Background: Night-shift lifestyles affect children as well as adults, and are associated with sleep and behavioral problems among children. This study aimed to investigate associations among sleep patterns, individual/environmental factors, and problematic behaviors in children at age 5 years. Methods: Data for sleep patterns, individual / environmental factors, and problematic behaviors for 8,689 5-yearold children were collected from health-checkup records. Problematic behaviors investigated were anxious behavior (being afraid, difficulty being separated from the mother), developmental behavior (violence, restlessness, rebellious behavior, restrictive diet, stereotypic play), personal habits (thumb-sucking, nail-biting, tic, masturbation), and excretory problems. The relationships between sleep patterns (bedtime, sleep duration) and the presence of these behaviors were analyzed. Individual / environmental factors that affected problematic behaviors were statistically identified using a tree-form model. Results: Late bedtime and short sleep duration showed significant adverse effects on children's problematic behaviorsodds ratio (OR): 1.07, 95% confidence interval (CI): 1.03-1.11 and OR: 0.92, 95% CI: 0.87-0.97, respectively. Long television watching time, abnormality at birth, and lack of father's support also showed significant adverse effects on problematic behaviors (OR: 2.34, 95% CI: 1.87-2.94), and significantly affected late bedtime and short sleep duration. Conclusions: There were significant associations among sleep patterns, individual / environmental factors, and problematic behaviors in 5-year-old children. Improving children's sleep patterns, reducing the duration of television watching, and improving support from fathers may reduce problematic behaviors.