The objective of this study was to compare the time to discharge between daytime and nighttime ketamine administration to children undergoing primary facial repair in the emergency department (ED). This retrospective, cross-sectional study was performed in a sample of children aged younger than 18 years and requiring sedation for primary facial repair in 2019. Children who received ketamine for reasons other than facial repair were excluded. All patients were initially injected with 4 mg/kg of ketamine intramuscularly and additionally injected if sedation failed. The time of injection and awakening were recorded in the electronic medical record system by nurses in charge, and the level of wakefulness was determined with a postanesthesia discharge scoring system administered by physicians. A total of 562 cases of ketamine administration were divided into 2 groups: daytime and nighttime. We defined daytime and nighttime as 8 a.m. and 8 p.m./sunrise and sunset, respectively. They found that there were no significant differences between 2 groups in each standard (95% confidence interval, -4.55-4.55; P = 0.877 and 95% confidence interval, -6.41-2.41; P = 0.487, respectively). The findings of the study suggest that the time of ketamine injection has no relationship to duration of sedation for primary facial repair in children.