Insomnia complaints and substance use in German adolescents: did we underestimate the role of coffee consumption? Results of the KiGGS study.

The purpose of the study was to study the associations of tobacco, alcohol, marijuana, and coffee use and insomnia complaints (IC) in adolescents with special consideration of the influence of coffee consumption on these relationships. 7698 Subjects aged 11-17 years were investigated in a cross-sectional study within the German Health Interview and Examination Survey for Children and Adolescents. Self-report questionnaires were distributed to the participants. Hierarchical regression analyses were performed to assess possible effects of coffee consumption on the association of tobacco, alcohol, and marijuana use with IC. Common risk factors for insomnia were included in the adjusted analyses. Tobacco, alcohol, marijuana and coffee use displayed significant bivariate associations with IC. After adjusting the first three substances for coffee consumption, their associations with IC were reduced considerably. After additionally adjusting for other potential confounders (age, gender, socio-economic status, externalizing and internalizing psychiatric problems, media use, bodyweight, medical condition), frequent coffee consumption, high alcohol intake and frequent smoking contributed to the prediction of IC in male subjects while frequent coffee consumption and high alcohol intake predicted the occurrence of IC in females. Coffee consumption could be an important risk factor for IC in adolescents and it significantly affects the association of smoking, alcohol, and marijuana with IC. Future research that includes long-term studies about psychoactive substance use (PSU) and sleep should also consider coffee consumption. Parents, educators, clinicians, and researchers should be aware of the potentially hazardous influence of PSU, especially coffee, alcohol and tobacco, on sleep in young individuals.