Sleep timing is associated with diet and physical activity levels in 9–11‐year‐old children from Dunedin, New Zealand: the PEDALS study

Abstract

It is well documented that short sleep duration is associated with excess body weight and poor food intake in children. It has been suggested that sleep timing behaviour may also be an important predictor of weight and other related behaviours, independent of sleep duration; however, there is a lack of research investigating these relationships. The present study investigated sleep timing in association with diet and physical activity levels in 439 children aged 9-11 years old from New Zealand. Sleep and physical activity data were collected using accelerometry, and food choice using a short food-frequency questionnaire. Participants were classified into one of four sleep timing behaviour categories using the median split for sleep-onset and -offset times. Differences between sleep timing groups for weekly consumption frequency of selected food groups, dietary pattern scores and minutes of moderate-to-vigorous physical activity were examined. Children in the late sleep/late wake category had a lower 'Fruit & Vegetables' pattern score [mean difference (95% CI): -0.3 (-0.5, -0.1)], a lower consumption frequency of fruit and vegetables [mean weekly difference (95% CI): -2.9 (-4.9, -0.9)] and a higher consumption frequency of sweetened beverages [mean weekly difference (95% CI): 1.8 (0.2, 3.3)] compared with those in the early sleep/early wake category. Additionally, children in the late sleep/late wake category accumulated fewer minutes of moderate-to-vigorous physical activity per day compared with those in the early sleep/early wake category [mean difference (95% CI): -9.4 (-15.3, -3.5)]. These findings indicate that sleep timing, even after controlling for sleep duration, was associated with both food consumption and physical activity.

Sleep and obesity among children: A systematic review of multiple sleep dimensions

“…Of the total 112 reviewed studies and 24 timing studies, only four measured sleep timing objectively via accelerometry. One of these assessed sleep‐wake timing, which supported the general nonsignificance consensus.…”

“…Of the total 112 reviewed studies and 24 timing studies, only four measured sleep timing objectively via accelerometry. One of these assessed sleep‐wake timing, which supported the general nonsignificance consensus. Two of the studies reported on the association between BT and WT with children's BMI z‐scores, both reporting nonsignificant results.…”

“…22,99,131 The second measure was sleep wake cycles, almost a combined sleep timing/duration variable, categorising children as late to bed/wake early (shortest duration), early to bed/wake early or late to bed/wake late (mid duration), and early to bed/wake late (long duration). 44,72,115,118 reported that although the number of wake episodes alone was nonsignificant with BMI, however the number of long wake episodes (those longer than 5 minutes) was associated with a significant increase in BMI among children. Contrasting evidence was also reported among sleep quality studies, with significant associations of poorer sleep quality and increased obesity risk reported among less than half of those exploring self or parent determined sleep quality.…”

“…One of the other two measures of sleep timing minimally outlined included sleep midpoint, which used as a single marker (the midpoint) to assess the timing of sleep, taking duration completely out of the equation. The second measure was sleep wake cycles, almost a combined sleep timing/duration variable, categorising children as late to bed/wake early (shortest duration), early to bed/wake early or late to bed/wake late (mid duration), and early to bed/wake late (long duration) . While results from the reviewed studies potentially suggest a stronger importance of sleep midpoint than sleep‐wake patterns, it is still unclear how reliable/useful these measures of sleep timing are when analyzing the sleep‐obesity association, due to the limited number of studies with these measures of timing and the discrepancies across results.…”

“…One of these assessed sleep-wake timing, 72 which supported the 136 ✓ Pos Self-report Abbreviations: Key: ✓ = significant association reported; NS = no significant association with weight status; Pos = positive association (later BT OR WT à higher weight status); Neg = negative association (earlier BT OR WT à higher weight status); BT = Bed Time; WT = Wake Time; LTB = late to bed; CS = cross-sectional association; LT = longitudinal association. general nonsignificance consensus.…”