(Received November 17, 1967; revision accepted January 17, 1968.)
This work was supported in part by NIH Grant number MH 12219-01.
ADDRESS FOR REPRINTS: (J.J.R.) Department of Pediatrics, University of Florida, College of
Medi-cine, Gainesville, Florida 32601.
324
SLEEP PATTERNS
IN PREADOLESCENT
CHILDREN:
AN
EEG-EOG
STUDY
John J. Ross, M.D., Harman W. Agnew, Jr., M.A., Robert 1. Williams, M.D., and Wilse B. Webb, Ph.D.
From the Departments of Pediatrics and Psychiatry, College of Medicine; and Department of Psychology,
College of Arts and Sciences, University of Florida, Gainesville, Florida
ABSTRAC’F. The typical all-night sleep pattern of
the pre-adolescent male was determined by
ana-lyzing the simultaneous EEG-EOG tracings of 18
healthy schoolboys (range 8 to 1 1 years). The sleep patterns of these boys resembled that of older
sub-jects by the occurrence of a more or less orderly
sequence of sleep stages which spontaneously
shifted from one stage to another. Stability of the
pattern for a given boy was observed in the
consis-tent amount of time spent in each sleep stage and
in the number of sleep stage changes night after night.
When compared with the adult sleep patterns,
pre-adolescent total sleep time was 23 hours longer
with unequal distribution of the added time to
each of the sleep stages. Sleep stages in children are longer in duration than in adults, and the sleep patterns are as stable as that of the adult.
Pediat-rics, 42:324, 1968, CHILDREN, DREAMS, ELECTROEN CEPHALOGRAPHY, SLEEP.
LTHOUGH sleep disturbances in childhood
are reported to be common, the nature and extent of these aberrations are difficult to ascertain. The difficulty has been due to three facts :
(
1)
the lack of proper scientific methods to study human sleep,(
2) the at-tempt of those engaged in sleep research to describe normal sleep by studying sleep pa-thology, and (3) the lack of normal sleep data obtained by using adequate scientific techniques. After the division of sleep into stages by Loomis, et al.1 and after establish-ment of the fact that Stage 1 rapid eye movement sleep(
REM)
was associated with dreaming by Aserinsky and Kleit-man2’3 and Dement and Kleitman,4’ ause-ful electrophysiological tool, the simulta-neous all-night recording of the electroen-cephalogram
(
EEG)
and electro-oculogram(
EOG),
became available to describe the typical EEG sleep patterns of humanbeings. Thus, a reliable documentation of
the electrophysiologic parameters of normal sleep could be accomplished. Major contni-butions toward describing normal adult sleep patterns were made by Dement and Kleitman,’ Oswald,6 Snyder,7 Jouvet,8 Lairy, et al., Roffwarg, et al.,b0,15 Williams,
et a!., 12,13 and Agnew, et al.,14 Through the efforts of these and other workers, the corn-posite picture of a typical night’s sleep in the male and female adult was established, and in the past decade the clinical useful-ness of the sleeping EEG and EOG has been shown to be an aid in diagnosis, ther-apeutics, and prognostication of sleep
disor-ders occurring in adult humans.
When one considers the fact that 19 to
25% of infants and preschool children have
sleep disturbances,15,16 it is astonishing that this EEG-EOG method has not been
cx-ploited in order to understand them. Both
Illingworth and Grant’8 have complained
of the lack of informative and reliable sleep data in the pediatric literature. Recently the present investigators noted that, during the past 12 years, there were only 11
sleep-oriented papers published in the five lead-ing, general pediatric journals written in the English language,lO1OSS and only one of these papers employed the EEG-EOG
technique.28
It is the purpose of the present
communi-cation to report the typical EEG and EOG patterns of sleep in normal S to 11-year-old
male children and to demonstrate how
STAGE 0
STAGE I (Descending)
STAGE 2
STAGE 3
EM
ARTICLES 32
STAGE 4
lOOgv1______ 2 SEC.
STAGE REM
REMs
Fic. 1. Modified Dement-Kleitman classification of stages of sleep in 8 to
1 1-year-old boys utilizing the simultaneous recording of EEC and EOG.
Rapid-eye-movements (REM’s) at the bottom of the figure are observed
olily during dreaming and normal slow wave eye movements (EM ) are seen
throughout non-REM sleep.
these data can be utilized to better under-stand sleep disturbances that occur in this age group.
METHODS
Simultaneous all-night EEG and EOG
recordings of natural sleep were obtained
on 18 healthy schoolboys (mean age 9.5
years; range 8 to 1 1 years
)
for fourconsecu-tive nights in a sleep laboratory which was carefully controlled and monitored for con-stancy of sound, light, and temperature. All boys had slept away from home and their parents at least once prior to this study, and none of them received medication to induce sleep.
in-TABLE I
MEAN SLEEP STAGE PERCENTS AVERAGED ACROSS
THREE NIGHTS OF SLEEP FOR EACH SUBJECT
Subject Sleep Stage 41. s .1 4 . 47 . 9 .3 43.3 40.7 45.6 36.8 5 .0 49.4 50.4 50.5 46.0 5 .4 42.9 4..2 47.9 44.2 6.5 3 9.4 9.1 6.2 6.1 8.1 4.3 4.7 7.5 5.8 5.8 6.2 2.6 3.4 5.7 3.6 4.9 7.8 4.6 5.9 1.9 4 18.9 24.8 19.8 14.5 21.1 19.9 17.3 15.9 19.9 15.5 17.4 16.4 14.8 19.2 12.4 15.9 22.9 16.1 17.9 3.1
jects retired to the sleeprooms about 8:00 P.M. and slept undisturbed until they
awoke spontaneously the next morning.
Because of the first night effect,29 in which there are numerous awake periods,
less REM sleep, a delay in onset of Stages 4 and REM, and more frequent sleep stage
-iT----i;
--
;-.-;
-I 0.2 6.5 23 .8 changes, the record from the first night of
2 3
:
61.8 0.5
:
#{149} 1 .25.6 11.9
:
#{149}7
:
2 26 .7 19.0::
#{149} 24:
laboratory sleep was not utilized in analysis
of these data. The remaining tracings from the next three consecutive nights of sleep were analyzed by identical methods.
Ini-7 0.7 6.S 30 .0 tially, each all-night sleep record was
8
9
10
I 1
1.4 2.2 1.5
2.5
8.2
8.5 4.8
2.9 21 .4 26 .7 20.4
21 .6
marked into 1-minute epochs, and each
1-minute epoch was scored using the
fol-. . . .
lowing criteria for epoch classification.
12 13 0.9 0.3 4.0 3.3 25.8
27.6 Stage 0
14
15
16
17
4.I 0.7 4.1
0.3 2.1
6.4 6.2
4.6 22 .8 24 .5
26.0
19.3
Epoch composed of at least 30 seconds of
8 to 12 cycles per second
(
alpha waves)
of. . . . . . .
occipital activity with a minimum
amph-18 1.9 6.9 22 .6 tude of 20 p.V. This represents a waking,
--
-----
resting, eyes-closed state.Mean 1.5 6.1 24.3
Standard Stage 1
(leviation 1.2 2.5 3.2
-
-
----
-
---structions and preparation. Fifteen Grass
E-1 silver disc electrodes were applied to the subjects’ heads, according to the Inter-national Ten-Twenty System, on F1, F2, F7,
F8, C1, C2, C5, C6, P1, P2, T,, T0, 03, 04, and
ozPz
(
halfway between O and P2)
. Each electrode was filled with a mixture of ben-tonite paste and Cambridge electrode jelly and was secured to the scalp with collodion saturated gauze pads. Two additionalelec-trodes were applied 1 cm above the outer canthus of the right eye and 1 cm below the outer canthus of the left eye. Eight EEG
recordings between F,-F7, F2-F8, C1-C5,
C2-C6, P,-T5, P2-T6, O3-OP, O4-OP. and
two EOG tracings between left outer
can-thus-right outer canthus, and left outer canthus-F7 were obtained on a 12-channel Grass Model VI electroencephalograph
which was run continuously throughout the night at a paper speed of 15 mm/second and which was calibrated at 50 p.V/5 mm.
With a technician in attendance, the
sub-.
Epoch contained less than 30 seconds of 8
to 12 cycles per second of 20 p.V occipital
ac-tivity and no more than one well defined
spindle or K complex.
Stage 2
Epoch contained at least two well
de-fined sleep spindles or two K complexes, or
one of each, and no more than 12 seconds of .5 to 3 cycles per second 20 tV or greater
slow waves.
Stage 3
Epoch contained at least 13 seconds of .5 to 3 cycles per second 20 &V or greater
activ-it>’, but less than 30 seconds of this activity.
Stage 4
Epoch contained at least 30 seconds of .5
to 3 cycles per second 20 p.V or higher slow waves.
Stage REM
A Stage 1 EEG plus evidence of conju-gate rapid eye movements. This activity
con-‘rABLE H
PERCENT OF TIME ONE SLEEP
STAGE FouowED ANOTHER
ARTICLES 327
tamed conjugate eye movement until the
eye movements terminated. Any
interrup-tions were subtracted. This is the dreaming
state.
These stages are shown in Figure 1. The
criteria for the five sleep stages are based on the EEC scoring criteria described by Dement and Kleitman,4 Williams, et al.,12,13
and Dement.3#{176}
After scoring for stage of sleep, each epoch of wakefulness and each epoch of
the various stages of sleep were recorded on a score sheet, giving a pictorial
histo-gram and making it possible to calculate
total sleep time, the number of minutes
spent in various sleep stages, the percent-age of total time for the five stages of sleep, sleep latency, sequence of sleep stages, and frequency distribution of the sleep stage
durations.
RESULTS
Overall Sleep Pattern
Using the onset of the first Stage 1 as the beginning of sleep and the beginning of the first prolonged Stage 0 in the morning as the termination, the average total sleep
time for these pre-adolescent schoolboys
was calculated to be 565 minutes (9.41 hours
)
with a range of483
to 596 minutes(8.05-9.93 hours). In general the sleep was
continuous except for occasional brief
awakenings as indicated by the occurrence
of a Stage 0 EEG pattern. Upon falling asleep, the boys’ EEC’s demonstrated a
more or less cyclic pattern which sponta-neously shifted back and forth from one stage to another. Initially most subjects moved rapidly through Stages 1, 2, and 3, reaching Stage 4 in 18 minutes and remain-ing in Stage 4 for an average of 42 minutes.
Stage 4 then gave way to Stages 3 or 2
(
Table II),
after which a brief epoch of Stage 1 accompanied by bursts ofbilater-ally synchronous, conjugate, rapid vertical and horizontal eye movements
(
REM’s)appeared. During the night the EEC rec-ord showed the cyclic pattern was re-peated four to five times with decreasing
amounts of Stage 4 and increasing amounts
This sleep stage
0 1 2 3 4
Was followed by this sleep stage
0 0.0 10.2 5.7 1.1 1.2
I 80.9 0.0 53.4 2.5 3.2
2 19.1 89.8 0.0 39.1 27.2
3 0.0 0.0 40.9 0.0 68.3
4 0.0 0.0 0.0 57.2 0.0
of REM sleep
(
Table III)
. Two outstand-ing characteristics of this sleep patternwere the occurrence of Stage 4 sleep,
pre-dominantly during the first third of the night, and the almost exclusive occurrence of REM sleep during the last two thirds. of
the night. When sleep was moving to deeper and toward lighter stages of sleep, the EEG change from one stage to the next
was smooth and regular, that is, the change
involved a movement across one stage at a
time. This represents a distinct departure from adult patterns when there are abrupt movements across several stages at a time
as the EEC moved toward lighter sleep
stages.
Percent of Total Sleep Time for Each Sleep Stage
Because each sleep stage does not appear at the same absolute time night after night for each subject, it was elected to
investi-gate the amount of time each boy spent in each sleep stage during the three sleep nights. In Table I are the mean percentages
of total sleep time for the five stages of sleep taken across three nights for each
subject. These percentages were obtained by adding the minutes spent in each sleep stage for three nights and dividing by the
total sleep time for three nights and con-venting to a percentage.
From these data it is evident that there
TABLE III
I)isrRIBLTI0N OF SLEEP STAGE AMOUNTS WITH
RESPECT TO THIRDS OF THE SLEEP PERIOD
Steep
Stage
I! ill
0 26.5 14.5 59.0
1 41.0 33.9 25.1
REM 6.0 33.6 60.4
2 26.4 40.8 32.8
3 55.7 26.5 17.8
4 77.5 18.2 4.3
total time spent in each stage of sleep. For example, Subject 5 spent 29.3% of his sleep in Stage 2, while Subject 15 spent 52.4% in Stage 2. In contrast to Stage 2, Stage 4 only had a range of 12.4 to
24.8%
and REM had arange of
19.0
to 30.0%. In spite of these indi-vidual variations, it is particularly interest-ing that each subject maintained approxi-mately the same percentage of total sleep for each sleep stage from night to night. The mean percentages of the sleep stages and their standard deviations are shown atTABLE IV
I)IMTuIHuTI0N OF SLEEL’ STAGE LENGTHS FROM
RECOHI)S REDUCED TO 483 MINUTES IN LENGTH
the bottom of Table I. They represent the average amount of time spent in each sleep
stage across 54 nights and thus indicate what
can be expected in the pre-adolescent boy.
Sequence of Stages
As mentioned before, the EEC’s of this group of subjects spontaneously showed cyclic shifts back and forth from one stage
to another. In Table II( a 5 X 5 contin-gency table) the frequency with which one stage followed another is presented. In 80.9% of the time Stage 0 (waking) is fol-lowed by Stage 1, and 19.1% of the time it is followed by Stage 2. Stage 1 is followed by
Stage 2 89.8% of the time. Stage 2 appears to be primarily a transitional stage because it is followed by Stage 3 only 40.9% of the time and Stage 1 approximately 53.4% of the
time. Stage 3 is followed by Stage 4 only
57.2% of the time and by Stage 2 about
39.1% of the time. These data demonstrate
the general trend seen in older age groups that, when sleep is moving toward Stage 4,
it involves a movement of only one stage at a time. However, absent in these data is the trend found with older subjects to lighten sleep rather abruptly, involving a jump of more than one stage. Rather, the sleep of these pre-adolescent boys is quite regular and smooth when moving to deeper or to-ward lighter stages of sleep.
Table II also demonstrates that the sub-ject does not enter slow wave sleep
(
Stage3 or 4) without passing through the transi-tional Stages of 1, 2, or 3, that is, one does
not go directly from the waking state into
slow wave sleep. Of almost similar consis-tency, upon leaving Stage 4 the subject
rarely wakes up.
Another important observation is that REM sleep is almost always preceded by Stage 2. Again, the transitional stages
ap-pear important in preparation for the bio-logically significant Stages 4 and REM.
Distribution of Sleep Stages Throughout the Sleep Period
Experience with older age groups has
shown that Stage 4 tends to appear in the first third of the night and REM sleep is
Sleep Stage 0 1 I)uralion (Minutes) 80-84 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24 15-19 10-14 5-9 1-4 Sum 2 5 9 7 7 19 25 36 33 50 61 56 69 134 151 665 3 5 21 113 294 433 4 2 3 2 ii 12 12 ii 17 22 26 19 27 44 36 247 3 3 4 4 11 16 15 25 22 24 28 34 43 53 206 491 1 0 0 0 l 0 0 0 I 1 1 6 81 92 REM 6 3 a 5 15 19 20 25 18 29 32 26 9 4 217
lour
49
42
30
39
37
33 32
45
37
35
40
23
28
36 30 ‘39
32
43
ARTICLES 329
concentrated in the last two thirds of the sleep period. To demonstrate a similar ten-dency in this group of boys, each of the 54 records was divided into thirds. The
amount of sleep in each sleep stage for the
first, second, and last thirds of the sleep
pe-nod was calculated, and the percent of the
total amount of each sleep stage was corn-puted for its occurrence within each third of the tracing.
Table III shows the percent of the total amount of sleep in a stage which occurred
in each third of the sleep period across all records. It is shown that, during the first third of the sleep period, 77% of total Stage 4 and 56% of total Stage 3 were seen while
only 6% of the total REM sleep was
ob-served. During the last third of the sleep period, the relationship is reversed, with
60% of the REM sleep appearing during this period and only 4% of total Stage 4 and 18% of total Stage 3. The middle third of
the period is characterized by the greatest
heterogeneity of the sleep stages. Worthy
of note is that the transitional stages of 1
and 2 have a fairly even distribution over
the entire sleeping period.
Duration of Sleep Stages
Table IV shows the frequency distribu-tion of the duration of each sleep stage
epoch for three nights of sleep. Each record
was reduced in length to that of the
short-est record (483 minutes
)
. By tallying thelength of each epoch of sleep, it is found
that 68% of the epochs were 19 minutes or
less. If one further reduces the length of
the records to 353 minutes in order to corn-pare with young adults
(
20 to 30 years ofage
)
,
the two groups give approximatelythe same distribution of sleep stage lengths. The brevity of the epochs demonstrates the
changeable nature of sleep and shows why
it is difficult to produce a typical sleep
stage histogram.
Number of Sleep Stage Changes
Table V shows the number of sleep stage
changes each night by subject. In order to
permit comparison of this variable between these subjects, all records were reduced in
length to that of the shortest tracing in this age group
(
483
minutes ). As with the stageamount variable, there are marked differ-ences between individuals in the number of times they change from one stage to an-other. Over the 54 nights of sleep, the num-ber of sleep stage changes ranged from 19 to 56 per night, with a mean of 35.7. There is no consistent pattern either to increase or de-crease the number of changes during the
study; however, there is a tendency for
sub-jects with few sleep stage changes per night to continue to have few changes and for subjects with a large number of changes to continue to change stages frequently. For
instance, Subject 18 had 56, 36, and 43 changes over three nights, which is
consis-tently above the mean, while Subject 12 had 32, 24, and 23 changes, which is consistently below the overall mean of 35.7 changes.
DISCUSSION
Within the past 10 to 12 years, knowledge
of sleep has advanced from the erroneous
‘FABLE V
NuInF:1t (IF SLEEP STAGE (IIAsoF IN RECORDS
REDUCED TO 483 MINUTES IN LENGTH
Night
Subject
H
- ---- --Tu’o Three
I 33 42
‘2 30 34
‘3 45 . 33
4 35 29
5 44 43
6 47 23
7 44 28
S 36 38
9 4! 41
10 32 2.5
II 52 32
12 32 24
13 30 29
14 31 26
13 35 19
16 49 38
17 34 29
Is 5(; 36
IeIIII 39.2 ‘31.(;
i!ean
41 .3
35.3 36 .(1 34.3
41 .3 34.3
34.7
40.7
39.7
30.7
41 .3
6.3
29(1
31 .0
25(1
42(1
31.7
45.0
330
concept of an unconscious suspension of
life punctuated by dreams to the general agreement that it is one of the primary ne-cessities of life, serving both biological and
psychological needs and consisting of
two qualitatively and quantitatively dis-tinct states which differ in their physio-logical properties. Non-rapid-eye-movement
(
NREM)
sleep, which consists of Stages 1,2, 3, and 4, occupies the greatest part of
sleep and is characterized in the EEG by
the presence of slow waves and sleep
spin-dies. The biological object of NREM sleep,
though not well understood, probably has something to do with physical recuperation and the maintenance of physiochemical homeostasis. This idea is based on several facts :
(
1)
non-REM sleep almost always precedes REM sleep on an ordinary night,(
2) the interval between sleep onset and the first REM period of the night tends to be longer than usual when the individual isvery tired or has stayed up unusually late,1#{176}
(
3)
children have an unusually long latency to the first recorded REM period starting about the time they discontinue their after-noon naps,1 and(
4)
trained athletes who have a vigorous afternoon of training orcontesting demonstrate an increased
amount of slow wave sleep.’ REM sleep is described as a distinct and regularly occur-ring psychophysiological state within the
night sleep cycle during which inward thought, consciousness, and dreaming oc-curs. The well known sleep patterns of high voltage slow waves and sleep spindles are replaced during REM periods by a low voltage, irregular pattern which is very sim-ilar to that of the activated waking state. REM periods occur at intervals of about 90 minutes and constitute 20 to 24% of total sleep time in the adult human. Dement has proposed that there is a need for a certain amount of dreaming,3233 and Fisher and Dement have suggested that dreaming may provide a necessary discharge for
instinc-tual tensions which cannot be gratified in reality.3 When awakened during REM pe-nods, subjects recall dreams in marked de-tail in 80 to 90% of the awakenings. Of
equal interest and significance are the physi-ological changes that occur during REM sleep. In contrast to NREM sleep, REM
sleep is accompanied by: an irregularity and increase in respiratory rate,3 an iregu-larity and increase in pulse rate,35’3 an ir-regular fluctuation and increase in systolic blood pressure,373s an increase in oxygen
consumption rate,3#{176}a decrease in the num-ber of spontaneous galvanic skin re-sponses,4#{176} bruxism,41 fine body movement,40 loss of muscle tone in some muscle groups,42 and penile erections.
Williams, et al.12,13 have shown in young adult males and females that an individual tends to spend a characteristic amount of
time in each sleep stage. They demon-strated that the percent of total sleep occu-pied by each of the four NREM sleep and the REM sleep stages and the number of sleep stage changes were so stable that a
change of 15% in any one sleep stage
ob-tamed in one night equaled one standard deviation from the sample mean. They
con-eluded that the sleep of any particular per-son showed a highly consistent pattern from night to night. However, individual differences were normally present. Data by Williams, et ai.12,13 20 to 30-year-old, adult males and females showed: Stages 0
and 1 occupied 1% and 5%, respectively, of total sleep time; Stage 2 occupied 48% of sleep time and was fairly evenly distributed
throughout the night; Stage 3 consumed only 8% of sleep; and Stage 4 sleep
occu-pied 13% of total sleep time and tended to appear in the first third of the night, while REM sleep occupied 24% of the total sleep time and appeared more frequently in the last third of the night.
When the sleep stage percentages of our pre-adolescent boys
(
S to 1 1 years)
were compared statistically(
t-test)
with those percentages presented by \Villiams, et al.12on 20 to 30-year-old males, there were no sig-nfficant differences between the two
percent-‘FABLE VI
MEAN NUMBER OF MINI’TES SL’ENT IN EACh STAGE
OF SLEEP BY Two (;ROIPS OF SIBJECTS
Pre..1do1e.eenf., }‘owi/ .I!iui,te (8-I 1 yr) 2()-.0) jjr) Difference
.S1(I’J(’ .
--
J’re-.ldolen-C;; .lIu,ule,, .iIt.,i!t’: centx-.ldult.,
0 1.5 5.3 0.9 :1.4 3.1
I 6.1 31.5 5.3 I.I 13.1
11E\1 4.3 137.6 4.I 1)1)6 35.0
44. 49J) 48.7 195.3 .51.6
3 5.9 33. 1 7.7 3I .3 IS
4 17.9 101.2 13. 53.8 47.4
Siini 99.9 5(11.5 1)1)9 407.S 157.1)
‘FABLE \lI
1)IMTRIBUTION OF ABNORMAL SIEEe STAGE
PERCENTAGES ASSOCIATED WITh I)ISEASE
Normal Ilyper- .4,,-Pre-.4doler’cent thyroid- orexia Sleep Value,, jsn ‘ervooa .‘t(Ije. -.- ---.. . I Ijoy, Girl,
(C .1).
10yearn I.. yf(?,
(1 I 1. 3 1
I 6 ‘2.5 :
IIESI li 3. 14 I))
44 6.5 l0 52
:t 6 1.9 15 K
4 IS 3. 1 0)
3+4 l4 3-I 31
ilyoteru,
Girl, Girl. Id yenra 12 ycar.
0 11
4 1
l0 17
32 29
6
17 34
43 40
ARTICLES
aM
age comparison. Table VI avoids some of
the difficulties in a percentage comparison
by comparing the mean number of minutes
that our pne-adolescents spent in each sleep
stage to that obtained by the adults. The
younger group was observed to sleep 157
rninutes
(
23 hours)
longer than young adults. It is also found that this additionalsleep time was not equally distributed to each of the stages. On the basis of an
hy-pothesis that an increase in sleep length is
distributed equally to each stage, one
rould expect a 26-minute increase in the
minutes of sleep in each stage for the
pre-adolescent boys. These data do not support this notion. Fifty-two minutes of the
addi-tional sleep time was distributed to Stage 2,
47 minutes to Stage 4, and 38 minutes to
REM. That this additional Stage 4 sleep
time is a function of the age of the subject
and not the additional sleep time is
sug-gested by a recent, unpublished study. A
group of 17 to 19-year-old subjects who
ha-bitually slept 9 hours or more were studied.
This group of subjects averaged 573 minutes
total sleep time, which is slightly more than
these pre-adolescent males. However, they
obtained only an average of 71 minutes in
Stage 4 sleep, which is 31 minutes less than
that obtained by the subjects of the present
study. Thus, although the pre-adolescent
males do sleep longer than the young
adults, there is evidence to suggest that the
relative great Stage 4 amount is a function
of their age and not of the sleep length.
Upon comparing the mean number of
sleep stage changes per night of the
pre-ad-olescent boys
(
35.7)
in Table V to the mean number of sleep stage changes in youngadult males
(
35.9),
there is no significantdifference. However, if one reduces all of
the pre-adolescent boys’ records to 353
mm-utes, vhich is the shortest record in the
adult normal data, the mean number of
sleep stage changes is 28.2, which is
signifi-cantly less than the 35.9 changes observed in
an identical record length for the young
adults. These comparisons suggest that
youthful sleep patterns over the night are
as stable as that of the young adult, but that
the sleep stages in children are longer in
duration. Table IV also demonstrates this.
The data presented by Williams, et
al.,12,13 Agnew, et al.,14 and the present
au-thors reveal that there are some aspects of
sleep which are typical of an individual and
others that are common for human sleep.
Typically, intra-subject stability and consis-tency was observed in the amount of time
spent in each sleep stage and in the number
of sleep stage changes night after night,
while inter-subject similarity of individuals
8 to 60 years of age is observed in the
occur-rence of a more or less cyclic pattern of
sleep stages which spontaneously shifts
from one stage to another, but in which
Stage 4 occurs predominantly in the first
part of the night and REM sleep in the
quan-titative and reproducible EEG-EOG
mea-surements, a substantial body of data about
children and adults is provided as an
effec-tive frame of reference against which
path-ological deviations may be evaluated.
Although much of an authoritative na-ture is written about sleep problems in chil-dren, there has been scant documentation of electrophysiologic alterations in sleep
pa-rameters. During the past year this
labora-tory had the opportunity to perform EEC-EOG studies on several pre-adolescent chil-dren with the following medical and
psy-chiatric illnesses : hyperthyroidism, anorexia nervosa, and hysteria (Table VII
)
. Thepatient with hyperthyroidism was a
10-year-old boy with typical signs and
symptoms of Crave’s disease, including
fret-ful sleep with frequent body movements, emotional disturbances, and diminution in school performance. On his initial hospital-ization at the University of Florida
Teach-ing Hospital, the EEG-EOC all-night sleep
recording showed a marked deviation of his sleep pattern from normal means. Stage 4
sleep occupied 39% of total sleep time,
which is about seven standard deviations
above the mean value for his group, and
REM was 14%, which is about three stan-dard deviations below the mean value. Of
particular interest to us was the return of
his percentage sleep stage values to normal
as he received appropriate treatment with
propylthiouracil and desiccated thyroid.
Our 12-year-old girl with anorexia nervosa also showed an abnormal sleep pattern dur-ing her hospital investigation. Particularly
noteworthy was the 10% REM value which was four standard deviations below the
mean value of 24% for the pre-adolescent
age group as well as a Stage 4 value of 26%.
Table VII also presents the sleep patterns of two other patients-one, a 12-year-old girl who was admitted for headaches, poor
school performance, insomnia, enuresis, hal-lucinations, and transient hemiparesis and who was diagnosed as having a psychoneu-rotic reaction with a hysterical personality. Another 12-year-old girl was admitted with
headaches, brief “lapses,” screaming and
kicking spells during which she threatened to kill somebody, insensitivity to pails over
half of her body, and tunnel vision on the
same side. The latter patient was thought
to have conversion hysteria. Of interest to us
was the finding in both of these girls of the
marked increase in total sleep time spent in Stage 4 sleep and the mild depression of
REM sleep. We have not had the
opportu-nity to retest the three girls to date.
The authors are not prepared to offer an
explanation for the divergent sleep
pat-terns. We have no idea whether the organic
and emotional illnesses are responsible for the abnormal patterns or whether abnormal
sleep patterns cause emotional
distur-bances. Abundant data from the electroen-cephalographic, endocrine, and sleep areas
effectively demonstrate that variations in the human sleep pattern can result from drugs,45-48 disease,#{176}5 and various forms of sleep deprivation
(
total,8 partial,’#{176}#{176}and selective)
33,61-63 The only point we wish tomake is that patients with severe medical
diseases, some of whom have marked sleep
disturbances, may have abnormal sleep
pat-terns. The significance of this observation
remains for future research to determine.
SPECULATIONS
In the minds of the authors the major
contribution of this research is the fact that it represents the first systematic application of the EEC-EOG methodology and of the modified Dement-Kleitman scoring criteria
to study childhood sleep and sleep distur-bances. Now mere visual observation and
conjecture have been eliminated, and a
safe, effective, convenient, quantitative,
re-producible, descriptive method is available for investigating sleep in children. Since there is so little basic, quantitative data which pertains to childhood sleep, this ap-proach represents an important
break-through in our attempt to understand
dis-turbed sleep in children and a vigorous ap-plication of these methods and concepts should speed a better understanding of
ARTICLES 333
adults,2,SS61GO and efforts to correct them
are being attempted.7 In children it
ap-pears to us that the measurement of percent
of total sleep time spent in the five sleep stages is a sensitive indicator of the electro-physiological characteristics of sleep, and
investigation of this measurement may
make it possible to gain an understanding
of the intra-sleep, medical, and psychiatric
disorders of sleep.
SUMMARY
Simultaneous all-night EEG and EOG
recordings have been shown to be an
effec-tive, quantitative, and reproducible method for studying children’s sleep. Application of a modified Dement-Kleitman scoring tech-nique to the 54 records obtained from 18 healthy, pre-adolescent boys made it
possi-ble to describe quantitatively their typical sleep pattern. Descriptive measurements
in-eluded: percent of total sleep time spent in
each stage of sleep, total minutes in each stage of sleep, sleep duration, sleep latency, sequence of sleep stages, distribution of
sleep stages throughout the sleep period,
duration of sleep stage epochs, and number of sleep stage changes. Although individual variations are apparent, it was found that
each boy maintained approximately the same percentage of total sleep for each sleep stage from night to night. First ex-perience utilizing this clinical all-night EEG-EOC tool in children suggests this technique should permit a higher yield of
significant scientific data in the study of
sleep problems.
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