BACKGROUND Postoperative emergence agitation remains a significant challenge in paediatric anaesthesia. Although short-lived, it may cause harm to the patient and negative experiences for all. Differentiating agitation, delirium and pain is difficult. Electroencephalography allows precise titration of anaesthetic depth, and heart rate variability monitoring permits immediate intervention regarding nociception and pain. We examined if one of these measures could be used to reduce postoperative agitation in an unselected paediatric day surgical population. OBJECTIVE The primary outcome was postoperative agitation with a Richmond Agitation-Sedation Scale greater than 0. Secondary outcomes were: length of stay, postoperative nausea and vomiting, fentanyl and propofol consumption, pain scores and use of postoperative analgesics. DESIGN A randomised, single-blinded study constituting children aged 1 to 6 years, undergoing minor general day surgical procedures. SETTING Paediatric day surgical department 29th March 2019 to 12th June 2020. PATIENTS Ninety-eight children (ASA 1 or 2) were enrolled, and 93 children were included in the final analysis. INTERVENTIONS Children received standard monitoring (n=31), standard monitoring plus either Narcotrend (n=31), or Anaesthesia Nociception Index monitoring (n=31). Sevoflurane or fentanyl was titrated immediately according to monitor thresholds. RESULTS Kaplan–Meier analysis yielded a statistically significant difference between the groups (P = 0.016) with the lowest agitation levels in the Anaesthesia Nociception Index group, intermediate levels in the control group and the highest agitation levels in the Narcotrend monitored group. Intergroup pairwise comparison however, showed no difference. The Anaesthesia Nocioception Index group received slightly more fentanyl (P = 0.277). The control group patients had the highest pain scores despite receiving more caudal blocks and the Narcotrend group had more sevoflurane adjustments. Other secondary outcomes were comparable. CONCLUSION Children in the Anaesthesia Nociception Index group were the least agitated with the highest fentanyl doses, without increasing the length of stay in the PACU or postoperative nausea and vomiting. CLINICAL REGISTRATION The study was registered in REDCap online trial database 1/11/2018 trial registration nr. OP720. https://open.rsyd.dk/OpenProjects/openProject.jsp?openNo=720&lang=da.