event duration.
3. When its hard to easily determine the breathing amplitude,
events can also be terminated when either there is a clear and
sustained increase in breathing amplitude or, in the case where a
desaturation has occurred, there is an event-associated
resaturation of at least 2%.

SCORING OF
APNEAS
An APNEA must have BOTH of the following:
1. Drop in peak signal excursion by > 90% of pre-event baseline
a) Oronasal thermal sensor diagnostic
b) PAP device flow therapeutic
c) Alternative sensor diagnostic
2. Score as Obstructive Apnea if associated with continued or
increased inspiratory effort throughout the entire period
of absent airflow.
3. Score as Central Apnea if associated with absent inspiratory effort
throughout entire period of absent airflow.

4. Score as Mixed Apnea if inspiratory effort is absent at the beginning o

the event but resumes in the second portion of the event.

More on Apnea Scoring

1. You DO NOT have to have a desaturation to score an apnea!
2. If a bit of the respiratory event that would otherwise meet criteria
for a hypopnea meets the criteria for Apnea, the entire event
should be scored as an apnea!
3. If the apnea or hypopnea begins or ends in an epoch scored as sleep,
this event is computed in the AHI. However, it the apnea or
hypopnea occurs exclusively in an epoch scored as wake, we
do not count toward AHI. If this occurs frequently in the study,
it should be addressed in the tech notes for the physician.
4. Theres not enough evidence to support a specific duration of the
central and obstructive components of a mixed apnea,
therefore there is no recommendation.

Most significant changes in the scoring

rules.
Recommended rule changed.
No acceptable rule is noted.
Removed the 90% of event duration must
meet amplitude reduction criteria.
Added definitions for scoring obstructive
and central hypopnea.
Noted that it is optional to score hypopneas
as central or obstructive.

Everything you ever wanted to know about..

SCORING HYPOPNEAS!

Its a Hypopnea if ALLLLLLL of the following criteria are met:

1. Peak signal excursion drops by > 30% of pre-event baseline
a) Nasal Pressure (diagnostic)
b) PAP device flow (therapeutic)
c) Alternative hypopnea sensor (diagnostic)
2. The duration of the > 30% drop is > 10 seconds.

3. There is a > 3% or 4% oxygen desaturation from pre-event

baseline or the event is associated with an arousal.* Rule 1A or
1B

But waittheres more!!!

You can differentiate between Obstructive and Central Hypopneas!

If scoring Obstructive Hypopneas, one of the following must be met:

1. Snoring during the event
2. Increased inspiratory flattening of the nasal pressure or PAP
device flow signal compared to baseline
3. Associated throracoabdominal paradox occurs during the
event but not during pre-event breathing

If scoring Central Hypopneas, NONE of the following must be present:

1. Snoring during the event
2. Increased inspiratory flattening of the nasal pressure or PAP
device flow signal compared to baseline
3. Associated throracoabdominal paradox occurs during the
event but not during pre-event breathing

The Fine Print.

Supplemental oxygen may blunt desaturation. There are currently no

scoring guidelines for when a patient is on supplemental oxygen
and no desaturation is noted. If the diagnostic study is performed
while the subject is on supplemental oxygen, its presence
should be mentioned in the narrative summary of the study.

Lets talk about

RERAs
An optional parameterin my opinion, valid reporting tool.
Score as Respiratory Event Related Arousals (RERA)
if there is a sequence of breaths lasting > 10 seconds
characterized by increasing respiratory effort OR flattening of the
inspiratory portion of the nasal pressure channel or PAP device
flow waveforms leading to AROUSAL from sleep.
Hypopnea wannabes.

SCORING HYPOVENTILATION.
Monitoring hypoventilation is an optional parameter to be reported but
I personally feel it is a critical item.
Score a Respiratory event as a hypoventilation during sleep if EITHER of the
Below occur:
1. There is an increase in the arterial PCO2 (or surrogate) to a
value of > 55mmHg for > 10 minutes.
2. There is > 10 mmHg increase in arterial PCO2 (or surrogate) during sleep
(in comparison to an awake supine value) to a value exceeding
50 mmHg > 10 minutes.

Surrogate = TcCO2 monitor

Cheyne-Stokes Breathing
Rule has been updated and language changed:
There are episodes of 3 consecutive central apneas
and/or central hypopneas separated by a crescendo and
decrescendo change in breathing amplitude with a cycle
length of 40 seconds.
There are 5 central apneas and/or central hypopneas
per hour of sleep associated with the
crescendo/decrescendo breathing pattern recorded over
2 hours of monitoring.

More
than 40
secs.
duration

Scoring during any stage of sleep if there

is an abrupt shift of EEG frequency
including alpha, theta, and/or
frequencies > 16 Hz (but not spindles)
that lasts at least 3 seconds, with at least
10 seconds of stable sleep preceding the
change.

Subjects must be asleep, defined as > 10

continuous seconds of the indication of
any stage of sleep, before an EEG arousal
can be scored.

A minimum of 10 continuous seconds of

intervening sleep is necessary to score a
second arousal.

The EEG frequency shift must be 3

seconds or greater in duration to be
scored as an arousal

Arousals in NREM sleep may occur

without concurrent increases in
submental EMG amplitude.

Arousals are scored in REM sleep only

when accompanied by concurrent
increases in submental EMG amplitude.

Arousals cannot be scored based on

changes in submental EMG amplitude
alone.

Artifacts, Kcomplexes or
Delta waves are
not scored as
arousals unless
accompanied by
an EEG frequency
shift in at least
one derivation.

If such activity
precedes an EEG
frequency shift, it
is not included in
reaching the 3second duration
criteria.

The occurrence of
pen blocking
artifact should be
considered an
arousal only if an
EEG arousal
pattern is
contiguous.

The pen blocking

event can be
included in
reaching duration
criteria.

Non-current, but contiguous EEG and

EMG changes, which were individually
less than 3 seconds but together greater
than 3 seconds in duration are not scored
as arousals.

Intrusion of alpha
activity of less
than 3 seconds
duration into
NREM sleep at a
rate greater than 1
burst per 10
seconds is not
scored as an EEG
arousal.

Three seconds of
alpha sleep is not
scored as an
arousal unless a
10 second episode
of alpha-free
sleep precedes.

Transitions from one stage of sleep to

another are not sufficient of themselves
to be scored as EEG arousals unless they
meet the criteria indicated above

Citations
The AASM Manual for the Scoring of Sleep and Associated
Events: Rules, Terminology and Technical Specifications
Version 2.1

1. Iber C, Ancoli-Israel S, Chesson A, and Quan SF for the American Academy of Sleep
Medicine. The AASM Manual for the Scoring of Sleep and Associated Events: Rules,
Terminology and Technical Specifications, 1st. Ed.: Westchester, Illinois: American
Academy of Sleep Medicine, 2007.
2. Berry RB, Brooks R, Gamaldo CE, Harding SM, Marcus CL, Vaughn BV and Tangredi
MM for the American Academy of Sleep Medicine. The AASM Manual for the Scoring
of Sleep and Associated Events: Rules, Terminology and Technical Specifications,
Version 2.0. www.aasmnet.org, Darien, Illinois: American Academy of Sleep Medicine,
2012.
3. Rechtschaffen A, Kales A, eds. A manual of standardized terminology, techniques
and scoring system for sleep stages of human subjects. Los Angeles, CA: BI/BR, 1968.

No change in age description

Rules can be used to score sleep and wake in children

2 months post-term

No change in terminology for staging

Technical specifications remain the
same as adult

Notes related to the need to reduce the distance for EOG and
chin EMG electrodes in children and infants with small heads

Change in notes related to when sleep spindles may be seen

in children and added a description of how spindles occur
during this age.
Sleep spindles may be seen by age 4-6 weeks post-term
and are present in all normal infants by age 2-3 months
post-term. At this age the spindles are asynchronous
between the hemispheres but become more synchronous
over the first year of life.2

If all epochs of NREM sleep contain no recognizable sleep spindles, K complexes or highamplitude 0.5-2 Hz slow wave activity, score all epochs of NREM sleep as stage N (NREM).
2

If some epochs of NREM sleep contain sleep spindles or K complexes, score those as stage N2
(NREM 2). If in the remaining NREM epochs, there is no slow wave activity comprising
more than 20% of the duration of epochs, score as stage N (NREM). 2

If some epochs of NREM sleep contain greater than 20% slow wave activity, score these as stage N3
(NREM 3). If in the remaining NREM epochs, there are no K complexes or spindles then score as
stage N (NREM). 2
If NREM is sufficiently developed that some epochs contain sleep spindles or K complexes and other
epochs contain sufficient amounts of slow wave activity, then score NREM sleep in this infant as
either stage N1, N2 or N3 as in an older child or adult. 2

Definitions for scoring Stage W are unchanged and

include:
Alpha Rhythm
Eye Blinks
Reading Eye Movements
Rapid Eye Movements
Dominant Posterior Rhythm

The term "posterior dominant rhythm" replaces the term "alpha rhythm" when scoring wakefulness and
NREM stages in children.
Epochs are scored as stage W when more than 50% of the epoch has either reactive alpha or ageappropriate posterior dominant rhythm over the occipital region.
Epochs with no discernible reactive alpha or no age-appropriate posterior dominant rhythm should be
scored as stage W if ANY of the following are present:
Eye blinks at a frequency of 0.5-2 Hz
Reading eye movements
Irregular, conjugate rapid eye movements associated with normal or high chin muscle tone

Stage N1 in Pediatrics
Definitions for scoring Stage W are unchanged and include:
Slow eye movements
Low-amplitude, mixed-frequency activity
Vertex sharp waves
Sleep onset
Rhythmic anterior theta activity
Hypnagogic hypersynchrony

If posterior dominant rhythm is present and attenuated or replaced by low-amplitude, mixed-frequency

activity >50% of the epoch , score the epoch as stage N1.
If the posterior dominant rhythm, is not present score stage N1 when any of the following occur:
Activity in the range of 4-7 Hz with slowing of background frequencies by 1-2 Hz from those of stage W
Slow eye movements
Vertex sharp waves
Rhythmic anterior theta activity
Hypnagogic hypersynchrony
Diffuse or occipital-predominant, high-amplitude, rhythmic 3-5 Hz activity2

Score stages N2 and N3 in children utilizing the same rules as adults

Score stage R in children utilizing the same rules as adults

The continuous, low-amplitude, mixed-frequency EEG activity of stage R in infants and

children resembles adults although the dominant frequencies increase with age:
approximately 3 Hz activity at 7 weeks post-term, 4-5 Hz activity with bursts of
sawtooth waves at 5 months, 4-6 Hz at 9 months, and prolonged runs or bursts of
notched 5-7 Hz theta activity at 1-5 years of age may populate the background
activity. By 5-10 years of age, the low-amplitude, mixed-frequency activity in stage R is
similar to that of adults.2