Urban exposome and sleep and overweight/obesity outcomes in European adolescents

Obesity is a chronic, multifactorial condition, a consequence of the interaction of genetic predisposition, lifestyle behaviors, psychological and social determinants, and environmental exposures (González-Muniesa et al., 2017; Daniels et al., 2021). Alarming rates of obesity in young ages have been reported in recent decades (Phelps et al., 2024), with over 340 million children and adolescents between ages 5-19 years with overweight in 2022 (World Health Organization (WHO), 2022). Childhood and adolescent obesity have been associated with various adverse health outcomes, such as type 2 diabetes mellitus, hypertension, dyslipidemia, and mental health problems (Kumar and Kelly, 2017). Moreover, it tracks into adulthood (Simmonds et al., 2016), reduces quality of life (Kumar and Kelly, 2017), and represents an important public health concern today. This complex, multifactorial condition is, however, largely preventable, as many of the well-known risk factors for obesity are modifiable, such as diet, physical activity and urban environment exposures (World Health Organization, 2025). The proportion of the population living in big cities has increased substantially in the past decades and is expected to rise even further. In the 1950s, 20% of the worldwide population lived in cities, and 40% in villages. In 2020 the proportion had shifted to 44% living in cities and 20% in villages (Our World in Data, 2025). This demographic change has been shown to have major impacts on public health and wellbeing, through factors such as increased air pollution and traffic incidents, reduced physical activity, high exposure to noise, and reduced availability of green spaces (Duminy et al., 2023). A number of studies has shown that these urban environmental exposures may also lead to excess weight gain among young individuals (Malacarne et al., 2022; Warkentin et al., 2023; De Bont et al., 2021; Ye et al., 2022). Sleep health and overweight/obesity are related aspects of adolescent health that may both be influenced by urban environmental characteristics. Sleep plays a vital role in shaping health throughout childhood and adolescence, by synchronizing circadian rhythms and maintaining energy balance. Longer sleep duration has been associated with lower body mass index (BMI) z-score, waist circumference and waist-to-height ratio in 4-to-13-year-olds (Glasgow et al., 2022), lower systolic blood pressure in 6-to-17-year-olds (Morgan et al., 2024), and better academic performance among children and adolescents in a meta-analysis (Dewald et al., 2010). Children and adolescents between ages 9-12 years are recommended to sleep at least 9 h per day (Paruthi et al., 2016), which is often not met due to early school starts and late bedtimes (Morgan et al., 2024; Rognvaldsdottir et al., 2017). Several characteristics of the urban physical environment may affect sleep health and overweight/obesity through partly overlapping pathways. For example, exposure to artificial light at night from outdoor sources may disrupt circadian rhythms, while air pollution may contribute to respiratory complications such as sleep apnea (Johnson et al., 2025). Ambient air pollution is suspected to contribute to overweight and obesity (Warkentin et al., 2023; McConnell et al., 2016), moderate to severe sleep apnea (Billings et al., 2019), and sleep disturbances (Wang et al., 2022) in childhood. Traffic noise is another urban exposure that has been associated with short sleep duration in children and may also be relevant to weight-related outcomes (Weyde et al., 2017, 2018; Wu et al., 2017). On the other hand, access to green spaces, the presence (or accessibility) of parks and recreational facilities may have beneficial effects on child weight (Daniels et al., 2021), childhood and adolescence obesity (Malacarne et al., 2022), and sleep duration and quality (Wu et al., 2017). Recent systematic reviews and meta-analyses indicate that higher exposure to artificial light at night is associated with an increased risk of obesity. However, evidence in pediatric populations remains limited, and many studies have not adequately controlled for other urban environment factors (Lin et al., 2022). Better understanding of the relation between exposures related to the urban environment, with sleep and overweight/obesity outcomes is crucial for the prevention and treatment of sleep disorders and adolescent overweight and obesity. However, the influence of multiple urban exposures on adolescents’ sleep and obesity odds remains unclear. Adolescence is a distinct developmental period characterized by changes in sleep timing and duration, pubertal development, greater independent mobility, and increasing autonomy in lifestyle behaviors, which may influence susceptibility to urban environmental exposures. Moreover, most studies on urban exposures and sleep rely on only on self-reported sleep outcomes (De Bont et al., 2021; Fernández-Barrés et al., 2022; Astell-Burt and Feng, 2020), rather than including objectively measured sleep. Therefore, extending an urban exposome framework to adolescence, while incorporating additional exposure domains and complementary sleep measures, may help clarify whether associations previously reported in younger children persist during this developmental period. In light of this, the aim of this study was to explore the association between urban exposome characteristics, namely built environment, noise, green spaces, artificial light at night and air pollution, with obesity and sleep outcomes (self-reported and physiological sleep characteristics) in adolescence. We hypothesized that adolescents exposed to less favorable urban environments, characterized by higher levels of air pollution, traffic noise and artificial light at night and lower availability of green/blue spaces, would have poorer sleep characteristics and higher odds of overweight/obesity. We examined sleep and overweight/obesity as parallel outcomes potentially linked to the adolescent urban exposome. We did not evaluate whether sleep mediates the relationship between urban environmental exposures and overweight/obesity, because our data lacked the necessary temporal resolution.