Sleep, 18(2):82-87
. .
.
© 1995 American Sleep Disorders AssociatIon and Sleep Research Society
Naps in Children: 6 Months-7 Years
Marc Weissbluth
Northwestern University School of Medicine, Chicago. Illinois. U.S.A.
Summary: A cohort of 172 children was followed from 6 months to 7 years of age to determine how nap patterns
change with age and whether there was individual stability of nap patterns. Results showed .that there were no
differences in nap patterns based on gender, ordinal position, whether nap~ spontaneousl.y dlsappeare.d ~r .were
stopped by the parents, and the number of naps at 6 months of.age. To.tal daytlme sle~p rem!med a stable mdlVldual
characteristic between 6 and 18 months of age. Age was assocIated With hours nappmg (r.- -0.73, p < 0.001) and
number of naps (r = -0.52, p < 0.001). A pattern of two naps per day was well estabhshed by 9-12 months. of
age and one afternoon nap by 15-24 months. Th: ~odal du~ation of naps from ~ to 6 years w~s 2 ~ours. ~unng
the 3rd and 4th year, napping occurred in the maJonty of children, but at decreasmg rates. A mmonty .of children
were napping at 5 and 6 years and naps usually disappeared by age 7. Key Words: Naps-Infants-Children.
Chronobiological features of daytime sleep/wake lution of nap patterns in these children is similar to or
rhythms have been studied in different culture~ a~d different from children of other cultures or social classacross species and ages (1). However, for the pedlatnc es.
age group, recent books contain little or no data ~n
naps (2,3). Previously published research among chilMETHODS
dren has utilized either a cross-sectional design, gathering data on different age groups at one point in time
From September 1, 1984 to April 1, 1986, all con(4-6) or following one group of children for a relatively
secutively born infants attending a general pediatrishort period of time (7-13). One study observed that
cian's office (M.W.) were enrolled in the study and
total sleep duration and the longest single period of
examined by the author. None were referred to the
sleep were stable individual characteristics, but that
author for any problems. They were from white middle
study examined three different groups of children at
and upper-middle class families residing in an urban
three different age intervals and did not specifically
area. Beginning at the 6-month routine office visit, the
examine nap patterns (14). The purpose of this study
parents were asked, "How many naps does your child
was to longitudinally study a single group of children
take?", "Adding up the total time asleep during the
until they stopped napping in order to determine
day, how many hours does your child sleep?", and if
whether nap patterns were stable individual characthere were no naps, "Did your child naturally stop
teristics. Additionally, the study was designed to detaking naps or did you not allow, and why did you not
termine whether nap patterns in children might be
allow your child to nap?". These questions were asked
associated with gender or ordinal position, and whethat all subsequent routinely scheduled office visits (9
er there were differences in nap patterns between chilmonths, 12 months, 15 months, 18 months, 24 months,
dren who were permitted to outgrow their naps comand annually thereafter). At 21 months, when no office
pared with children whose naps were stopped by their
visit was scheduled, each family was contacted by the
parents. Data are presented which would assist cliniauthor. Sleep durations were rounded to the nearest 112
cians in determining whether an abnormal nap pattern
hour. Patients were included in this report if they remight be considered to be a sleep problem. The data
mained in the pediatric practice at the time when they
will permit investigators to determine whether the evostopped napping or reached their seventh birthday.
Patients were excluded if they left the practice at a time
when they were still napping. Of 266 children enrolled
Accepted for publication September 1994.
in the study at 6 months of age, 172 children (65%)
Address correspondence and reprint requests to Marc Weissbluth,
M.D., 680 North Lake Shore Drive, # 123, Chicago, IL 60611, U.S.A.
remained in the study until completion.
82
83
NAPS IN CHILDREN
Napping: Number Per Day
2.5
Naps Per Day
-- ----.. - -.. -... - --.. -... ---... --. ---. ·j_Mean NapslDay
2
~.-
1.5
1
0.5
0
6
9
12
15
18
21
24
36
48
60
# Children (N)
172
172
172
172
172
172
172
158
98
46
20
Mean Naps/Day
Std. Dev.
Minimum
Maximum
2.21
2.03
1.86
1.52
1.28
1.14
1.07
0.88
0.72
0.58
0.43
0.4
0.29
0.36
0.48
0.44
0.33
0.28
0.23
0.28
0.28
0.28
1
1
1
0.5
0.21
0.14
0.21
0.14
3
3
3
2
4
3
2
72
3
Age In Months
FIG. 1. Number of naps per day by age in months.
Data on the number of naps, duration of naps,
whether the naps stopped spontaneously or were not
allowed by the parents ("scheduled"), child's gender
and ordinal position were analyzed by the Statistical
Package for the Social Sciences computer program for
MS WINDOWS Release 5.0. To determine whether
or not there was individual stability of nap patterns,
five groups of infants based on nap duration were created at 6 months of age. Repeated-measures analysis
of variance (ANOVA) using multivariate analysis of
variance (MANOVA) was performed to evaluate interactions between duration groups and age. One-way
ANOV A was used to compare these five groups based
on hours napped at each subsequent age. To determine
whether those infants who at 6 months of age had more
than two naps per day, when compared with those
infants who had only two naps per day, continued to
sleep more in terms of more naps or longer nap durations at subsequent ages, one-way AN OVA was performed. ANOV A using repeated measures utilizing
MANOV A was performed to evaluate interactions between gender and nap patterns and also between ordinal position and nap patterns. One-way ANOVA was
utilized to compare children who naturally stopped
napping and children whose parents scheduled naps to
stop. This analysis was performed first on all children
in the study and second on groups of infants based on
nap duration at 6 months of age. Pearson productmoment correlations were computed to determine the
relationship between age and number of naps and age
and duration of naps. Results are reported as significant
ifp < 0.05.
RESULTS
Of the 172 children in the study, 96 (56%) were boys
and 134 (78%) were firstborn. At 7 years of age, 20
(12%) of children were still napping. Within a few
months after their seventh birthday, only four children
were still napping. Napping ended naturally in 112
(65%), napping was stopped by the parents in 56 (33%),
and was unknown in 4 (2%). No differences were observed with regard to the number of hours napping per
day, the number of naps per day or the age when napping stopped (whether natural or scheduled) between
boys and girls, between firstborn and subsequent born
children, or between infants at 6 months of age who
had more than two naps per day compared with those
who had two naps per day. Therefore, subsequent analyses were performed on the entire group. In Fig. 1, for
Sleep. Vol. 18. No.2. 1995
M. WEISSBLUTH
84
Percent of Children Taking 1, 2, or 3 Naps Per Day by Age
120
100
Percent (among those still napping)
-- - -------- ---
----
-- - -- - --- -- -------
--
----
...................................
-~----~-----
80
- --- -
1- IlDay -
2IDay 1@@3IDay
60
40
20
0
6
1IDay
2IDay
3IDay
0
83.7
16.3
9
12
15
18
21
24
36
48
60
72
3.5'
17.4
81.4
1.2
55.8
43.6
0.6
76.7
22.7
0.6
87.8
12.2
0
94.2
5.2
0.6
100
0
0
100
0
0
100
0
0
100
0
91.3
5.2
0
Age In Months
FIG. 2.
Percent of children taking one, two or three naps per day by age. Percent of those still napping by age in months.
ages 3, 4, 5 and 6 years, the mean number of naps per
day represents about six, five, four and three naps per
week, respectively. Figures 1 and 2 show that at 6
months, infants nap two to three times per day and
the third nap disappears by 9-12 months. Between 15
and 24 months, the morning nap disappears. At age 3
years, 92% ofchildren are still napping 6 days per week,
and at age 4, the majority ofchildren (57%) are napping
5 days per week. At age 5, 27% of children are napping
4 days per week. Figure 3 shows that at 6 months, the
mean number of hours per day napping is 3.5. The
range is wide (1-6 hours), however 80% of these infants
sleep 2.5-4 hours per day, with 5% sleeping <2.5 and
15% sleeping >4 hours per day. At 9 and 12 months,
93% and 94% of infants, respectively, nap between 2
and 4 hours. With increasing age, infants' nap durations were restricted to narrower time frames; for example, at 15, 18,21 and 24 months, 91%, 98%, 97%
and 99% ofinfants, respectively, napped 1.5-3.5 hours.
The mode duration of the single nap from 2 to 6 years
is 2 hours. The percent of children who are napping
near the mode, 1.5-2.5 hours, is 76%, 80% and 80%
at age 2, 3 and 4 years, respectively. At ages 5 and 6,
most children who are still napping are sleeping 1-2
hours (89% at age 5 and 90% at age 6). Figure 4 shows
Sleep, Vol. 18, No.2, 1995
that at 3 years, parents reported that only 1.8% of these
children had stopped napping during their 2nd year.
However, during their 3rd and 4th year, 18.5% and
34.5% of the children, respectively, naturally stopped
napping. From the data shown in Fig. 5, repeated measures ANOVA using MANOV A showed significant interactions between duration groups and age (F = 1.73,
df = 36, p = 0.005). Statistically significant differences
were observed between these groups at 9 months (p <
0.001), 12 months (p < 0.001), 15 months (p < 0.05)
and 18 months (p < 0.05). At 21 months (p = 0.08)
and 24 months (p = 0.07) there is a tendency for children to maintain their initial nap duration pattern. The
Pearson product-moment correlation of age by hours
of napping was significant (r = -0.73, p < 0.001), as
was the correlation of age by number of naps (r =
-0.52, p < 0.001).
DISCUSSION
Ontogenetic development of sleep processes has matured into a consolidated circadian rhythm of wakefulness and sleep by 6 months of age (15-20). Among
infants and children no consistent relationship has been
reported between the duration of daytime sleep and
................
------------------------
85
NAPS IN CHILDREN
Napping: Hours Per Day
4.0
3.5
Hours Per Day
~ ..
............................................... ~ .Mean Naptime
3.0
2.5
2.0
1.5
1.0
0.5
0.0
# Children (N)
6
9
12
15
18
21
24
36
48
60
72
172.0
172.0
172.0
172.0
172.0
172.0
172.0
157.0
98.0
46.0
20.0
Mean Naptime
3.5
3.1
3.0
2.7
2.5
2.4
2.3
2.1
1.9
1.7
1.6
Std. Dev.
0.8
0.7
0.7
0.8
0.6
0.6
0.5
0.6
0.7
0.5
0.5
Minimwn
1.0
1.0
1.5
1.0
1.5
1.0
1.0
1.0
05
1.0
0.5
Maximum
6.0
5.5
55
55
4.0
4.0
4.0
3.5
5.0
3.0
2.5
Age in Months
FIG. 3. Number of hours per day spent napping by age in months.
Percent of Children Who Stopped Napping
By Age Stopped and Natural vs Scheduled*
Percent
40.0
34.5
35.0
30.0
• Natural
........................
fBI Scheduled
'---------'
25.0
20.0
15.0
10.0
5.0
1.2
0.6
0.0
24Mo
36Mo
48Mo
60Mo
72+Mo
Age Napping Stopped
*These are percents of all children, e.g., 345% of all children stopped napping naturally in their 4th year.
FIG. 4. Percent of children who stopped napping by age (months) when napping stopped and natural vs. scheduled end to napping.
Sleep, Vol. 18, No.2, 1995
M. WEISSBLUTH
86
Napping: By Duration Groups At 6 Months
Hours Per Day
5.0
"'1-2.5 Hrs (Mean) .3 Hrs (Mean)
+3.5 Hrs (Mean)
4.0
+4 Hrs (Mean)
+> 4 Hrs (Mean)
3.0
2.0
1.0
0.0
6
9
12
15
18
21
24
36
48
60
72
1-2.5 Hrs (Mean)
2.3
2.7
2.5
2.4
2.2
2.2
2.2
2.0
1.8
1.6
1.5
3 Hrs (Mean)
3.0
2.9
2.8
2.6
2.5
2.4
2.3
2.1
1.8
1.7
1.7
3.5 Hrs (Mean)
3.5
3.1
3.1
2.7
2.5
2.4
2.4
2.3
2.2
1.9
4 Hrs (Mean)
> 4 Hrs (Mean)
4.0
3.2
3.2
2.9
2.5
2.6
2.5
2.2
1.9
1.7
1.7
1.5
4.8
3.6
3.3
3.0
2.8
2.6
2.3
2.0
1.8
1.8
1.6
Age In Months
FIG.S. Napping by duration groups at 6 months (hours per day by age in months). Number per duration group
(3 hours), 41 (3.5 hours), 3S (4 hours) and 2S (>4 hours).
nighttime sleep (13,21-24). Thus, it was decided to
begin at 6 months and focus on daytime sleep; because
of the time constraints imposed by the context of a
busy general pediatric office, data were not gathered
on night sleep or temporal patterns of sleep. Newborns
were enrolled in the study before the publication of the
author's parent advice book on sleeping (25); thus, it
is unlikely that parents selected the author for pediatric
care based on expectations regarding sleeping. Parent
education regarding sleep habits has been shown to
produce better sleep patterns (26), and advice was given to parents regarding napping based on generally
available published information. Therefore, the data
may reflect optimum napping.
The age-specific decrease for nap duration observed
in this survey is the same as previously reported in
1981 and 1927 (27). Other studies of young infants
(14), children (17), and adults (1) showed a tendency
for individual stability of sleep patterns. Intrasubject
stability, despite the intersubject variability, was also
observed in this study between 6 and 18 months. Stable
age-specific trends and individual stability may reflect
biological processes. Finally, the fact that the range of
nap duration around the mode is narrow and the mode
Sleep, Vol. 18, No.2, 1995
=
31 (1-2.5 hours), 40
stays constant from 2 to 6 years despite variation in
caretaking and social activities suggests that nap duration in children has a biological basis. Another study
reported similar results regarding the ages and percent
of children when daily naps stopped: 21f2-3 years (20%),
3-4 years (17%) and 4-5 years (40%) (4). Thus, it appears that naps naturally become less common after
the third birthday. Some parents stop their child from
napping, but, as a group, their children did not have
different nap patterns from those children who naturally outgrew naps. There were three reasons why parents stopped their children from napping. Among 36-year-old children, scheduled preschool or school activities conflicted with the nap (60%) and parents of
5-year-olds wanted the child to go to sleep earlier at
night (30%) because the children were fighting going
to sleep or falling asleep around 9-10 p.m. Stressful
events that disorganized home routines, such as death
of a parent, divorce, move to a new home or birth of
twin siblings, caused an additional 10% of parents to
stop a child's napping. Simply having a new sibling
was not associated with a change in napping. Furthermore, there were three children between 21f2 and 31/2
years of age who stopped napping for about a year
NAPS IN CHILDREN
87
sleep rhythm of children aged from 21h to 41h years. Acta Paediatr
during a period of marital discord or problems with
Scand 1984;73:667-73.
caretakers. After resolution of the conflicts, all three 13. Klackenberg G. The development ofchildren in a Swedish urban
children resumed napping and continued to nap for
community. A prospective longitudinal study. VI. The sleep
behavior of children up to three years of age. Acta Paediatr Scand
years. Additionally, there were many other children
1968;Suppl 187:105-21.
whose families experienced deaths (including Sudden 14. Jacklin CN, Snow ME, Gahart M, Maccoby EE. Sleep pattern
Infant Death Syndrome), divorces or moves but there
development from 6 through 33 months. J Pediatr Psychol1980;
5:295-303.
were no napping problems. It appears that when par15. Harper RM, Leake B, Miyahara L, et al. Temporal sequencing
ents and caretakers maintain nap routines, despite poin sleep and waking states during the first 6 months oflife. Exp
tentially disruptive stressful events, children continue
NeuroI1981;72:294-307.
16. Coons S, Guilleminault C. Development of sleep-wake patterns
to nap.
REFERENCES
1. Dinges DF, Broughton RJ, eds. Sleep and alertness. Chronobiological, behavioral, and medical aspects of napping. New York:
Raven Press, 1989.
2. Guilleminault C, ed. Sleep and its disorders in children. New
York: Raven Press, 1987.
3. Touitou Y, Haus E, eds. Biologic rhythms in clinical and laboratory medicine. Berlin: Springer Verlag, 1992.
4. Dales RJ. Afternoon sleep in a group of nursery-school children.
J Genet Psychol1941 ;58:161-80.
5. Moore T, Ucko Le. Night waking in early infancy. Arch Dis
Child 1957;32:333-45.
6. Holliday J, Sibbald B, Tooley M. Sleep problems in two-yearolds. Family Practice 1987;4:32-5.
7. Wooding AR, Boyd J, Geddis DC. Sleep patterns in New Zealand infants during the first 12 months of life. J Paediatr Child
Health 1990;26:85-8.
8. Bramford FN, Bannister RP, Benjamin CM, Hillier VF, Word
BS, Moore WM. Sleep in the first year of life. Dev Med Child
NeuroI1990;32:718-24.
9. Wladimirova G. Study of cyclic structure of daytime sleep in
normal infants aged 2 to 12 months. Acta Physiol Pharmacol
Bulg 1983;9:62-9.
10. Traisman AS, Traisman HS, Coatti RA. The well-baby care of
530 infants. A study ofimmunization, feeding, behavioral, and
sleep habits. J Pediatr 1966;73:608-14.
11. Crowell J, Keener M, Ginsburg N, Anders T. Sleep habits in
toddlers 18-36 months old. JAm Acad Child Adolesc Psychiatry
1987;264:510-5.
12. Koch P, Soussignan R, Montagner H. New data on the wake-
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
and non-rapid eye movement sleep during the first six months
of life in normal infants. Pediatrics 1982;69:793-8.
Hoppenbrowers T, Hodgman J, Arakawa K, Geidel SA, Sterman MB. Sleep and waking states in infancy; normative studies.
Sleep 1988;11 :387-401.
Louis J, Zhang JX, Revol M, Debilly G, Challamel MJ. Ontogenesis of nocturnal organization of sleep spindle: a longitudinal study during the first 6 months oflife. Electroencephalogr
Clin NeurophysioI1992;83:289-96.
Salzarulo P, Fagioli I. Post-natal development of sleep organization in man: speculations on the emergence of the 'S process'.
Neurophysiol Clin 1992;22:107-15.
de Roquefeuil G, Djakovic M, Montagner H. New data on the
ontogeny of the child's sleep-wake rhythms. Chronobiollnt 1993;
10:43-55.
Koch P, Soussignan R, Montagner H. New data on the wakesleep rhythm ofchildren aged from 21h to 41h years. Acta Paediatr
Scand 1984;73:667-73.
Weissbluth M. Sleep duration and infant temperament. J Pediatr
1981;99:817-9.
Michelsson K, Rinne A, Paajanen S. Crying, feeding and sleeping patterns in I to 12-month-old infants. Child Care Health
Dev 1990; 16:99-111.
Weissbluth M. Sleep duration, temperament, and Connors' ratings of three-year-old children. Dev Behav Pediatr 1984;5: 120-3.
Weissbluth M. Health, sleep habits, happy child. New York:
Ballantine, 1987.
Wolfson A, Lacks P, Futtman A. Effects of parent training on
infant sleeping patterns, parents' stress, and perceived parental
competence. Clin PsychoI1992;60:41-8.
Weissbluth M, Poncher J, Given G, Schwab J, Mervis R, Rosenberg M. Sleep duration and television viewing. J Pediatr
1981;99:486-8.
Sleep, Vol. 18, No.2, 1995