Objective: The main purpose of the present study was to evaluate sleep duration for nighttime sleep from early infancy to late adolescence in a German sample to illustrate the developmental course and age-specific variability of these variables among subjects. Methods: A total of 17,641 subjects from the KiGGS study were evaluated. The questionnaires contained questions about physical health, living circumstances, health behavior and risks, health supply, mental health, health-related quality of life and sleep. KiGGS assessed sleep by using parent questionnaire of children aged 0 to 10 years (n = 9944) and self-reports of adolescents (n = 7697) aged 11 to 17 years. Results: Total sleep duration decreased from 14.28 hours (SD = 2.33) at the ages 0 -0.5 to 9.50 hours (SD = 0.82) at the ages of 10.5 -11. Above the age of 11 adolescents report a decrease of sleep at night from 9.41 hours (SD = 1.33) at the age of 11 -11.5 to 7.42 (SD = 1.73) at the age of 17.5 -18 years. Unspecified sleep problems were reported of 19.5%, 13.0% of the children had difficulties falling asleep, difficulties sleeping through the night showed 8.8% of the children, whereas 3.0% report both symptoms-difficulties falling asleep and difficulties sleeping through the night. Conclusions: Age-specific variability of sleep duration is reported as well as sleep difficulties from infancy to adolescence. This is important knowledge for the health care professional who deals with sleep problems in pediatric practice.* The items concerning sleep problems used in KiGGS do not provide diagnostics of sleep disorders-for this reason, the terms "sleep difficulties" or "sleep problems" will be used synonymously. A. A. Schlarb et al.1398