Background: Short sleep durations are related to risks for obesity
in preschool children. However, the underlying mechanism or
mechanisms are not clear.
Objectives: We evaluated the relationships between sleep characteristics
and body composition, energetics, and weight-regulating
behaviors in preschool-aged children, as well as the longitudinal
associations between children’s sleep and eating patterns and body
composition at a 1-year follow-up.
Methods: Data were drawn from a longitudinal study of 118 children
aged 3–5 years. Sleep (duration, midpoint, regularity) and physical
activity (PA) were measured by accelerometry over 6 consecutive
days; total energy expenditure (TEE) was measured using the
doubly labeled water method; body composition (fat mass, fat-free
mass, and percent body fat) was measured by DXA; and dietary
intake (energy intake, timing) was measured using two 24-hour
recalls.Multivariable regression was used to estimate interindividual
associations of sleep parameters with body composition, PA,
TEE, and dietary outcomes and to examine the relationships
between sleep and dietary behaviors and body composition 1 year
later.
Results: Cross-sectionally, later sleep midpoint is associated with
having a greater fat mass (0.33; 95% CI: 0.05, 0.60) and a higher
percent body fat (0.92; 95% CI: 0.15, 1.70). Later sleep midpoint
was associated with delayed morning mealtimes (0.51; 95% CI:
0.28, 0.74) and evening mealtimes (0.41; 95% CI: 0.29, 0.53),
higher nighttime energy intakes (45.6; 95% CI: 19.7, 71.4), and
lower morning energy intakes (−44.8; 95% CI: −72.0, −17.6).
Longitudinally, shorter sleep duration (−0.02; 95% CI: −0.03, 0.00)
and later meal timing (0.83; 95% CI: 0.24, 1.42) were associated with
higher percent body fat measurements 1 year later.
Conclusions: Shorter sleep duration and later meal timing are
associated with adiposity gains in preschoolers. Am J Clin Nutr
2022;116:1334–1342.
Keywords: sleep, obesity, physical activity, dietary behaviors,
energy expenditure
Introduction
Short sleep duration has been linked to higher BMI z-scores
(BMIz values) and elevated risks for obesity in young children
(1–3). Furthermore, sleep duration has received the bulk of
attention in assessments of risks for obesity, despite being only
1 component of sleep. Other dimensions of sleep, such as day-today
regularity and timing, may impact the energy balance–related
behaviors of young children [e.g., dietary patterns, physical
activity (PA)]. Indeed, sleep patterns are maturing as children
transition from multiple sleep periods per day to 1 consolidated
sleep period at night. Moreover, the process of phasing out
daytime naps (4) may contribute to greater variability in sleep
schedules, as napping results in delayed sleep onset (5); thus,
there may be greater opportunity for day-to-day shifts in young
children’s sleep. Later sleep timing and greater variability in
sleep patterns may contribute to shorter sleep duration, especially
among young children, who often fail to compensate for later
bedtimes with later wake times (6–8).
It is possible that later sleep timing and greater day-to-day
variability in sleep timing may result in the mistiming of sleep
with the endogenous circadian clock, affecting the timing of other
energy balance–related behaviors, including dietary patterns and
PA. The misalignment of these behaviors with endogenous
rhythms may result in metabolic changes and weight gain in
This work was made possible with grant funding from the USDA and
Agricultural Research Service CRIS Awards 6250-5100-054 (to NFB) and
3092-5-001-057 (to FB).
The content is solely the responsibility of the authors and does not
necessarily represent the official views of the NIH or the USDA and
Agricultural Research Service.
Address correspondence to Fida Bacha (e-mail: fbacha@bcm.edu).
Abbreviations: BMIz, BMI z-score; MVPA, moderate to vigorous physical
activity; PA, physical activity; TEE, total energy expenditure.
Received February 23, 2022. Accepted for publication July 12, 2022.
First published online July 14, 2022; doi: https://doi.org/10.1093/ajcn/
nqac197.
