Background: Sleep-related problems are a common occurrence during childhood and adolescence. Over the past decade, there has been mounting evidence for a relationship between sleep disturbance and anxiety during this developmental period. The literature suggests that these associations are likely complex and bidirectional. That is, sleep disturbance may serve as a precursor to poor psychological outcomes (e.g., anxiety), or conversely, anxiety may predict the development of sleep-related problems (SRPs). However, the direction of effect between sleep and anxiety remains unclear. Aim: The purpose of this review is to explore the evidence for a bidirectional relationship between sleep and anxiety in children and adolescents. Methods: A literature search was conducted to identify articles relating to the relationship between paediatric sleep and anxiety. Results: A plethora of cross-sectional research has demonstrated that SRPs and anxiety frequently overlap in the child and adolescent population. Preliminary support for the role of sleep disturbance as a precursor to the development of anxiety has been evidenced by a small number of longitudinal, experimental, and treatment studies. However, there is a paucity of such research examining the opposite direction of effect. Conclusions: The research has provided preliminary support for the role of sleep problems serving as a "red flag" for the later development of anxiety in childhood and adolescent populations. However, empirical evidence supporting a relationship in the opposite direction has not been as conclusive. Additional studies of longitudinal, experimental, and treatment design are warranted to further delineate the direction of effect between childhood sleep and anxiety. (Contains 3 tables.)