Introduction: Some studies have shown that sleep problems in early life is associated with child temperament so that children with difficult temperament have lower sleeping time during the night and have more sleep problems compared to easy children. Objectives: The purpose of this study was to examine the results of those studies that investigated the factors influencing the development of sleep problems in infants and young children. It was also aimed to investigate the reciprocal relation between sleep problems and temperament in children. Method: A library study and review of the literature was conducted. Results: Results showed that many factors can cause sleep problems in infants and young children including sleep environment, culture, age, gender, nutrition, physical, psychological and genetic problems, sleep-wake schedule of the child, parental psychopathology, quality and quantity of their sleep, family distress and so on. Results also demonstrated that children’s temperament has a mutual relationship with sleep problems of infants and young children. Furthermore, the child\'s temperament may affect the quality and quantity of his sleep, ability to regulate attention, processing, and interactions. Conclusion: There are different reasons for sleep problems of infants and young children. Therefore, services for this age group should be provided by a team of experts. Diagnosis and treatment of sleep problems in children may prevent some negative behavioral consequences.

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