STUDY OBJECTIVES The aim of this study was to assess the role of clinical context in determining the correspondence between actigraphic and reported sleep measures in preschool children. METHODS Sleep was assessed using actigraphy and parental reports in a clinical sample of 109 preschool children between the ages 4 and 6 years suffering from significant nighttime fears and in a sample of 30 healthy controls. RESULTS In comparison to actigraphy, parents in both groups indicated that their children fell asleep earlier and overestimated their sleep period. These gaps were significantly larger in the control group than the clinical group. Parents from both groups similarly underestimated the time their child was awake during the night in comparison to actigraphy. Significant correlations were found in both groups between parental reports and actigraphy sleep schedule measures. Low correlations were found for wake after sleep onset in both groups and for the number of night wakings. CONCLUSIONS Clinicians and researchers should be highly aware that parental reports on their children's sleep may not be accurate, and that accuracy may be affected by the context of the study. The use of complimentary sleep assessment tools in clinical and research settings should be encouraged.