(P07-001-23) A Tendency Towards Evening Chronotype Associates With Unhealthier Sleep Habits and Diet Among Preschoolers

Objectives: Evidence suggests that adolescents and adults with later chronotypes have poorer sleep habits and are more susceptible to unhealthy behaviors that could increase the risk for metabolic diseases. However, little is known about these associations among younger children. The objective of the study was to 1) identify and compare sleep habits in different chronotype tendencies in preschool-aged children from midpoint of sleep (an objective measure of chronotype) and 2) investigate the associations of chronotype with diet.

Methods: Participants were 3–6-year-old preschoolers from the cross-sectional DAGIS-study (Fall 2015- Summer 2016) in Finland. Sleep variables, including midpoint of sleep on weekends adjusted for sleep debt on weekdays (MSWEadj), were measured from a 7-day accelerometer. MSWEadj lowest and highest 10^th percentile defined morning and evening chronotype tendencies. Energy (MJ), macronutrient (%energy), and food intake (g/MJ) were assessed from 3-day food records. Chronotype and diet associations were assessed with regression models adjusting for age, sex, sleep duration, day length, screen time, physical activity, single-adult household (yes/no), and parental education (low/middle/high).

Results: Participants included 702 children (mean±sd age: 4.74±0.89 years, 48.0% girls). MSWEadj was 1:13am±15min for morning (n=71), 2:25am±28min for intermediate (n=560) and 3:39±14min for evening (n=71) chronotype tendency. Children with evening chronotype tendency had less sleep, higher sleep duration and onset variability, and greater social jetlag and were associated with consuming more added sugar (B-estimate: 1.67, (95%CI: 0.54, 2.80), p< 0.01), and sugary foods (4.68, (2.49, 6.87), p< 0.001) and less vegetables (log-transformed variable: -0.31, (-0.62, -0.001), p< 0.01) compared to intermediate chronotypes. A later MSWEadj was additionally associated with lower fiber (-0.08, (-0.15, -0.01), p< 0.05) and energy (-0.16, (-0.28, -0.05), p< 0.01) intake.

Conclusions: The start of circadian misalignment in preschoolers is worrisome. Public health efforts into sleep and diet intervention should focus on children with later chronotypes, who are at higher risks for poor quality sleep and diet.

Funding Sources: Juho Vainio Foundation, Yrjö Jahnsson Foundation, and the Doctoral Program in Food Chain and Health, University of Helsinki