Children's Sleep: An Interplay Between Culture and Biology

Abstract

Pediatricians provide a major source of knowledge for parents about children's behavior and development, although their advice is largely based on their own cultural values and beliefs in interaction with their personal and clinical experience. This review presents cross-cultural aspects of children's sleep behavior in industrialized and complex modern societies and provides a basis for understanding dimensions and mechanisms of cultural differences. We submit that it is the interaction between culture and biology that establishes behavioral and developmental norms and expectations regarding normal and problematic children's sleep. Pediatricians need to recognize the cultural environment in which children live and be knowledgeable about how cultural beliefs and values of both families and physicians interact with the needs and biological characteristics of individual children.

Full text

Children’s Sleep: An Interplay Between Culture and Biology
Oskar G. Jenni, MD*‡, and Bonnie B. O’Connor, PhD§
ABSTRACT. Pediatricians provide a major source of
knowledge for parents about children’s behavior and
development, although their advice is largely based on
their own cultural values and beliefs in interaction with
their personal and clinical experience. This review pre-
sents cross-cultural aspects of children’s sleep behavior
in industrialized and complex modern societies and pro-
vides a basis for understanding dimensions and mecha-
nisms of cultural differences. We submit that it is the
interaction between culture and biology that establishes
behavioral and developmental norms and expectations
regarding normal and problematic children’s sleep. Pe-
diatricians need to recognize the cultural environment in
which children live and be knowledgeable about how
cultural beliefs and values of both families and physi-
cians interact with the needs and biological characteris-
tics of individual children. Pediatrics 2005;115:204–216;
sleep, culture, children, child development, child rearing.
Pediatricians are widely accepted as experts in
child development. In Western countries, they
are a major source of knowledge for parents
about children’s behavior and development.
1–3
Many pediatricians, however, lack sound training in
developmental and behavioral pediatrics, and thus
their advice is largely based on their own cultural
values and beliefs (many of which may be operating
out of their own direct awareness
4
) in interaction
with their personal and clinical experience. A recent
study of pediatricians’ knowledge about breastfeed-
ing and advice to mothers illustrates this point: pe-
diatric residents or practitioners who responded cor-
rectly to questions about breastfeeding were
overwhelmingly those who had personal experience
with breastfeeding of their own children.
5,6
In recent years, pediatricians have increasingly
been confronted with families of widely differing
cultural origins. Worldwide geopolitical boundary
shifts, changes in patterns of immigration, and refu-
gee relocation in response to political or economic
pressures have created dramatic demographic
changes in many countries. In addition, many na-
tions’ internal ethnic groups have grown to comprise
significant percentages of the patient population,
whose distinct needs and varied views can no longer
be missed (or dismissed) in health care.
Cross-cultural issues in child development have
received considerable attention not only in the pedi-
atric but also in the psychologic and anthropologic
literature.
7–10
Because much of this literature ap-
proaches development through the lens of encultura-
tion and socialization, it may tend to stress the role of
culture over that of biology as a “prime mover” in
child development. Here, we also focus on cultural
aspects of childhood sleep and sleep behavior and
their interpretation. In doing so, we emphasize that
both biological determinants of sleep and the ways in
which culture and biology interact play a major role
in establishing behavioral and developmental norms
and expectations regarding normal and problematic
children’s sleep. Both influences must be taken into
account in the provision of optimal health care and
parenting advice to the full range of pediatricians’
patients and their families. We draw on pediatric,
psychologic, sociologic, historical, and anthropologic
literature in cross-cultural research about sleep along
with some references from literary and journalistic
sources that (as representatives of cultural opinion
and assumption) also provide valuable information
and insights on the topic. It is worth mentioning that
information about cultural issues in children’s sleep
in the scientific literature is scant, widely scattered,
and fairly narrowly focused (eg, mostly regarding
cosleeping and bedtime ritual). On the whole, the
topic of children’s sleep culture is not studied very
thoroughly in any one discipline.
Small tribal, traditional, and nonindustrialized so-
cieties’ sleep behaviors were the topic of a recent
outstanding comparative survey by Worthman and
Melby.
11
We expect such societies to differ radically
from our own in almost every regard, but the general
conclusions drawn by these authors apply equally to
complex and industrialized societies, which also
show considerable variability in their approaches
and expectations regarding sleep. Japan and the
United States, for example, are both highly industri-
alized and economically successful “first-world”
countries, yet their deep cultural difference between
emphasis on interdependence and collectivity in the
former and on independence and direct competition
in the latter is reflected in dramatically different ap-
proaches to training and patterning of children’s
sleep.
12
In another example, Western European
countries, although geographic neighbors, do not
From the *Department of Psychiatry and Human Behavior, Division of
Child and Adolescent Psychiatry, E. P. Bradley Hospital Chronobiology and
Sleep Research Laboratory, and §Division of Pediatric Ambulatory Medi-
cine, Department of Pediatrics, Brown Medical School, Providence, Rhode
Island; and ‡Department of Pediatrics, Growth and Development Center,
University Children’s Hospital, Zurich, Switzerland.
Accepted for publication Aug 5, 2004.
doi:10.1542/peds.2004-0815B
No conflict of interest declared.
Address correspondence to Bonnie B. O’Connor, PhD, Division of Pediatric
Ambulatory Medicine, Department of Pediatrics, Rhode Island Hospital/
Brown Medical School, 593 Eddy St, Potter Suite 200, Providence, RI 02903.
E-mail: boconnor@lifespan.org
PEDIATRICS (ISSN 0031 4005). Copyright © 2005 by the American Acad-
emy of Pediatrics.
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share common orientations about how children
should fit into contemporary family styles. Italians
view children as more central in their lives than do
the Dutch,
13
for instance, and their approaches to
child sleep vary accordingly. In this review our pri-
mary focus will be on culture and children’s sleep in
industrialized and complex modern societies.
Sleep can be considered a biologically driven be-
havior of the child that is strongly shaped and inter-
preted by cultural values and beliefs of the parents. It
is important to note that many “problems” with
sleep during childhood, such as difficulties falling
asleep alone or waking at night and seeking parental
attention, are based on culturally constructed defini-
tions and expectations and are not necessarily rooted
in sleep biology. For example, Stearns and Row-
land
14
point out that in Japan (in contrast to the
United States), insomnia is not a matter of great
concern and is seldom a subject of medical consulta-
tion. In a recent study, Italian parents reported it
customary and preferable to have infants sleep in
their rooms with them irrespective of the availability
of separate rooms and considered the American
norm of putting children to bed in separate rooms to
be “unkind.”
15
Steger describes this practice more
strongly as “hard and difficult training . . . that . . .
causes a lot of tears,”
16
raising in our minds the
question of whether at least some sleep-related prob-
lems of children are not in fact created by cultural
practices that may be incongruent with aspects of
sleep biology or with stages of a child’s emotional
development. Clearly, there is a need to understand
better the effects of cultural norms on children’s
sleep behavior and their interplay with biology. Such
an understanding is fundamental to comprehending
what constitutes a sleep problem, when and for
whom, how best to approach it, and perhaps even to
work to modify some cultural standards and prac-
tices as a means of improving quality of life for
children and families.
DEFINING AND UNDERSTANDING CULTURE
We are accustomed to thinking of culture as sets of
beliefs, norms, and expectations; as matters of pref-
erence or habits of mind that may reflect nothing
more than an uncritical or unconscious continuity of
tradition. However, culture is much more encom-
passing and complex. In effect, “culture is the entire
nonbiological inheritance of human beings.”
17(p35)
Everything that human beings inherit from one gen-
eration to the next that is not passed on biologically
(ie, “everything that is socially constructed and
learned”
17[p35]
) is a part of culture. In the most
straightforward language, one might accurately say,
“if you got it from other human beings and you
didn’t get it through biology, then you got it through
culture.” This understanding of culture as a holo-
graphic and encompassing context of human life,
learning, and behavior is critically different from the
more simplistic views that have long prevailed, es-
pecially in the literature of the health professions. In
these disciplines, culture is typically reduced to sets
of “novel” (from the medical perspective), “quaint,”
or even implicitly erroneous beliefs that are attrib-
uted to patients (or perhaps only to some patients as
a proxy for racial or ethnic minority status) but not to
health professionals or the majority culture. Addi-
tionally, culture is commonly regarded as relevant to
medicine principally when it is identified as an etio-
logic factor in certain health problems or considered
a potential “complication” of medical care.
17
Culture and biology are the 2 great streams of
human continuity and change. The broad definition
of culture that we have adopted encompasses far
more than the “developmental niche” in which chil-
dren’s behavior is conditioned and regulated,
18
and
this has significant implications. For one thing, it
means that we are all included in the cross-cultural
equation: culture is not something that only comes
through the door with patients.
19
It means that not
only values, languages, religions, arts, cuisines,
modes of dress, family structures, authority relation-
ships, gender roles and expectations, behavioral
norms, and modes of communication are elements of
culture. So also are economic and political structures,
sciences, mathematics, modern information technol-
ogies, bodies of knowledge and the texts and refer-
ence works that convey them, and health care re-
sources including modern biomedicine and sleep
research. All are products of culture, and all reflect
cultural shaping. It is also important to bear in mind
that all cultures are partial, in the sense that they
select for certain human preferences and possibilities
and omit (or never even imagine) others. All are
characterized by fundamental world views, and all
presume their views of reality to be actual, factual,
and correct: the “way things are.”
SLEEP BIOLOGY AND SLEEP CULTURE
Biology
Over the past 50 years, much has been learned
about the structure of sleep, its biological regulation,
and purpose.
20
Among the explanations for the bio-
logical function of sleep, 2 hypotheses have domi-
nated the field: (1) sleep is restorative for brain me-
tabolism and (2) sleep serves memory consolidation
and learning.
21,22
Considering such vital functions
for the organism, sleep must be regulated by biolog-
ical processes. In fact, deprivation or restriction of
sleep leads to a compensatory response with in-
creased need for sleep.
23
Specific biological processes
(circadian and homeostatic) play an important role in
determining the duration and timing of sleep.
23–25
The endogenous nature of sleep and its regulation
have been well described on the basis of general
mechanisms, but human beings obviously demon-
strate considerable interindividual differences in
their sleep patterns as well as in their ability to
compensate for deviations from “normal” sleep. A
recent study indicated that the intersubject variabil-
ity of habitual sleep duration has a biological basis
through the individually programmed circadian
clock.
26
The large variability between individuals is
also reflected in their biologically preferred bed-
times. “Larks,” or “morning people,” show a prefer-
ence for waking at an early hour and find it difficult
to remain awake beyond their usual bedtimes, as
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compared with “owls,” or “night people,” who show
a preference for sleeping at later hours and often find
it difficult to get up in the morning.
Although most research on sleep biology has been
performed with adults, an increase of interest is also
apparent in how sleep is regulated in children and
adolescents and in what function(s) sleep serves dur-
ing development.
27–32
It is most likely that children,
like adults, exhibit large individual differences in
their ability to regulate sleep and in their particular
“natural” sleep rhythms. Differences in sleep pat-
terns as a function of development add to the com-
plexity of understanding sleep biology in children.
Culture
Numerous aspects of sleep are influenced by di-
verse cultural standards. How we sleep, with whom
we sleep, and where we sleep are molded by culture
and customs. Culture influences sleeping and wak-
ing times including whether sleep is consolidated
into a single continuous period and thus is associated
with a single specific “bedtime” (a term reflecting the
cultural assumptions of those societies sleeping on
beds); whether it is confined to nighttime or to pri-
vate spaces or may also occur acceptably in daytime
or in public spaces; whether it is tied to seasonal,
cosmological, religious, or spiritual periods and
events; and so forth. Worthman and Melby
11
re-
ported on several tribal societies across the globe
whose sleep patterns include lengthy daytime sleep
in social groups including children; periods of both
daytime and nighttime sleep with frequent arousals
that may include intervals of conversation, play, or
other social interaction; and acceptability of individ-
ual napping in the presence of others. (See also Ste-
ger
16
with respect to inemuri [“to be present and
sleep”] in Japan.) Richter
34
describes the association
of sleep patterns with seasonal change in China,
particularly with respect to sleep amount and dura-
tion. Numerous anthropologic studies describe, as a
feature of a more complete cultural ethnography,
associations of sleep with cosmologic and religious
or spiritual events, particularly as the observance of
these culturally significant phenomena may super-
cede otherwise usual patterns of sleep. For instance,
in Balinese society, many important spiritual obser-
vances and performances occur at night and con-
tinue until daybreak or beyond. Such events include
both children and adults, either or both of whom
may sleep and wake without censure several times
during the course of the event, in the midst of the
“audience” or celebrants, as their own needs or bio-
logical demands dictate.
35,36
Variability among cul-
tures in regard to sleep-patterning expectations, and
interpretations is enormous, and one can find for
almost any preference, pattern, or norm its opposite
number in some other cultural setting.
Cultural norms determine the boundaries between
“normal” and “problematic” sleep behavior, typi-
cally based on the extent to which individuals con-
form to sleep-schedule and sleep-behavior expecta-
tions. Sleeping too little, too much, at the wrong
times, or in the wrong places may be indicators of
“abnormality” and indicative or constitutive of prob-
lematic sleep, problem behavior, or character flaw
(eg, “laziness” in cultures that value industriousness,
self-control, or strict regularity). Sleeping in the
wrong ways, so to speak, may indicate other kinds of
problems, be they physical (organic disorder causing
intermittent or unrestful sleep), emotional or spiri-
tual (restlessness, sleep talking, tossing and turning,
sleep walking, nighttime fears or bad dreams inter-
rupting sleep), or magical/supernatural (eg, sleep
paralysis, which is widely interpreted culturally and
individually as a form of supernatural assault
37
).
Any of these sleep behaviors/events may be biolog-
ical in origin or comprise an interplay of biological
and cultural elements; however, their interpretation
as problematic or not is by definition cultural, as will
be the prescribed remediation for any matters iden-
tified as problems.
Cultural regulation of sleep patterns both encodes
and responds to larger cultural values and social
pressures, which are not in and of themselves actu-
ally “about” sleep. These include such matters as
values placed on independence or interdependence
of individuals and establishment of the sense of
self
12,38
; establishment and maintenance of social
class or rank identity and the behavioral emblems of
their differentiation
14,34
; gender roles (eg, whether
women rise earlier than others and prepare the
household and its members for the day or whether
men retire later than others because of work or social
activities to which they are mandated or entitled);
idealized family structures and behaviors (including
not just the question of cosleeping of children and
parents but also that of cosleeping of spouses); defi-
nition and enactment of religious duty; concepts of
character and of moral and admirable behavior as
persons; and so forth.
34,39,40
Social institutional demands, such as requirements
that school or work be standardized to begin at cer-
tain hours and that the children and adults who
attend them be on time or that certain sectors of the
society or the economy be available and functional at
specific (including any and all) hours, influence the
cultural regulation of sleep across societies. These
patterns are both relieved and reinforced by the ex-
istence of special times (vacations, days of rest, or
days of special religious or social obligation) in
which the typical pattern is permitted or required to
be broken in recognition of a form of social “time
out.” Enculturation to these broader cultural values
and social demands begins in the sleep patterning of
children.
INTERPLAY BETWEEN BIOLOGY AND CULTURE IN
SLEEP BEHAVIOR
In the past century, a number of developmental
theorists have conceptualized the bidirectional inter-
play of culture and biology in human behavior by
interactional or transactional models.
41
These models
stress that all aspects of complex systems are mutu-
ally interinfluential, covariant, and constantly dy-
namic. As spelled out by Chess and Thomas,
41
ap-
plication of this approach to human behavior
requires that “behavioral attributes must always be
considered in their reciprocal relationship with other
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characteristics of the organism and in their interac-
tion with environmental demands, opportunities and
stresses.” Similarly, Sadeh and Anders
42,43
framed a
transactional model for infants’ sleep behavior by
integrating “… constitutional propensities of the in-
fant into the infant’s multiple contexts...”
43(p11)
Chess and Thomas provided an integrative analy-
sis of the nature and dynamics of interactional pro-
cesses in their concept of “goodness of fit.”
41
Goodness of fit results when the organism’s capacities, moti-
vations and style of behaving and the demands and the
expectations of the environment are in accord. Such conso-
nance between organism and environment potentiates opti-
mal positive development. Should there be a dissonance be-
tween capacities and characteristics of the organism on the
one hand and the environmental opportunities and demands
on the other, there is poorness of fit, which leads to maladap-
tive functioning and distorted development.
41(p21)
In the context of this article, goodness of fit means
specifically that culturally defined expectations of
how the child is taught and permitted to sleep match
well with the individual child’s sleep biology or in-
dividual characteristics (eg, physical or emotional
needs). Culturally guided parental strategies around
bedtime that best satisfy adult interests and needs,
for example, may not be in accord with those that
best serve the child’s needs (poor fit for the child).
Imagine, for instance, a situation in which the par-
ents biologically prefer to go to bed late and it is an
expected cultural custom to eat dinner late at night,
as observed in many Southern European countries. If
their child’s biological preference is to wake up early
in the morning, it may not be in harmony with the
parents’ demands and cultural expectations. As an-
other example, American parents generally seek to
provide confidence and emotional security and to
accommodate individual needs of their children dur-
ing the day,
44
but on the other hand they expect their
children to go to bed at a specified time irrespective
of evidence of sleepiness and to sleep alone and
isolated in a dark room as culturally anticipated. The
American child whose individual emotional needs
might be for close proximity to parents or other
family members while sleeping or for a bedtime
congruent with his or her internal biological clock
might find a better fit for sleeping in the normative
practices of Italy or Japan than in his or her own
culture.
12,15,16
Worthman and Melby
11
portrayed
these inconsistencies in child care practices between
day and night:
American parents put their infants to sleep under conditions
of minimal sensory load, but later expect them to focus atten-
tion appropriately in a world with high sensory loads and
heavy competing demands for attention.
11(p110)
Poor fit between culturally normative bedtime
practices and individual sleep biology or individual
emotional needs may eventually lead to behavioral
sleep problems. Current clinical recommendations in
pediatric sleep medicine are often based on changing
the individual child (extinction of the undesired be-
havior) or altering parental behavior (eg, reducing
parental involvement around bedtime) toward ac-
cepted cultural standards rather than trying to find a
balance between the child’s and parents’ individual
needs and thus to translate a poor fit into a good fit
(or at least a better fit). This approach will sometimes
involve questioning, modifying, or rejecting aspects
of the childhood sleep behavioral norms of one’s
own culture.
COMPARATIVE PERSPECTIVES OF CHILDREN’S
SLEEP BEHAVIOR
Cross-cultural comparative research among societ-
ies of different political, economic, ideological, and
historical backgrounds will provide an opportunity
to delineate the respective roles of culture and biol-
ogy on sleep behavior and its interpretation. Also
contributory to this effort are historical studies of
changes in sleep behavior and attendant attitudes
within a culture over time.
14
Cultures are inherently
dynamic, changing as new ecologic or political con-
ditions emerge or old demands fade, adopting or
adapting elements of other cultures with which they
come into contact, incessantly testing conservation of
the time-honored and traditional against the impulse
to innovate. Cultural changes over time may be grad-
ual or rapid and dramatic, with sudden shifts.
39
In
contrast, biological change is slow. Low variability
across cultures and over time would indicate that
biological processes contribute to sleep behavior to a
greater extent than does culture. Conversely, high
cross-cultural variability would suggest less influ-
ence of biological mechanisms on the behavior.
Studies of children’s sleep in the medical and sci-
entific literature have focused primarily on a few key
aspects of sleep behavior: sleep duration and sleep
need; bedtime routines; napping; children’s use of
sleep aids; sleeping arrangements, particularly
cosleeping of children and parents (not so much
cosleeping of siblings or other children, although
that also is a common practice in many cultures and
social settings); sleep problems including bedtime
resistance; nighttime awakenings; and sleep terrors.
Clearly, these all are interconnected aspects of chil-
dren’s sleep, although for heuristic purposes they
have often been teased apart. We address each of
these areas and the questions that arise in consider-
ing the influence of cultural variation on them.
Sleep Duration/Sleep Need
Sleep duration and sleep need (terms sometimes
used interchangeably, sometimes indicating separate
measures) stand in many respects at the hub of re-
search about children’s sleep, inasmuch as many
other areas of interest are directly or indirectly linked
to the concern with identifying, comparing, and
eventually prescribing and helping promote ade-
quate sleep for children at varying stages of devel-
opment.
Before the early 20th century, professional esti-
mates of children’s sleep requirements in Anglo-Eu-
ropean cultures were built on culturally normative
opinions and loose personal observations. The Ger-
man child psychologist Preyer, a pioneer in infant
biography, elaborated in Die Seele des Kindes (The
Mind of the Child) in 1881 on the phenomenon of
schlafsucht (abnormal need for sleep) and noted the
long sleep hours of his son Axel in his first 3 years.
45
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According to 19th-century estimates in these cultural
milieus, the optimum sleep amount for a 3-year-old
child was believed to be ⬃12 hours, whereas at 7
years old, only 8 to 9 hours were recommended for
normal daytime functioning.
14
In the early 1900s,
when psychologic experiments had begun to pro-
duce scientific data on children’s sleep, a new level of
interest arose, and concerns about the adequacy of
children’s sleep time permeated both the scientific
and popular literature.
14
At that time, a number of
authors from different countries gave details about
sleep duration across childhood and adoles-
cence.
46–49
The main theme of all these reports was
that children at the beginning of the 20th century did
not get enough sleep, a view that was in sharp con-
trast to the 19th-century opinion. Wulffen, a district
attorney in Dresden, Germany, in the early 1900s,
included a short section about insufficient sleep time
among German school-aged children in Psychologie
des Verbrechers (Psychology of the Criminal), implic-
itly relating inadequate sleep to the development of
criminal behavior.
47
In more recent decades, a proliferation of studies
in different countries and ethnic groups have ex-
panded the picture. For example, in the 1990s, Italian
preschool children 2 to 4 years old were reported to
have a shorter nightly sleep duration than did chil-
dren in other countries.
50
The Italian children went to
bed later and woke up earlier. This finding is in line
with results from a comparative survey of bedtime
behavior in Italian and American children between
1979 and 1981, which found Italian children with no
clear bedtime schedules, no consistent bedtime ritu-
als, and later bedtimes than American children, be-
cause (unlike American children at this age) Italian
children often participated in evening social activi-
ties with adults and regularly fell asleep before they
were put to bed.
51
Chinese school children also show substantially
shorter sleep duration than children in other cultures
because of late bedtimes and early rise times.
52
This
pattern is believed to result in part from academic
pressures that lead to a great social and familial
emphasis on study time,
52,53
although there is also a
traditional aphorism recommending “late to bed and
early to rise”
34
(in contrast to Benjamin Franklin’s
advice in America).
54
In Japan, as well, high cultural
values placed on pursuit of study and learning may
lead to reduced sleep amounts among school-aged
children, who may commonly take a short sleep after
dinner and later be awakened by their mothers with
tea and snacks so that they may pursue their studies
in peace and quiet for a few hours after their parents
have retired.
16
The aforementioned examples of Italian, Chinese,
and Japanese sleep patterns raise a number of im-
portant questions: (1) Do primarily methodologic
differences between studies account for the differ-
ences in sleep duration? (2) Do Italian, Chinese, and
Japanese children get enough sleep? (3) Is the day-
time behavior of Italian, Chinese, and Japanese chil-
dren different from that of children in other cultures?
(4) Have Chinese and Japanese children become bi-
ologically adapted to less sleep? (5) Is the culturally
defined perception of sleep function in Italy, China,
and Japan different from that in other countries? The
bald answer to all of these questions is: We do not
know.
Only a few investigations have been specifically
designed to compare cultures directly.
55–57
For exam-
ple, Super et al
55
compared sleep patterns between
American and Dutch infants using parental reports
(with their well-known limitations, especially under-
estimation of time awake during the night
58
). They
found that American infants in the 1990s slept 13
hours per day at 3 months old, whereas at the same
age Dutch infants slept 15 hours per day. Up to 8
years of age, Dutch children went to bed significantly
earlier than did American children, although the dif-
ference in total amount of sleep between American
and Dutch youngsters diminished with increasing
age. Dutch parenting in infancy and childhood is
described to be organized around “the 3 Rs”: rust,
regelmaat,eet reinheid (rest, regularity, and cleanli-
ness).
55
This concept was promoted in ⬃1900 by the
Dutch Green Cross, a professional association of
baby nurses, and it is still the centerpiece of advice
that Dutch parents receive from pediatricians, mid-
wives, home health visitors, and their own parents
(T. Deboer, PhD, written communication, 2004). Cul-
tural differences between Dutch and American par-
ents in theories about children and child rearing have
not been investigated in systematic ways. Thus, it is
not known whether differences in sleep patterns be-
tween Dutch and American children are in fact par-
alleled by differences in child care practice.
Another example of cross-cultural comparison (al-
though with somewhat different findings than those
of Super et al) was provided by Lavigne et al,
56
who
evaluated sleep duration in white, black, and His-
panic preschool children in the United States in the
1990s. They found no difference in the total amount
of sleep within a 24-hour period between white and
“minority” children, although differences in timing
and diurnal distribution of sleep were observed.
“Minority” children went to bed later, got up later,
and slept less during the night than did white chil-
dren but had more and longer daytime naps.
Historical trends of sleep behavior in a single
country have been reported very rarely in the scien-
tific literature.
59,60
In a Swiss study, Iglowstein et al
60
demonstrated a decrease of sleep duration and a
delay in bedtime between their examined cohorts in
the 1970s and 1990s. Additional analysis of the same
cohorts revealed that bedtime resistance was signif-
icantly lower in the later cohorts than in the earlier
cohort, which tempted these authors (among them
the first author of this review) to conclude that par-
ents in the 1990s adjusted bedtime more appropri-
ately (better fit) to children’s individually preferred
bedtimes.
61
Because changes in social institutions
and cultural practices were not assessed directly dur-
ing this interval, however, the authors provided no
specific cultural explanation for this phenomenon.
Bedtime Routines
Child and parent sleep-related behavior in middle-
class Euro-American societies is notably character-
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ized by a distinct presleep bedtime “ritual” for chil-
dren.
62
Bedtime routines usually take place within
the core family, in the bedroom allocated to an indi-
vidual child, under firm parental supervision, and
with strict procedures and explicit organization.
They include a set of activities: an after-dinner bath,
dressing in a particular nightdress, telling stories and
singing lullabies as a gradual diminution of external
stimuli, putting the child to bed followed by good-
night kisses, and then leaving the child alone in his
or her room. Frequently, children insist on sleeping
with a light on or taking a treasured object to bed
with them (such as a soft doll or stuffed animal,
blanket, toy, or pacifier) or repeatedly call their par-
ents after being put to bed for various reasons such
as “another drink” or “another story” (“curtain
calls”).
Consistent bedtime routines, however, are not al-
ways typical for Western industrialized societies.
New and Richman,
51
for example, compared infant
care practices in families from the greater Boston
area with those in families from a small town north
of Rome, Italy. Whereas in American families bed-
time rituals were well established and children were
required to go to bed regardless of their resistance,
Italian children were typically allowed to participate
in the family’s late-evening life and to fall asleep in
the carriage or in someone’s lap instead of their own
rooms. Parents of Italian children were less con-
cerned about the sleep habits of their children than
were American parents and believed that their chil-
dren were getting adequate amounts of sleep. On the
contrary, American mothers were worried about
whether their infants got “enough” sleep even when
they showed strong resistance to bedtime and naps.
The unstructured bedtime habits of Italian children
were also reflected in their later and more fluid bed-
times than those of children from several other in-
dustrialized countries and are paralleled by the typ-
ically unstructured and flexible bedtimes reported
for children from other southern European countries
such as Spain and Greece.
50
In still other societies, the wake-to-sleep transition
of children is not a culturally “marked” event, set
apart from other social activities in specialized ways.
There is no formalized “bedtime”; indeed, in several
cultures, it is probably more accurate to say that
there is no such concept as “bedtime” per se, and
there are no specific preparations of children for
sleep. Of the tribal societies discussed by Worthman
and Melby,
11
several seem to fall into this category,
as do other “traditional” populations such as the
highland Mayan community in Guatemala described
by Morelli et al.
63
In this sample of 14 Mayan fami-
lies, infants and young children simply fell asleep
when they were sleepy, usually in someone’s arms or
when they were taken to bed along with a parent.
Infants typically slept with their mothers from birth
until they were ⬃2 or 3 years old or until the birth of
the next child, if sooner, when they moved to sleep
with their fathers or occasionally with an older sib-
ling. Both parents and children slept in the same
room by preference, and parents would commonly
occupy separate beds so that each young child could
have a parental sleeping partner.
No bedtime routines were observed in the Mayan
community,
63
and none were reported to the study’s
interviewers. There were no specific sleeping clothes
(although some mothers dressed children in their
oldest clothes for sleep), no stories read or recited,
and no lullabies involved in putting children to
sleep. The Mayan mothers interviewed in this study
reported no sleep resistance on the part of their chil-
dren and no problems with their children’s sleep.
The normative infant-feeding practice of nursing on
demand continued during the night and was not
considered a disturbance by mothers, because it did
not require their full arousal. Older children in the
household also share beds with one another by cus-
tom; having to sleep alone at any age is considered
undesirable and a pity. The Mayan mothers in this
study believed this pattern of social sleeping and
child sleep behavior to be “the only reasonable way
for a infant and parents to sleep.” They responded
with shock when told of the American pattern of
putting infants and young children to sleep alone in
rooms of their own and disapprovingly regarded this
practice as “tantamount to child neglect.”
63
These
mothers also felt that their small children learned
reliably to observe social precautions and prohibi-
tions quite early on, because sleeping together with
their parents made them feel close to other people
and therefore more readily able to understand and
learn from them.
63
Thus, the Mayan parents clearly
and explicitly draw the connection between child
sleeping patterns and promotion of desirable social-
ization goals, just as American parents do when they
explain their belief that having children sleep alone
from an early age fosters the culturally valued trait of
independence.
In the more complex Balinese society, infants are
held continuously, day and night, by a variety of
adults or older children involved in their care.
35
Be-
ing alone for even brief periods during sleep is con-
sidered undesirable for persons of any age, because it
leaves them vulnerable to spiritual risks including
soul loss
64
; infants and young children may be par-
ticularly vulnerable. Ritual and spiritual obser-
vances, which are a centerpiece of Balinese culture
and social life, typically take place at night and last
for many hours, sometimes until daybreak. These
events are attended by adults and children of all ages
including babes in arms. Persons of any age and
station in attendance at these events may slip in and
out of sleeping and waking states ad libitum and in
any posture, including standing.
11
Infants quickly
acquire the capacity to sleep and to transition rapidly
and smoothly between sleeping and waking states
under any circumstances including situations of high
stimulation, musical and theatrical performances,
and noisy public observances, and this capacity is
retained during adolescence and into adulthood
(where it is exercised frequently, including by audi-
ence members and even key performers in ritual
events
36
).
In part because Balinese ritual and spiritual obser-
vances require regular periods of adult sleep avoid-
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ance (on the order of 1–2 days per week),
11
and
because children are regularly included in all forms
of adult social activity, there is no such thing as a
routinely delineated child “bedtime.” Under a wide
variety of circumstances, adults and children alike
sleep and wake according to their own innate im-
pulses. Transitions into sleep and wakefulness are
characterized by virtually complete fluidity and
broad social acceptability. The example of Bali pro-
vides perhaps the most extraordinary and thorough
departure from so-called “Western” standards of
sleep behavior and their culturally conditioned envi-
ronmental requirements. This polarity is one of the
most compelling examples of cross-cultural variabil-
ity in sleep behavior and the range of possibilities in
the cultural shaping of the biological drives propel-
ling sleep.
Sleep Aids
In 1951, Winnicott
65
introduced the concept of
“transitional objects and transitional phenomena” as-
sociated with facilitating children’s transitions from
waking into sleep. These sleep aids, commonly ob-
jects such as pacifiers, blankets, toys, stuffed animals,
or children’s thumbs for sucking, are depicted as
facilitating children’s falling asleep by providing a
sense of comfort and security.
66
The use of a sleep aid
is intimately linked to bedtime behavior, sleeping
arrangements, and individuation-separation pro-
cesses during the transition from wakefulness to
sleep and, thus, to cultural beliefs and standards.
Notably, Morelli et al
63
reported that no transitional
objects were used by the Mayan infants in their
study, a pattern that seems to typify cosleeping cul-
tures.
Children in industrialized societies (and particu-
larly in urban areas) frequently use sleep aids,
whereas in nonindustrialized cultures there is a
much lower prevalence of object attachment associ-
ated with sleep. It has been hypothesized that more
physical contact between parents and children dur-
ing both day and night may explain the lower inci-
dence of sleep aids in these cultures.
67,68
For exam-
ple, fewer Korean infants (18%) or Italian children
(rural: 4.9%; urban: 31.1%) used transitional objects
as sleep aids than did American children (54%) or
non-Italian Western European children (61.5%).
67,68
In the United States, Litt
69
compared transitional
object use between white middle-class children seen
in private practice (77%) and black children seen in
an outpatient clinic (46%). Black children more fre-
quently used stuffed toys or dolls as sleep aids, and
white children primarily used blankets. In all of these
studies, sleeping arrangements appeared to be the
main factor that determined whether children used
sleep aids: Children sleeping alone were more likely
to use sleep aids or transitional objects.
Sleeping Arrangements
The norm for children in many cultures around
the world is to sleep with adults or siblings, if not
in the same bed or sleeping structure, then at least
in the same room. Private bedrooms for children
are the exception rather than the rule worldwide.
Importantly, it is not only less industrialized soci-
eties that practice cosleeping but also highly tech-
nologically advanced and complex communities,
of which the classic example is Japan.
70
From a
social-ecological perspective, climatic factors, fam-
ily size, and space availability have often deter-
mined sleeping arrangements.
11,14,71
Space avail-
ability and climate, however, seem to play only a
minor role in cosleeping in highly industrialized
modern societies. Rather, parental beliefs and cul-
tural preferences such as a high value being placed
on individual independence (individualism) or on
familial interdependence (collectivism) have been
proposed as “driving forces” for choosing sleeping
arrangements.
70
To illustrate this point, Claudill
and Weinstein
72
described the difference between
Japanese and American parental beliefs about in-
fants.
In Japan, the infant is seen as a separate biological organism
who from the beginning, in order to develop, needs to be
drawn into increasingly interdependent relations with others.
In America, the infant is seen more as a dependent biological
organism who, in order to develop, needs to be made increas-
ingly independent of others.
72(p15)
Sleeping arrangements have been subjected to in-
tensive cross-cultural analysis,
52,63,70,71,73–78
in part
because they have attracted the attention of clinicians
and researchers on the basis of their high cultural
visibility and the extent to which they have been
regarded as “strange” (and therefore calling for ex-
planation) in their distinction from norms in the
scholars’ own cultures. A number of thorough, well-
written, insightful reviews are available.
11,14,79,80
Less attention has been paid to historical shifts in
sleeping arrangements within a single country or
culture.
14
Night Waking and Other Sleep Problems
Among behavioral sleep disturbances, frequent
night waking and difficulties getting children to bed
are the problems most commonly reported by par-
ents of young children. The similarities in prevalence
of such problems across cultural boundaries have led
some authors to conclude that either intrinsic biolog-
ical sleep regulation may play the driving role in
behavioral sleep disturbances or societies around the
world share common ecological features relevant to
children’s sleep.
81
In contrast, Rona et al
82
found that
families originating from the Indian subcontinent
were more likely to report children’s sleep problems
than were British or African-Caribbean families.
Lower-prevalence estimates were also found for
sleep problems among British children than among
children from other European countries.
83,84
Cross-
cultural comparison of behavioral sleep problems is
no less hampered by methodologic difficulties than
is the comparison of sleep amount,
85
and in fact
exerts even more complex demands on researchers,
because the definition of what constitutes a “prob-
lem” in children’s sleep varies widely across cul-
tures.
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Napping
There is a small but growing literature focused on
the subject of daytime napping and its relationship to
both nighttime sleep patterns and biologically driven
total sleep requirements and to cultural responses to
various forms of daytime sleep for adults as well as
for children. The term “siesta culture” is widely used
to refer to cultures that sanction napping by adults.
86
Because the circumstances and degrees of social in-
stitutionalization of napping are so variable in these
descriptions, we suggest that it would be useful to
draw a distinction between (1) “nap” cultures, in
which individual or collective napping occurs and is
considered normal but other aspects of social and
institutional life continue (eg, Japan), and (2) “siesta”
cultures, redefined to refer specifically to those soci-
eties in which nap or rest time at the heat-filled
midday is institutionalized to the extent that busi-
nesses and government offices close down and ordi-
nary public social interaction ceases for the duration
(eg, Italy, Mexico, or China at various times in their
histories). Our searches yielded no cross-cultural
studies of children’s daytime sleep patterns in “si-
esta” cultures as compared with others, because
most of this literature seems to focus on adult sleep
behavior.
Social institutionalization of a midday rest or sleep
time as a cultural ideal or, indeed, as a legal right of
workers has sometimes been the subject of political
and even constitutional protection.
39
Cultures that
institutionalize napping stand in strong contrast to
the American and Northern European monophasic
sleep culture, in which daytime sleep is discouraged
and avoided (or relegated to socially recognized
“time-out” occasions such as weekends and vaca-
tions) except for infants and young children.
16,86
Pre-
school or day care settings for American children
frequently have institutionalized and enforced nap
times as part of their daily routines. Although in
countries around the Mediterranean Sea and in
South America, Africa, and Asia a biphasic sleep
pattern is still predominant, in this time of globaliza-
tion and “24/7” economies, daytime napping as a
cultural standard is slowly disappearing.
33
In some
countries such as Chile, Greece, and, more recently,
China, the disappearance of the normative or once-
institutionalized siesta has been accelerated by gov-
ernmental legal decree.
87–89
Adolescent Sleep Behavior
Biological maturation of sleep patterns around pu-
berty occurs within the context of culturally defined
demands and expectations. In recent years, one ma-
jor trend in regard to sleep behavior of teenagers has
emerged from scientific studies
28,90
: The timing of
sleep is delayed in older versus younger adolescents,
resulting in presumed insufficient sleep during the
school week and “catch-up sleep” during weekends.
These changes may originate from shifts in family
configurations, peer culture, academic demands,
school culture, employment opportunities, and ex-
tracurricular activities.
91
Moreover, modern teenag-
ers in developed countries are living in an environ-
ment in which television, computers, telephones, and
video games are widely available, often without pa-
rental monitoring and regulation of the time spent on
these activities.
92
Maturation of biological sleep pro-
cesses, however, is strongly related to sleep timing
and amount during adolescence. In this context, Car-
skadon and colleagues proposed that intrinsic bio-
logical changes may either compel or control the
adolescent sleep phase delay, or they may be permis-
sive of the phase delay and, thus, of social opportu-
nities at night.
28(p279)
As Conger and Peterson stated,
it seems that adolescence “begins in biology and
ends in culture.”
93(p92)
In other terms, sleep biology
may be the driving force behind adolescent sleep
patterns and “open the gate” for increasing capacity
to participate in social opportunities in the evenings
and at night. It is important to bear in mind, how-
ever, that “certain aspects of the intrinsic regulatory
processes may themselves respond to alterations of
sleep and wakefulness associated with behavioral
regulation.”
28(p279)
For example, behaviorally driven
changes in the timing of light exposure (eg, by tele-
vision watching late at night) directly interact with
the phase-resetting mechanism of the circadian tim-
ing system and can reinforce or strengthen a phase-
delay tendency.
94
Cross-cultural comparisons of sleep patterns may
contribute to the understanding of how cultural and
biological sleep regulation interact. Presently, a com-
prehensive cross-cultural data set on adolescent
sleep using appropriate measurement tools does not
exist, although available studies from different coun-
tries seem to parallel US data on adolescent sleep
patterns.
95
A major cultural influence on adolescent sleep pat-
terns in the United States is evening employment for
pay,
91
which is fairly uncommon for Western Euro-
pean adolescents.
96
By the age of 15, most American
adolescents have progressed from working in casual
jobs to having regular part-time employment.
97
It is
important to note that children’s work for payment is
not a phenomenon restricted to modern society.
Ravenhill
46
reported that in England of the early
1900s, 53% of 12-year-old boys worked for payment
before and after school (eg, delivering milk, bedding
horses, selling various articles such as newspapers).
She believed that “premature employment during
childhood is a powerful influence adverse to the
enjoyment of sleep either sufficient in quantity or
satisfactory in quality.”
46(p25)
School schedules and demands are major cultur-
ally determined factors that affect the timing of sleep.
Later bedtimes and shorter sleep durations have
been reported for Taiwanese adolescents than for
American teenagers as a result of the Taiwanese
educational system’s high academic demands and
competition.
53,95
Evidence is accumulating that early
school start times in the United Sates run counter to
the biological needs of most adolescents, who exhibit
a tendency to fall asleep later in the evening and
wake up later in the morning (poor fit).
95
Thus, mod-
ifying current standards in school scheduling may
improve sleep quantity and, eventually, quality of
life of teenagers. Other factors open to cross-cultural
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study include parental roles that regulate adolescent
sleep patterns both individually and in their partic-
ular cultural contexts.
INTERDISCIPLINARY SOURCES IN SLEEP
RESEARCH
Historical, social science, and literary accounts of
sleep behavior are additional invaluable resources in
the challenge of understanding how and why sleep is
regulated both biologically and culturally and what
the outcomes of this variability may be. Ekirch,
40
for
example, provides an informative historical over-
view of changes in sleep amount in the British Isles
from preindustrial times, including commentary on
sleep patterning and duration. Strikingly, he ad-
dresses at length the once commonly accepted notion
of “first sleep,” an initial and distinct period of deep
and restful sleep that was fully expected to be fol-
lowed by an interval of wakefulness before the re-
mainder of the night’s sleep, referred to as “second
sleep” or “morning sleep.” This pattern of sleep was
widely recognized, as is demonstrated by Ekirch’s
compendious list of medical, literary, and popular
sources referencing the term in English, French, and
Italian from before the 13th century through the 19th
century. This was considered a normal and unprob-
lematic sleep pattern. There is no particular mention
in print of waking in the middle of the night as
undesirable or pathologic. Quite the contrary, Ekirch
located scores of references in journals and diaries to
the peacefulness and meditative appeal of this wak-
ing period. Medical books from the 15th to the 18th
centuries advised the public to take “the fyrste slepe”
on their right side and thereafter to sleep on the left
side to promote good digestion and “more tranquil
repose,”
40
and Christian publications suggested ap-
propriate prayers and meditations for the pensive
and quiet waking interval.
Interestingly, a polyphasic distribution of noctur-
nal sleep was also observed by Wehr et al
98
in a
recent experiment with adult subjects. In this well-
conducted study in the early 1990s, they found that
during long nights (14 hours of darkness), sleep is
separated into ⱖ2 bouts, with intervals of wakeful-
ness between them, strikingly similar to Ekirch’s de-
scriptions of the preindustrial sleep pattern and to
young children’s sleep. Ekirch did not directly ad-
dress children’s sleep in his article. It can safely be
inferred, however, that as children were socialized at
that time they also would have learned to consider
polyphasic sleep normative. Thus, both historical de-
scriptions and modern experimental findings raise
the possibility that “sleeping through the night” (an
important developmental milestone of early child-
hood) may be an “artifact of modern lighting tech-
nology.”
98
In the United States, 19th-century attitudes toward
sleep differed from those of the 20th century in a
number of respects.
14
The topic of sleep was absent
in 19th-century public media discussions about chil-
dren, and the plentiful parent-advisory literature did
not include sections about sleep. Children’s sleep
behavior was not considered an issue that merited
attention and comment, because it was generally
presumed that children’s sleep was by nature self-
regulating and untroubled. Commentary on adult
sleep focused largely on health and character and in
the latter part of the century exhibited a clear moral
tone: It was asserted that adult sleep difficulties
could be managed with proper self-discipline, in-
cluding avoidance of idleness and that “healthy peo-
ple always sleep well.”
14
American children were
thought to need no more than ⬃12 hours of sleep per
day at age 3, with requirements diminishing to 8 or 9
hours by age 7 and to still less during adolescence.
Adult sleep was considered sufficient at 6 to 7 hours
per day, although 6 hours was plenty, and worry
about getting any more sleep than that was consid-
ered a “waste of time.”
14
Concerns about children’s sleep began to develop
through the release of new scientific data in the early
20th century,
46–48
coupled with an increase in the
number of specialists in child development between
1910 and 1920.
14
Sleep began to be characterized as
essential for the physical health and emotional de-
velopment of children and, at the same time, as a less
robust and self-regulating process than had been
assumed previously. Estimations of children’s sleep
requirements rose dramatically, to 10 to 12 hours
well into the teenage years, and considerably more
for those ⬍10 years old; for infants, the more sleep
the better. In 1910, the pediatrician L. Emmett Holt,
speaking as a member of the Child Health Commit-
tee, declared with alarm that “the American child is
kept on a starvation ration of sleep.”
14
During the
1920s, parents’ handbooks, women’s magazines, and
professional literature began to devote space often to
children’s sleep. A primary concern was the preven-
tion of (especially evening or nighttime) excitability
that might interfere with or delay an easy transition
to sleep. Activities promoting excessive excitability
included reading captivating stories or waiting up
with anticipation until Father came home from work.
Bedtimes as early as 7:00 pm were recommended for
children of all ages. Daytime sleepiness, as a poten-
tial consequence of insufficient sleep, appeared in the
literature as a concern with fatigue or “the tired
child.” The primary health goal in promoting plen-
tiful sleep was avoidance of susceptibility to infec-
tious diseases and, worse, to nervous upset or imbal-
ance that could initiate a vicious cycle of excitability
that further impeded normal sleep.
Thus began an era of extreme concern with regu-
lation of children’s sleep both for health promotion
and to advance the now-explicit goal of fostering the
independence and self-control that were desirable
characteristics of all upstanding citizens. Part and
parcel of this training was the practice of children’s
sleeping alone in their own beds and preferably in
their own rooms and being taught at an early age the
discipline of bedtime through the use of regular rou-
tines and firm (if distant) parental oversight. In the
waning years of the 1800s and into the early 20th
century, several child experts also pronounced
against the use of cradles as being potential instru-
ments of overstimulation through rocking, and
teaching children to become overdependent on adult
attention at bedtime.
99
The aforementioned Dr Holt
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was a leading crusader against the cradle and against
the “vicious practice” of rocking children to sleep.
99
The material culture of the country began to reflect
the new mores as cradles became less common and
the stationary crib emerged as the child bed of pref-
erence. The strong moralism of child-sleep regula-
tion also exerted social pressure on parents, whose
own characters could be impugned if they “gave in”
to children’s bedtime resistance or “overindulged”
their infants by rocking them to sleep.
99
Such con-
nections between sleep behavior and the moral order
of the larger society are a cultural commonplace and
figure prominently among the reasons such deep
feelings are attached to the propriety of child sleep
behaviors and why preferred patterns of child
sleep are so strongly resistant to acculturative pres-
sures.
100,101
METHODOLOGIC CONSIDERATIONS IN CROSS-
CULTURAL RESEARCH
The scientific pediatric sleep literature cited in this
review illustrates some of the inherent difficulties in
comparative and cross-cultural research. For exam-
ple, studies within and across countries and cultures
have used different recruitment strategies (eg, pop-
ulation randomly selected from national surveys or
from clinical, urban, or rural populations), measure-
ment formats (frequencies of occurrence of the key
variables), numbers of subjects, and descriptions of
age ranges. In addition, the variation of reported
sleep behavior across decades and within cultures
limits comparability between studies performed at
different times. Problems in cross-cultural research
particularly arise in the attempt to compare studies
of cultural groups conducted with instruments (eg,
questionnaires sent by mail or filled out in the pedi-
atrician’s office or face-to-face or telephone inter-
views) that have not been cross-culturally standard-
ized, appropriately translated, or validated for the
populations under study.
Another problem lies in the various definitions of
key terms. For example, “sleep amount,” “sleep
need,” “sleep duration,” and “time in bed” are terms
that often are used interchangeably in the literature.
Apart from the obvious problem that “time in bed”
may not correlate with actual “time asleep” and thus
is not a reliable proxy for sleep amount or duration,
these common research terms may have different
conceptual meanings across the cultures in which the
studies were conducted. In a substantial number of
studies, cultural beliefs, practices, and theories have
not been assessed with appropriate instruments or
qualitative inquiry. Rather, general cultural influ-
ences have been assumed or inferred according to
the investigators’ own (often tacit) guiding assump-
tions.
Even when attention has been paid to specific
cultural mores and their formative role in the under-
standing and orchestration of children’s sleep, a sa-
lient problem with the majority of cross-cultural
research is its tacit assumption of cultural homoge-
neity: Chinese people believe x, Dutch parents do y,
Americans or Balinese embrace z. We have even
fallen prey to this problem in this article as a kind of
linguistic convenience. Yet cultures are not mono-
lithic, and considerable internal variability exists in
every culture. Subcultures and differing ethnic, so-
cial-class, or other identity groups can be found in
any culture (each with its own values, mores, and
purposes), and knowledge of a general “macrocul-
tural” feature does not predict individual belief and
behavior.
102
As a caveat, it is essential to bear in
mind that the now-common term “cultural diver-
sity” has, in reality, a dual meaning and should, as a
guiding principle in research, be understood to refer
to diversity within as well as between cultures.
102
Cross-cultural research in children’s sleep ideally
should include investigation of folk illnesses and
health-belief systems and the ways in which sleep is
interpreted with respect to them. In addition to con-
tributing to better understanding of cultural inter-
pretations of the nature and purposes of sleep and
the relationships between sleep and health, informa-
tion of this type is of direct relevance to clinical
practice with differing populations. In Haiti, for ex-
ample, it is a common belief that if a person does not
get sufficient rest, the volume and condition of blood
in the body will be affected adversely, to the detri-
ment of overall health and well-being.
103
In the Latin
American phenomenon of susto, a form of soul loss
caused by sudden fright or shock, restlessness dur-
ing sleep is a diagnostic sign.
104
Soul loss is a cross-
culturally common category of event that may itself
be an illness or may lead to illness if not properly
treated and is related to sleep in quite a variable
range of ways.
105
These include the common notion
that human souls wander from the body during
sleep; their experiences may produce the content of
some types of dreams (eg, passim
106
), and awakening
a sleeper too abruptly or at the wrong time may
result in the soul’s inability to return properly,
thereby producing soul loss.
19,35,106
Children are typ-
ically considered especially susceptible to this risk as
well as to other forms of supernatural danger during
sleep.
We also underscore the assertion of Pachter and
Harwood
7
that linguistic, conceptual, and measure-
ment equivalence must be achieved in cross-cultural
research before firm conclusions about effects of cul-
ture on sleep behavior can be drawn (although we
add and emphasize that the first 2 can only be
accomplished to the extent that terminological or
conceptual equivalence exists between cultural cate-
gories relevant to sleep). Indeed, thorough investiga-
tion of the “language of sleep” in every cultural
setting in which studies are conducted will be a
requisite for understanding the local meanings and
taxonomy of sleep and sleep-related activities and
objects and a key to broader understanding of the
organization and nature of human sleep. To illustrate
with a few examples relevant to research: The Ba-
linese recognize a sleep category called tadoet poeles,
or “fear sleep,” in which social circumstances of ex-
treme stress induce instantaneous deep sleep, appar-
ently as a form of escape or stress relief, which can
occur even in very public circumstances and from
which the sleeper has to be shaken awake.
11,35,36
Preyer wrote about schlafsucht, an “abnormal need
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for sleep,” in his infant son,
45
his term implicitly
revealing normative assumptions about sleep in in-
fants; and Japanese society today recognizes a par-
ticular type of napping called inemuri, specifically
signifying being present with others (implicitly in
daytime social and business surroundings) and
asleep.
16
CONCLUSIONS
Pediatricians need to recognize the cultural envi-
ronment in which children live and how cultural
beliefs and values interact with the needs of the
individual child and with the biological characteris-
tics of his or her sleep patterns. It is not necessary to
know everything about cultural diversity or to be an
“expert” on culture, but it is important to understand
basic dimensions and mechanisms of cultural differ-
ences and their interaction with biology as they func-
tion in individual children and families. Knowing
that children “typically” exhibit a particular behavior
at a specific developmental stage is unsatisfactory; to
best meet the needs of patients and families it is
imperative to acknowledge individual behaviors in
the context of the cultural background and social
circumstances. In addition, clinicians and researchers
should attend systematically to their own cultures’
values and preferences and to the ways in which
they condition their responses and expectations, both
in the clinic and in all aspects of research design and
interpretation.
Documentation and description of the cultural di-
versity in which children grow up and the effect of
culture on their development and behavior, of which
sleep is at the core, may provide an important basis
for the reconsideration of our own cultures. Are the
cultural standards provided by our own society op-
timal for the development of our children? The large
diversity of children’s sleep behaviors among societ-
ies and cultures may in fact indicate that an “optimal
cultural standard” does not exist. Instead, individual
biological determinants and needs of children must
be taken into account when children’s sleep pattern-
ing and sleep problems are addressed. Are all chil-
dren able to adapt their biological sleep requirements
to culturally defined sleep demands? Notably, the
goodness of fit between individual children’s needs
and their cultural environments may provide a con-
ceptual basis for clinical practice.
Internationally collaborative and broadly interdis-
ciplinary studies are needed to disentangle the re-
spective roles of culture and biology in children’s
sleep behavior. These studies must be carried out
with methodologic rigor, according to disciplinary
standards, with both subjective and objective mea-
sures standardized for different cultures and using
both qualitative and quantitative approaches. This
breadth, depth, and conceptual clarity of investiga-
tion are needed to help clinicians better understand
the culture-biology interaction in the establishment
of behavioral and developmental norms and expec-
tations and eventually to comprehend what consti-
tutes a sleep problem, when and for whom, and how
best to approach it. The time is ripe.
ACKNOWLEDGMENTS
O.G.J. is supported by Swiss National Science Foundation fel-
lowship grant 81 ZH-068474. B.B.O. is supported in part by Health
Resources and Services Administration Faculty Development in
General Internal Medicine/General Pediatrics Program grant 1
D14 HP 00174.
We thank Drs Mary A. Carskadon, Remo H. Largo, Monique
LeBourgeois, and Ron Seifer for comments on the manuscript.
REFERENCES
1. Hickson GB, Altemeier WA, O’Connor S. Concerns of mothers seeking
care in private pediatric offices: opportunities for expanding services.
Pediatrics. 1983;72:619–624
2. McCune YD, Richardson MM, Powell JA. Psychosocial health issues in
pediatric practices: parents’ knowledge and concerns. Pediatrics. 1984;
74:183–190
3. Young KT, Davis K, Schoen C, Parker S. Listening to parents. A
national survey of parents with young children. Arch Pediatr Adolesc
Med. 1998;152:255–262
4. Hall ET. The Silent Language. Garden City, NY: Anchor Press/
Doubleday; 1959
5. Freed GL, Clark SJ, Sorenson J, Lohr JA, Cefalo R, Curtis P. National
assessment of physicians’ breast-feeding knowledge, attitudes, train-
ing, and experience. JAMA. 1995;273:472–476
6. Freed GL, Clark SJ, Lohr JA, Sorenson J. Pediatrician involvement in
breast-feeding promotion: a national study of residents and practitio-
ners. Pediatrics. 1995;96:490–494
7. Pachter LM, Harwood RL. Culture and child behavior and psychoso-
cial development. J Dev Behav Pediatr. 1996;17:191–198
8. Rubin KH. Social and emotional development from a cultural perspec-
tive. Dev Psychol. 1998;34:611–615
9. Harkness S. Cross-cultural research in child development: a sample of
the state of the art. Dev Psychol. 1992;28:622–625
10. Harkness S, Super CM. Parents’ Cultural Belief Systems: Their Origins,
Expressions, and Consequences. New York, NY: Guilford Press; 1996
11. Worthman CM, Melby MK. Toward a comparative developmental
ecology of human sleep. In: Carskadon MA, ed. Adolescent Sleep
Patterns: Biological, Social, and Psychological Influences. Cambridge,
England: Cambridge University Press; 2002:69–117
12. Doi T. The Anatomy of Dependence. Tokyo, Japan: Kodansha Inter-
national; 1981
13. Jones RK, Brayfield A. Life’s greatest joy? European attitudes towards
the centrality of children. Soc Forces. 1997;75:1239–1270
14. Stearns PN, Rowland P. Children’s sleep: sketching historical change.
J Soc Hist. 1996;30:345–367
15. Wolf AW, Lozoff B, Latz S, Paludetto R. Parental theories in the
management of young children’s sleep in Japan, Italy, and the United
States. In: Harkness S, Super CM, eds. Parents’ Cultural Belief Systems:
Their Origins, Expressions, and Consequences. New York, NY: Guilford
Press; 1996:364–384
16. Steger B. Negotiating sleep patterns in Japan. In: Steger B, Brunt L, eds.
Night-time and Sleep in Asia and the West: Exploring the Dark Side of Life.
London, England: Routledge Curzon; 2003:65–86
17. Hufford DJ. Culturally sensitive delivery of health care and human
services. In: Staub S, ed. Proceedings of the Governor’s Conference on
Ethnicity. Harrisburg, PA: Pennsylvania Heritage Affairs Commission;
1990:35–37
18. Super CM, Harkness S. The developmental niche: a conceptualization
at the interface of child and culture. Int J Behav Dev. 1986;9:545–569
19. O’Connor BB. Healing Traditions: Alternative Medicine and the Health
Professions. Philadelphia, PA: University of Pennsylvania Press; 1995
20. Kryger M, Roth T, Dement W. Principles and Practice of Sleep Medicine.
3rd ed. Philadelphia, PA: W. B. Saunders Co; 2000
21. Benington JH, Heller HC. Restoration of brain energy as the function
of sleep. Prog Neurobiol. 1995;45:347–360
22. Maquet P. The role of sleep in learning and memory. Science. 2001;294:
1048–1052
23. Borbe´ly A, Achermann P. Sleep homeostasis and models of sleep
regulation. In: Kryger M, Roth T, Dement W, eds. Principles and Practice
of Sleep Medicine. 3rd ed. Philadelphia, PA: W. B. Saunders Co; 2000:
377–390
24. Borbe´ly AA. A two process model of sleep regulation. Hum Neurobiol.
1982;1:195–204
25. Daan S, Beersma DG, Borbe´ly AA. Timing of human sleep: recovery
process gated by a circadian pacemaker. Am J Physiol. 1984;246(2 pt
2):R161–R183
214 CHILDREN’S SLEEP: AN INTERPLAY BETWEEN CULTURE AND BIOLOGY
at Brown Univ on January 3, 2005 www.pediatrics.orgDownloaded from

26. Aeschbach D, Sher L, Postolache TT, Matthews JR, Jackson MA, Wehr
TA. A longer biological night in long sleepers than in short sleepers.
J Clin Endocrinol Metab. 2003;88:26–30
27. Peirano P, Algarin C, Uauy R. Sleep-wake states and their regulatory
mechanisms throughout early human development. J Pediatr. 2003;
143(4 suppl):S70–S79
28. Carskadon MA, Acebo C, Jenni OG. Regulation of adolescent sleep:
implications for behavior. Ann N Y Acad Sci. 2004;1021:276–291
29. Jenni OG, Borbe´ly AA, Achermann P. Development of the nocturnal
sleep electroencephalogram in human infants. Am J Physiol. 2004;286:
R528–R538
30. Jenni OG, Carskadon MA. Spectral analysis of the sleep electroenceph-
alogram during adolescence. Sleep. 2004;27:774–783
31. Sadeh A, Gruber R, Raviv A. Sleep, neurobehavioral functioning, and
behavior problems in school-age children. Child Dev. 2002;73:405–417
32. Frank MG, Issa NP, Stryker MP. Sleep enhances plasticity in the
developing visual cortex. Neuron. 2001;30:275–287
33. Steger B, Brunt L, eds. Night-time and Sleep in Asia and the West:
Exploring the Dark Side of Life. London, England: Routledge Curzon;
2003
34. Richter A. Sleeping time in early Chinese literature. In: Steger B, Brunt
L, eds. Night-time and Sleep in Asia and the West: Exploring the Dark Side
of Life. London, England: Routledge Curzon; 2003:24–44
35. Mead M. Children and ritual in Bali. In: Belo J, ed. Traditional Balinese
Culture. New York, NY: Columbia University Press; 1970:198–211
36. Mead M, MacGregor FC. Growth and Culture: A Photographic Study of
Balinese Childhood. New York, NY: GP Putnam’s Sons; 1951
37. Hufford DJ. The Terror That Comes in the Night: An Experience-Centered
Study of Supernatural Assault Traditions. Philadelphia, PA: University of
Pennsylvania Press; 1982
38. DeCraemer W. A cross-cultural perspective on personhood. Milbank
Mem Fund Q Health Soc. 1983;61:19–34
39. Yi L. Discourse of mid-day napping: a political windsock in contem-
porary China. In: Steger B, Brunt L, eds. Night-time and Sleep in Asia and
the West: Exploring the Dark Side of Life. London, England: Routledge
Curzon; 2003:45–64
40. Ekirch AR. Sleep we have lost: pre-industrial slumber in the British
Isles. Am Hist Rev. 2001;106:343–386
41. Chess S, Thomas A. Origins and Evolution of Behavior Disorders. New
York, NY: Brunner/Mazel; 1984
42. Sadeh A, Anders TF. Infant sleep problems: origins, assessment, inter-
ventions. Infant Ment Health J. 1993;14:17–34
43. Anders TF. Infant sleep, nighttime relationships, and attachment. Psy-
chiatry. 1994;57:11–21
44. Brazelton TB, Greenspan SI. The Irreducible Needs of Children: What
Every Child Must Have to Grow, Learn, and Flourish. Boulder, CO: Per-
seus Publishing; 2000
45. Preyer W. Die Seele des Kindes. Leipzig, Germany: Th. Grieben’s Verlag
(L. Fernau); 1881
46. Ravenhill A. Some results of an investigation into hours of sleep
among children in the elementary schools in England. Int Mag Sch Hyg.
1908;5(1):9–25
47. Wulffen E. Psychologie des Verbrechers.Ein Handbuch fu¨r Juristen, ⌬rzte,
Pa¨dagogen und Gebildete aller Sta¨nde. Gross-Lichterfelde-Ost: Verlag Dr
P. Langenscheidt; 1908
48. Terman LM, Hocking A. The sleep of school children: its distribution
according to age and its relation to physical and mental efficiency. J
Educ Psychol. 1913;4:138–147, 199–208, 269–282
49. Foster JC, Goodenough FL, Anderson JE. The sleep of young children.
J Genet Psychol. 1928;35:201–218
50. Ottaviano S, Giannotti F, Cortesi F, Bruni O, Ottaviano C. Sleep char-
acteristics in healthy children from birth to 6 years of age in the urban
area of Rome. Sleep. 1996;19:1–3
51. New RS, Richman AL. Maternal beliefs and infant care practices in
Italy and the United States. In: Harkness S, Super CM, eds. Parents’
Cultural Belief Systems: Their Origins, Expressions, and Consequences.
New York, NY: Guilford Press; 1996:385–404
52. Liu X, Liu L, Wang R. Bed sharing, sleep habits, and sleep problems
among Chinese school-aged children. Sleep. 2003;26:839–844
53. Gau SF, Soong WT. Sleep problems of junior high school students in
Taipei. Sleep. 1995;18:667–673
54. Franklin B. Poor Richard’s Almanack. 1735
55. Super CM, Harkness S, Van Tijen N, Van der Vlugt E, Fintelman M,
Dijkstra J. The three R’s of Dutch childrearing and the socialization of
infant arousal. In: Harkness S, Super CM, eds. Parents’ Cultural Belief
Systems: Their Origins, Expressions, and Consequences. New York, NY:
Guilford Press; 1996:447–466
56. Lavigne JV, Arend R, Rosenbaum D, et al. Sleep and behavior prob-
lems among preschoolers. J Dev Behav Pediatr. 1999;20:164–169
57. Tynjala J, Kannas L, Valimaa R. How young Europeans sleep. Health
Educ Res. 1993;8:69–80
58. Tikotzky L, Sadeh A. Sleep patterns and sleep disruptions in kinder-
garten children. J Clin Child Psychol. 2001;30:581–591
59. Hicks RA, Pellegrini RJ. The changing sleep habits of college students.
Percept Mot Skills. 1991;72:1106
60. Iglowstein I, Jenni OG, Molinari L, Largo RH. Sleep duration from
infancy to adolescence: reference values and generational trends. Pe-
diatrics. 2003;111:302–307
61. Jenni OG, Zinggeler Fuhrer H, Iglowstein I, Molinari L, Largo RH. A
longitudinal study of bed sharing and sleep problems among Swiss
children in the first 10 years of life. Pediatrics. 2005;115(1 pt 2):233–240
62. Beltramini AU, Hertzig ME. Sleep and bedtime behavior in preschool-
aged children. Pediatrics. 1983;71:153–158
63. Morelli G, Rogoff B, Oppenheim D, Goldsmith D. Cultural variation in
infants’ sleeping arrangements: questions of independence. Dev Psy-
chol. 1992;28:604–613
64. Wikan U. Managing Turbulent Hearts: A Balinese Formula for Living.
Chicago, IL: University of Chicago Press; 1990
65. Winnicott DH. Transitional objects and transitional phenomena. In:
Winnicott DH, ed. Through Paediatrics to Psychoanalysis. London,
England: Hogart Press; 1975:229–242
66. Burnham MM, Goodlin-Jones BL, Gaylor EE, Anders TF. Use of sleep
aids during the first year of life. Pediatrics. 2002;109:594–601
67. Gaddini R. Transitional objects and the process of individuation: a
study in three different social groups. J Am Acad Child Psychiatry.
1970;9:347–365
68. Hong KM, Townes BD. Infants’ attachment to inanimate objects. JAm
Acad Child Psychiatry. 1976;15:49–61
69. Litt CJ. Children’s attachment to transitional objects: a study of two
pediatric populations. Am J Orthopsychiatry. 1981;51:131–139
70. Claudill W, Plath DW. Who sleeps by whom? Parent-child involve-
ment in urban Japanese families. Psychiatry. 1966;29:344–366
71. Abbott S. Holding on and pushing away: comparative perspectives on
an eastern Kentucky child-rearing practice. Ethos. 1992;20:33–65
72. Claudill W, Weinstein H. Maternal care and infant behavior in Japan
and America. Psychiatry. 1969;32:12–43
73. Shweder RA, Arnett Jensen L, Goldstein WM. Who sleeps by whom
revisited: a method for extracting the moral goods implicit in practice.
New Dir Child Dev. 1995;67:21–39
74. Lozoff B, Askew GL, Wolf AW. Cosleeping and early childhood sleep
problems: effects of ethnicity and socioeconomic status. J Dev Behav
Pediatr. 1996;17:9–15
75. Latz S, Wolf AW, Lozoff B. Cosleeping in context: sleep practices and
problems in young children in Japan and the United States. Arch
Pediatr Adolesc Med. 1999;153:339–346
76. Schachter FF, Fuchs ML, Bijur PE, Stone RK. Cosleeping and sleep
problems in Hispanic-American urban young children. Pediatrics. 1989;
84:522–530
77. Yang CK, Hahn HM. Cosleeping in young Korean children. J Dev
Behav Pediatr. 2002;23:151–157
78. Cortesi F, Giannotti F, Sebastiani T, Vagnoni C. Cosleeping and sleep
behavior in Italian school-aged children. J Dev Behav Pediatr. 2004;25:
28–33
79. McKenna JJ, Thoman EB, Anders TF, Sadeh A, Schechtman VL,
Glotzbach SF. Infant-parent co-sleeping in an evolutionary per-
spective: implications for understanding infant sleep development and
the sudden infant death syndrome. Sleep. 1993;16:263–282
80. McKenna JJ. Cultural influences on infant and childhood sleep biology
and the science that studies it: toward a more inclusive paradigm. In:
Loughlin GM, Carroll JL, Marcus CL, eds. Sleep and Breathing in
Children: A Developmental Approach. New York, NY: Marcel Dekker;
2000:199–230
81. Scher A, Tirosh E, Jaffe M, Rubin L, Sadeh A, Lavie P. Sleep patterns
of infants and children in Israel. Int J Behav Dev. 1995;18:701–711
82. Rona RJ, Li L, Gulliford MC, Chinn S. Disturbed sleep: effects of
sociocultural factors and illness. Arch Dis Child. 1998;78:20–25
83. Kahn A, Van de Merckt C, Rebuffat E, et al. Sleep problems in healthy
preadolescents. Pediatrics. 1989;84:542–546
84. Klackenberg G. Sleep behaviour studied longitudinally. Acta Paediatr
Scand. 1982;71:501–506
85. Stein MA, Mendelsohn J, Obermeyer WH, Amromin J, Benca R. Sleep
and behavior problems in school-aged children. Pediatrics. 2001;107(4).
Available at: www.pediatrics.org/cgi/content/full/107/4/e60
86. Webb WW, Dinges DF. Cultural perspectives on napping and the
siesta. In: Dinges DF, Broughton RJ, eds. Sleep and Alertness: Chrono-
SUPPLEMENT 215
at Brown Univ on January 3, 2005 www.pediatrics.orgDownloaded from

biological, Behavioral, and Medical Aspects of Napping. New York, NY:
Raven Press; 1989:247–265
87. Rezohazy R. The methodological aspects of a study about the social
notion of time in relation to economic development. In: Szalai A, ed.
The Use of Time. The Hague, Netherlands: Mouton; 1972:449–465
88. Soldatos CR, Madianos MG, Vlachonikolis IG. Early afternoon
napping: a fading Greek habit. In: Koella WP, ed. Sleep ’82. Basel,
Switzerland: Karger Verlag; 1983:202–205
89. Dinges DF, Broughton RJ. The significance of napping: a synthesis. In:
Dinges DF, Broughton RJ, eds. Sleep and Alertness: Chronobiological,
Behavioral, and Medical Aspects of Napping. New York, NY: Raven Press;
1989:299–308
90. Carskadon MA, Acebo C. Regulation of sleepiness in adolescents:
update, insights, and speculation. Sleep. 2002;25:606–614
91. Carskadon MA. Factors influencing sleep patterns of adolescents. In:
Carskadon MA, ed. Adolescent Sleep Patterns: Biological, Social, and
Psychological Influences. Cambridge, England: Cambridge University
Press; 2003:4–26
92. Van den Bulck J Television viewing, computer game playing, and
Internet use and self-reported time to bed and time out of bed in
secondary-school children. Sleep. 2004;27:101–104
93. Conger JJ, Peterson A. Adolescence and Youth: Psychological Development
in a Changing World. New York, NY: Harper & Row; 1984
94. Lewy AJ, Wehr TA, Goodwin FK, Newsome DA, Markey SP. Light
suppresses melatonin secretion in humans. Science. 1980;310:1267–1269
95. Wolfson AR, Carskadon MA. Sleep schedules and daytime functioning
in adolescents. Child Dev. 1998;69:875–887
96. Giannotti F, Cortesi F. Sleep patterns and daytime function in
adolescence: an epidemiological survey of an Italian high school stu-
dent sample. In: Carskadon MA, ed. Adolescent Sleep Patterns: Biological,
Social, and Psychological Influences. Cambridge, England: Cambridge
University Press; 2003:132–147
97. Finch MD, Mortimer JT, Ryu S. Transition into part-time work: health
risks and opportunities. In: Schulenberg J, Maggs JL, eds. Health Risks
and Developmental Transitions During Adolescence. New York, NY: Cam-
bridge University Press; 1997:321–344
98. Wehr TA, Moul DE, Barbato G, et al. Conservation of photoperiod-
responsive mechanism in humans. Am J Physiol. 1993;265:
R846–R857
99. Valsiner J. Culture and Human Development. London, England: Sage
Publications; 2000
100. Nottingham C. “What time do you call this?” Change and continuity
in the politics of the city night. In: Steger B, Brunt L, ed. Night-time and
Sleep in Asia and the West: Exploring the Dark Side of Life. London,
England: Routledge Curzon; 2003:191–214
101. Small M. Our Babies, Ourselves: How Biology and Culture Shape the Way
We Parent. New York, NY: Anchor Books; 1998
102. O’Connor BB. Promoting cultural competence in HIV/AIDS care. J
Assoc Nurses AIDS Care. 1996;7(suppl 1):41–54
103. LaGuerre MS. Afro-Caribbean Folk Medicine. South Hadley, MA: Bergin
& Garvey Publishers, Inc; 1987
104. Rubel AJ, O’Nell CW, Collado-Ardon R. Susto: A Folk Illness. Berkeley,
CA: University of California Press; 1985
105. Simons RC, Hughes CC, eds. The Culture-Bound Syndromes. Dordrecht,
Netherlands: D. Reidl Publishing; 1985
106. Tedlock B, ed. Dreaming: Anthropological and Psychological Interpreta-
tions. Santa Fe, NM: School of American Research Press; 1992
216 CHILDREN’S SLEEP: AN INTERPLAY BETWEEN CULTURE AND BIOLOGY
at Brown Univ on January 3, 2005 www.pediatrics.orgDownloaded from