Shorter sleep among adolescents is associated with lower fruit and vegetable consumption the following day.

BACKGROUND: Insufficient sleep has been associated with weight gain and metabolic dysregulation, with one suggested mechanism being through reduction in diet quality. Experimental evidence supports a causal effect of sleep timings on diet but this may not be applicable to a free-living adolescent population. In this analysis we use daily measures of sleep timings and diet quality, to examine the effect of sleep duration and timing on diet quality the following day among free-living adolescents. METHODS: The ROOTS study is a prospective cohort recruited from secondary schools in Cambridgeshire and Suffolk (UK). Participants (n = 815) at mean age 15.0y (SD 0.3y) completed a diet diary and wore a combined heart rate and accelerometer device over 4 consecutive days. Sleep duration and timing (midpoint) were derived from acceleration and heart rate traces, while daily energy density and fruit and vegetable intake were calculated from dietary data. Analyses were performed at day-level (1815 person-days). Multilevel random effects models were used to test associations between sleep each night and subsequent day diet, with daily sleep and diet measures nested within individuals and schools, and adjusted for day-level and individual-level confounding variables. RESULTS: Adolescents slept a mean of 7.88 hrs (SD 1.10) per night, reporting a mean energy density of 2.12 kcal/g (SD 0.48) and median energy-adjusted daily fruit and vegetable intake of 137.3 g (IQR 130.4). One hour shorter sleep duration was associated with lower intake of fruit and vegetables (-6.42 g, 95%CI -1.84, -10.99) the following day. An association with higher dietary energy density (0.016 kcal/g, 95%CI 0.034, -0.002) the following day was observed but did not reach statistical significance. Sleep timing was not associated with either fruit and vegetable intake (-2.52 g/d, 95%CI -7.66, 2.62) or dietary energy density (-0.001 kcal/g, 95%CI -0.022, 0.020). CONCLUSIONS: Our observational findings from a free-living adolescent population support the experimental evidence for a causal role of sleep on diet, with shorter sleep duration at night leading to a small decrease in diet quality the following day. These findings support experimental evidence to suggest inclusion of sleep duration as one component of interventions designed to improve diet quality and weight status in adolescents.

Device-measured sleep onset and duration in the development of depressive symptoms in adolescence.

BACKGROUND: Sleep deprivation in adolescence is increasing in prevalence and may be linked to subsequent depression. Findings regarding associations between sleep duration, sleep onset time, and the development of depressive symptoms over time in adolescents are mixed, and rely on subjective measures of sleep. METHODS: Sleep onset and duration were assessed using a combined heart rate monitor and accelerometer and self-report in 688 participants from the ROOTS study at age 15. Participants reported depressive symptoms at ages 14.5, 16, and 17.5, using the Mood and Feelings Questionnaire. Latent growth curve modelling was used to model development of depressive symptoms and test associations with baseline sleep onset and duration. RESULTS: Cross-sectionally, falling asleep later and shorter sleep duration were both associated with higher depressive symptoms in males and females, using both device-measured and self-reported sleep. There were no longitudinal associations between baseline sleep duration and change in depressive symptoms. A later sleep onset-time was associated with a decrease in depressive symptoms over time, in females only, using device-measured sleep only. LIMITATIONS: The current sample was more economically advantaged and ethnically white than the UK average, and with lower MFQ symptoms than the original cohort, which may reduce generalisability. CONCLUSIONS: Adolescents who fall asleep later or sleep less have higher levels of depressive symptoms cross-sectionally, but do not show increases in depressive symptoms over time. Interventions targeting sleep onset and duration in adolescence may improve mental health in the short-term but the possibility of reverse causality should be explored further.

Using behavioural insights to reduce sugar in primary school children's packed lunches in derby; A cluster randomised controlled trial.

Children's packed lunches contain more sugar than school-provided meals. Interventions to improve the provision of healthier packed lunches have modest effects on lunch contents. This cluster randomised controlled trial tested an intervention to encourage healthier provision of packed lunches by parents of primary school children in Derby. Schools were randomised to intervention (n = 8) or control (n = 9) using blocked random allocation. In the intervention group, parents of children who brought packed lunches to school in years 3-6 (age 7-11 years) received three bundles of materials (including packed lunch planner, shopping list, information on sugar content of popular lunchbox items and suggestions for healthier swap alternatives) in bookbags/lunchboxes over a 4-week period. Control parents received no materials. Photos of lunchbox contents were taken at baseline, immediately post-intervention and at three-month follow-up. A parental survey aimed to assess capability, opportunity and motivation for packing a healthier lunchbox. No intervention effects were observed for primary outcomes (presence and number of sugary snacks or chilled sugary desserts). The intervention had a significant impact on one secondary outcome (increased number of healthier "swap" items suggested in intervention materials) immediately post-intervention, but this effect had disappeared at three-month follow-up. No intervention effects were found on survey variables. Parent comments revealed that materials were either received positively (as they reinforced existing behaviours) or negatively (as they were not perceived to be helpful or appropriate). The results of this study suggest that providing educational materials and resources to parents of primary school children in Derby was not sufficient to increase provision of healthier packed lunches. Future research should investigate how behavioural science can support families to improve the nutritional content of primary school children's lunchboxes.