New research exploring the links between sleep, diet, and weight development in Finnish children has revealed that circadian health may play a significant role in long-term health outcomes.
A child's chronotype - their natural preference for being active in the morning or evening - as well as irregular sleep patterns may influence dietary habits and weight gain over time.
The study carried out at the University of Helsinki in cooperation with Folkhälsan Research Center was based on data from the DAGIS research project, which included 864 preschoolers in 2015-2016 and 210 preadolescents in a 2023 follow-up study. Using mainly objective sleep tracking with activity monitors, the dissertation of doctoral candidate Anna Abdollahi, from the Department of Food and Nutrition, Faculty of Agriculture and Forestry, provides new insights into how sleep habits relate to children's health.
Evening chronotype may add dietary risks
Compared with having an intermediate chronotype tendency, having an evening chronotype tendency was associated with less healthy diet components, such as lower vegetable and higher sugary food consumption. They also experienced greater social jetlag - differences in sleep patterns between weekdays and weekends - and had more sleep variability, though their sleep duration was no shorter than that of children with intermediate chronotype tendencies.
While having an evening chronotype tendency was not associated with weight outcomes in early childhood, it was linked to greater weight gain in the eight-year follow-up study. Similarly, preschool-age children with higher social jetlag were also more likely to experience weight gain by preadolescence.
Risk for long-term health issues
Nighttime sleep duration was not significantly associated with dietary habits or weight outcomes in this sample of children.
Abdollahi's findings suggest that even without shorter sleep duration, children with a later chronotype may be more vulnerable to unhealthy dietary patterns and weight gain over time. Furthermore, they indicate that the potential negative effects of circadian misalignment may begin as early as preschool years - the very start of children's school careers - and continue throughout childhood.
"The results suggest that chronic disruptions in circadian health, such as having a chronotype misaligned with sleep-wake behaviors or high social jetlag, may put children at risk of long-term health issues. This emphasises the importance of maintaining consistent sleep routines and considering individual chronotypes from an early age," explains Abdollahi.
Stable routines could be beneficial
Abdollahi suggests that interventions targeting children with a later chronotype during the preschool years could be beneficial. Strategies to support more stable sleep patterns and reduce circadian misalignment may help prevent unhealthy eating habits and excessive weight gain later in childhood. However, further research is needed to determine the need and long-term effectiveness of such interventions.
"Sleep is a fundamental pillar of health, especially for growing children. While much attention has been given to sleep duration, this dissertation highlights that when children sleep may be just as important as how long they sleep," says Abdollahi.
Doctoral defence
Anna Abdollahi will defend the doctoral dissertation entitled "Sleep habits of Finnish preschoolers: Associations with diet and weight" in the Faculty of Agriculture and Forestry, University of Helsinki, on 8 February 2025 at 12:00. The public examination will take place at the following address: Suomen Laki Sali, Porthania, Yliopistonkatu 3. Assistant Professor Erica Jansen, University of Michigan, will serve as the opponent, and professor Maijaliisa Erkkola as the custos.The dissertation is also available in electronic form in Helda .
