Active Preschoolers Sleep Better, German Accelerometer Study Finds

Young children who run, jump, and play at higher intensities during the day tend to sleep longer and more efficiently at night, according to new research tracking hundreds of German preschoolers with wrist-worn accelerometers. The study, published in the Journal of Activity, Sedentary and Sleep Behaviors, is among the first to examine how objectively measured physical activity relates to sedentary time, nighttime sleep, and mental health in children as young as two years old, offering fresh insight into a critical and often overlooked developmental window.

Early childhood is a period of extraordinarily rapid development, and the habits formed during these years can echo across a lifetime. The World Health Organization has long emphasized that children under five need to sit less, play more, and sleep well to grow up healthy. Yet despite guidelines, public health initiatives, and childcare structures designed to promote movement, many German children under the age of six fail to reach recommended levels of physical activity, sedentary behavior, and sleep. Survey data from nearly 13,000 German children and adolescents revealed that only about a quarter achieved a minimum of 60 minutes of moderate-to-vigorous physical activity daily, a shortfall that researchers warn may undermine healthy lifestyle formation and long-term wellbeing.

The research team, led by Katarina Osojnicki of the University of Guelph and Christoph Buck of the Leibniz Institute for Prevention Research and Epidemiology in Bremen, set out to close a persistent gap in the literature. Most previous studies of the relationship between movement and mental health have focused on school-aged children and adolescents, and few investigations in the early years have relied on device-based measurement rather than parent reports, which are vulnerable to recall bias and social desirability effects. In a systematic review of studies on physical activity and sleep in young children, the authors note, only three had used objective measures of both behaviors in children between two and seven years of age.

The data came from a subsample of children enrolled in a Germany-wide daycare health promotion trial called JolinchenKids – Fit and Healthy in Daycare, originally launched by the health insurance company AOK. Baseline measurements were collected between September and December 2016, with one-year follow-up the following autumn. Children wore GENEActiv triaxial accelerometers taped to the left wrist for seven consecutive days and nights at 100 Hz sampling, while parents kept logbooks to record non-wear time. In total, 212 children aged two to six years provided valid accelerometer data at both time points; just over half were female, and roughly five percent were classified as overweight or obese.

Raw accelerometer signals were processed with the open-source GGIR software package in R, using the Euclidean Norm Minus One with Adjustment method and age-specific cut-points calibrated for preschoolers. Light physical activity was defined by accelerations of at least 61.8 milligravity, moderate-to-vigorous activity by 100.4 milligravity or more, and inactivity below that threshold served as a proxy for sedentary behavior. Sleep was detected with the van Hees algorithm, which identifies sustained periods when the arm remains within five degrees of horizontal for at least five minutes, allowing the researchers to derive total sleep time and sleep efficiency, the proportion of time in bed actually spent asleep.

The results paint a vivid picture of an active, well-rested cohort. At baseline, children spent an average of 418.7 minutes per day inactive, 112.7 minutes in light activity, and a striking 252.6 minutes in moderate-to-vigorous activity, comfortably exceeding the WHO recommendation of 60 daily minutes. They slept roughly eight hours per night with a sleep efficiency of about 80 percent. Mental health was assessed through the parent-completed Strengths and Difficulties Questionnaire, a validated screening tool for social, emotional, and behavioral difficulties, and average scores fell well within the normal range at both measurement points, declining slightly over the year.

Statistical modeling with linear mixed models, adjusted for the child’s age and sex, household income, parental education, migration background, and urbanity, revealed clear and consistent patterns. Moderate-to-vigorous and total physical activity were positively associated with both total sleep time and sleep efficiency, and all activity variables were positively associated with sedentary time, findings that held in both crude and adjusted analyses. In plain terms, the most vigorously active children also tended to sleep longer and better. Girls scored lower on the difficulties questionnaire, while children of parents with lower educational attainment or income scored higher, an important socioeconomic signal within the data.

Notably, however, the study found no association between physical activity and mental health scores in this age group. The authors point to a recent meta-analysis reporting similarly modest effects, suggesting that younger children generally enjoy high baseline levels of mental health, leaving little room for improvement detectable by broad screening instruments. It is also plausible that in early childhood, psychological wellbeing is shaped more powerfully by the home environment, relationships, and developmental processes than by activity duration and intensity alone. Subtle benefits to behavioral regulation or emotional competence may simply be invisible to a general-purpose questionnaire validated primarily for children aged four and older.

The findings sit within a complicated and sometimes contradictory literature. Some studies have reported no link between activity and sleep in preschoolers, others found that more active children took longer to fall asleep, and one analysis even observed an inverse relationship between high activity and total sleep duration. The researchers attribute these inconsistencies to differences in accelerometer placement, wear time, cut-point selection, and sleep algorithms, as well as the natural variability of young children’s routines, which are shaped by parental attitudes, weather, the built environment, screen time, bedtime rituals, and nutrition. They also acknowledge limitations of their own work: daytime naps could not be captured without sleep diaries, the sample skewed toward high-income households, and the analysis was underpowered and exploratory in nature.

Looking ahead, the team argues that tracking 24-hour movement behaviors with device-based measures over time is essential for understanding how activity, sedentary time, and sleep jointly influence development, and they call for future multi-component interventions that address all three behaviors simultaneously to test for synergistic benefits to mental health. Compositional data analysis, which treats the 24-hour day as a fixed budget of interdependent behaviors, may offer a more realistic statistical framework than examining each behavior in isolation. For now, the message for parents and educators is straightforward: keeping preschoolers vigorously active during the day appears to pay dividends at bedtime, in deeper and longer sleep during a stage of life when every hour of rest counts toward growing bodies and minds.

Subject of Research: Associations between device-measured physical activity, sedentary behavior, sleep, and mental health in German preschool children

Article Title: Exploring the associations between physical activity, sleep, sedentary behaviour, and mental health in young German children

Article References: Osojnicki, K., Brandes, B., Brandes, M., Zeeb, H., Vallis, L. A., & Buck, C. (2026). Exploring the associations between physical activity, sleep, sedentary behaviour, and mental health in young German children. Journal of Activity, Sedentary and Sleep Behaviors, 5(1), Article 12. https://doi.org/10.1186/s44167-026-00104-3

Image Credits: AI Generated

DOI: 10.1186/s44167-026-00104-3

Keywords: physical activity, sleep, sedentary behavior, mental health, preschool children, accelerometry, GGIR, Strengths and Difficulties Questionnaire, 24-hour movement behaviors, early childhood, Germany, public health