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PEDIATRIC ORIGINAL ARTICLE
Association between sleep duration and overweight:
the importance of parenting
E de Jong
1,2
, T Stocks
3,4
, TLS Visscher
1,2
, RA HiraSing
5
, JC Seidell
1,2
and CM Renders
1,2
OBJECTIVE: Sleep duration has been related to overweight in children, but determinants of sleep duration are unclear. The aims
were to investigate the association between sleep duration and childhood overweight adjusted for family characteristics and
unhealthy behaviours, to explore determinants of sleep duration and to determine with sleep competing activities.
METHOD: A cross-sectional study was carried out in 2006 among 4072 children aged 4–13 years in the city of Zwolle, The
Netherlands. In these children, data were available on measured height, weight and waist circumference, and from a parental
questionnaire, on socio-demographic characteristics, child’s sleep duration, nutrition, physical activity and sedentary behaviour.
Associations were studied in 2011 using logistic and linear regression analyses, adjusted for potential confounders.
RESULTS: Short sleep duration was associated with overweight for 4–8-year-old boys (odds ratio (OR):3.10; 95% confidence
interval (CI):1.15–8.40), 9–13-year-old boys (OR:4.96; 95% CI:1.35–18.16) and 9–13-year-old girls (OR:4.86; 95% CI:1.59–14.88).
Among 4–8-year-old girls no statistically significant association was found. Determinants for short sleep duration were viewing
television during a meal, permission to have candy without asking, not being active with their caregiver and a late bedtime.
For all children, short sleep duration was strongly associated with more television viewing and computer use.
CONCLUSIONS: Association between sleep duration and overweight is not explained by socio-demographic variables, drinking
sugared drinks and eating snacks. Parents have a key role in stimulating optimal sleep duration. Improving parenting skills and
knowledge to offer children more structure, and possibly with that, increase sleeping hours, may be promising in prevention
of overweight.
International Journal of Obesity (2012) 36, 1278–1284; doi:10.1038/ijo.2012.119; published online 24 July 2012
Keywords: childhood overweight; sleep; parenting; home environment; healthy lifestyle; prevention
INTRODUCTION
Over the past decades, there has been a growing interest in the
relationship between sleep duration and high body weight. A large
number of studies has shown an association between reduced sleep
duration and childhood overweight, especially in young children.
1–3
The association between short sleep duration and overweight
seems to be stronger for boys than girls,
4
although not all studies
have reported a gender difference.
2
Possible explanations for the association between sleep
duration and overweight include the role of behavioural and
hormonal factors; short sleep leaves more time for eating,
particularly snacking or drinking sugared drinks, and causes
alterations in appetite-regulating hormones resulting in over-
eating.
1,2,5
Moreover, sleepiness may result in reduced physical
activity and increased sedentary behaviour.
1,2,5
Determinants of short sleep duration have not yet been fully
explored. Presumably, sleep duration is influenced by a combina-
tion of socio-demographic, behavioural and environmental factors.
With regard to socio-demographic factors, children of Caucasian
ethnicity have been indicated to sleep longer than children of other
ethnicities.
6–9
Age is inversely associated with sleep deprivation.
10
The role of environmental factors on sleep duration is unclear,
but there are indications that the physical and socio-cultural
home environment play an important role.
3,11
A recent study
among children aged 8–11 years suggested that less structure
and rules in the home environment is associated with less
sleep and more unhealthy behaviour, which is also associated
with overweight.
11
It remains unclear whether the association
between such family characteristics and unhealthy behaviours
explain the association between sleep duration and overweight,
or whether sleep duration and overweight are also associated
independently. This is important information to learn whether
overweight prevention should target sleep duration per se and/or
the determinants and behaviours that are associated with sleep
duration.
Before starting developing interventions to increase sleeping
time, it is also important to know what the competing acti-
vities are for sleeping. Some studies indicate that shorter sleep
duration is associated with more television viewing and computer
use;
12–15
others found a relation between physical activity and
sleep duration in girls, only.
12
However, these results are
inconsistent.
14,16,17
1
Research Centre for the Prevention of Overweight, VU University Amsterdam/Windesheim University of Applied Sciences, Zwolle, The Netherlands;
2
Department of Health
Sciences, Faculty of Earth and Life Sciences and EMGO Institute for Health and Care Research, VU University Amsterdam, Amsterdam, The Netherlands;
3
Department of Surgical
and Perioperative Sciences, Urology and Andrology, Umeå University, Umeå, Sweden;
4
Institute of Preventive Medicine, Copenhagen University Hospitals, Copenhagen,
Denmark and
5
Department of Public and Occupational Health, EMGO Institute for Health and Care Research, VU University Medical Centre, Amsterdam, The Netherlands.
Correspondence: E de Jong, Research Centre for the Prevention of Overweight, VU University Amsterdam/Windesheim University of Applied Sciences, PO box 10090, Zwolle,
Overijssel 8000 GB, The Netherlands.
E-mail: e.de.jong@windesheim.nl
Received 20 December 2011; revised 28 May 2012; accepted 18 June 2012; published online 24 July 2012
International Journal of Obesity (2012) 36, 1278– 1284
&
2012 Macmillan Publishers Limited All rights reserved 0307-0565/12
www.nature.com/ijo
The aims of this study are as follows: (1) To investigate the
association between sleep duration and childhood overweight
adjusted for family characteristics and unhealthy behaviours.
(2) To explore determinants of sleep duration in the home
environment. (3) To determine what the competing activities are
with sleeping in these children.
MATERIALS AND METHODS
Study population
Data collected in the ChecKid 2006 study have been used for this study.
ChecKid is a cross-sectional study carried out among children of primary
schools (4–13 years) within 3 weeks in October and November 2006 in the
city of Zwolle. This study was aimed at identifying neighbourhoods/
communities at high risk for overweight, other high-risk groups and
behaviours related to overweight in the city of Zwolle to develop and
implement an integrated approach to tackle overweight in children.
Details on the study population and data collection have been described
elsewhere.
18
All 51 primary schools in the city were invited to participate and
80% of the schools (n¼41) agreed to participate. Number of students per
primary schools ranged from around 50 to around 840. Participating schools
were equally spread over the neighbourhoods of Zwolle. The parent(s) of
65% of children (n¼5219) gave written informed consent. ChecKid was
approved by the Medical Committee of the VU Medical Centre.
Measures
Trained students from the University of Applied Sciences Windesheim
measured body height, weight and waist circumference according to the
protocol for the National Dutch Growth Study in 5035 children.
19
Four
percentage of children could not be measured, mostly because of illness-
related school absence. The children’s BMI cutoff points defined by Cole
et al.
20,21
were used to define overweight and obesity. Owing to relatively
low numbers of obese children in the sample, overweight and obesity
were combined in the analyses.
The questionnaire for parents included socio-demographic issues, and
questions about sleeping habits, diet, physical (in)activity, home environ-
ment and rules were included. A total of 4257 parents (81%) returned the
questionnaire.
Parental characteristics
SES was classified as low, medium or high based on the highest completed
education level of parents.
22
Ethnicity was dichotomized as non-western
background (one or both parents born in Turkey, Morocco, Surinam,
Netherlands Antilles) versus the rest (both parents born in the Netherlands
or in a country not specified).
18
Mothers self-reported data on body weight
and height were used to calculate their BMI and to define maternal
overweight (BMI X25.0). Single parenting was dichotomized (yes/no).
Sleep duration
Sleep duration was measured with the questions: ‘What time does your
child usually go to bed on weekdays?’ and ‘What time does your child
usually wake up on weekdays?’. Parents indicated bedtime between 1800
and 22.30 hours, and wake up time between 0600 and 8.30 hours, with
15-min precision. For the purpose of this paper, information regarding
sleep behaviour on weekdays was used because it is more constant than
sleep behaviour on weekends. Hours of sleep were calculated by the hours
elapsed between going to bed and waking up. Sleep duration in hours and
also standardised sleep duration scores, calculated according to the method
Bayer et al.
23
described, were not linearly related to overweight in our data.
Therefore, we categorized sleep duration according to small categories in
order to decrease loss of information that is potentially occurring when
studying sleep duration as categories. Lacking standard categories for
sufficient hours of sleep, a reference category was defined for 4–8-year-old
children (X12 h per night) and 9–13-year-old children (X11.25 h sleep
per night) so that about 20% of the children would be in this category.
For 4–8-year-old children the other categories were: 11.5–12 h, 11–11.5 h
and o11 h of sleep per night. For 9–13-year-old children these were:
10.75–11.25 h, 10.25–10.75 h and o10.25 h sleep per night.
Home environment
Parents were asked whether their children had a television or computer in
their bedroom. In addition, structure and routine in the household were
assessed: viewing television during a meal (breakfast, lunch or dinner) (yes/
no); child’s permission to have candy without asking (no/mostly not,
sometimes, yes/mostly); 1–5 weekdays of eating an ordered meal (yes/no);
0–4 days of eating a home-cooked meal (yes/no) (not a ready-made meal);
0 days of being active (cycling, sporting going outside in a forest/park)
together with caregiver (yes/no), work situation of the mother (part time,
full time or not a paying job) and late bedtime. Late bedtime was defined
so that around a third of the children would be categorized as having a
late bedtime, resulting in a bedtime of 2000 hours, or later for 4–8-year-old
children and in a bedtime of 20.45 hours or later for 9–13-year-old children.
Lifestyle nutrition behaviour
Consumption of sugared drinks (total of fruit juice and cordial, soft drinks
and sweetened milk drinks) was dichotomized as p3 and 43 glasses per
day,
24
and eating snacks (total of sweet candy bars, savoury snacks and
crisps) as o0.5 and X0.5 per day so that around a third of the children
would fall in the highest category.
(In)activity behaviour
Lacking (applicable) standards for TV viewing and computer use,
categories were defined such that around a third of the children would
fall in the highest category. As a result, television viewing was categorized
as o60 min, 60–89 min and X90 min per day. Computer use was
categorized as o30 min, 30–59 min and 460 min per day. Playing outside
was dichotomized as at least 1 h a day
25
and involvement in organized
sports was dichotomized as o1orX1 h per week.
Statistical analyses
All analyses were conducted separately for boys and girls (P-value for
interaction: o0.001) and for younger (4–8 year) and older (9–13 year)
children. Differences were studied by using w
2
and t-tests. Associations
between sleep duration and overweight were adjusted for age and for
potential confounders using multivariable logistic regression analyses.
Overweight and obesity were combined in these analyses. We were
interested in the potential confounders SES, ethnicity, maternal over-
weight, single parenting, sugared drinks and eating snacks, and how these
confounders influenced the association between sleep duration and
overweight separately. Whether the association between sleep duration
and overweight differed across categories of SES and ethnicity was
checked. The environmental determinants (television/computer in child’s
bedroom and variables regarding routine and structure) were investigated
with respect to sleep duration using linear regression analyses. Moreover,
associations between sleep duration and other activities (participating in
organized sports, playing outside, television viewing and computer use)
were investigated also using linear regression analyses. All linear regression
analyses were adjusted for age, SES and ethnicity. Statistical analyses were
performed in 2011, using SPSS for Windows, version 17.0 (SPSS Inc.,
Chicago, IL, USA).
RESULTS
Data on anthropometrical and a parental questionnaire were
available for 4072 children (78% of children with informed consent).
The prevalence of overweight (including obesity (1.6%)) in the total
study population was 11.7%. Girls aged 9–13 years were more often
overweight than boys in contrast to the younger age group (4–8
years) where no gender differences were found (Table 1). The
range of sleep duration was 9–13.25 h per night for 4–8-year-old
children and 8.5–12.5 h per night for 9–13-year-old children. Boys
aged 4–8 years had a lower mean of sleep duration than 4–8-year-
old girls. Older girls slept fewer hours per night than younger girls.
Among 4–8-year-old boys, sleeping o11 h per night compared
with sleeping X12 h per night was associated with overweight
(odds ratio (OR): 2.83; 95% confidence interval (CI): 1.40–5.37)
(Table 2). This association remained similar after adjustment for all
family characteristics, drinking sugared drinks and eating snacks.
Among 4–8-year-old girls, the association between shorter sleep
duration and overweight was not significant.
Among 9–13-year-old boys and girls, sleeping o10.25 h per
night compared with sleeping X11.25 h per night was associated
with overweight (Table 3). After adjustment, this association
Sleep duration associated with childhood overweight
E de Jong et al
1279
&2012 Macmillan Publishers Limited International Journal of Obesity (2012) 1278 – 1284
remained similar for 9–13-year-old boys (OR: 4.96; 95% CI:
1.35–18.16) and altered slightly for 9–13-year-old girls (OR: 4.86;
95% CI: 1.59–14.88).
The associations did not differ across categories of SES but it did
differ across categories of ethnicity. The association between short
sleep duration and overweight was, in contrast to 4–8-year-old
Table 1. Characteristics of the study population
4–8-year-old (n¼2429) 9–13-year-old (n¼1643)
Boys (n¼1201) Girls (n¼1228) Boys (n¼803) Girls (n¼840)
Children0s characteristics
Age in years, mean (s.d.) 6.4 (1.4)
ww
6.5 (1.3)
ww
10.5 (1.1) 10.4 (1.0)
Children’s overweight (%) 9.7 11.9
w
10.2** 15.6
Sleep
Sleep duration in hours, mean (s.d.) 11.4 (0.5)* 11.6 (0.5)
w
10.7 (0.5) 10.8 (0.5)
Categories 4–8-year-old children (%)
X12 h per night 19.2** 24.8 — —
11.5–12 h per night 39.2 42.8 — —
11–11.5 h per night 29.8 25.9 — —
o11 h per night 11.8 6.5 — —
Categories 9–13-year-old children (%)
X11.25 h per night — — 18.1* 24.2
10.75–11.25 h per night — — 35.6 36.1
10.25–10.75 h per night — — 32.2 30.2
o10.25 h per night — — 14.0 9.5
Family characteristics (%)
Socio-economic status
Low 6.4* 8.9 8.1* 12.1
Medium 36.3 33.1 35.8 32.7
High 57.3 58.0 56.2 55.2
Ethnicity: non-western 4.4 5.5 5.1 7.4
Household: two parents 84.1 83.1
w
80.8 79.4
Maternal overweight 31.0
w
29.2 26.2 29.6
Home environment (%)
Viewing television during breakfast, lunch or dinner 27.4 25.0 26.5 28.6
Television in bedroom 13.7
ww
11.9
ww
29.4* 24.0
Computer in bedroom 18.2**
ww
10.1
ww
39.9** 24.7
Permission to have candy without asking
No/mostly not 87.2
ww
87.3
ww
71.4 73.6
Sometimes 10.7 11.3 21.4 19.9
Yes/mostly 2.2 1.5 7.2 6.5
1–5 weekdays eating ordered meal 18.9 16.5 21.5* 16.0
0–4 weekdays eating home-cooked meal 19.4 20.3 21.0 17.2
0 weekdays being active (cycling, sporting or being
outside in a forest/park) with caregiver
9.6
ww
8.0
ww
22.7 20.4
Late bedtime
a
22.1
ww
22.5 31.9* 26.0
Work situation mother
No paying job 21.2
w
22.8
w
20.2 20.4
Part time 74.3 72.8 71.9 72.0
Full time 4.5 4.3 7.9 7.7
Lifestyle behaviours (%)
Television viewing
0–1 h per day 66.2
ww
67.3
ww
55.3 57.9
1–1.5 h per day 29.5 27.6 36.2 32.4
41.5 h per day 4.3 5.1 8.6 9.8
Computer use
0–30 min per day 78.6**
ww
91.7
ww
38.7** 63.3
30–60 min per day 16.3 6.4 37.8 27.2
460 min per day 5.1 1.9 23.6 9.5
Sugared drinks 43 glasses per day 37.6 35.6 35.4 32.3
Snack 40.5 portion per day 20.1
ww
19.7
ww
30.0 29.4
Organized sports o1 h per 7days 43.5**
ww
54.1
ww
19.9** 35.7
Playing outside o1 h per day 62.8** 72.0 60.4** 69.8
*Pp0.05 for difference between boys and girls of the same age; **Pp0.001 for difference between boys and girls of the same age;
w
Pp0.05 for difference
between 4–8- and 9–13 year old;
ww
Pp0.001 for difference between 4–8 and 9–13 year olds.
a
Late bedtime for 4–8-year-old children was 2000 hours or later
and 20.45 hours or later for 9–13-year-old children.
Sleep duration associated with childhood overweight
E de Jong et al
1280
International Journal of Obesity (2012) 1278 – 1284 &2012 Macmillan Publishers Limited
boys with a western background, not statistical significant and
reversed compared with those with a non-western background
(OR: 0.40; 95% CI: 0.06–2.80; respectively, OR: 4.14; 95% CI:
1.82–9.40) (P-value for interaction o0.05).
Among 4–8-year-old boys viewing television during a meal,
permission to have candy without asking and a late bedtime were
associated with short sleep duration (Table 4). Among 4–8-year-
old girls short sleep duration was associated with not being active
with caregiver and a late bedtime.
For 9–13-year-old boys, short sleep duration was associated
with permission to have candy without asking, eating an ordered
meal one or more times a week, not being active with caregiver
and a late bedtime. For 9–13-year-old girls, short sleep duration
was associated with viewing television during a meal, a television
in the bedroom, not being active with caregiver and a late
bedtime.
Boys and girls aged 4–8 years and 9–13 years who viewed
television more than 1 h per day more often had short sleep
duration compared with children who viewed television less
(Table 5). Also, 4–8-year-old and 9–13-year-old boys and girls who
used the computer more than 60 min per day more often slept
fewer hours per night than children who used the computer less.
No statistically significant association was found between short
sleep duration and playing outside and participating in organized
sport.
DISCUSSION
In this cross-sectional study, short sleep duration is found to be
associated with overweight for 4–8- and 9–13-year-old boys and
9–13-year-old girls. This association is at best only marginally
explained by family characteristics and unhealthy dietary factors.
For 4–8-year-old girls a weaker, and statistically not significant,
association between short sleep duration and overweight is found.
Late bedtime is a determinant of short sleep duration for all
children, and not being active with their caregiver was associated
with sleep duration in younger and older girls and older boys.
Other age- and gender-specific determinants of sleep duration
were viewing television during a meal (younger boys and older
girls), television in the bedroom (older girls), permission to have
candy without asking (younger and older boys) and eating at least
1 day per week an ordered meal (older boys). For all children,
viewing television and using the computer more than 1 h per day
is strongly associated with sleeping fewer hours per night.
The association between sleep duration and overweight, as well
as the gender difference, is supported by other studies.
1,2,4
An
explanation might be that girls are less affected by sleep
deprivation than boys, because from an evolutionary perspective
boys are more vulnerable for environmental stress than girls,
especially in early life.
26
Determinants are found that are associated with sleep duration
in both the physical and socio-cultural home environment. For
example, children who were active with their parents were found
to sleep longer than children that are less active. A causal
association could either relate to a positive effect of physical
activity on sleep duration, or a positive effect of a close
relationship between child and parent. Another explanation is
that parents who spend more time with their child also apply
earlier bed times. Moreover, having more restrictive rules
for candy eating, not viewing television during meals and
not eating an ordered meal is associated with longer sleep
duration. Reporting plenty of subgroups raises the problem of
Table 2. Association between sleep duration and overweight
adjusted for possible confounders (4–8-year-old children)
Boys (n¼1201)
4–8 year old
OR (95% CI)
a
Girls (n¼1228)
OR (95% CI)
a
Unadjusted model: sleep duration
X12 h per night 1 (–) 1 (–)
11.5–12 h per night 1.13 (0.61–2.09) 0.65 (0.42–1.01)
11–11.5 h per night 1.77 (0.96–3.28) 0.70 (0.43–1.15)
o11 h per night 2.83 (1.40–5.73) 1.20 (0.61–2.36)
Adjusted for family characteristics
Adjusted for SES, ethnicity, maternal overweight and single parenting
X12 h per night 1 (–) 1 (–)
11.5–12 h per night 1.53 (0.77–3.05) 0.74 (0.46–1.19)
11–11.5 h per night 2.13 (1.06–4.26) 0.92 (0.54–1.56)
o11 h per night 3.47 (1.56–7.72) 1.94 (0.91–4.13)
Adjusted for lifestyle nutrition behaviours
Adjusted for drinking sugared drinks 43 glasses per day and
eating snacks 40.5 portion per day
X12 h per night 1 (–) 1 (–)
11.5–12 h per night 1.77 (0.81–3.86) 0.76 (0.46–1.25)
11–11.5 h per night 2.12 (0.95–4.74) 0.76 (0.43–1.34)
o11 h per night 2.97 (1.18–7.46) 1.40 (0.63–3.09)
Full model: adjusted for both family characteristics and lifestyle
nutrition behaviours
X12 h per night 1 (–) 1 (–)
11.5–12 h per night 2.04 (0.91–4.61) 0.82 (0.48–1.39)
11–11.5 h per night 2.11 (0.91–4.90) 0.87 (0.48–1.60)
o11 h night 3.10 (1.15–8.40) 2.05 (0.85–4.97)
Abbreviations: CI, confidence interval; OR, odds ratio; SES, socio-economic
status.
a
Results are adjusted for age.
Table 3. Association between sleep duration and overweight
adjusted for possible confounders (9–13-year-old children)
Boys (n¼803)
9–13-year-old
OR (95% CI)
a
Girls (n¼840)
OR (95% CI)
a
Unadjusted model: sleep duration
X11.25 h per night 1 (–) 1 (–)
10.75–11.25 h per night 2.66 (1.12–6.31) 0.87 (0.52–1.47)
10.25–10.75 h per night 2.48 (1.00–6.13) 1.13 (0.64–1.98)
o10.25 h per night 4.30 (1.62–11.42) 3.23 (1.57–6.65)
Adjusted for family characteristics
Adjusted for SES, ethnicity, maternal overweight and single parenting
X11.25 h per night 1 (–) 1 (–)
10.75–11.25 h per night 7.60 (2.23–25.87) 0.94 (0.52–1.70)
10.25–10.75 h per night 4.42 (1.41–13.87) 1.15 (0.61–2.20)
o10.25 h per night 4.63 (1.53–14.06) 3.32 (1.46–7.56)
Adjusted for lifestyle nutrition behaviours
Adjusted for drinking sugared drinks 43 glasses per day and
eating snacks 40.5 portion per day
X11.25 h per night 1 (–) 1 (–)
10.75–11.25 h per night 1.81 (0.69–4.78) 1.09 (0.55–2.17)
10.25–10.75 h per night 1.84 (0.67–5.05) 1.59 (0.78–3.27)
o10.25 h per night 3.51 (1.17–10.50) 5.46 (2.08–14.38)
Full model: adjusted for both family characteristics and lifestyle nutrition
behaviours
X11.25 h per night 1 (–) 1 (–)
10.75–11.25 h per night 2.77 (0.87–8.80) 1.04 (0.48–2.25)
10.25–10.75 h per night 2.92 (0.88–9.63) 1.33 (0.59–2.99)
o10.25 h per night 4.96 (1.35–18.16) 4.86 (1.59–14.88)
Abbreviations: CI, confidence interval; OR, odds ratio; SES, socio-economic
status.
a
Results are adjusted for age.
Sleep duration associated with childhood overweight
E de Jong et al
1281
&2012 Macmillan Publishers Limited International Journal of Obesity (2012) 1278 – 1284
multiple testing. Some of the associations in Table 4 are weak and
were also non-significant when using Bronferroni0s correction.
Therefore we want to be careful in our conclusions. However, we
also want to emphasize that the results are very plausible, not only
because of the results shown in this paper but also because other
research that shows similar results. For example, Spilsbury et al.
11
found in a population of 8–11-year-old children that high
presence of rules and routines, such as having set times for
doing homework and so on, having the child cleaning his/her
bedroom and consistently applied family rules were significantly
related to longer sleep duration. More rules in general may include
rules for bedtime, but explanations for results in present study
might also be part of a bigger context of parenting style and
parent–child interaction. For example, an authoritative parenting
style, a parenting style characterized by a clear and firm direction,
but also by warmth, flexibility and acceptance, is associated with a
healthier lifestyle of the child, such as, less sedentary behaviour
27
and higher fruit consumption
28
and a healthier weight.
29
The association between television viewing and computer
use and sleep duration is supported by several other studies.
13,16
They might impair sleep quality and duration, for example, by
increasing the arousal state,
30
or alternatively, sleeping less might
lead to more leisure time to fill in with television viewing and
computer use.
As short sleep duration in children has been related to other
adverse effects, for example poor school and cognitive perfor-
mance,
31,32
increasing the hours of sleep can have multiple
benefits. Sleep duration might be a good point of entry for
promoting and discussing a healthier lifestyle and weight in
children and the role of parents in this.
3
Table 4. Determinants in the home environment of sleep duration in hours
4–8-year-old (n¼2429) 9–13-year-old (n¼1643)
Boys (n¼1201)
b(95% CI)
a
Girls (n¼1228)
b(95% CI)
a
Boys (n¼803)
b(95% CI)
a
Girls (n¼840)
b(95% CI)
a
Viewing television during breakfast,
lunch or dinner
0.08 ( 0.15; 0.02) 0.06 ( 0.12; 0.00) 0.05 ( 0.12; 0.03) 0.09 ( 0.16; 0.02)
Television in bedroom 0.03 ( 0.11; 0.06) 0.02 ( 0.07; 0.11) 0.04 ( 0.12; 0.04) 0.08 ( 0.16; 0.01)
Computer in bedroom 0.03 ( 0.10; 0.05) 0.03 ( 0.06; 0.13) 0.01 ( 0.08; 0.05) 0.01 ( 0.07; 0.08)
Permission to have candy without asking
No/mostly not Ref Ref Ref Ref
Sometimes 0.06 ( 0.15; 0.04) 0.08 ( 0.17; 0.01) 0.10 ( 0.19; 0.02) 0.06 ( 0.14; 0.03)
Yes/mostly 0.25 ( 0.44; 0.06) n.a.
b
0.22 ( 0.35; 0.08) 0.04 ( 0.17; 0.09)
1–5 Weekdays eating ordered meal 0.06 ( 0.13; 0.01) 0.03 ( 0.10; 0.04) 0.13 ( 0.21; 0.05) 0.07 ( 0.15; 0.02)
0–4 Weekdays eating home-
cooked meal
0.04 ( 0.11; 0.03) 0.01 ( 0.05; 0.08) 0.06 ( 0.14; 0.02) 0.07 ( 0.15; 0.02)
0 Weekdays being active (cycling,
sporting or being outside in forest/
park) with caregiver
0.07 ( 0.17; 0.03) 0.11 ( 0.21; 0.00) 0.16 ( 0.24; 0.07) 0.08 ( 0.17; 0.00)
Late bedtime
c
0.55 ( 0.62; 0.49) 0.62 ( 0.68; 0.56) 0.54 ( 0.61; 0.47) 0.58 ( 0.65; 0.51)
Work situation mother
Part time Ref Ref Ref Ref
Full time 0.10 ( 0.23; 0.03) 0.04 ( 0.09; 0.18) 0.10 ( 0.23; 0.03) 0.11 ( 0.23; 0.01)
No paying job 0.02 ( 0.09; 0.05) 0.00 ( 0.07; 0.06) 0.06 ( 0.03; 0.14) 0.02 ( 0.07; 0.10)
Abbreviations: CI, confidence interval; NA, not applicable; SES, socio-economic status; b, Beta.
a
Results are adjusted for SES, ethnicity and age.
b
nis too small.
c
Late bedtime for 4–8-year-old children was 20.00 hours or later and 20.45 hours or later for 9–13-year-old children.
Table 5. Association between media use and physical activity on weekdays and sleep duration in hours
4–8-year-old (n¼2429) 9–13-year-old (n¼1643)
Boys (n¼1201)
b(95% CI)
a
Girls (n¼1228)
b(95% CI)
a
Boys (n¼803)
b(95% CI)
a
Girls (n¼840)
b(95% CI)
a
Television viewing
0–1 h per day Ref Ref Ref Ref
1–1.5 h per day 0.09 ( 0.15; 0.03) 0.09 ( 0.15; 0.03) 0.10 ( 0.17; 0.03) 0.06 ( 0.13; 0.01)
41.5 h per day 0.23 ( 0.37; 0.09) 0.17 ( 0.29; 0.05) 0.13 ( 0.25; 0.01) 0.13 ( 0.24; 0.02)
Computer use
0–30 min per day Ref Ref Ref Ref
30–60 min per day 0.06 ( 0.13; 0.21) 0.02 ( 0.13; 0.09) 0.02 ( 0.09; 0.06) 0.02 ( 0.13; 0.09)
460 min per day 0.21 ( 0.34; 0.08) 0.27 ( 0.46 0.07) 0.19 ( 0.28; 0.10) 0.27 ( 0.46; 0.07)
Playing outside o60 min per day 0.04 ( 0.10; 0.01) 0.06 ( 0.12; 0.00) 0.01 ( 0.07; 0.06) 0.00 ( 0.07; 0.07)
Organized sport o60 min per week 0.05 ( 0.11; 0.02) 0.02 ( 0.07; 0.04) 0.00 ( 0.09; 0.08) 0.05 ( 0.02; 0.11)
Abbreviations: CI, confidence interval; SES, socio-economic status; b, beta.
a
Results are adjusted for SES, ethnicity and age.
Sleep duration associated with childhood overweight
E de Jong et al
1282
International Journal of Obesity (2012) 1278 – 1284 &2012 Macmillan Publishers Limited
Strengths of present study is the equal spread of participating
schools across one city in the Netherlands. Moreover, all children
were measured according to protocol by trained students within
the same time range of 3 weeks, this short time range is of
particular importance in the assessment of sleep duration as
it is related to seasonal variation.
16
Data were available about
socio-demographic characteristics, physical and social home
environment, physical and dietary behaviours. Nevertheless
there are a few limitations of this study. The cross-sectional
study design precludes causal interpretation of the observation.
The children that participated in this study were not repre-
sentative for all children in the city of Zwolle, despite high
participation rates. Children from low and middle SES families
were underrepresented.
33
This selective participation could
have an impact on studied associations, making the observed
associations possibly weaker. Another limitation is the use of
questionnaires on environmental determinants, sleep duration,
food intake and physical activity; as in other monitoring studies,
this can possibly lead to issues of social desirability and to
difficulties with recalling the actual behaviour of the child in the
past month. Time in bed, calculated from parents’ information on
evening bedtime and wakeup, was used as a proxy for sleep
duration. In older children, self-reported sleep duration is probably
a more valid measure. A recent study of 10–12-year-old children,
however, showed that children’s self-reported sleep duration and
parents’ estimations showed very similar associations with BMI of
the child,
5
which indicated a good validity of parents’ estimations
as compared with self reports. The use of questionnaire data,
constructed to study health in general, but not specifically in
relation to sleep, limited us to investigate only a selection of
factors on the association with sleep duration. Similar factors were
grouped together, but were only able to explore a small part of
rules, eating patterns and physical activity.
Implications
The associations studied in this study should be investigated
further in longitudinal studies and also in study populations
where sleeping behaviour of children is different than in the
Netherlands, where children sleep relatively long compared
with other countries.
34
Further insight into the relationship
between sleep duration and overweight and in the deter-
minants of sleeping behaviour can provide implications for
the development of interventions to improve sleep duration
and possibly reduce overweight. Parenting skills may have an
important role in this.
CONCLUSION
The results show an association between sleeping o11 h per
night compared with sleeping X12 h per night and overweight
for 4–8-year-old boys. The results also show an association
between sleeping o10.25 h per night compared with sleeping
X11.25 h per night and overweight for 9–13-year-old boys and
girls. These associations are stronger for boys than for girls and
stronger for older boys than for younger boys. Determinants in the
home environment are identified as they could be targeted to
increase the hours of sleep in children. Interventions should
support parents by enabling them with parenting skills and
knowledge so that they can offer their children structure and
routine by, for example, not allowing their children having a
television in the bedroom, viewing television during a meal,
having candy without asking and by having rules for an early
bedtime. Parents also have a strong impact on being active by
cycling, sporting or going outside together with their child. These
home environmental changes seem promising in increasing the
hours of sleep and through that, at the same time, possibly in
preventing overweight in children.
CONFLICT OF INTEREST
The authors declare no conflict of interest.
ACKNOWLEDGEMENTS
We would like to thank our partners in this monitoring study: the Zwolle city council,
the local health services and several welfare organizations in the city. We are greatly
thankful to all the students who helped with the measurements, the participated
schools and sponsorships.
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