Are sleep duration and sleep quality associated with diet quality, physical activity, and body weight status? A population-based study of Canadian children.
Khan, Mohammad K.A. ; Chu, Yen Li ; Kirk, Sara F.L. 等
The increasing prevalence of obesity among children is recognized
as a public health concern. As the rise in obesity prevalence is
paralleled by declining duration and quality of sleep, (1) short sleep
duration and compromised sleep quality have been considered as
contributing factors to the obesity epidemic. (2-4) Prospective and
cross-sectional studies examining the relationship between sleep and
body weight status have shown that children who slept less or who had
poorer quality sleep were more likely to be overweight or obese compared
to their peers. (2, 3, 5, 6)
Potential mechanisms linking sleep and obesity may include
decreased physical activity and consumption of a low-quality diet. (7,
8) Participants in sleep deprivation studies who slept less were more
likely to report higher levels of calorie intake and lower levels of
physical activity. (9-11) Furthermore, there is some evidence indicating
that sleep duration and quality may affect energy balance and metabolism
through altered levels of regulating hormones such as leptin and
ghrelin. (11)
Currently, the evidence linking sleep duration and quality to
obesity and its related lifestyle factors is limited mostly to studies
conducted among small and selected samples. (7-10) Furthermore, while
the physiologic mechanisms linking sleep and energy balance are well
described, large-scale population-based studies describing these
associations are limited. While there were a few larger-scale studies
that have reported on the relationships between sleep and obesity, (2,
3, 5, 6) studies specific to the Canadian context remain scarce.
Therefore, the purposes of this study are to describe sleep duration and
other sleep characteristics, and to examine the associations among sleep
duration, sleep characteristics, diet quality, physical activity levels,
and body weight status among a provincially representative sample of
grade 5 children in Nova Scotia.
METHODS
Study population
This analysis was conducted using data collected as part of the
2011 Children's Lifestyle And School performance Study (CLASS), a
large cross-sectional provincial survey that studied health, nutrition,
physical activity, and other lifestyle factors of grade 5 students (aged
10-11 years) in Nova Scotia. The vast majority of grade 5 students in
Nova Scotia attend public schools, and all public schools were invited
to participate in the survey. Of the 286 invited schools, 269 (94.1%)
agreed to participate and 5,913 parents provided informed consent for
their child to participate, resulting in an average response rate of
67.4%. Trained evaluation assistants visited the schools to administer
the student surveys and to complete anthropometric measurements. Student
surveys consisted of a questionnaire on physical and sedentary
activities, mental health, and body image, and the Harvard Youth/
Adolescent Food Frequency Questionnaire (YAQ) adapted for Canadian
settings. Parents also completed a survey that included questions on the
home environment and on socio-economic factors. All survey instruments
used in this study are available on the CLASS project website. (12) The
Human Research Ethics Boards at the University of Alberta and Dalhousie
University approved all study procedures.
Measures of interest
Sleep Duration and Sleep Characteristics
The primary exposures of interest in this study were sleep duration
and sleep characteristics, including snoring and daytime sleepiness.
Sleep duration was calculated based on parent responses to a question
adapted from Project EAT-III (Eating and Activity in Teens and Young
Adults) (13) where they were asked to indicate the time their child
usually goes to bed and the time their child usually wakes up for both a
typical weekday and a typical weekend day. Sleep duration for a typical
night was then calculated based on five weekdays and two weekend days.
Bedtime was indicated through responses to the question asking about the
time the child went to bed; these responses were then grouped into the
categories of "before 9 pm", "9-10 pm", and
"after 10 pm" for regression analyses. Parents were also asked
to indicate how often their child snored and how often their child was
sleepy during the daytime, with response options of "never",
"rarely", "occasionally", "frequently" and
"almost always". In order to allocate a sufficient number of
observations in each category, responses to these questions were
re-categorized by collapsing the groups of students who answered
"occasionally", "frequently" and "almost
always" into one response category ("frequently").
Diet Quality
Overall diet quality in this study was measured using the Diet
Quality Index--International (DQI-I). (14) The DQI-I is a composite
score (range: 0-100) derived to measure diet quality based on the
aspects of variety, adequacy, moderation, and overall balance. The DQI-I
was calculated based on child responses to the YAQ, a validated tool to
assess dietary intake among children and youth, (15) and nutrient
information from the 2007 Canadian Nutrient File. (16) Of the children
who completed the YAQ, 138 (2%) children with average daily energy
intake <500 kcal or >5000 kcal were excluded from analyses related
to diet quality as these results were considered to be unreliable. (17)
Physical Activity
Level of physical activity was determined using the Physical
Activity Questionnaire for Children (PAQ-C). The PAQ-C was included in
the student survey and is a validated instrument to assess frequency and
duration of physical activity in children over a 7-day period. (18)
PAQ-C scores range from 0 to 5, with higher scores indicative of higher
levels of physical activity.
Body Weight
Body mass index (BMI) was calculated using measured child height
and weight. Height was measured to the nearest 0.1 cm after children had
removed their shoes, and body weight was measured to the nearest 0.1 kg
on calibrated digital scales. Body weight status (normal weight,
overweight including obese, obese) was determined using age- and
gender-specific cut-off points for children and youth established by the
International Obesity Task Force. (19)
Other Covariates
Demographic information, such as parental education attainment
(secondary or less, college, university and above) and household income
(<$20,000, $20,001-$40,000, $40,001-$60,000, >$60,000), was
obtained from responses to the parent survey. Region of residence
(urban/rural) was determined using postal codes collected from parent
surveys.
Data analysis
Data from a total of 5,560 children were used in analyses after
excluding 353 (6%) children due to non-response to at least one of the
questionnaires. All statistical analyses were weighted to represent
provincial estimates of the grade 5 student population in public schools
across Nova Scotia and for non-response bias. Linear and logistic random
effects models with children clustered within schools were used to test
for associations among diet quality, physical activity, weight status,
and sleep duration and quality. These multivariable analyses were
adjusted for the potential confounding effects of gender, household
income, parental education, and place of residence. Analyses with diet
quality as an outcome were also adjusted for energy intake. Further
analyses where all exposures were included simultaneously in the model
were conducted to determine whether each of the exposures of interest
were independently associated with the outcomes. The table of
descriptive statistics and the histogram of sleep duration were
constructed with Stata version 12 (StataCorp, College Station, TX, USA).
The regression analyses were conducted in R (version 3.0.2).
RESULTS
Characteristics of the surveyed children are shown in Table 1.
Parents reported that their grade 5 child slept an average of 10.0 hours
on a typical night (median 10 hours, range 7.8-12.1 hours), where half
(50%) of the children slept less than the recommended 10 hours per
night. Average sleep duration on a typical night was distributed
normally throughout the study population (Figure 1). Most parents also
reported that their children went to bed before 9 pm on weekdays (57%)
and after 9 pm on weekends (88%). Among all surveyed children, 31% were
reported to snore frequently and 22% to frequently feel sleepy during
the day.
Sleep duration and associations with weight status, diet quality,
and physical activity levels
Logistic random effects models were used to investigate
relationships between sleep duration and weight status, with normal
weight children as the reference group. After adjusting for potential
confounding effects of the child's gender, parental education,
household income, and place of residence, longer sleep duration was
significantly associated with decreased odds of being overweight or
obese (OR = 0.81, 95% CI: 0.75, 0.88; Table 2). Linear random effects
models were used to investigate relationships among sleep duration, diet
quality, and physical activity levels as measured through PAQ-C scores,
adjusting for potential confounding effects of gender, parental
education, household income, and region of residence. Longer sleep
duration was associated with higher DQI-I scores ([beta] = 0.60, 95% CI:
0.11, 1.09) and higher PAQ-C scores ([beta] = 0.03, 95% CI: 0.01, 0.05)
(Table 3). Furthermore, children who went to bed at a later hour on
weekday nights were less physically active and had higher odds of being
overweight or obese.
[FIGURE 1 OMITTED]
Other sleep characteristics and associations with weight status,
diet quality, and physical activity levels
Logistic random effects models were used to investigate
relationships between sleep characteristics such as snoring and daytime
sleepiness, and weight status, with normal weight children as the
reference group. Both snoring and daytime sleepiness were found to be
associated with body weight status, and were reported to occur more
frequently among children who were overweight or obese compared to
normal weight children. Regression analysis revealed that children who
were reported to snore or to be sleepy during daytime frequently had
higher odds of being overweight or obese compared to children who never
snored. Linear random effects models were used to investigate
relationships between snoring and daytime sleepiness, and diet quality
and physical activity levels. While there was no association observed
between snoring and being physically active, children who were reported
to frequently be sleepy during the daytime scored lower on the PAQ-C
compared to children who were never sleepy ([beta] = -0.11,95% CI:
-0.17, -0.06).
Independence of associations among sleep duration and other sleep
characteristics and weight status, diet quality, and physical activity
levels
Further analyses were conducted to determine whether each of the
exposures of interest (sleep duration, bedtime, snoring, daytime
sleepiness) were independently associated with weight status, diet
quality, and physical activity levels. Logistic (for weight status) and
linear random effects models (for diet quality and physical activity)
where all exposures of interest were included simultaneously were used.
After adjusting for all exposures, being sleepy during daytime was
significantly associated with lower PAQ-C scores, suggesting that this
association was independent of other indicators of sleep quality or
duration. Similarly, snoring and sleep duration were found to be
significantly associated with increased odds of being overweight or
obese independent of other exposure variables.
DISCUSSION
Results from this study indicated that almost half of the surveyed
children in Nova Scotia were not getting adequate amounts of sleep per
night. These estimates of sleep duration among children are not
consistent with those reported in a previous study among children in the
province of Quebec where mean sleep duration was observed to be longer
at 10.8 hours per night. (2) Adequate sleep has been shown to be
important for metabolic regulation, cognitive and psychological
functioning, and school performance in children. (20, 21) In recognition
of the importance of sleep in children, the National Sleep Foundation
currently recommends that children aged 5-12 years sleep an average of
10-11 hours per night for optimal physical and mental development and
health. (22) The influence of sleep duration on health and weight status
has been consistently demonstrated. (2-4, 23) Furthermore, prospective
studies have confirmed the causal pathway between sleep duration and
obesity by showing that short sleep duration leads to increased risk for
obesity at a later age. (5, 6) This study further stressed the potential
importance of adequate sleep to health by showing that sleep duration,
independent of other measured indicators of sleep such as bedtime,
snoring, and daytime sleepiness, influenced overweight risk. However,
despite these recommendations and evidence for the importance of sleep,
sleep durations among children and youth are progressively getting
shorter, (1) indicating a need for health promotion messages encouraging
adequate sleep among children.
Previous studies have indicated that children who went to bed late
were more likely to lead a sedentary lifestyle with lower levels of
physical activity and more screen time. (24) Similar findings were
observed in the current study. However, the effects of bedtime on health
outcomes are difficult to separate from that of sleep duration, given
that a late bedtime is generally associated with shorter sleep duration.
While studies conducted among Australian children found that bedtime had
an effect on health behaviours independent of sleep duration, (24, 25)
the independent effect of bedtime was not observed in the current study.
This suggests that bedtime and sleep duration may be more intricately
linked among children in this study, thus an association between bedtime
and health outcomes independent of sleep duration could not be observed.
Snoring and daytime sleepiness were more likely to be reported
among overweight or obese children in this study. These findings are
consistent with those of previous studies. (26, 27) These associations
are not surprising given that snoring and daytime sleepiness are both
common symptoms of obstructive sleep apnea, a sleep disorder that is
more prevalent among children who are overweight or obese. (26, 27) The
observed independent association between snoring and weight status in
this study may be explained by the higher risk for sleep disorders among
overweight or obese children, where snoring is indicative of the
presence of a sleep disorder. Future analysis where there is a diagnosis
of a sleep disorder is needed in order to increase understanding of this
relationship, however this study has helped to further clarify the
magnitude of compromised sleep among Canadian children.
In addition to weight status, this study also revealed associations
between sleep and lifestyle factors, including diet quality and physical
activity levels. These findings suggest that encouraging healthy sleep
habits among children should be integrated into public health strategies
to promote healthy lifestyles. Therefore, future studies to obtain
further insight into the social and environmental determinants of
healthy sleep are essential to inform these intervention efforts. For
instance, factors including family characteristics such as rules for
bedtime (28) and the presence of electronic devices in the sleep
environment (29) have been shown to be associated with sleep duration
and quality, and should be targeted in interventions promoting healthy
sleep habits.
A strength of this study is the inclusion of analysis to establish
the independent importance of each sleep indicator in an attempt to
separate the effects of each of these highly linked indicators on health
behaviours and weight status. Other strengths include the large sample
of children surveyed that is representative of the grade 5 student
population in Nova Scotia, and the response rate that can be considered
high for school-based research. This study was limited by the use of
self-reported information. While parental report of sleep duration is
shown to be highly correlated with objective measures among pre-school
children, (30) it has also been shown to overestimate sleep duration by
up to 50 minutes among school-aged children. (31) Nevertheless,
validated measures for dietary intake (15) and physical activity (18)
were used to minimize potential bias. Future studies using objective
measurements for sleep and physical activity are needed to strengthen
the observed findings. Finally, temporality and causality cannot be
inferred based on the cross-sectional design of this study. It is
possible that the associations observed are due to reverse causality.
For instance, overweight and obese children have more difficulty
sleeping and thus are more likely to sleep less.
In conclusion, results from this study indicated that short sleep
duration and compromised sleep, such as snoring and daytime sleepiness,
are associated with increased risk for overweight and obesity, and are
prevalent among Canadian children. Furthermore, sleep duration is also
associated with less desirable health behaviours, including poorer diet
quality and lower physical activity levels. These findings suggest the
need for further research to better understand the factors influencing
sleep duration in children to inform intervention strategies, so that
these strategies can be tailored to address these factors. Furthermore,
public health obesity prevention strategies should include messages
promoting healthy sleep behaviour among children.
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Received: November 7, 2014
Accepted: March 15, 2015
Mohammad K.A. Khan, MSc, [1] Yen Li Chu, PhD, [1] Sara F.L. Kirk,
PhD, [2] Paul J. Veugelers, PhD [1]
Author Affiliations
[1.] School of Public Health, University of Alberta, Edmonton, AB
[2.] School of Health and Human Performance, Dalhousie University,
Halifax, NS
Correspondence: Paul J. Veugelers, PhD, Professor, School of Public
Health, University of Alberta, 3-50 University Terrace, 8303-112 St,
Edmonton, AB, T6G 2T4, Tel: [telephone] 780-492-9095, E-mail:
paul.veugelers@ualberta.ca
Acknowledgements: The authors thank stakeholders from the Nova
Scotia Government and Nova Scotia School Boards, as well as schools,
parents and students for their participation in this study. This
research was funded by an operating grant from the Canadian Institutes
of Health Research (CIHR). Paul Veugelers acknowledges the support from
a CIHR Canada Research Chair in Population Health and an Alberta
Innovates Health Solutions Scholarship. Sara Kirk acknowledges the
support from a CIHR Canada Research Chair in Health Services Research
and an IWK Scholar Award. All interpretations and opinions in the
current study are those of the authors.
Conflict of Interest: None to declare.
Table 1. Characteristics of grade 5 children in
Nova Scotia (n = 5560) * ([dagger])
Characteristic
Sex
Male 48
Female 52
Household income
<$20,000 6
$20,000-$40,000 14
$40,001-$60,000 14
>$60,000 47
Not reported 20
Parental education attainment
Secondary or less 18
College 40
University or higher 38
Not reported 4
Region of residence
Urban 64
Rural 36
Sleep duration, hours 10.0 [+ or -] 0.5
(mean [+ or -] SD)
Bedtime, weekday
Before 9 pm 57
9-10 pm 39
After 10 pm 4
Bedtime, weekend
Before 9 pm 12
9-10 pm 47
After 10 pm 41
Snoring
Never 31
Rarely 38
Frequently 31
Sleepy during daytime
Never 27
Rarely 52
Frequently 22
DQI-I (mean [+ or -] SD) 63.0 [+ or -] 9.7
([double dagger])
PAQ-C (mean [+ or -] SD)
([section]) 3.3 [+ or -] 0.7
Overweight ([parallel]) 35
Obese 12
SD = standard deviation;DQI-I = Diet Quality Index - International;
PAQ-C = Physical Activity Questionnaire for Children.
* Numbers are presented as% unless otherwise indicated.
([dagger]) Results are weighted to represent provincial
estimates of the grade 5 student population in Nova Scotia.
([double dagger]) Score range 0-100, higher score indicating
better diet quality.
([section]) Score range 0-5, higher score indicating higher
physical activity level.
([parallel]) Including obese percent.
Table 2. Associations between sleep duration and indicators
of sleep quality and body weight status among grade 5
children in Nova Scotia *
Overweight
Univariable
Sleep characteristic OR (95% CI)
Sleep duration (hours 0.86 (0.8, 0.93)
per day)
Bedtime on typical weekday
Before 9 pm ([section]) -- --
9-10 pm 1.33# (1.17, 1.5)#
After 10 pm 1.62# (1.19, 2.22)#
Bedtime on typical weekend
Before 9 pm ([section])
9-10 pm 1.2 (0.98, 1.47)
After 10 pm 1.6# (1.3, 1.96)#
Snoring
Never ([section]) -- --
Rarely 1.41# (1.21, 1.63)#
Frequently 2.27# (1.94, 2.64)#
Sleepy during daytime
Never ([section]) -- --
Rarely 1.01 (0.88, 1.17)
Frequently 1.34# (1.13, 1.58)#
Overweight
Multivariable
model 1 ([dagger])
Sleep characteristic OR (95% CI)
Sleep duration (hours 0.81 (0.75, 0.88)
per day)
Bedtime on typical weekday
Before 9 pm ([section]) -- --
9-10 pm 1.35# (1.19, 1.52)#
After 10 pm 1.53# (1.12, 2.1)#
Bedtime on typical weekend
Before 9 pm ([section])
9-10 pm 1.19 (0.97, 1.45)
After 10 pm 1.54# (1.26, 1.9)#
Snoring
Never ([section]) -- --
Rarely 1.37 (1.18, 1.59)#
Frequently 2.14 (1.83, 2.49)#
Sleepy during daytime
Never ([section]) -- --
Rarely 1.02 (0.89, 1.18)
Frequently 1.31# (1.1, 1.55)#
Overweight
Multivariable
model 2 ([double dagger])
Sleep characteristic OR (95% CI)
Sleep duration (hours 0.82 (0.73, 0.91)
per day)
Bedtime on typical weekday
Before 9 pm ([section]) -- --
9-10 pm 1.11 (0.95, 1.29)
After 10 pm 1.06 (0.74, 1.51)
Bedtime on typical weekend
Before 9 pm ([section])
9-10 pm 1.04 (0.84, 1.29)
After 10 pm 1.19 (0.94, 1.51)
Snoring
Never ([section]) -- --
Rarely 1.38# (1.18, 1.6)#
Frequently 2.07# (1.77, 2.43)#
Sleepy during daytime
Never ([section]) -- --
Rarely 0.95 (0.82, 1.1)
Frequently 1.11 (0.93, 1.32)
Obese
Univariable
Sleep characteristic OR (95% CI)
Sleep duration (hours 0.75 (0.67, 0.85)
per day)
Bedtime on typical weekday
Before 9 pm ([section]) -- --
9-10 pm 1.48# (1.22, 1.8)#
After 10 pm 2.64# (1.75, 4.00)#
Bedtime on typical weekend
Before 9 pm ([section])
9-10 pm 1.43# (1.00, 2.03)#
After 10 pm 2.26# (1.59, 3.22)#
Snoring
Never ([section]) -- --
Rarely 1.54# (1.2, 1.98)#
Frequently 2.92# (2.29, 3.73)#
Sleepy during daytime
Never ([section]) -- --
Rarely 1.11 (0.89, 1.4)
Frequently 1.51# (1.16, 1.96)#
Obese
Multivariable
model 1 ([dagger])
Sleep characteristic OR (95% CI)
Sleep duration (hours 0.72 (0.64, 0.81)
per day)
Bedtime on typical weekday
Before 9 pm ([section]) -- --
9-10 pm 1.53 (1.26, 1.85)
After 10 pm 2.50 (1.64, 3.80)
Bedtime on typical weekend
Before 9 pm ([section])
9-10 pm 1.39 (0.97, 1.98)
After 10 pm 2.13 (1.49, 3.03)
Snoring
Never ([section]) -- --
Rarely 1.46 (1.14, 1.88)
Frequently 2.68 (2.1, 3.42)
Sleepy during daytime
Never ([section]) -- --
Rarely 1.13 (0.90, 1.42)
Frequently 1.44 (1.11, 1.89)
Obese
Multivariable
model 2 ([double dagger])
Sleep characteristic OR (95% CI)
Sleep duration (hours 0.80 (0.68, 0.95)
per day)
Bedtime on typical weekday
Before 9 pm ([section]) -- --
9-10 pm 1.17 (0.92, 1.48)
After 10 pm 1.51 (0.94, 2.45)
Bedtime on typical weekend
Before 9 pm ([section])
9-10 pm 1.22 (0.84, 1.76)
After 10 pm 1.53 (1.02, 2.29)
Snoring
Never ([section]) -- --
Rarely 1.42 (1.1, 1.83)
Frequently 2.52 (1.96, 3.23)
Sleepy during daytime
Never ([section]) -- --
Rarely 1.02 (0.81, 1.29)
Frequently 1.13 (0.86, 1.49)
* All analyses are weighted to represent provincial
estimates and for non-response bias. Statistically
significant results are highlighted in bold.
([dagger]) Multivariable regression model adjusting for sex
of child, household income, parental education attainment,
and place of residence.
([double dagger]) Multivariable regression model adjusting
for all exposure variables listed in the table, sex of
child, household income, parental education attainment, and
place of residence.
([section]) Reference category.
Note: Statistically significant results are indicated with #.
Table 3. Associations among sleep duration and indicators of
sleep quality and diet quality and physical activity among
grade 5 children in Nova Scotia *
Diet quality
Univariable
Sleep characteristic [beta] (95% CI)
Sleep duration 0.11 (-0.20, 0.42)
(hours per day)
Bedtime on
typical weekday
Before 9 pm ([section]) -- --
9-10 pm -0.02 (-0.58, 0.54)
After 10 pm -0.84 (-2.32, 0.63)
Bedtime on typical weekend
Before 9 pm ([section]) -- --
9-10 pm -0.11 (-0.99, 0.77)
After 10 pm -0.17 (-1.07, 0.73)
Snoring
Never ([section]) -- --
Rarely -0.32 (-0.97, 0.32)
Frequently -0.38 (-1.06, 0.30)
Sleepy during daytime
Never ([section]) -- --
Rarely -0.08 (-0.72, 0.56)
Frequently -0.20 (-0.97, 0.58)
Diet quality
Multivariable
model 1 ([double dagger])
Sleep characteristic [beta] (95% CI)
Sleep duration 0.11 (-0.21, 0.43)
(hours per day)
Bedtime on
typical weekday
Before 9 pm ([section]) -- --
9-10 pm -0.08 (-0.63, 0.48)
After 10 pm -0.74 (-2.21, 0.74)
Bedtime on typical weekend
Before 9 pm ([section]) -- --
9-10 pm -0.08 (-0.96, 0.8)
After 10 pm -0.07 (-0.96, 0.83)
Snoring
Never ([section]) -- --
Rarely -0.21 (-0.85, 0.44)
Frequently -0.12 (-0.8, 0.56)
Sleepy during daytime
Never ([section]) -- --
Rarely -0.12 (-0.76, 0.52)
Frequently -0.08 (-0.86, 0.69)
Diet quality
Multivariable
model 2 ([double dagger])
Sleep characteristic [beta] (95% CI)
Sleep duration 0.60# (0.11, 1.09)#
(hours per day)
Bedtime on
typical weekday
Before 9 pm ([section]) -- --
9-10 pm 0.17 (-0.51, 0.85)
After 10 pm -0.42 (-2.04, 1.20)
Bedtime on typical weekend
Before 9 pm ([section]) -- --
9-10 pm -0.05 (-0.96, 0.86)
After 10 pm 0.15 (-0.88, 1.18)
Snoring
Never ([section]) -- --
Rarely -0.14 (-0.79, 0.51)
Frequently -0.04 (-0.74, 0.65)
Sleepy during daytime
Never ([section]) -- --
Rarely -0.02 (-0.66, 0.63)
Frequently 0.03 (-0.76, 0.82)
Physical activity
Univariable
Sleep characteristic [beta] (95% CI)
Sleep duration 0.02 (0, 0.04)
(hours per day)
Bedtime on
typical weekday
Before 9 pm ([section]) -- --
9-10 pm -0.02 (-0.05, 0.02)
After 10 pm -0.16# (-0.26, -0.06)#
Bedtime on typical weekend
Before 9 pm ([section]) -- --
9-10 pm 0.03 (-0.03, 0.09)
After 10 pm -0.02 (-0.08, 0.04)
Snoring
Never ([section]) -- --
Rarely 0.02 (-0.03, 0.06)
Frequently -0.01 (-0.06, 0.04)
Sleepy during daytime
Never ([section]) -- --
Rarely -0.07# (-0.11, -0.02)#
Frequently -0.12# (-0.17, -0.06)#
Physical activity
Multivariable
model 1 ([double dagger])
Sleep characteristic [beta] (95% CI)
Sleep duration 0.03# (0.01, 0.05)#
(hours per day)
Bedtime on
typical weekday
Before 9 pm ([section]) -- --
9-10 pm -0.02 (-0.06, 0.02)
After 10 pm -0.17# (-0.27, -0.07)#
Bedtime on typical weekend
Before 9 pm ([section]) -- --
9-10 pm 0.03 (-0.03, 0.09)
After 10 pm -0.01 (-0.07, 0.05)
Snoring
Never ([section]) -- --
Rarely 0.02 (-0.02, 0.06)
Frequently -0.01 (-0.05, 0.04)
Sleepy during daytime
Never ([section]) -- --
Rarely -0.06# (-0.11, -0.02)#
Frequently -0.11# (-0.17, -0.06)#
Physical activity
Multivariable
model 2 ([double dagger])
Sleep characteristic [beta] (95% CI)
Sleep duration 0.02 (-0.01, 0.06)
(hours per day)
Bedtime on
typical weekday
Before 9 pm ([section]) -- --
9-10 pm -0.02 (-0.05, 0.05)
After 10 pm -0.13 (-0.24, -0.02)
Bedtime on typical weekend
Before 9 pm ([section]) -- --
9-10 pm 0.04 (-0.02, 0.11)
After 10 pm 0.02 (-0.05, 0.09)
Snoring
Never ([section]) -- --
Rarely 0.02 (-0.02, 0.07)
Frequently 0.01 (-0.04, 0.06)
Sleepy during daytime
Never ([section]) -- --
Rarely -0.06# (-0.1, -0.02)#
Frequently -0.11# (-0.16, -0.05)#
* All analyses are weighted to represent provincial
estimates and for non-response bias. Statistically
significant results are highlighted in bold.
([dagger]) Multivariable regression model adjusting for sex
of child, household income, parental education attainment,
and place of residence. Analyses with diet quality as an
outcome are further adjusted for energy intake,
([double dagger]) Multivariable regression model adjusting
for all exposure variables listed in the table, sex of
child, household income, parental education attainment, and
place of residence. Analyses with diet quality as an outcome
are further adjusted for energy intake.
([section]) Reference category.
Note: Statistically significant results are highlighted are
indicated with #.
