Abstract
Loneliness among young people is a significant public health concern, yet research on its prevalence, longitudinal trends, and associated risk and resource factors in Germany remains limited. This paper draws on two German longitudinal panel surveys with refreshment sampling – the BELLA study (2003–2017) and the subsequent COPSY study (2020–2024), and includes ten nationwide measurement points. The sample comprised N = 3,043 participants (49.9% female; age range 11–17 years) from the BELLA study, and N = 1,909 participants (51.0% female; age range 11–17 years) from the COPSY study. Our findings indicate that loneliness rates remained relatively stable between 2003 and 2017 (9.5–15.5%) but spiked dramatically in 2020 (34.6%) during the COVID-19 pandemic. By 2024, 20.5% of young people still reported feeling lonely at least sometimes during the past week. Consistently, girls were more likely to report loneliness than boys. Mixed model panel regression analyses identified key risk factors for loneliness, like female gender, screen time, parental mental illness, as well as mental and physical health complaints in children and adolescents. In contrast, personal, familial, and social resources were associated with lower levels of loneliness. While some degree of loneliness is a common experience in youth, persistent loneliness poses a risk to mental and physical health. Our findings underscore the need for targeted interventions, particularly in school, leisure, and family settings, where social and emotional skills can be fostered. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00787-025-02779-6.