Quantitative Sleep Monitoring - Quantitative EEG Analysis Methods and Clinical Applications - page 265

Table 10.4 Summary of Sleep Stage Characteristics

Characteristic a, b

Stage EEG EOG EMG

Wake
(eyes open)

Low-voltage, high-frequency,
attenuated alpha activity

Eye blinks, REMs Relatively high

Wake
(eyes closed)

Low-voltage, high-frequency > 50% Slow-rolling eye

movements

Relatively high

alpha activity

Stage 1 Slow-rolling eye

movements

May be lower than
wake

Low-amplitude mixed-frequency 50%
alpha activity NO spindles, K complexes
Sharp waves near transition to stage 2

Stage 2 At least one sleep spindle or K complex

20% slow-wave activity b

May be lower than
wake

c

Stage 3 20-50% Slow-wave activity Usually low

c

Stage 4 Usually low

50% Slow-wave activity

Stage REM Low-voltage mixed-frequency

Sawtooth waves—may be present

Episodic REMs Relatively reduced

(equal to or lower than
the lowest in NREM)

a
Boldface type indicates required characteristics.
b
Slow-wave activity, frequency < 2 Hz; peak-to-peak amplitude > 75 μ V; > 50% means slow-wave activity present in more than 50% of the

epoch.
c

Slow waves usually seen in EOG tracings.

10.8.2 Sleep Staging in Infants and Children
Newborn term infants do not have the well-developed adult EEG patterns to allow
staging according to R&K rules. The following is a brief description of terminology
and sleep staging for the newborn infant according to the state determination of
Anders, Emde, and Parmelee [17]. Infant sleep is divided into active sleep (corre-
sponding to REM sleep), quiet sleep (corresponding to NREM sleep), and
indeterminant sleep, which is often a transitional sleep stage. Behavioral observa-
tions are critical. Wakefulness is characterized by crying, quiet eyes open, and feed-
ing. Sleep is often defined as sustained eye closure. Newborn infants typically have
periods of sleep lasting 3 to 4 hours interrupted by feeding, and total sleep in 24
hours is usually 16 to 18 hours. They have cycles of sleep with a 45- to 60-minute
periodicity with about 50% active sleep. In newborns, the presence of REM (active
sleep) at sleep onset is the norm. In contrast, the adult sleep cycle is 90 to 100 min-
utes, REM occupies about 20% of sleep, and NREM sleep is noted at sleep onset.
The EEG patterns of newborn infants have been characterized as low-voltage
irregular, tracé alternant, high-voltage slow, and mixed (Table 10.5). Eye move-
ment monitoring is used as in adults. An epoch is considered to have high or low
EMG if more than one-half of the epoch shows the pattern. The characteristics of
active sleep, quiet sleep, and indeterminant sleep are listed in Table 10.6. The
change from active to quiet sleep is more likely to manifest indeterminant sleep.
Nonnutritive sucking commonly continues into sleep.
As children mature, more typically adult EEG patterns begin to appear. Sleep
spindles begin to appear at 2 months and are usually seen after 3 to 4 months of age
[18]. K complexes usually begin to appear at 6 months of age and are fully devel-
oped by 2 years of age [19]. The point at which sleep staging follows adult rules in